Symposium Organizers
Jonathan Rivnay, Northwestern University
Magnus Berggren, Linkoping University
Rylie Green, Imperial College London
Ni Zhao, The Chinese University of Hong Kong
Symposium Support
MilliporeSigma
Suzhou Fangsheng Optoelectronics Co., Ltd
Vigor Tech USA LLC
SM1.1./SM3.1./SM4.1: Joint Session I
Session Chairs
Mohammad Reza Abidian
Martin Kaltenbrunner
Jonathan Rivnay
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 121 AB
11:30 AM - *SM1.1.01/SM3.1.01/SM4.1.01
Nano-Bioelectronics: From Biological Sensor Chips to Cyborg Tissues and Seamless Brain-Electronics Implants
Charles Lieber 1 , Jae-hyun Lee 1
1 , Harvard University, Cambridge, Massachusetts, United States
Show AbstractNanoscale materials enable unique opportunities at the interface between the physical and life sciences, for example, by integrating nanoelectronic devices with cells and/or tissue to make possible communication at the length scales relevant to biological function. In this presentation, I will present an overview of bioelectronics, including general questions, primary research results, and future opportunities. First, general questions and issues for developing electronic devices for biological sensors through implants will be introduced. Second, transistor-based nanoelectronic chip-based platforms will be introduced and selected studies detection of biological analytes as well as neuron and cardiac cell action potentials will be briefly reviewed. Third, the design and implementation of new nanoelectronic probes capable of intracellular recording and stimulation at scales heretofore not possible with existing techniques will be discussed, including applications in neuroscience and the prospects of biologically-targeting of nanoscale devices. Fourth, a new concept will be introduced for seamless three-dimensional integration of addressable networks of multi-functional devices in engineered tissue, and exemplified with studies of cyborg cardiac tissue. Last, an ‘out-of-the-box’ approach for seamlessly merging nanoelectronic arrays with brain using syringe-injectable polymer-like mesh electronics will be discussed, including quantitative studies demonstrating unprecedented absence of tissue immune response and stable recording at the single neuron/neural circuit level for more than a year. Finally, the prospects for broad-ranging applications in the life sciences as the distinction between electronic and living systems is blurred in the future will be discussed, as well as future challenges.
12:00 PM - *SM1.1.02/SM3.1.02/SM4.1.02
Soft Wearable Robots Improve Walking Function and Economy after Stroke and Grasping Function after Spinal Cord Injury
Conor Walsh 1
1 , Harvard School of Engineering, Cambridge, Massachusetts, United States
Show Abstract
Stroke-induced hemiparetic gait is characteristically slow and metabolically-expensive. Conventional rehabilitation efforts have had limited effectiveness in restoring normal walking behavior, often relying on gait compensations for the limited gains observed. We sought to determine if a unilateral, soft wearable robot (exosuit) designed to supplement the paretic limb’s residual ability to generate forward propulsion and ground clearance during walking could facilitate more normal walking behavior after stroke. Herein, we evaluate the effects of walking with an exosuit actively assisting the paretic limb of nine individuals in the chronic phase of stroke recovery compared to walking with an exosuit unpowered. Spinal cord injury patients often lose the ability to grasp objects and their poor hand function limits their ability to perform activities of daily living. We sought to determine if lightweight, fabric-based soft fluidic actuators would be capable of applying sufficient assistance when integrated into a glove to improve grasping functions. Herein, we evaluate the effects of grasping when wearing the glove of five individuals who have suffered a spinal cord injury and compared to their baseline ability.
SM1.2/SM3.2/SM4.2: Joint Session II: Bioelectronics
Session Chairs
Mohammad Reza Abidian
Martin Kaltenbrunner
Jonathan Rivnay
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 121 AB
2:30 PM - *SM1.2.01/SM3.2.01/SM4.2.01
Skin-Inspired Materials, Devices and Applications
Zhenan Bao 1
1 , Stanford University, Stanford, California, United States
Show AbstractIn this talk, I will discuss fabrication of skin-inspired devices and related applications in bioelectronics and robotics.
3:00 PM - *SM1.2.02/SM3.2.02/SM4.2.02
Biocompatible Gel Electrodes and Ultraflexible Organic Devices for Implantable Electronics
Takao Someya 1 , Tsuyoshi Sekitani 2 , Sungwon Lee 3 , Tomoyuki Yokota 1
1 Electrical and Electronic Engineering and Information Systems, University of Tokyo, Tokyo Japan, 2 The Institute of Scientific and Industrial Research, Osaka University, Osaka Japan, 3 , Daegu Gyeongbuk Institute of Science and Technology, Daegu Korea (the Republic of)
Show AbstractWe report recent progress of ultraflexible organic photonic and electronic devices for implantable electronics. In particular, we describe the fabrication of different organic devices such as organic thin-film transistors (OTFTs), organic photodetectors (OPDs), and organic light-emitting diodes (OLEDs) that are manufactured on ultrathin plastic film with the thickness of 1 μm. We also fabricate two types of gels that are patterned on the surface of ultrathin film devices for implantable applications. First, by designing and fabricating smart, stress-absorbing electronic devices with sticky gels that can adhere to wet and complex tissue surfaces, we realize reliable, long-term measurements of vital signals. We fabricated a multielectrode array, which can be attached to the surface of a rat heart, resulting in good conformal contact. Second, a biocompatible highly conductive gel composite comprising multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel. By using gel composites, we fabricated an ultrathin organic active matrix amplifier on a 1-μm-thick polyethylene-naphthalate film to amplify weak biosignals. This work is financially supported by JST/ERATO Bio-harmonized electronics project.
3:30 PM - *SM1.2.03/SM3.2.03/SM4.2.03
Interfacing with the Brain Using Organic Electronics
George Malliaras 1
1 , ENSM Saint-Etienne, Gardanne France
Show AbstractOne of the most important scientific and technological frontiers of our time lies in the interface between electronics and the human brain. It promises to help elucidate aspects of the brain’s working mechanism and deliver new tools for diagnosis and treatment of a host of pathologies including epilepsy and Parkinson’s disease. The field of organic electronics has made available materials with a unique combination of attractive properties, including mechanical flexibility, mixed ionic/electronic conduction, enhanced biocompatibility, and capability for drug delivery. I will present examples of organic-based devices for recording and stimulation of brain activity, highlighting the connection between materials properties and device performance. I will show that organic electronic materials provide unparalleled opportunities to design devices that improve our understanding of brain physiology and pathology, and can be used to deliver new therapies.
4:00 PM - SM1.2./SM3.2./SM4.2
BREAK
4:30 PM - *SM1.2.04/SM3.2.04/SM4.2.04
Materials and Devices Designs for Flexible, Active Electronic Interfaces to the Brain and the Heart
John Rogers 1
1 , Northwestern University, Evanston, Illinois, United States
Show AbstractAdvanced capabilities in electrical recording and stimulation are essential to the treatment of heart rhythm diseases and brain disorders and to progress in cardiac and brain science. The most sophisticated technologies for this purpose utilize geometrically conformal, active electronics that achieve high speed, high resolution electrophysiological mapping through direct measurement interfaces to adjacent, contacting tissues. Unfortunately, slow penetration of biofluids through the materials of the surface layers and/or through localized defects in them prevent chronic modes of use. Here we present advances in materials for ultrathin biofluid barriers and in actively multiplexed device designs for capacitive signal detection that, together, enable flexible electronic devices with stable, long-term operational capabilities as full implants. Systematic studies, including accelerated in vitro testing that suggests lifetimes of several decades, reveal the fundamental materials considerations and highlight the practical advantages of such platforms. High resolution mapping of cardiac function in Langendorff hearts and of brain activity in live animal models demonstrates the capabilities, with quantitative validation against control measurements. The results establish pathways for use of flexible electronics as long-term implants, with important implications for basic scientific study and future clinical use.
5:00 PM - *SM1.2.05/SM3.2.05/SM4.2.05
Conformal, Microfabricated Electrode Array for Optimization of Spectral Content in the Auditory Brainstem Implant (ABI)
Amelie Guex 1 , Ariel Hight 2 , Daniel Lee 2 , M. Brown 2 , Stephanie Lacour 1
1 , Ecole Polytechnique Federale de Lausanne, Switzerland, Lausanne Switzerland, 2 , Harvard Medical School, Boston, Massachusetts, United States
Show AbstractThe auditory brainstem implant (ABI) is a neuroprosthesis that provides sound sensations to patients who cannot benefit from a cochlear implant (CI) by stimulating the cochlear nucleus (CN) surface, the first auditory processing nucleus in the central nervous system. Compared to the CI however, ABI users lag behind in speech comprehension, which may be due to the poor spatial resolution of its stimulating channels leading to a low spectral resolution.
In this study, we test whether using a flexible microfabricated electrode array with high channel resolution and small contacts (100 µm diameter) coated with conducting polymer PEDOT:PSS can provide significant spectral information, and how the presentation of stimulus current can be optimized (e.g. monopolar or bipolar stimulation, distance and angle between the two electrodes of a pair). Using a rat model of the ABI, we place the electrode array along the length of the dorsal cochlear nucleus (DCN) surface to selectively stimulate different locations, and we record evoked activity along the tonotopic axis of the inferior colliculus (IC), an auditory structure located in the midbrain, to measure the resolution of evoked tonotopic cues.
Initially, we found high variability in the pattern of evoked activity but upon further analysis found two components that revealed tonotopic cues. Specifically, we found that there was a common pattern of evoked activity across all electrodes that masks tonotopic cues, and that early latency spikes following each stimulus pulse are more tonotopic than later spikes. While focusing our analysis on tonotopic cues, we found minimal measured differences between monopolar vs. bipolar stimulation, but found that small inter-electrode distances were better than large ones. These results suggest that modifications in the electrode design, particularly an increase in the density of stimulation electrode sites, could ultimately improve tonotopic cues for ABI users.
5:30 PM - *SM1.2.06/SM3.2.06/SM4.2.06
Interfacing Neurons with Electronic Devices
Andreas Offenhaeusser 1
1 , Forschungszentrum Juelich, Juelich Germany
Show AbstractA challenging issue in Neuroscience is tightly monitoring and controlling of the functionality of neural networks. Direct interfacing of devices based on inorganic and organic semiconductor and (non conventional) electrode material with nerve cells and brain tissue open novel perspective for multifunctional electrophysiological tools in vitro and in vivo with high spatiotemporal resolution and improved sensitivity.
We aim for the fabrication of chip-based sensors that enable an efficient neuro-electronic interface towards precise recording of cellular signals. Within this framework, we have developed a variety of microelectrode array (MEA) designs that enable non-invasive, parallel, multi-site recording of action potentials from primary neurons and cardiomyocyte-like HL-1 cell line. We have modified standard planar 64 electrode MEA design with different geometries ranging from nanometer-sized cavities that allow for cellular protrusion into the sensor to mushroom-shaped 3D electrodes. Furthermore, we investigate various field-effect transistor (FET) designs ranging from silicon nanowires to graphene. Recently we could demonstrate successful interfacing of electrogeneic cells with fully printed and flexible MEA and flexible graphene FETs.
SM1.3: Poster Session
Session Chairs
Paul Meredith
Jonathan Rivnay
Ni Zhao
Wednesday AM, April 19, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - SM1.3.01
Real Time Monitoring of Osteogenic Differentiation of Human Mesenchymal Stem Cells Using 2D and 3D Capacitance Cell Sensors
Jun Ho Song 1 , Sun-Mi Lee 2 , Nalae Han 1 , Kyung-Hwa Yoo 1 2
1 Physics, Yonsei University, Seoul Korea (the Republic of), 2 Nanomedical Graduate Program, Yonsei University, Seoul Korea (the Republic of)
Show AbstractHuman mesenchymal stem cells (hMSCs) are useful for cell-based therapies due to their pluripotent property that can differentiate into various cell types. For stem cell-based engineering, it is critical to monitor the process of in vitro hMSCs differentiation and to identify differentiated cell phenotypes. For real-time and label-free monitoring, we have developed both 2 and 3 dimensional (2D and 3D) capacitance cell sensors. 2D sensors consist of two gold electrodes and 3D sensors are composed of vertically aligned pairs of electrodes. First, we investigated whether proliferation and differentiation can be discriminated using 2D capacitance cell sensors. The hMSCs were placed between two electrodes and the real-time capacitance was measured while hMSCs were proliferated or differentiated. The capacitance increased continuously during proliferation, whereas it increased up to 3 days, followed by a slow increase or a decrease in capacitance during differentiation. Analysis of hMSCs stained with Alizarin Red S (ARS) revealed that the decreased capacitance might be related to an increase in Calcium deposition by differentiation. For 3D cell culture, hMSCs were encapsulated in alginate hydrogel and cultured in 3D cell culture system. As for 2D cell culture, the capacitance increased monotonically during proliferation. However, while hMSCs were differentiated, the capacitance did not increase until about 7 days and then increased. Possible origins of difference between 2D and 3D cell culture are discussed.
9:00 PM - SM1.3.02
Nanowire-Mesh Templated Three Dimensional Fuzzy Graphene as Electrochemical Sensors
Raghav Garg 1 , Sahil Rastogi 1 , Michael Lamparski 3 , Gordon Pace 1 , Noel Nuhfer 2 , Vincent Meunier 3 , Tzahi Cohen-Karni 1 2
1 Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 3 Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Show AbstractGraphene, a two-dimensional (2D) hexagonal arrangement of sp2 carbon, is gaining popularity as a material for electrochemical sensors. Graphene’s outstanding electrical properties have led researchers to develop three-dimensional (3D) atomic layer graphene materials with increased surface area for more efficient electrodes. Although 3D graphene materials such as foams and multilayered carbon nanowalls have already been synthesized, the synthesis of 3D vertical atomic layer graphene still remains a challenge.
Here we demonstrate a novel synthesis of high-density single-to-few layer vertical graphene on semiconductor nanowire mesh templates. The presence of graphene on the nanowires was confirmed by Raman spectroscopy. The progression of the templated growth of the 3D graphene flakes was verified by scanning electron microscopy. Moreover, the growth of single to few layer crystalline graphene flakes that are vertically oriented with respect to the nanowire axis was validated by transmission electron microscopy. The sheet resistance of this new hybrid nanomaterial decreased with an increase in graphene flake size and density. Lastly, high electrochemically active surface area of the material was ascertained by cyclic voltammetry. These results pave way for the use of 3D vertical atomic layer graphene on nanowire mesh templates as electrodes for electrochemical sensing of biomolecules, quantification of fast-electron transfer reactions, and energy harvesting in fuel cells.
9:00 PM - SM1.3.03
3D Printed Flexible and High Transconductance Organic Electrochemical Transistors
Jiaxin Fan 1 2 , Carlo Montemagno 3 2 4 , Manisha Gupta 1 2
1 Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada, 2 , Ingenuity Lab, Edmonton, Alberta, Canada, 3 Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada, 4 , National Institute for Nanotechnology, Edmonton, Alberta, Canada
Show AbstractThe field of organic bioelectronics has been growing rapidly in the past few decades, and organic electrochemical transistor (OECT) draws great interests in the biosensing application due to its biocompatibility, ease of fabrication, and low operation voltage. Even though different techniques have been utilized for printing OECTs in the past, 3D printing has not been utilized. 3D printing techniques can be utilized for fast production of uniquely designed and disposable OECTs at an economical price point under ambient conditions. In this study, we have successfully implemented functional PEDOT: PSS based OECTs with a single 3D printing system (nScrypt 3Dn direct print dispensing and 3D printing system). The flexible substrate and insulating layer was produced with soft polylactic acid (PLA) filament using fused deposition modeling technique. The source and drain electrodes were deposited with commercially available silver conductive paste using direct writing technique, and PEDOT: PSS ink was used as the channel material printed with the same technique. The fully printed OECT’s steady state characteristics have been studied. Devices with average channel thickness of 10 μm and active channel area of 0.045 ± 0.005 mm2 have shown a high transconductance (38.0 ± 6.1 mS) that with a maximum at zero gate voltage, indicating a low operating voltage, and a high current ON/OFF ratio (1.3 x 103). Furthermore, these transistors showed robust behavior after several measurement cycles. Preliminary tests have demonstrated that the printed OECTs were able to responds to different dopamine concentration levels. Due to the thickness of the channel, limited by current printer and ink, the device has a large turn off current. This can be tuned further to improve the operating speed. Details from these OECT devices based on 3D printing will be presented here.
9:00 PM - SM1.3.05
Three-Dimensional Graphite-Polymer Flexible Strain Sensors with Ultrasensitivity and Durability for Real-Time Human Vital Signal Monitoring and Posture Correction of Musical Instrument Learners
Weigu Li 1 , Jianhe Guo 1 , Donglei (Emma) Fan 1
1 , University of Texas at Austin, Austin, Texas, United States
Show AbstractThe design and fabrication of various types of portable and stretchable devices have been a major research focus owing to the remarkable potential in impacting peoples’ lives including real-time health monitoring, point-of-care diagnosis, and sport training. In this work, we present three-dimensional graphite as the key sensing component of a polymer composite strain sensors that offer ultrahigh sensitivity and durability in detection of fine motions. The graphite-polymer sensors provide one of the highest bending sensitivity, which is reproducible with only a few percent signal shifts after going through 11,000 bending cycles, as well as a high gauge factor of 100 and 52 at a strain of 80% and 100%, respectively. The sensing mechanism is modeled and correlated with experimental studies. Such graphite-polymer sensors have been demonstrated in detecting fine features of human pulses, respiration rates, speeches in real-time, and also employed in posture correction of musical instrument learners.
9:00 PM - SM1.3.06
Wearable Graphene Temperature Sensor Arrays for Diabetic Ulcer Prevention
Eric Boon 1 , Yiqian Jin 1 , Linh Le 1 , Woo Lee 1
1 , Stevens Institute of Technology, Hoboken, New Jersey, United States
Show AbstractMaintaining the foot health of diabetic patients is of great clinical and financial significance with even minor damage to the foot surface leading to serious complications including amputation and death. Clinical studies suggest that monitoring plantar skin temperatures can significantly reduce ulceration in high-risk patients with diabetic complications, but current devices are unable to directly monitor foot temperature continuously and comfortably. We have developed a highly sensitive (<0.01oC), fast response (<500ms), flexible temperature sensor based on inkjet-printed reduced graphene oxide suitable for wearable healthcare applications. These innovative sensors has been integrated into a wearable, wireless temperature sensing system. We have demonstrated, for the first time, the use of this rGO sensor array to directly monitor the temperature of the plantar surface on healthy human subjects during physical activity as a proof-of-concept for subsequent interventions in high-risk diabetes patients. Reduced graphene oxide has been of interest in a wide variety of electronic devices such as transparent conducting films, transistors, sensors, and supercapacitors, however little work has investigated the long-term changes in the properties of these devices during operation. As part of our experiments, we have investigated the long-term stability and changes rGO films undergo in various environments with specific focus on the effect of moderate temperature (39°C) and a high humidity environment (60%RH). These results bring to light changes in the electronic properties due to slow oxidation and absorption of humidity from ambient as well as methods to minimize or reverse these changes.
9:00 PM - SM1.3.07
Multifunctional Flexible Piezoelectric Tactile Sensor
Sung-Ho Shin 1 , Yang Hyeog Kwon 1 , Younghwan Kim 1 , Joo-Yun Jung 2 , Junghyo Nah 1
1 , Chungnam National University, Daejeon Korea (the Republic of), 2 Department of Nano Manufacturing Technology, Korea Institute of Machinery and Materials, Daejeon, Chungchungnam-Do, Korea (the Republic of)
Show AbstractRecently, biomimetic electronic sensors have been actively investigated to develop highly sensitive and multifunctional sensors that mimics the sensory system of different animals. Development of such devices has a significant impact on robotics and health care applications. Recently, various tactile sensor that can simultaneously perceive thermal and mechanical stimuli in dynamic condition have been developed. However, it is still challenging to integrate multiple functionalities in a single device due to complexities and difficulties in fabricating on flexible substrates. In this work, we report a simple approach to fabricate high performance multifunctional flexible piezoelectric tactile sensor. Using silver (Ag) nanowires (NWs), PEDOT:PSS, and lithium (Li)-doped ZnO NWs, we developed E-whisker, which can detect mechanical strain, temperature, and subtle vibration or surface roughness. Specifically, Si wafer was treated with anti-adhesive trichloro(1H,1H,2H,2H-perfluorooctyl) silane (FOTS), followed by Ag NWs and PEDOT:PSS spray-coating and transferring processes using polydimethylsiloxane (PDMS). Subsequently, Li-doped ZnO NWs-PDMS composite was sandwiched between PDMS covered Ag NWs electrode layers. The both of strain and temperature sensitivities of the developed sensor were comparable to the previous report and demonstrated superior mechanical durability. In addition, owing to the piezoelectric element, the sensor can more precisely detect the objects in dynamic condition. As proof-of-concept, the fabricated device has been used for monitor three dimensional spatial and temperature distribution. The approach introduced here is a simple, effective, and cost-competitive route to realize the high performance multifunctional artificial electronic sensor devices.
9:00 PM - SM1.3.08
Bioinspired Anisotropic Carbon Network for Highly Selective Pressure Sensing
Yan Huang 1 , Ningqi Luo 1 , Ni Zhao 1 , Ching Ping Wong 1 2
1 , The Chinese University of Hong Kong, Hong Kong Hong Kong, 2 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractFlexible pressure sensors hold a great potential in biomedical applications such as human health monitoring, E-skin and bio-robotics, since they can conform to curved surfaces such as human skin and provide highly sensitive responses to mechanical stimulations at the same time. However, strains caused by skin torsion or bending during motions can reduce the accuracy of pressure measurement. In this work, we address this problem by developing an anisotropic conductive network as the skeleton of the pressure sensor. The work exploits the interconnected multi-tube structure of wood and produces a carbon skeleton that can be embedded in flexible matrices such as polydimethylsiloxane. Through device design and material engineering, we achieved sensors with highly anisotropic pressure responses (in terms of sensitivity and hysteresis) in the vertical and horizontal directions respectively. A mechanistic model is proposed to correlate such anisotropic response with the structure of the composites. This work highlights the importance of controlling the morphology of percolation paths in piezoresistive pressure sensors, and provides a promising method to achieve highly selective pressure sensing.
9:00 PM - SM1.3.09
Integrated Electrochemical-Biological Systems for the Production of Fuels and Chemicals from CO2
Antaeres Antoniuk-Pablant 1 , Frauke Kracke 1 , Joerg Deutzmann 1 , Thomas F. Jaramillo 1 , Alfred Spormann 1
1 , Stanford University, Stanford, California, United States
Show AbstractAs our energy demand increases, we must move toward more sustainable options. One promising method is though converting electrical energy into chemical energy. More specifically, electrochemically converting CO2 to a useful form such as a fuel. One of the challenging processes in producing fuels or chemicals from CO2 has been efficiently and selectively producing C4-C6 and higher multifunctional organic compounds from CO2. In efforts to overcome these challenges, a system that combines the faster kinetics of electrochemical inorganic CO2 reduction catalysts with highly selective microbial metabolism is being designed and investigated.
This system is unique to most bioelectrochemical systems as it is designed from the concepts of a specialized reactor developed for detailed studies on electrochemical CO2 reduction on metal surface1, but modified for the addition of select microorganisms. This allows us to focus on combining the strengths of each individual process to develop a selective, efficient, and sustainable process for converting CO2 to a fuel. Initially we are investigating the combination of a Sn catalyst which electrochemically reduces CO2 to formate, and the microoganism Methanococcus maripaludis which metabolizes formate and produces methane. In our first prototype set up a Sn cathode with a surface area of 5.89 cm2 was poised at a potential of -1.3 V vs NHE, and had an average current density of -0.9 mA/cm2. The resulting formate produced was able to be metabolized by the microoganisms and methane was produced at a rate of 0.0289 mL/cm2 per minute. This result is promising as the rate of methane production was 100 fold greater than other similar bioelectrochemical systems.2 One of the main challenges of this research is to develop methods which enable the electrochemical CO2 reduction process to be robust, efficient, and stable on the time scale of months. Studies of a Sn electrocatalyst over long periods of time in the conditions in the reactor provide an insight of the mechanism of the deactivation of Sn in large time frames as well as the causes of deactivation in this kind of a combined system. These studies will allow for the development of methods to maintain the electrocatalysts activity and/or inhibit its deactivation. These studies will also be aimed toward developing larger scale electrochemical CO2 reduction systems, as in order to use these electrochemical systems commercially, many of the same issues on the electrochemical side must be overcome.
References
(1) Kuhl, K. P.; Cave, E. R.; Abram, D. N.; Jaramillo, T. F. New Insights into the Electrochemical Reduction of Carbon Dioxide on Metallic Copper Surfaces. Energy Environ. Sci. 2012, 5, 7050–7059.
(2) Van Eerten-Jansen, M. C. A. A.; Veldhoen, A. B.; Plugge, C. M.; Stams, A. J. M.; Buisman, C. J. N.; Ter Heijne, A. Microbial Community Analysis of a Methane-Producing Biocathode in a Bioelectrochemical System. Archaea 2013, 2013.
9:00 PM - SM1.3.10
Mussel-Inspired Fabrication of a Flexible Biocathode Based on Bacterial Cellulose for Implantable Glucose Fuel Cells
Yi Sun 1
1 , University of Science and Technology Beijing, Beijing China
Show AbstractImplantable glucose fuel cells are promising candidates to power active implantable medical devices. Due to the relatively low concentration of oxygen in body fluid, oxygen reduction reaction on the cathode is often regarded as a restricting factor. In this work, we present a flexible membrane cathode fabricated via the electroless metallization of bacterial cellulose (BC) by polydopamine (PDA) and silver nanoparticles. A BC/PDA composite membrane was synthesized by the self-assembly of PDA on the nanofibers of BC. Silver ions were in-situ reduced by the reducing groups present in PDA, such as the catechol groups. SEM showed that PDA formed a uniform coating on the nanofibers of BC, and that silver nanoparticles (Ag NPs) were uniformly and densely decorated on the PDA coated BC fibers. Cyclic voltammetry showed that the membrane electrode had good electrocatalytic activities towards oxygen reduction reaction (ORR) in neutral phosphate buffer solution. Furthermore, the BC/PDA/Ag electrode exhibited better stability than that without PDA. Polarization curves showed that BC/PDA/Ag had excellent cathode performance. The synthesized membrane bioelectrode shows potential in implantable or flexible fuel cells in the future.
9:00 PM - SM1.3.11
Thermally-Drawn Nano Electrode for Photosynthetic Energy Harvesting from Algal Cells
Dasom Yang 1 , Hyeonaug Hong 1 , WonHyoung Ryu 1
1 , Yonsei University, Seoul Korea (the Republic of)
Show AbstractPhotosynthesis is one of the most efficient natural processes that convert light energy into electrical energy. Solar energy from incident lights excites electrons to higher energy levels and the excited electrons are used in cellular respiration. Instead of mimicking or fabricating artificial energy conversion system, this delicate natural system can be utilized for energy harvesting by direct extraction of photosynthetic electrons from plant cells. In our previous work, it was demonstrated that high energy electrons could be directly harvested via nanoelectrode insertion into algal cells before their consumption for production of carbohydrates.
In this paper, we will report fabrication of polymer-based nanoscale electrodes for single cell insertion by thermal drawing. Although there exist numerous techniques for nanoelectrode fabrication, most of them suffered from limited choice of materials as well as expensive and time consuming process. Thermal drawing method is a highly favored rapid prototyping method, especially in fabrication of ultra-high aspect ratio structure. It features a simple setup, extremely short process time and excellent processability. The size and geometry of fabricated structure can be easily adjusted to optimize for minimally invasive cell insertion and analysis.
To fabricate a cell-insertable polymer nanoprobe, first we patterned SU-8 2150 on the glass substrate. After soft baking, a substrate was mounted on an inverted microscope stage for real time process monitoring. The polymer was partially melt by a heated tungsten pillar and a polymer nanoprobe was directly drawn from the pattern. Geometry factors of polymer nanoprobe such as tip diameter, total length and aspect ratio were optimized for cell insertion by contact and drawing parameter studies.
The fabricated polymer nanoprobes were cured with UV laser to finalize their geometry. Single algal cell (Chlamydomonas reinhardtii) was held by a glass pipette and inserted into prepared polymer nanoprobe. Inserted cell remained its original shape without leakage nor damage to the membrane. It confirmed that the fabricated polymer nanoprobes were cell insertable.
For precise analysis of electrical signal at an intercellular level, only cell inserted part of electrode has to be exposed and the remainder should be insulated. To achieve this, polyethylene glycol (PEG) was used as a sacrificial layer for insulator masking. After Pt layer deposition, a tip part of the nanoprobe was capped with the melted PEG. The Pt layer was then exposed by PEG removal, and polymer based nanoelectrode was fabricated without increasing the tip diameter. Electrochemical functions of the nanoelectrode were evaluated by cyclic voltammetry (CV). After PEG removal, increase of current level at CV results confirmed that the Pt layer was successfully exposed and electrode worked properly.
9:00 PM - SM1.3.12
Ultrahigh and Selective Cr(VI) Detection Based on a Doubly-Clamped Si Microbeam
Ansoon Kim 1 2 , In-Bok Baek 3 , Sook Heun Kim 1 , Ha Na Cho 1 , Han Young Yu 3
1 , Korea Research Institute of Standards & Science, Daejeon Korea (the Republic of), 2 Department of Nano Science, University of Science & Technology, Daejeon Korea (the Republic of), 3 , Electronics and Telecommunications of Research Institute, Daejeon Korea (the Republic of)
Show AbstractChromium exists in different oxidation states in the groundwater, seawater, and soil of our environment. Although Cr(III) is an essential trace element in the human body, Cr(VI) has been found to be toxic to animals and humans because it causes different disorders, and is classified as a carcinogen. Currently California limits the total amount of chromium in drinking water to 50 ppb, whereas federal regulations limit total chromium to 100 ppb. Those regulations don’t differentiate between chromium oxidation states. Most of the current analysis methods for Cr(VI) detection are generally time-consuming, have less than desired accuracy, or are expensive. Therefore, developing new sensitive techniques for the in situ detection of Cr(VI) in the environment with high sensitivity and selectivity is urgently required in environmental remediation and monitoring.
The silicon based resonators fabricated by well-known micro and nano electromechanical systems (MEMS/NEMS) technology have been rapidly developed for a wide range of gravimetric sensing applications due to their high sensitivity and resolution for mass loading. In order to achieve a highly sensitive mass detection, a resonator with low effective mass, high resonance frequency, and high quality factors are required.
In this presentation, we discuss the results for ultrahigh sensitive and selective Cr(VI) detection by using a doubly-clamped Si microbeam. For the ultrahigh sensitive mass detection, a SiNx anchor was introduced at both edge of the microbeam to accumulate oscillation energy in resonant mode. In order to perform the selective Cr(VI) detection, the Si microbeam surface was functionalized with a pyridinium receptor through covalent linkage. It was found that a concentration of 1 ppb Cr(VI) can be detected using this sensor, while other anions have minimal effect on the resonance frequency shift of the microbeam. Here, we discuss the mass sensitivity of Si microbeam depending on the dimension of Si microbeams and the SiNx anchor coverage. Furthermore, the effect of SiNx anchor on the oscillation mode and the chemistry of microbeam functionalization are discussed.
9:00 PM - SM1.3.13
Proton Conductivity of Carbon Nanotubes
John Selberg 1 , Noah Christie 1 , Zahra Hemmatian 1 , Xenofon Strakosas 1 , Marco Rolandi 1
1 , University of California Santa Cruz, Santa Cruz, California, United States
Show AbstractCarbon Nanotubes (CNTs) are diameter-selective nanopores with high electrical conductivity and exhibit fluid flow rates higher than expected from traditional fluid dynamics. Carbon nanotubes have become increasingly relevant in the field of bioelectronics, being used as high-capacitance electrodes, sensitive transistors, and ion channel analogs. Simulations of water filling inside of CNTs suggest that water forms a regular structure similar to proton-wires formed within biological ion channels such as Gramicidin. This ordered structure hints that CNTs may exhibit proton conductivity by way of the Grotthuss mechanism. Here we explore proton conductivity of CNTs as a function of CNT diameter, length, and chirality with devices utilizing palladium contacts capable of directly inducing and measuring a proton current. These measurements of proton conductivity in CNTs will help uncover the mechanisms for proton transport and water filling within CNTs, allowing for application to bioprotonics.
9:00 PM - SM1.3.14
Biobased Hydrogel/Carbon Nanotubes Nanocomposites for the Electrostimulated Transdermal Delivery of Insulin
Jean-Francois Guillet 1 2 3 , Muriel Golzio 3 , E. Flahaut 2
1 , Univ Toulouse 3-Paul Sabatier, Toulouse France, 2 , CNRS - CIRIMAT, Toulouse France, 3 , CNRS - IPBS, Toulouse France
Show AbstractAccording to World Health Organization statistics [1], there were about 422 millions of people living with diabetes in 2014. Currently, the common way to deliver insulin is the parenteral route, that can be painful for patients, especially for children. Alternative routes that avoid the use of needles for injection and improve the quality of life of patients are under development to enhance the transdermal delivery of large molecules. Indeed, the permeability of skin allows the passive diffusion across the epidermis to reach blood vessels only for small molecules like nicotine. In order to achieve transdermal delivery of large molecules like insulin (6KDa), the permeability of skin and mainly the permeability of the stratum corneum must be increased. A method named “electroporation” has been shown to increase this permeability. Here, we report the fabrication of an innovative biomedical device, made of nanocomposite material. This device aims to permeabilize the skin and to deliver drug molecules at the same time. It includes a biocompatible polymer matrix (hydrogel) and double-walled-carbon-nanotubes (DWCNT) in order to improve both mechanical and electrical properties. Carbon nanotubes and especially DWNTs [2] are ideal candidates, combining high electrical conductivity with a very high specific surface area together with a good biocompatibility when included in a material or deposited on a surface [3]. The preparation of the nanocomposite material as well as our first results of electro stimulated transdermal delivery using an ex vivo mouse skin model will be presented. Moreover, eventual toxicity aspects have to be considered for such an application and will also be discussed.
References:
[1] http://www.who.int/diabetes/global-report/en/
[2] E. Flahaut, R. Bacsa, A. Peigney, Ch. Laurent, "Gram-Scale CCVD Synthesis of Double-Walled Carbon Nanotubes", Chem. Commun., (2003), 1442-1443
[3] A. Béduer, F. Seichepine, E. Flahaut, I. Loubinoux, L. Vaysse, Ch. Vieu, "Elucidation of the role of carbon nanotube patterns on the development of cultured neuronal cells", Langmuir, 28, (50), (2012), 17363 –17371
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Organic Optoelectronics for Integrated Lateral Flow Immunoassay-Based Diagnostic System
Vishak Venkatraman 1 , Ralph Liedert 2 , Andrew Steckl 1
1 , University of Cincinnati, Cincinnati, Ohio, United States, 2 , VTT Technical Research Centre of Finland Ltd, Oulu Finland
Show AbstractThe goal of this project is to a create point-of-care (POC) diagnostic device with several desirable characteristics, combining high sensitivity and semi-quantitative output in a cost effective and disposable package. Another important component of an POC system is power and in this project we are also exploring several options. The biosensor used in this project is lateral flow immunoassay (LFIA), which is a paper based device. LFIAs have several desirable characteristics such as capillary action and affinity to proteins that makes them ideal candidates for LOC applications.
The POC described in this paper is a combination of LFIA and organic optoelectronics as the signal detection component. Organic light emitting diodes (OLEDs) and organic photoduodes (OPDs) have been found to be desirable candidates1 over their inorganic counterparts for POC applications. Organic devices provide the distinct advantages of being planar and large area in nature which is suitable for the integration with LFIAs.
Phosphorescence-based green OLEDs fabricated on plastic substrates were integrated as excitation light sources for fluorescent quantum dot (QD)-based LFIA devices. A 10× improvement in visual signal intensity was achieved compared to conventional LFIA, resulting in a 7× improvement in the limit-of-detection (LOD) of 3 nM concentration2. OPDs fabricated on plastic substrates were also integrated with the LFIA and quantitative results were successfully obtained.
For power source options, a zero-power (on board) system was designed on a flexible plastic substrate. The system utilized the power provided by near field communication (NFC) antenna to an LED array formed on the same substrate using hybrid manufacturing techniques. Such a system can harvest power from smartphones, which are a ubiquitous prsence in this digital century. The NFC LED chip was used to excite the QD-based fluorescent LFA, which demonstrated again a ~10× higher sensitivity compared to conventional commercial devices. The hybrid manufacturing approach using roll-to-roll manufacturing and integration has theb potential to significantly decreases the fabrication cost.
1 Williams, G., Backhouse, C. & Aziz, H. Integration of organic light emitting diodes and organic photodetectors for lab-on-a-chip bio-detection systems. Electronics 3, 43-75 (2014).
2 Venkatraman, V. & Steckl, A. J. Integrated OLED as excitation light source in fluorescent lateral flow immunoassays. Biosensors and Bioelectronics 74, 150-155 (2015).
9:00 PM - SM1.3.17
Unidirectional Polarization Alignment of Self-Assembled M13 Bacteriophage for Piezoelectric Energy Harvesters
Ju-Hyuck Lee 1 2 , Ju Hun Lee 1 2 , Malav Desai 1 2 , Seung-Wuk Lee 1 2
1 , University of California, Berkeley, Berkeley, California, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractThe piezoelectric effect can be defined as an interconversion between mechanical and electrical energies induced by charge redistribution and separation when mechanical or electrical stimulus is applied to materials that lack inversion symmetry. Many natural biomaterials (e.g., virus, fibrillar collagen, DNA, amino acids, and cellulose) that can be synthesized in an environmentally friendly manner have also been shown to have piezoelectric properties. In addition to safe synthesis schemes, such bio-piezoelectric materials are often highly uniform and are potentially more compatible alternatives for future biomedical applications. Recently, it has been reported that piezoelectric and liquid-crystalline properties of M13 bacteriophage can be used to generate electrical energy and operate a liquid-crystal display. However, it is noted that M13 bacteriophage favor the formation of antiparallel orientation, such that the opposite polarization of neighboring phage cancel each other and reduce the overall piezoelectric properties. Therefore we hypothesize that the piezoelectric property can be enhanced further through unidirectional orientation of M13 bacteriophage. In this work, we developed a genetically engineered M13 bacteriophage that can self-assemble into in-plane aligned piezoelectric nanostructure. First, the M13 bacteriophage was genetically modified to display hexa-histidine (6-His) on the tail protein (pIII). Next, a gold-coated substrate was chemically modified with nickel-nitrilotriacetic acid (Ni-NTA). Phage with 6-His displayed pIII protein anchored to the Ni-NTA modified surface through Ni-NTA and 6-His reaction. The resulting in-plane aligned M13 bacteriophage have unidirectional polarization and can effectively translate external forces to electrical energy.
9:00 PM - SM1.3.18
Synthesis of PEDOT:Polyssacharide Dispersions as Versatile Materials for Bioelectronics
Isabel del Agua 1 2 , Daniele Mantione 2 , Ana Sanchez-Sanchez 2 , George Malliaras 1 , David Mecerreyes 2
1 BEL, Ecole de mines de Saint Etienne, Gardanne France, 2 Polymat, University of the Basque Country, San Sebastian Spain
Show Abstract
In response to the demand of new conductive organic materials in the field of Bioelectronics, we present new PEDOT composites materials based on polyssacharides. Poly(3,4-dioxythiophene) (PEDOT) aqueous dispersions are synthesized by oxidative polymerization of EDOT in the presence of polysaccharides as stabilizers. These PEDOT dispersions can be used as starting materials for the syntheses of new PEDOT-Ion gels, porous PEDOT Xerogels or PEDOT Hydrogels. The synthetic conductions of PEDOT:polyssacharides aqueous dispersions are done in a very straightforward manner and characterized in terms of particle size, conductivity, reaction kinetics, and UV-Vis NIR absorbance.
There are different strategies to develop innovative PEDOT:polyssacharides materials starting from the aqueous dispersions. Particular attention is paid to the preparation of novel PEDOT-Ion gels combining the intrinsic electrical properties of PEDOT, and the ionic conductivity of ionic liquids resulting in highly ionically conductive materials (10-2 S/cm) with gel properties. Overall, these polymeric composites are biocompatible and biodegradable and they have promising applications in tissue engineering, nerve regeneration, biosensors, flexible electrodes, supercapacitors or drug delivery.
Due to their characteristics, these innovative PEDOT materials are good candidates to perform the interface role between electronic materials and biological tissues.
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Water-Stable Transparent Microelectrode Arrays Based on Biocompatible Crystalline PEDOT:PSS
Youngseok Kim 1 , Seong-Min Kim 1 , Myung-Han Yoon 1
1 , Gwangju Institute of Science and Technology, Buk-gu Korea (the Republic of)
Show AbstractAmong many biointeractive electrical platforms, a planar-type multi-electrode array (MEA) has been regarded as one of the most effective biointerfaces owing to the reliability of electrical measurement and the cost-effectiveness of device fabricatioin. Nonetheless, in the case of the conventional MEAs based on gold, iridium, or indium oxide, the Johnson-Nyquist noise is typically very high compared with the actual cellular signal, leading to low signal fidelity. Furthermore, their poor optically transparency impeded cell monitoring as well as stimulation when an inverted microscope is employed. Herein, we report electrochemically-durable transparent MEAs based on the crystallized-PEDOT:PSS (c-PEDOT) for the long-term cellular recording and stimulation. Remarkably, c-PEDOT electrodes exhibited very high electrochemical activity, prolonged mechanical/electrical stability, and excellent cell viability due to the absence of surfactants and/or chemical crosslinkers. Furthermore, these electrodes showed no degradation in electrical properties even after autoclave sterilization at high temperature and pressure. Finally, the c-PEDOT-based MEAs were successfully constructured via photolitography and SU-8 passivation, and the long-term extracellular recording and stimulation of cardiomyocytes with high signal-to-noise ratio was effectively demonstrated.
9:00 PM - SM1.3.20
High-Adhesion Stretchable Electrodes Based on Nanopile Interlocking
Zhiyuan Liu 1 , Xiaodong Chen 1
1 , Nanyang Technological University, Singapore Singapore
Show AbstractStretchable electrodes and strain sensors provide the fundamental platform for investigating the electrophysiology of tissues in vivo/vitro as well as mechanical deformation in medical therapy and tissue engineering. Since naturally there is nearly no intrinsic stretchable materials that is fully conductive, various strategies have been proposed to achieve the stretchability based on the combinations of inorganic conductive materials (e.g. metals and carbon) and organic elastic polymers (e.g. polydimethylsiloxane (PDMS) and polyurethane). These particular combination of materials faces one intrinsic problem related to interfacial adhesion, especially for the thin film electrode on elastic substrate. This is due to the huge difference in physical and chemical properties (e.g., Young’s modulus: tens of GPa for gold while only several MPa for PDMS) between the conductive material and the elastic substrate. Adhesion is crucial for the long-term use of stretchable electronics. Thus, one overarching materials challenge is to simultaneously obtain electrodes with desirable stretchability and high adhesion to the supporting polymer substrate.
Inspired by the plants, like trees, standing firmly on the ground by stretching out fractal roots underneath, we could introduce an interlocking layer by growing biomimetic roots under the electrode to significantly enhance the adhesion. More importantly, it is also desired that the roots extending into the soft substrate could regulate the strain distribution in the metal film thus avoiding throughout cracks induced by the strain concentration. Herein, we report a new strategy - nanopile interlocking - to fabricate high-adhesion stretchable electrodes that can also be used as strain sensors with tunable stretchability, high gauge factor and stability. The nanopile not only provides an interlocking effect to significantly improve the adhesion, but also ensures that the tensile strain in the film is redistributed to release the strain energy by randomly distributed cracks forming the connection network and achieving the stretchability. The adhesion is significantly improved by over an order of magnitude compared to stretchable thin gold film with initial nanocracks and non-stretchable flat gold film. The stretchability of the electrode can reach ~ 50% which is more than enough for the body-surface measurements that typically encounter deformations up to ~ 30%. Our strategy provides a new perspective to achieve stretchability that is vital for stretchable electronics. It also opens up for exploration of the advanced property-function relationships combining high adhesion and stretchability.
See more at Adv. Mater. 2016, 28, doi: 10.1002/adma.201603382.
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DOPA-Engineered M13 Bacteriophage Based Conductive Porous 3D Architectures Templated by Ice Crystals
Ju Hun Lee 1 2 , Seung-Wuk Lee 1 2
1 Bioengineering, University of California, Berkeley, Berkeley, California, United States, 2 Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractHigh aspect ratio one-dimensional (1D) nanostructures have been actively investigated in electronic, optic, biomedical and energy applications due to their unique properties associated functionalities. The primary challenge for practical applications is to efficiently assemble those nanostructures into macroscopically desired architecture in controllable manner. Biological systems provide great inspiration to design hierarchical macroscopic structures. Based on their basic nanoscale fibrous building blocks, e.g. collagen, a variety of structures with distinct functionalities can be constructed under ambient conditions. Particularly, biomineralization in biological system has great potential to controllably nucleate, grow inorganic nanomaterials with combining self-assembling ability of nature. As a good example, specific peptide incorporated filamentous M13 bacteriophage by genetic engineering has been utilized as a 1D nucleation scaffold and their macro-architecture employed for various applications. To this end, we develop a novel three-dimensional conductive porous structure based on genetically and enzymatically engineered dihydroxyphenylalanine (DOPA) phage driven metal deposition and demonstrate a strain sensor with conductivity characterization. We first genetically engineered tyrosine groups on the phage major coat proteins and enzymatically converted tyrosine to DOPA. We then assembled the phage into hierarchical porous structures using ice templating method and glutaraldehyde-based crosslinking. Depending on the freezing temperature, we could tune the resulting micro porous size and lamellar structure. Much of the previous research on inorganic crystal nucleation and growth has been conducted on single phage or at micro scale level with limited focus on creating conductive macroscopic architecture using connected networks of phage. To achieve macroscale conductive phage structure, the phage needs to be fully covered with a continuous inorganic layer rather than a string of randomly nucleated nanoparticles. Due to the unique bioinspired glue like properties of DOPA displayed the close packed major capsid proteins, we successfully covered the microporous structures in large scale with gold and silver by manipulating chemical parameters without any need for annealing. The resulting porous noble metal deposited structures exhibited high electrical conductivity. In addition, the electrical resistance of the structure changed under mechanical deformation.
9:00 PM - SM1.3.22
Transferrable, Ultra-Flexible Organic Transistor with Sub-Micron Thickness and Its Integration with Medial Catheter for Biomarker Detection
Xudong Ji 1 , Paddy K. L. Chan 1
1 , University of Hong Kong, Hong Kong Hong Kong
Show AbstractThe application of organic thin film transistors (OTFTs) covers a wide range of areas from active-matrix displays, wearable electrics to smart sensors. When the device is integrated with human skin or medical tools with tortuous shape, the flexibility of the transistor is critical to ensure a conformal contact between the device and the targeted surface. As the degree of flexibility of transistor is limited by its thickness, it is necessary to manufacture a transistor as thin as possible including the substrate. Here we reported imperceptible low-voltage transistor based on newly developed thermally stable organic semiconductor 2,10-diphenylbis[1]benzothieno[2,3-d;2',3'-d']naphtho[2,3-b;6,7-b']dithiophene (DPh-BBTNDT) with total thickness of 630 nm. The OTFT was fabricated on 250 nm Polyacrylonitrile(PAN)/CYTOP hybrid substrate which was spin-coated on a glass slide. A thin hybrid gate dielectric based on anodized Al2O3 and Octadecylphosphonic acid (ODPA) self-assembled monolayer (SAM) with a capacitance around 350 nF/cm2 was utilized to ensure low operating voltage (below 3V) of OTFT. Another 250 nm CYTOP layer was used as top encapsulation layer to prevent the organic semiconductor degradation during the water flotation transfer process. As the whole device is encapsulated, the OTFT can be operated in various extreme conditions including acidic and alkaline environments. The pre-transferred OTFT showed a high mobility around 5.7 cm2V-1s-1 and on/off ratio of 1×107. The device with total thickness 630nm can then be transferred to other substrate through water floatation method. After consecutively transfer the device to rigid glass substrate, flexible PEN substrate and rough banknote substrate, the mobility and on/off ratio only slightly decrease to 5.2 cm2V-1s-1 and 5×106, which proves the stability of the device during transfer process. Based on the high performance of the OTFT device, we take a step further to use it for C-reactive protein (CRP) (an indicator of inflammation) sensing by integrating the device with an extended gate serving as sensing electrode. The extended gold gate electrode was also fabricated on 250 nm PAN/CYTOP hybrid substrate and functionalized with 3-Mercaptopropionic acid (MPA) to capture CRP antibody. The sensitivity can be as high as 1μg/mL. Separately fabricated transistor and sensing electrode were transferred to a medical catheter with diameter 2mm and connected through via hole connection. Such device can be implanted to human blood vessel and has extremely high potential on real-time CRP sensing as well as other kinds of biomarkers.
9:00 PM - SM1.3.23
Effects of Spin and Cluster Size on Electrochemical and Photophysical Properties of Nucleotide Base Ligated Silver Cluster
Mohammed Jabed 1 , Svetlana Kilina 1
1 , North Dakota State University, Fargo, North Dakota, United States
Show AbstractDNA relaxed small silver is considered a promising new type of fluorophore for various application due to its exhibition of bright emission from visible to near-infrared range. Single strand DNA synthesized silver cluster has fluorescence properties and it has been shown distinct photophysical properties when linked through DNA strand and formed a dimer. Mechanism of dimer formation, electrochemical and photophysical properties of Ag cluster is still unknown. We have performed Density Functional Theory (DFT) calculations to optimize varying sizes of the silver cluster with different nucleotide ligands. We also made Ag dimer by the different mechanism and optimized by DFT method. Calculated electrochemical properties show that redox potential is dependent on the cluster size and spin state of the system as well. We have performed Time Dependent DFT (TD-DFT) for all monomer and dimer. It has shown that absorption of a monomer depends on size and charge of the cluster. On the other hand, partial replacement of cytosine by guanine could increase the intensity of lower energy band. We made conjugate bridged dimer to study any possible charge transfer nature of Ag clusters. We have found that dimer absorption could be red shifted due to conjugation bridge and size independent absorption of doublet spin system.
9:00 PM - SM1.3.24
50-µm-Wide Silver Nanowire Electrodes Patterned on Hydrophilic/Hydrophobic Treated Surface for Transparent Organic Transistors
Ashuya Takemoto 2 1 , Teppei Araki 2 1 , Yuki Noda 2 1 , Shusuke Yoshimoto 2 1 , Takafumi Uemura 2 1 , Tsuyoshi Sekitani 2 1
2 ISIR, Osaka University, Osaka, Ibaraki, Japan, 1 Graduate School of Engineering, Osaka University, Osaka, Suita, Japan
Show AbstractThe present work demonstrates a patterning method of silver nanowires (AgNWs) based on controlled surface wettability for transparent organic transistors. In this method, AgNWs electrodes are spontaneously deposited with line and space width of 50/50 μm according to the hydrophilic/hydrophobic pattern surface fabricated with fluorine-coating and photoactivation. This patterning method can precisely follow the design of transparent AgNWs electrodes, resulting in operation of transparent organic field-effect transistors (OFETs).
For next-generation flexible devices, AgNWs electrodes have been expected as indium tin oxide (ITO) replacement owing to their transparency and mechanical flexibility [1, 2]. In the device fabrication, patterning AgNWs electrodes on a target area is an essential process for the precise manufacture. Fine patterning method of AgNWs electrodes will provide a versatile design for integrated devices such as flexible displays, tactile sensors, and implantable bio-electrodes. Furthermore, an attractive aspect of AgNWs electrodes is their applicability to additive manufacturing, which has been demonstrated with ink jet printing, screen printing, and gravure printing [3-5]. These additive processes can benefit by low consumption and high-throughput, compared to subtractive processes referred to as Etching. However, the above printing methods face hurdles on unintended bleeding or dewetting of ink which lead to difficulty in finely patterning the AgNWs electrodes with a line and space width of less than 100 μm [3-5]. Because of these limitations, device integration with AgNWs electrodes by additive processes is still challenging.
In our work, we developed fine-patterned transparent AgNWs electrodes by using the hydrophilic/hydrophobic surface treatment method. A parylene, poly(p-xylylene) polymer, substrate was coated with fluorine and then selectively photoactivated with an excimer lamp through a photo mask. AgNWs ink was uniformly applied to the treated parylene substrate with a glass rod [1], and the ink was spontaneously deposited only on the hydrophilic area. Lines and spaces of the patterned AgNWs electrodes achieve well-defined edges and a minimum width of 50 µm. Finally, using the AgNWs electrodes, we fabricated transparent OFETs with 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) [6]. The detail of this patterning method and the transistor characteristics will be presented. Our developing technique of patterning AgNWs electrodes is a promising way to manufacture and integrate transparent flexible devices.
References
[1] L. Hu, H. S. Kim et al., ACS nano 4 (5), 2955 (2010).
[2] D. Langley, G. Giusti1 et al., Nanotechnology 24 (45), 452001 (2013).
[3] D. J. Finn, M. Lotya et al., ACS Appl. Mater. Interfaces 7, 92541(2015).
[4] J. Liang, K. Tong et al., Adv. Mater. 28 (28), 5986 (2016).
[5] J. D. Park, S. Lim et al., Thin Solid Films 586, 70 (2015).
[6] Y. Yuan, G. Giri et al., Nature communications 5, 3005 (2014).
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Self-Aligned, Conductive and Lithography-Less Patterns for Stretchable and Skin-Conformal Sensors
Youngjin Park 1 , Jongwon Shim 2 , Gi-Ra Yi 1 , Heeyeop Chae 1 , Jong Wook Bae 1 , Sang Ouk Kim 1 , Changhyun Pang 1
1 , Sungkyunkwan University, Suwon-si Korea (the Republic of), 2 , Amorepacific Research Center, Suwon Korea (the Republic of)
Show AbstractRecently, numerous emerging thin and flexible sensor technologies have been made for realization of practical use of invasive/non-invasive cost-efficient healthcare devices, showing high sensitivity, stretchability, bio-compatibility, skin/organ-conformity, and often transparency. In this respect, we developed the facile/cost-efficient method for fabricating thin sensor array (144 pixels) having self-aligned, conductive, and lithography-less patterns, which is capable of high adaptability with intimate contacts between device and rough surface. The sensing network of device was consisted of stacked layers of graphene nano-platelets, which can be spontaneously collected and arranged via the Marangoni self-assembly on liquid surface, and self-patterned conductive layers were easily achieved by transferring them on a micro-structured support. We proceeded to demonstrate that our conductive layered-architectures can be used for a skin-conformal sensor monitoring amplified waveforms, a mechanical/thermal-sensitive electric rubber-balloon, and an electric blood vessel, suggesting promising cost-effective method toward expeditious diagnosis of cardiovascular and cardiac illnesses.
9:00 PM - SM1.3.26
Transient Thermoresponsive Conductive Materials
Xin Zhang 1 , Leon Bellan 1
1 , Vanderbilt University, Nashville, Tennessee, United States
Show AbstractTransient electronics are an emerging platform that enables the formation of circuitry designed to disintegrate and irreversibly lose function. Several materials have been integrated in the past to form these architectures, including zinc oxide(ZnO), magnesium(Mg) and silicon nanomembranes(Si NMs). Circuitry formed from these materials slowly dissolves in aqueous environments and thus function is lost after a predetermined period of time. To add additional stimulus-response behavior to a transient electronics system, we employ as a “binder” polymers that exhibit lower critical solution temperature (LCST) behavior. We have confirmed that multiple polymers, including methyl cellulose and Poly(N-isopropylacrylamide), with different LCST thresholds may be utilized to form such thermoresponsive transient systems. In conjunction with these stimulus-responsive polymeric binders, we apply silver nanowires (AgNWs) to form the percolating conductive network. After characterizing the thermoresponsive electrical conductivity behavior of these composites, we demonstrate the ability to pattern conductive traces onto thermoresponsive insulating substrates and form various transient passive electrical components.
We first deposited ~4 mm thick parylene onto a clean silicon substrate. Standard photolithography was then used to define the desired pattern in the photoresist layer, which served as a mask during an oxygen plasma etch of the exposed parylene. Drops of AgNWs suspended in isopropanol were cast onto the entire wafer and allowed to dry for 1 hour. Next, the parylene film was peeled off, leaving the AgNWs on the wafer surface in the desired pattern. To form the thermoresponsive substrate, clear methyl cellulose solution was spin coated onto the surface at 100 rpm. After drying overnight, the polymer film is removed from the wafer, and the patterned AgNWs are buried just below the methyl cellulose surface.
To characterize the thermoresponsive transient behavior of the composite conducting system, we cast various formulations of AgNWs and LCST polymer mixtures onto gold electrodes and measured I-V curves immersed in controlled temperature water baths. When immersed in a warm water bath (Twater>LCST), the polymeric binder enables stable electrical performance with negligible change in conductivity over 24 hours. When the temperature drops below the LCST, the polymeric binder dissolves, irreversibly destroying the circuit and rendering it untraceable. A heat-sensitive LED circuit was demonstrated utilizing methyl cellulose film as the substrate and patterned AgNWs as electrodes. The LED functioned only when the solution temperature was above the LCST, and turned off when the thermoresponsive conductive composite disintegrated. The reported thermoresponsive transient conductive composites open up new possibilities for exciting applications employing stimulus-responsive transient electronic devices.
9:00 PM - SM1.3.27
DNA and DNA-CTMA Polyelectrolytes for Biodegradable Light-Emitting Electrochemical Cells
Serpil Tekoglu 1 2 , Guan Ni Yeo 1 2 , Markus Bender 3 , Anthony Morfa 1 2 , Manuel Hamburger 3 , Uli Lemmer 1 , Gerardo Hernandez-Sosa 1 2
1 Light Technology Institute, Karlsruhe Institute of Technology, Karlsruhe Germany, 2 , InnovationLab GmbH, Heidelberg Germany, 3 Organic Chemistry Institute, Ruprecht-Karls-Universitat Heidelberg, Heidelberg Germany
Show AbstractOne of the important arguments in the organic electronics field today, is to replace the synthetic polymers with biopolymers for biodegradable, biocompatible electronics. This is comforted by the present scientific policy related to the humanity problem of creation of sustainability and minimizing the environmental pollution by reducing the electronic-waste.
In our work, we highlight DNA and the DNA-lipid complex (DNA-CTMA) as Solid Polymer Electrolytes (SPEs) from aqueous and organic solvent media for Light-Emitting Electrochemical Cells (LECs). Different salts were engaged as additional ionic source and the ionic conductivity for different ratios was investigated. The blend of SPEs and commercially available water-soluble blue emitter or organo-soluble yellow emitter was deposited between two electrodes to form the active layer. The luminance-voltage-current density characteristics and lifetime were investigated. The maximum luminance was recorded 2000 cd/m2 and 7 cd/m2 for yellow and blue LECs, respectively, with the turn on voltages of 3.5-10 V. The ionic conductivity of SPEs was obtained at the range of 10-6 S/cm at RT using impedance spectroscopy. Additionally, surface morphology of the blend films and electrochemical stability window of SPEs were explored.
9:00 PM - SM1.3.28
Determining Saline, Canine Blood, and Human Blood Composition by Congealing Microliter Drops into Homogeneous Thin Solid Films (HTSFs) via HemaDrop™ Technology
Yash Pershad 1 2 , Harshini Thinakaran 1 2 , Nicole Herbots 1 4 , Shawn Whaley 1 4 , Alvaro Martinez 1 , Sabrina Suhartono 1 , Robert Culbertson 1 , Mark Mangus 3 , Barry Wilkens 3 , Grady Day 1 2 , Nehal Gupta 4
1 Department of Physics, Arizona State University, Tempe, Arizona, United States, 2 , BASIS Scottsdale, Scottsdale, Arizona, United States, 4 , SiO2 Innovates, Tempe, Arizona, United States, 3 LeRoy Erying Center for Solid State Sciences, Arizona State University, Tempe, Arizona, United States
Show AbstractAccurate analysis of microliter blood samples can improve patient care during medical testing and forensics. Most critically ill patients suffer from anemia due to the larger volume required for blood tests, 7 milliliters per vial. Also, blood analysis is crucial for forensics, but its use is limited to situations with large volumes of blood.
Attempts at analysis of nanoliter blood samples by Theranos have systematic errors > 10%, higher than medically acceptable thresholds. Our research aims to analyze composition of microliters of blood. This research investigates accuracy of analyzing blood via HemaDrop™, a patented technique to create a Homogenous Thin Solid Film (HTSF) on super-hydrophilic surfaces with small droplets of blood, about 5 microliters in volume. To investigate HemaDrop™’s accuracy, Ion Beam Analysis (IBA) is conducted on dried blood spots (DBS) and HTSFs from congealed blood drops on HemaDrop™-treated samples. HTSFs are observed via optical microscopy to compare uniformity, precipitation, and phase separation.
First, IBA via MeV Rutherford Backscattering Spectrometry and Particle-Induced X-Ray Emission is conducted on surfaces after canine blood application. HTSFs congealed on treated surfaces yield well-defined spectra where individual species and electrolytes (e.g., Ca, K, Fe, etc.) can be identified, unlike on DBS. The damage curve method [2] enables extracting accurate blood composition for elements, accounting for IBA damage. Four consecutive spectra enable interpolation to a 0-analyzing dose to determine original concentrations. Error in blood electrolyte composition is < 5%.
Preliminary testing with human blood yields similar results. HemaDrop™ provides consistent measurements independent of location of analysis and sample, showing HTSFs are uniform, reproducible, and free of phase separation,.
Second, DBSs and HTSFs are compared via optical microscopy for Balanced Saline Solution (BSS), canine blood, and human blood. After drying untreated samples, canine and human blood exhibit cratering, phase separation, and lack of uniformity. Conversely, treated films are uniform, exhibiting no cratering and little phase separation. Additionally, the residue left by BSS after drying on untreated substrates is non-uniform, with visible particulates. BSS on treated films leave uniform and nearly transparent residues.
Thus, HemaDrop provides a reliable way to prepare HTSFs to measure blood composition from μL-volume drops based on comparative IBA results and optical observations. Through HemaDrop™, measurements of elemental composition of blood droplets can be made with high accuracy and reproducibility. HemaDrop allows for analysis in vacuo from congealed μL of blood, thereby greatly expanding the range of techniques to identify elements and molecules.
[1] HemaDrop™: Int & US Patents Pending, 2016.
[2] Nuc. Instruments and Methods in Phy Sect. B Beam Interact. with Mat. and Atoms, 2012.
[3] MRS Advances, 2016.
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Cerium Oxide Immobilized on Polymer Nanostructures as Dopamine Biosensor
Swetha Barkam 1 , Madison Peppler 1 , Shashank Saraf 1 , Brandon Carpenter 1 , Jayan Thomas 1 , Sudipta Seal 1
1 Materials Science and Engineering, University of Central Florida, Orlando, Florida, United States
Show AbstractDopamine, being a vital neurotransmitter, plays an important role in the proper function of central nervous system, human metabolism and cardiovascular system. Several neurological disorders such as schizophrenia, Parkinson’s disease, and Huntington’s disease are instigated due to deficiency of dopamine. The detection of lower levels of dopamine in non-invasive biological samples (sweat /urine) is very important. In this study, we propose the use of cerium oxide immobilized on polymer nanopillars as a dopamine sensor with high sensitivity and selectivity for diagnostic applications. Cerium oxide nano-constructs (nanoceria) have proven to act as potential antioxidants attributed to switching of oxidation state from Ce+3 to Ce+4, mediated at the oxygen vacancies. Cerium oxide has a unique chemical interaction with dopamine, creating a signature signal in optical characterization. It has been previously studied that, a strong attachment exist between dopamine and nanoceria leading to formation of a charge transfer complex. Additionally, nanoceria is coated on high aspect ratio polymer nanopillars, fabricated using soft lithography to increase the surface area of interaction with dopamine. The sensor is developed by recording the corresponding changes in surface chemistry and redox potential of nanoceria upon interaction with dopamine using optical techniques. Nanoceria developed with different surface chemistry was used to improve the detection limit of dopamine.
9:00 PM - SM1.3.30
Tattoo-Based Wearable Iontophoretic-Biosensing Device for Noninvasive Alcohol Monitoring
Jayoung Kim 1 , Joseph Wang 1
1 , University of California, San Diego, La Jolla, California, United States
Show Abstract
We present a novel tattoo-based transdermal noninvasive alcohol monitoring device for wearable applications. The wearable alcohol sensor platform integrates an iontophoretic-biosensing system on a temporary tattoo platform along with flexible wireless electronics. The device delivers the pilocarpine drug via iontophoresis through the skin to induce sweat. Then, alcohol in the generated sweat is detected using an enzymatic reaction with alcohol-oxidase and a Prussian Blue transducer. The body-compliant flexible wireless electronics are coupled with a wearable tattoo sensor, which controls the iontophoretic/amperometric operations and enables wireless data transmission in real-time via Bluetooth communication. On-body evaluations with human subjects have been demonstrated using this completely wearable wireless tattoo sensor. Distinct differences in current responses are measured before and after alcohol consumption, reflecting the increased blood alcohol levels of the human subjects. This new wireless transdermal iontophoretic-bionsensing system holds considerable promise for noninvasive monitoring of alcohol consumption, and it can be readily extended to reduce alcohol-impaired driving accidents and alcohol abuse.
9:00 PM - SM1.3.31
Molecular Imprinted Graphene Based Portable Gas Sensor to Detect Diabetes and Alcohol Level by Tracking Human Breathing Molecule
Md Saleh Akram Bhuiyan 1 , Qiquan Qiao 1
1 , South Dakota State University, Brookings, South Dakota, United States
Show AbstractOwing to its unique electrical, mechanical, thermal, optical and nano scale properties, Graphene is now globally known as a promising biocompatible material. A Graphene based portable gas sensor is developed which can sense Acetone and Ethanol molecule from human breathing to detect diabetic and alcoholic patients. It is a fast process to detect diabetes and alcohol rather than lab based diagnosis like testing patient’s blood or urine sample. It is observed that the graphene based gas sensor has sensitivity to various gases or vapors, but the selectivity is an issue. The selectivity of the sensor was improved by using SnO2 nanofiber based molecular imprinting method and it can show sensitivity to either acetone or ethanol depending on the imprinting procedure. Current level base detection system was used to see the change in electrical property of the graphene in both molecular imprinted or non imprinted sensor. The quality, morphology, structure and thickness of the sensing layer were investigated by Scanning Electron microscope (SEM), Raman Spectroscopy, X-Ray diffraction (XRD) and fluorescence spectroscopy technique. The sensitivity of the gas sensor was investigated by I-V measurement and FTIR-ATR (Fourier transform infrared – attenuated total reflectance) analysis. The result showed that the current flow through the gas sensor decreased while it was exposed by the Acetone and Ethanol vapor. Finally, it is found that the molecular imprinted graphene based gas sensor has excellent acetone and ethanol sensing properties like high sensitivity, quick response and good linearity in wide voltage range.
9:00 PM - SM1.3.32
Electrical Detecting of Cancer Biomarker on MoS2 Field-Effect Transistor
Heekyeong Park 1 , Geonwook Yoo 2 , Hyungbeen Lee 3 , Seokhwan Jeong 1 , Sangwoo Lee 3 , Sunkook Kim 1
1 School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon Korea (the Republic of), 2 School of Electronic Engineering, Soongsil University, Seoul Korea (the Republic of), 3 Department of Biomedical Engineering, Yonsei University, Wonju Korea (the Republic of)
Show AbstractField-effect transistor (FET)-based biosensors have attracted a great attention because they can provide highly sensitive and label-free detection. Furthermore, detection of cancer biomarker for early diagnosis using FET sensor is the most popular issues in biotechnology. In this work, we present a sensing performance analysis and its application of MoS2 FET-based biosensors for sensing prostate specific antigen (PSA). First, we demonstrated that MoS2-based FETs could be candidates for biological sensors and reported an optimized absorption condition of the biomolecules on MoS2 surface. MoS2 has the nature of hydrophobic surface (the contact angle ~75.77 °), which affords a physical adsorption to biomolecule binding directly. Kelvin probe microscopy (KPFM), the microscopy equipment to investigate surface potential, can recognize the charge state and the spatial distribution of biomolecules, and the surface potential on MoS2 surface. This demonstration can not only be used to optimize the immobilization conditions for captured molecules, but can also be applied as a diagnostic tool to complement the electrical detection of a MoS2 FET biosensor. Second, we presented epidermal skin-type point-of-care (POC) devices that enable real-time detection of PSA. This biochip device is composed with a flexible MoS2-FET biosensor, read-out circuits and light-emitting diode. Regardless of the physical forms of mechanical stress conditions, out proposed MoS2 biosensors can detect a PSA concentration of 1 pg/mL which is several orders of magnitude below the clinical cut-off level of 4 ng/mL. Furthermore, our integrated MoS2 biochip shows relatively fast response, 10min, and current modulation was stably maintained for longer than
2-3min. This results indicate that flexible MoS2 FET biosensors have great potential for POC diagnostics for PSA as well as other biomarkers.
Symposium Organizers
Jonathan Rivnay, Northwestern University
Magnus Berggren, Linkoping University
Rylie Green, Imperial College London
Ni Zhao, The Chinese University of Hong Kong
Symposium Support
MilliporeSigma
Suzhou Fangsheng Optoelectronics Co., Ltd
Vigor Tech USA LLC
SM1.4: Novel Materials and Mixed Conduction
Session Chairs
Rylie Green
Jonathan Rivnay
Wednesday AM, April 19, 2017
PCC North, 100 Level, Room 121 A
9:00 AM - SM1.4.01
Electroactive Silk Based Micropatterns for Flexible Biosensing Applications
Ramendra Pal 1 , Subhas Kundu 2 , Vamsi Yadavalli 1
1 , Virginia Commonwealth University, Richmond, Virginia, United States, 2 , University of Minho, Guimaraes Portugal
Show AbstractThe convergence of naturally derived and synthetic polymers provides exciting opportunities to develop physiologically compliant bioelectronics systems. The combination of silk proteins and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) enables the formation of functional biocomposites with unique properties. On one hand silk proteins are mechanically strong, optically transparent, and efficient at entrapping enzymes along with their biocompatibility and degradability. Conversely, PEDOT:PSS possesses electrical/ionic conductivity, electrochemical properties and chemical stability in biological environments. In recent work, we demonstrated a photopatternable, water-based conductive ink comprising PEDOT:PSS and in-house synthesized photoreactive silk proteins.[1, 2] The presence of photoreactive groups permits a fully aqueous photolithographic strategy to form conductive micropatterns on both rigid substrates as well as flexible silk films. Here we will discuss how this composite ink can function as a flexible electrode as well as an electroactive coating material for conventional rigid electrodes to enhance their electrochemical performance.[3] The investigations with conductive ink have led to the development of biosensing systems in multiple formats without the use of other charge collector support materials. We further show how electroactive biomolecules such as ascorbic acid and dopamine can be detected sensitively, while non-electroactive biomolecules such as glucose and glutamic acid, can be detected by encapsulating specific enzymes. The electroactivity of conductive ink can be improved by the addition of small amounts of reduced graphene oxide(rGO) dopant to obtain highly sensitive detection. Using these doped composites, we further demonstrate flexible energy storage devices due to the capacitive nature of the biomaterial. The presence of silk proteins as the matrix of the composite makes it completely biodegradable, potentially resulting in implantable devices. The mechanical, biochemical and electrochemical characterization of the composite and its microfabrication are discussed. By virtue of this range of properties, utility as bio-sensors, opto-electronic devices and flexible energy storage systems are envisioned.
[1] R.K. Pal, A.A. Farghaly, M.M. Collinson, S.C. Kundu, V.K. Yadavalli, Photolithographic Micropatterning of Conducting Polymers on Flexible Silk Matrices, Advanced Materials 28(7) (2016) 1406-1412.
[2] N.E. Kurland, T. Dey, C. Wang, S.C. Kundu, V.K. Yadavalli, Silk Protein Lithography as a Route to Fabricate Sericin Microarchitectures, Advanced Materials 26(26) (2014) 4431-4437.
[3] R.K. Pal, A.A. Farghaly, C. Wang, M.M. Collinson, S.C. Kundu, V.K. Yadavalli, Conducting polymer-silk biocomposites for flexible and biodegradable electrochemical sensors, Biosens Bioelectron 81 (2016) 294-302.
9:15 AM - SM1.4.02
Tailored Materials for Organic Bioelectronics
Dan-Tiberiu Sbircea 1 , Christian Nielsen 1 3 , Jonathan Rivnay 2 , George Malliaras 4 , Iain McCulloch 1
1 , Imperial College London, London United Kingdom, 3 , Queen Mary University of London, London United Kingdom, 2 , Palo Alto Research Center, Palo Alto, California, United States, 4 , Ecole Nationale Superieure des Mines, Gardanne France
Show AbstractOrganic semiconductor materials are ideally positioned to interface with the biological environment. We present bespoke materials with significantly enhanced bioelectronic properties compared to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) – the current workhorse material for bioelectronics. Our work is based on novel organic semiconductors which display combined ionic and electronic conductivity. Through utilization of the organic chemistry toolbox, energy levels, transport properties and processability have been tuned for specific applications. Furthermore, we show facile biofunctionalization with biological cues via a pendant functional group. These materials display enhanced signal to noise in recording neuronal activity when employed in an Organic Electrochemical Transistor (OECT). When used to electrically stimulate neurons, materials functionalized with cell adhesion promoters display large enhancement in neurite outgrowth without scar formation or device degradation. This offers many opportunities in the field of neural prosthetics and nerve regeneration.
9:30 AM - *SM1.4.03
Bioelectronic Devices with Protons (H+), Ion Channels, and Cells
Marco Rolandi 1
1 Department of Electrical Engineering, University of California, Santa Cruz, California, United States
Show AbstractBioelectronic devices face a challenge at the interface with physiological systems. Electronic devices are dry and use electrons (and holes) as charge carriers. Physiological systems are wet and use ions and neurotransmitters as charge carriers. Here, I will present examples of wet bioelectronic devices that use protons (H+) as charge carriers, bioprotonics. These include biotic-abiotic devices with integrated lipid bilayers and ion channels that mimic cell signaling, and devices that include cells and affect cell function with an electronic signal transduced by an H+ current.
10:00 AM - SM1.4.04
Controlling of (supra)Molecular Structure of Polymers from Natural Sources to Assess Their Electrical Properties
Ri Xu 1 , Carmela Prontera 2 3 , Luiz Gustavo Simao Albano 4 , Eduardo Di Mauro 1 , Prajwal Kumar 1 , Paola Manini 3 , Clara Santato 1 , Francesca Soavi 5
1 , Polytechnique Montreal, Montreal, Quebec, Canada, 2 SSPT-PROMA NANO, C.R. Portici, ENEA (Agenzia Nazionale per le Nuove Tecnologie, l'Energiae lo Sviluppo Economico Sostenibile), Portici Italy, 3 Department of Chemical Sciences, Università degli Studi di Napoli Federico II, Portici Italy, 4 , São Paulo State University, Bauru Brazil, 5 , University of Bologna, Bologna Italy
Show AbstractPolymers extracted from natural sources are, in general, chemically disordered, such that establishing structure-property correlations to exploit their technological potential for applications in environmentally and human friendly electronics is a truly challenging task. Controlling their (supra)molecular structure is imperative to exploit their full potential.
Eumelanin is a brown-black pigment, ubiquitous in the human body, obtained from the oxidative polymerization of 5,6-dihydroxyindole (DHI) and/or 5,6-dihydroxyindole-2 carboxylic acid (DHICA). The pigment features interesting functional properties, such as photoprotection and free radical scavenging [1]. It also features biodegradability and biocompatibility. From the electrical point of view, eumelanin has been reckoned as an amorphous semiconductor since the early 70s [2], [3] until recently, when the mixed electronic-protonic conductivity hypothesis has been proposed after studies on eumelanin pellets exposed to different levels of relative humidity [4]. Despite impressive progress, the effect of the (supra)molecular structure of eumelanin on the electrical response of eumelanin is largely undiscovered and the possibility of electrochemical processes at eumelanin/metal electrodes interfaces has been overlooked, such that a complete description of the charge transport mechanism is still missing.[5].
Here we report on the electrochemical (cyclic voltammetry and electrochemical impedance spectroscopy, ESI) and electrical (current-voltage, I/V and transient curves) behavior of films of chemically controlled eumelanin (namely polyDHI, polyDHICA and their combinations in different ratios). We observed dramatic changes in the behavior of I/V curves and we disentangled, through ESI, the ionic/electronic contributions to the transport at different relative humidity (RH, ranging from 50% to 90%). We investigated the presence of products of irreversible interfacial processes by nano-IR, which is a combination of AFM and IR (infrared) signals at nanoscale special resolution.
Our study offers a novel approach, well beyond eumelanin, to understand the behavior of natural materials, notoriously chemically complex, to pave the way for tomorrow’s electronics.
10:15 AM - *SM1.4.05
Development of Semiconducting Polymers for Electrochemical Transistors
Iain McCulloch 1 2
1 KAUST Solar Center (KSC), King Abdullah University of Science and Technology, Thuwal Saudi Arabia, 2 Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London United Kingdom
Show AbstractOrganic electrochemical transistors (OECTs) have been shown to be promising devices for amplification of electrical signals and selective sensing of ions and biologically important molecules in an aqueous environment, and thus have potential to be utilised in bioelectronic applications. The sensitivity, selectivity and intensity of the response of this device is determined by the organic semiconducting polymer employed as the active layer. Until now, most OECTs have been fabricated with commercially available conducting poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) as the active layer, and therefore operated in depletion mode with limited modulation. This work presents the design of new organic semiconducting materials which demonstrate significant improvements in OECT performance, through operation in accumulation mode, with high transconductance and low operating voltage.
We discuss here the design, synthesis and performance of novel intrinsic semiconducting polymers for efficient accumulation mode OECT devices. Key aspects such as ion and charge transport in the bulk semiconductor and operational voltage and stability of the devices are addressed in order to elucidate important structure-property relationships. A range of new semiconducting polymers, designed to exhibit facile electrochemical doping of either holes or electrons, facilitate ion penetration and migration, as well as have aqueous compatibility are reported. Optimisation of a series of polymer parameters including electrochemical doping, charge carrier mobility and capacitance are discussed. This approach leads to the design of polymers that can outperform state-of-the-art PEDOT:PSS based depletion mode devices with peak transconductances above 20 mS, peak currents in the mA regime, on/off ratios above 105 and excellent switching times below 1 ms. In addition, we demonstrate that polymers with sufficiently high electron affinities and low ionisation potentials can achieve charge carrier ambipolarity, with both p and n-type device operation. Analysis by spectroelectrochemical measurements as well as electric impedance spectroscopy demonstrate a capacitance per volume unit (C*) of 397 F/cm3.
11:15 AM - *SM1.4.06
Volumetric Gating in All-Solid-State Bioelectronic Transducers
Paul Meredith 1 2 , Margarita Sheliakina 1 , Bernard Mostert 1
1 Centre for Organic Photonics & Electronics, School of Mathematics and Physics, University of Queensland, Brisbane, Queensland, Australia, 2 Physics Department, College of Science, Swansea University, Swansea United Kingdom
Show AbstractOne of the critical tasks in realising a bioelectronic interface is the transduction of ion and electron signals at high fidelity, and with appropriate speed, bandwidth and signal-to-noise ratio [1]. This is a challenging task considering ions and electrons (or holes) have drastically different physics. For example, even the lightest ions (protons) have mobilities much smaller than electrons in the best semiconductors, effective masses are quite different, and at the most basic level, ions are ‘classical’ entities and electrons ‘quantum mechanical’. These considerations dictate materials and device strategies for bioelectronic interfaces alongside practical aspects such as integration and biocompatibility [2].
In my talk I will detail some of these ‘differences in physics’ and demonstrate how materials that can support both ion and electronic signals can be used in simple all-solid-state electrochemical transistors. I will exemplify a new transducing interface based upon the proton conductor melanin [3], in a simple electrochemical transistor with a p-type conducting polymer. I will describe the basic mode of action of this device, and particularly outline a model for ‘volumetric gating’ whereby ions injected in the semiconductor channel perturb the transconductance. This model provides deep insight into how to design and realise optimised novel bioelectronic interfaces.
[1] “Ion bipolar junction transistors”, K. Tybrandt, K.C. Larsson, A. Richter-Dahlfors & M. Berggren, Proc. Natl Acad. Sci., 107, 9929 (2010).
[2] “Electronic and optoelectronic materials and devices inspired by nature”, P Meredith, C.J. Bettinger, M. Irimia-Vladu, A.B. Mostert & P.E. Schwenn, Reports on Progress in Physics, 76, 034501 (2013).
[3] “Is melanin a semiconductor: humidity induced self doping and the electrical conductivity of a biopolymer”, A.B. Mostert, B.J. Powell, F.L. Pratt, G.R. Hanson, T. Sarna, I.R. Gentle & P. Meredith, Proceedings of the National Academy of Sciences of the USA, 109(23), 8943-8947 (2012).
11:45 AM - SM1.4.07
Study of Short Channel-Effect and Protonic Transport in H-Bonded Molecules
Mihai Irimia-Vladu 1
1 , Joanneum Research mbH, Weiz Austria
Show AbstractThe class of H-bonded molecules of natural and nature-inspired origin introduced recently by our research group for electronics applications lacks perceptive information regarding the transport mechanism and their ultimate potential for electronics development. This presentation will report on our recent findings regarding the short channel effect on H-bonded semiconductors in OFET configuration when contact electrodes forming channels lengths down to few micrometers are deposited via nanoimprint and photolithography techniques. We assessed also the potential of those semiconductors to function as protonic transporters. These results have a crucial importance when extended to the transport mechanism of nucleic bases (adenine, guanine, thymine, cytosine and uracil).
12:00 PM - *SM1.4.08
How to Enable Ions to Flow in Bioelectronics Blend Systems
Natalie Stingelin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractIn recent years, the bioelectronics field has seen the use of an increasing variety of conducting polymers because they promise to display tunable mechanical properties (flexibility) and the ability to form an intimate interface with living tissue – in strong contrast to their inorganic counterparts. Even though transduction of ionic bio-signals into electronic signals is thought to be the key mechanism for successful integration of electronic devices in biological systems, little insight has so far been gained that allows understanding the interplay of electronic and ionic conductivity in the currently employed materials. Here we present a materials science approach to this challenge that promises to control mixed ionic/electronic transport in ‘plastics’ by blending organic semiconductors with insulating polymers – and that assists to elucidate the two processes. Since blending allows to manipulate the nature of the resulting systems with respect to its polarity and water swellability, it introduces the capability of controlling the interdiffusion of biological media through the final structures. We will also demonstrate that electronic transport can be maintained in such multicomponent systems upon blending with the insulating matrix. In addition, ion transport can be modulated via blend composition, control of solidification mechanism and selection of insulating component, which illustrates that the use of conducting/insulating polymer blends has the potential to gain more insight in such complex systems and assists in bringing multifunctionality to the final architecture, including biological activity, biodegradation, topological cues, and beyond.
12:30 PM - SM1.4.09
Imaging Ionic Transport in Organic Electrochemical Transistors with Electrochemical Strain Microscopy
Rajiv Giridharagopal 1 , Lucas Flagg 1 , Jeffrey Harrison 1 , David Ginger 1
1 , University of Washington, Seattle, Washington, United States
Show AbstractPolymer semiconductors have become increasingly popular in electrochemical transistors because of their high transconductance, simple fabrication for flexible devices, and compatibility with aqueous environments. These materials form highly nanostructured films, yet to date there are few studies investigating the interplay between ionic transport and nanoscale morphological properties. We show that in situ electrochemical strain microscopy (ESM) in aqueous electrolytes can directly probe local variations in polymer devices by measuring the sub-nanometer volumetric expansion in the film upon ion diffusion. ESM image data show that poly(3-hexylthiophene) electrochemical devices exhibit heterogeneous swelling in response to forward bias and changes in molarity of the electrolyte. Indeed, these ESM data can be explained by correlations with nanoscale stiffness maps taken on the same area. Areas of lower elastic modulus are correlated with higher ion permeability and thus greater volumetric response, which we attribute to the polymer being more amorphous and less densely packed in these regions. Similarly, areas of higher elastic modulus where the polymer is largely crystalline seem to partially impede ion diffusion. We correlate our local AFM data with device level metrics and optical absorption data to further show that these devices indeed operate in a mixed electrochemical and field-effect regime with nanometer-scale variations. We also use ESM on other polymer systems to prove the generalizability of this approach. These data show that in situ scanning probe microscopy techniques can uniquely elucidate operational physics in electrochemical transistors that are otherwise obscured at the device level and can be used to guide materials processing and design.
12:45 PM - SM1.4.10
Energetic and Spatial Mapping of the Polymer/Electrolyte Interface in Organic Electrochemical Transistors Using Electrochemical Impedance Spectroscopy and Scanning Electrochemical Microscopy
Melanie Rudolph 1 , Erin Ratcliff 1
1 , University of Arizona, Tucson, Arizona, United States
Show AbstractOrganic electrochemical transistors (OECTs) based on conductive polymers are gaining increasing interest as platforms for biomedical sensing. Their high transconductance allows for ultrasensitive detection of analytes without the need for complex electrode modifications that are typically required to achieve high sensitivity in classic electrochemical biosensors. Combination of OECTs with flexible substrates and microfluidic structures presents an attractive pathway towards the development of on-body electronic patches that will enable non-invasive, point-of-collection monitoring of biomarkers like dopamine. In such devices, the polymer film will be exposed to a spatially heterogeneous flux of analytes as well as to electric fields applied to collect the measurement signal, resulting in a heterogeneous distribution of local doping levels and, hence, conductivities. Detailed knowledge of – and ultimately control over – this spatial distribution of the polymer doping level is crucial for quantitatively accurate biomarker detection, especially if sensing with spatial resolution is required.
The focus of the present work was to study the electronic structure of polymer channels in OECTs with both energetic and spatial resolution. Films of the polymers P3HT and PEDOT:PSS were prepared on interdigitated source/drain electrode structures by spin casting or electrochemical deposition. Potential-dependent mass transport and charge transfer between the polymer channel and an electrolyte were investigated by electrochemical impedance spectroscopy (EIS), which offered a detailed insight into the polymer electronic structure. Scanning electrochemical microscopy was used to probe the spatial variation of the electrochemical activity of the polymer parallel and perpendicular to the length of the channel in OECT-type structures.
SM1.5: Wearables—Flexible, Stretchable and/or Self-Healing
Session Chairs
Wednesday PM, April 19, 2017
PCC North, 100 Level, Room 121 A
2:30 PM - *SM1.5.01
Journal of Materials Chemistry Lectureship—Catechol-Based Polymers in Bioelectronics—Biocompatible Energy Storage and Flexible Electronics
Christopher Bettinger 1
1 , Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Show AbstractInterest in catechol-bearing polymers has expanded rapidly in recent years. Catechols have been used in as functional moieties in hydrogel-based networks, adhesives, coatings, and redox-active materials. Here we present recent advances in catechol-bearing networks for applications ranging in fabricating ultracompliant electronic devices and biologically-derived electrochemical storage devices. First, the use of catechol-bearing hydrogels in transfer printing of electronic structures to ultracompliant hydrogel substrates will be presented. Photocrosslinkable hydrogels composed of poly(2-hydroxyethylmethacrylate-co-dopamine methacylate)-co-poly(ethyleneglycol)diacrylate (P(HEMA-co-DMA)-PEGDA) are prepared and characterized. The adhesive properties of P(HEMA-co-DMA)-PEGDA were measured using force-distance measurements across a range of substrate materials. These functionalized hydrogels are then used as substrates that permit transfer printing of microelectronic structures to swollen hydrated networks. Next, the use of catechol-bearing melanin networks as electrochemical storage devices will be described. Redox-active biologically-derived pigments will be used as electrode materials in both primary (secondary) batteries that utilize monovalent (multivalent) cations and aqueous electrolytes. Implications in bioelectronics and edible electronic medical devices will be discussed.
3:00 PM - SM1.5.02
Multiscale, Hierarchical Structuring of Graphene on a Polymer Substrate Using Conformal Wrinkling
Won-Kyu Lee 1 , Junmo Kang 1 , Kan-Sheng Chen 1 , Mark Hersam 1 2 3 , Teri Odom 1 2
1 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States, 2 Chemistry, Northwestern University, Evanston, Illinois, United States, 3 Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois, United States
Show AbstractPatterning three-dimensional (3D) structure into two-dimensional (2D) graphene is important for applications in stretchable bio-electronics, sensors and actuators, and energy storage devices. In particular, the crumpling of graphene via strain-relief of polymeric substrates has been pursued due to its ability to achieve large-area (> cm2) texturing. Delaminated crumpling is limited as a general approach for the 3D patterning of one-atom-thick graphene, however, because: (1) the resulting feature sizes have been limited to less than 100 nm; (2) feature ordering cannot be controlled; and (3) the design of hierarchical graphene patterns is not possible. Hierarchical structuring is critical for modulating the mechanical, chemical, and optical properties of graphene on a single surface. Here we demonstrate a conformal wrinkling process that can generate hierarchical graphene architectures. Multi-scale graphene patterning is achieved by sandwiching a soft fluoropolymer skin layer between as-synthesized graphene and pre-strained polystyrene substrates. Because the thickness of the skin is controllable with one-nanometer accuracy, the resulting graphene wrinkle wavelengths can be tuned from tens of nanometers to several micrometers. Moreover, since graphene wrinkles only occur on the skin layer regions, patterning the substrate with different skin thicknesses results in multiscale graphene wrinkles with different wavelengths and orientations side-by-side. In this manner, the mechanical stiffness of graphene can be locally tuned as a function of wrinkle wavelength without compromising the macroscale electrical conductivity. With rational design of the hierarchical structuring, our conformal wrinkling allows exquisite tailoring of graphene for advanced applications, such as sensors and nano-bio interfaces, where tunable mechanical properties and surface interactions are necessary together with electrical conductivity.
3:15 PM - SM1.5.03
Stretchable Transistor Arrays Based on Intrinsically Stretchable Polymer Semiconductor
Sihong Wang 1 , Francisco Molina-Lopez 1 , Jie Xu 1 , Jia Liu 1 , Jong Won Chung 1 , Zhenan Bao 1
1 Department of Chemical Engineering, Stanford University, Stanford, California, United States
Show AbstractFor human integrated or implanted electronic applications, transistors as the core component in electronic systems needs to have comparable mechanical properties with human skin and tissues, such as low modulus, good stretchability and flexibility. Therefore, a new generation of thin-film transistors that can function under large strain are highly desirable. Besides the device structural engineering approaches, the realization of stretchable electronics based on the development of intrinsically stretchable electronic materials could offer a number of important advantages, including larger strain tolerance, higher device density and simpler fabrication. In order to construct stretchable circuits and functional systems utilizing the intrinsically stretchable materials, the fabrication technology of stretchable transistor array is critically important. With polymer as the primary material system for the intrinsically stretchable semiconductors and dielectrics, the traditional fabrication processes for Si-electronics are not compatible. In this work, we developed the first all-solution-processed fabrication strategy that gives the first stretchable transistor array based on polymer semiconductor and dielectrics. This innovative fabrication process gives the record-high device density, a yield almost 100%, and little performance variation among individual devices. With the intrinsic stretchability of the semiconductor and the strain-engineering design, this array can keep its original performance without any degradation under a large strain up to 100%. In order to reveal its practical applicability in the development of next-generation electronics, this stretchable transistor array is further utilized as the backplane in a constructed stretchable active-matrix LED array display. In another demonstration, prototypes of stretchable logic circuits have been realized based on this stretchable transistor array. With the fabrication process reported here, future-developed intrinsically stretchable semiconductors and dielectrics can be combined to generate transistor arrays with even higher stretchability and robustness. Moreover, the nature of all-solution-processing makes this fabrication strategy scalable and cost-effective for the industrialization.
4:30 PM - SM1.5.04
Stretchable and Self-Healed Bioelectronic Devices Based on Novel Materials for Wearable Applications
Joseph Wang 1
1 , University of California, San Diego, San Diego, California, United States
Show AbstractPrinted flexible biolectronic devices, such as electrochemical biosensors and biofuel cells, have received considerable attention in the fields of wearable devices and mobile health. A challenge unique to such wearable electrochemical devices is mechanical resiliency. Mechanical damage-induced device failure is a common occurrence that can limit the operational lifespan of wearable sensors and biofuel cells. Recognizing these issues and challenges, this presentation will describe specially-engineered stretchable inks, based on conducting polymers, carbon-nanotubes and elastomeric binders that can be utilized to realize soft, highly stretchable electrochemical devices. These devices can endure strains as high as 500% with minimal impact on electrochemical properties. To address the critical issue of device failure, we will describe the first example of a self-healing all-printed electrochemical device. The self-healing inks have been carefully formulated to achieve suitable printability, favorable electrochemical behavior, along with a rapid self-healing capacity. The autonomous healing ability is incorporated within the inks by adding healing-agent loaded microcapsules. When the device is damaged, the capsules, along the crack, rupture and release the healing agent, rapidly restoring the electrical conductivity and the electrochemical response. These devices can be easily mated with the human skin for continuous non-invasive monitoring of vital chemicals, such as, electrolytes (sodium, potassium), and metabolites (lactate, alcohol). The remarkable stretchable and self-healing abilities of these devices enable them to endure extreme deformations commonly experienced by the human skin and yet perform without much impact of their sensing ability. Our work thus holds great promise in the wearable healthcare domain wherein defiance towards extreme mechanical deformations is crucial.
4:45 PM - *SM1.5.05
Ultrathin Soft Epidermal Electronics for Ambulatory Physiological Monitoring
Roozbeh Ghaffari 1
1 , MC10, Inc., Lexington, Massachusetts, United States
Show AbstractExisting classes of monitoring devices capture high fidelity physiological signals over multiple days of use. Although these existing systems have proven their utility in clinical settings, they lack the form factor and mechanical properties necessary for intimate skin contact and extended use outside of the hospital. These limitations are due in large part to the bulky and packaged components with terminal connections to wires and rigid circuit boards, which typically do not bend, stretch or adjust with the dynamic processes of the human body.
We have developed a different approach that relies on electronics and biosensors configured in ultrathin formats that achieve intimate coupling in ways that are mechanically invisible to the user. Here we describe new mechanical and electrical design strategies for achieving these medical systems with physical properties that approach that of a soft bandage worn on the epidermis. These ‘soft bioelectronics’ could measure linear motion, angular motion, temperature, cardiac activity, muscle potentials and pulse waveforms in the hospital and home settings. The sensors and associated circuitry (i.e. microcontroller, memory, voltage regulators, rechargeable battery, wireless communication modules) are embedded within an ultrathin, highly stretchable elastomeric substrate. These unique physical attributes are ideally suited for monitoring physiological signals from many regions of the body. Pilot clinical studies in patient cohorts with cardiac and neurological diseases have demonstrated the utility of this technology compared to the standard of care systems.
5:30 PM - SM1.5.07
Soft, Wearable Epidermal Microfluidic Systems Capable of Capture, Storage and Colorimetric Sensing of Sweat
Ahyeon Koh 1 , Daeshik Kang 2 , John Rogers 3
1 , Binghamton University, Binghamton, New York, United States, 2 Mechanical Engineering, Ajou University, Suwon Korea (the Republic of), 3 Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractThe ability to monitor health and disease status transdermally via analysis of sweat obviating the need for a blood draw is a medical goal and unmet need. Present sweat monitoring technology remains limited as a largely experimental practice, relying on lab-based systems. Further, these approaches are unsuitable for actively monitoring sweats during dynamic fitness, athletic and army activities. Herein, I will present the study of epidermal, flexible, conformal microfluidic devices with integrated wireless communication electronics that allow collection and point-of-care analysis of sweat. Constructed devices offer advanced biomechanical capabilities affording strong skin adhesion, in situ sweat collection via perspiration, and thus the determination of local sweat rate and volume as well as biomarker content under dynamic conditions. Microfluidic channel designs satisfying sufficient stretchability, structure stability, and vapor permeability for epidermal sweat patch applications were studied. The sweat patch enables multiple analysis of the concentration of representative biomarkers in sweat—glucose, lactate, chloride, and pH via quantitative colorimetric analysis and interrogates to smartphone utilizing near-field communication electronics. Two human studies were conducted to demonstrate assessment of perspiration with the devices: temperature and humidity controlled mild indoor cycling, and real-world outdoor use during a long distance cycling race. Indeed, the epidermal microfluidics for sweat analysis yield information of sweat loss and rate in situ and demonstrates reliable chemical assessment of perspiration compared to traditional lab-based analysis.
5:45 PM - SM1.5.08
A Several-Nanometers-Thick Gold Layer on Silver Nanowires Enhancing Migration Durability on Stretchable Electrodes for Long Therapeutic Bio-Applications
Teppei Araki 1 , Shusuke Yoshimoto 1 , Yuki Noda 1 , Ashuya Takemoto 1 , Takafumi Uemura 1 , Tsuyoshi Sekitani 1
1 , Osaka University, Osaka Japan
Show AbstractWe report gold-plating and photo-sintering methods that enable to enhance properties of silver nanowires electrodes in terms of conductivity, cyclic stretchability, and durability of ion-migration without the loss of transparency. By using bio-electrodes fabricated with these methods, electroencephalogram (EEG) was successfully monitored under wireless communication. The high reliable and high flexible bio-electrodes will be useful to record the other bio-potentials such as electromyograph (EMG), electrocardiograph (ECG), and neuron activities, etc.
Bio-electrode is required to have high reliability in exposure to saline solution and in touching soft skins and organs. Traditional bio-electrodes had MPa~GPa order of Young’s modulus values, which are more rigid than biological body. The rigidness causes inflammation and damage to the cells, tissues, and organs [1,2]. Less invasiveness and long lasting therapeutic benefits are required for soft materials such as thin polymers, rubbers, and gels. Ion-migration and degradation are also critical issues for metal electrodes because electrodes are exposed to saline solution during monitoring bio-signals.
In this report, we successfully overcame the issue against electrode reliability on ion-migration by plating a several-nanometers-thick gold on the silver nanowire’s surface. A silver nanowires film was fabricated by spraying an ethanol dispersion onto a poly(p-xylylene) (parylene) or a polyurethane substrate, followed by a treatment of electroless gold plating at 80 degree celsius for 60 seconds. The treated films showed an improved sheet resistance by 20-30% and no severe change of impedance under immersed condition in saline solution over 2 months. The gold-plated silver nanowire on rubber substrate with an additional photo-sintering process revealed the less change of electrical resistance up to 100 cyclic between 0-60% strain. With the high reliable stretchable electrode which also allowed light transmission, EEG were successfully monitored under wireless communication. The fabrication process will open a new way of transparent and stretchable bio-electrodes for long therapeutic interfaces.
Reference
[1] I. R. Minev et al., Science, 347, 159, 2015.
[2] S. Lee et al., Nature Comm., 5, 5898, 2014
Symposium Organizers
Jonathan Rivnay, Northwestern University
Magnus Berggren, Linkoping University
Rylie Green, Imperial College London
Ni Zhao, The Chinese University of Hong Kong
Symposium Support
MilliporeSigma
Suzhou Fangsheng Optoelectronics Co., Ltd
Vigor Tech USA LLC
SM1.6: Biosensing Devices and Platforms
Session Chairs
Andreas Offenhaeusser
Feng Yan
Thursday AM, April 20, 2017
PCC North, 100 Level, Room 121 A
9:00 AM - SM1.6.01
Sensitive and Reliable Bio-Detection in Fused Silica Capillary Using Streaming Current Method
Apurba Dev 1 2 , Josef Horak 1 , Amelie Eriksson Karlstrom 1 , Jan Linnros 1
1 , KTH Royal Institute of Technology, Kista Sweden, 2 Department of Engineering Sciences, Solid State Electronics, Uppsala University, Uppsala Sweden
Show AbstractA simple and inexpensive sensor that offers label-free detection of a broad range of different molecular targets has been a long-sought milestone and consequently motivated the development of novel techniques for a lab-on-chip compatible biosensor. Given the enormous potential in medical diagnostics and in personal health monitoring, a major focus of the emerging biosensor technologies has been to achieve high sensitivity and reliability, low production cost and operational convenience. In addition, a practical biosensor would also need a compatible microfluidic module to rapidly isolate potential target species from a complex medium and deliver them towards the sensing element and avoid contamination while maintaining a low sample volume. Therefore, irrespective of the sensing modality, microfluidic systems have become an important component of sensor design. However, electrokinetic effects such as streaming potential/current, which arises due to flowing electrolyte often interfere with electronic sensor and thereby complicate their integration with a microfluidic module.
We turn the problem of electrokinetic interference to our advantage and present a simple and inexpensive method for label-free detection of biomolecules. The method utilizes the streaming current technique to monitor changes in the zeta potential in a fused silica capillary as target biomolecules bind to immobilized receptors on the inner surface of the capillary. Using the method we have investigated the selectivity and response time of a panel of different biomolecules varying in size and charge: Barstar, dimeric barnase (dibarnase), human immunoglobulin (hIgG), and nucleic acids. We show that specific binding of these biomolecules can be reliably monitored using a very simple setup. We have also investigated the limit of detection of different disease markers such as C1q and CanF1 both from purified sample as well as human serum. Our results demonstrate that the method can be used for reliable detection of biomolecules down to 10 pM concentration level without requiring any advanced device fabrication procedures.
9:15 AM - SM1.6.02
Patterning of Highly Stretchable Conducting Polymer Transistors
Shiming Zhang 1 , Prajwal Kumar 1 , Gaia Tomasello 1 , Fabio Cicoira 1
1 , Polytechnique Montreal, Montreal, Quebec, Canada
Show AbstractThe fabrication of stretchable electronic devices is presently rather challenging due to the limited number of materials showing the desired combination of mechanical and electrical properties and to the lack of techniques to process and pattern them. Here we report on a fast and reliable transfer patterning process to fabricate high-resolution metal microelectrodes on polydimethylsiloxane by using ultrathin Parylene films (2 μm thick). By combining transfer patterning of metal electrodes with orthogonal patterning of the conducting polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) on a pre-stretched polydimethylsiloxane (PDMS) substrate and a biocompatible “cut and paste” hydrogel, we demonstrated a fully stretchable organic electrochemical transistor, relevant for wearable electronics, biosensors and surface electrodes to monitor body potentials.
9:30 AM - SM1.6.03
Nanosensing Platform for Drug Screening and Cytokine Detection in Inflammatory Bowel Diseases Using Carbon Nanotube-Based Biosensors
Taewan Kim 1 , Gyuyeob Oh 1 , Joo Sung Kim 2 , Byung Yang Lee 1
1 Department of Mechanical Engineering, Korea University, Seoul Korea (the Republic of), 2 Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul Korea (the Republic of)
Show AbstractMany studies in regards to methods for developing efficient drug delivery systems and detecting biomarkers for inflammatory bowel disease (IBD) have been reported. However, they are currently not in use for clinical diagnosis due to the lack of preclinical research platform which could predict treatment response of efficient drugs for IBD. Here, we report a nanoplatform based on single-walled carbon nanotube (SWCNT) field-effect transistors (FETs) for the detection of cytokines secreted by cells from inflammatory bowel disease. The nanoplatform consists of human colon epithelial cell line COLO 205 integrated with CNT FETs. First, CNT FET-based sensors that can specifically bind to the cytokine TNF-alpha, a biomarker of IBD, were prepared. It resulted in the real-time, highly sensitive and selective detection of cytokine TNF-alpha by utilizing the electrostatic gating effect from the binding of TNF-alpha to the carbon nanotubes. This mechanism is in contrast to a conventional biochemical, immunofluorescence and biophysical assays. Our sensors showed a wide detection range from 0.1pg mL-1 to 10 μL-1 with a low detection limit of 100fg mL-1. Afterwards, target activated endothelial cells were integrated with target activated endothelial cells. Using this system, the dynamic secretion of TNF-alpha was observed during the immune response of macrophages and cultured cells to the stimulation of bacteria endotoxin. We injected fluoxetine drug into cultured cells for response monitoring to cell cytokine secretion from real-cell. Sensor for drug response measured time course of cytokine secretion from the macrophage culture medium at different time points after macrophages were stimulated with 100ng mL-1 drug. The concentrations of the cytokine TNF-alpha secreted by cells in the culture medium were calculated using the calibration curve. We expect that the resultant biosensor nanoplatform for monitoring secretion of TNF-alpha by cultured live cells in real time and label-free before, during and after in vitro modeled therapeutics to enhance drug delivery specificity and IBD detection.
9:45 AM - SM1.6.04
pH Sensing with Silicon Nanoribbon Field Effect Transistors Incorporating Carbon Nanotube Porins
Xi Chen 1 2 , Huanan Zhang 1 3 , Ramya Tunuguntla 1 , Aleksandr Noy 1 2
1 Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 School of Natural Sciences, University of California, Merced, Merced, California, United States, 3 Department of Chemical Engineering, University of Utah, Salt Lake City, Utah, United States
Show AbstractAbility to monitor the acidity of cellular environment in vivo is an important medical diagnostics problem (for example, elevated glucose uptake and lactic acid release is a metabolic hallmark of cancer cells). Silicon nanoribbon field effect transistor (FET) has been extensively studied as a potential pH sensing platform, however, low anti-fouling stability and biocompatibility severely limits the applications of these devices. Recent studies have demonstrated that sub-1nm diameter carbon nanotube porins (CNTPs) embedded in lipid bilayers form very efficient proton conductor pathways. We demonstrate that incorporation of CNTPs into the silicon nanoribbon FETs results in devices that are capable of pH sensing in physiological conditions and are resistant to fouling. We will also discuss potential applications of these devices for real-time intracellular biosensing.
10:00 AM - SM1.6.05
Functionalized Atomically Thin Membrane as Motion Sensor for Ultrafast, Accurate DNA Sequencing
Alex Smolyanitsky 1
1 , Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, Colorado, United States
Show AbstractWe describe the recently introduced concept of water-immersed nucleobase-functionalized suspended atomically thin nanoribbon as an intrinsically selective device for nucleotide detection [1, 2]. This novel sensing method combines Watson-Crick selective base pairing with the ability of atomically thin membranes to deflect considerably in the out-of-plane direction under nanomechanical stress arising from only a few selectively formed hydrogen bonds. Such deflections are shown to be effectively convertible into electrical signal variation. In the case of graphene, strain-induced bandgap modification can be used. Alternatively, capacitive effect at the nanoscale can be utilized.
Using density functional theory and carefully designed atomistic molecular dynamics, we simulated continuous translocation of single-strand DNA through nucleobase-functionalized nanoribbon sensors at the rate of 12 to 66 million nucleotides per second. Graphene and monolayer molybdenum disulfide nanoribbons were used. The simulations were performed at room temperature and yield a single-measurement sequencing accuracy in the vicinity of 90% without false positives at a single base resolution. In addition, reliable detection of repeated DNA motifs is demonstrated. Simulated data is used to demonstrate electrical measurability of the described sequencing events. Sequencing is then shown to be reducible to an electrical measurement without the need for microscopy equipment. Of critical importance, the timescales of the useful events and the thermal noise differ drastically, thus requiring only low-pass filtering of the electrical current for robust signal resolution. The proposed approach is demonstrated to hold significant promise for a realistic DNA sequencing device without needing advanced data processing or highly restrictive operational conditions.
1. Paulechka, E., et al., Nucleobase-functionalized graphene nanoribbons for accurate high-speed DNA sequencing. Nanoscale, 2016. 8(4): p. 1861-1867.
2. Smolyanitsky, A., et al., A MoS2-Based Capacitive Displacement Sensor for DNA Sequencing. ACS Nano, 2016.
10:15 AM - SM1.6.06
Using DNA Devices to Track Anticancer Drug Activity
Jason Slinker 1 , Dimithree Kahanda 1 , David Boothman 2
1 Department of Physics, The University of Texas at Dallas, Richardson, Texas, United States, 2 Simmons Cancer Center, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
Show AbstractCancer treatments that exploit inherent differences in redox active enzymes to induce selective DNA damage represent a promising strategy for circumventing common therapeutic resistances. Challenges in attaining full understanding of the activity and lethality of these DNA damaging drugs involve controlling the pathways and cofactors present within the system and precisely understanding damage repair activity at the level of DNA. The Slinker Lab at UT Dallas has designed a chip platform of arrayed DNA modified electrodes that can be used to mimic the cellular environment and follow DNA repair activity. This approach enables selective management of biological cofactors and preservation of critical features of the cellular environment for real-time, selective study of repair activity, offering benefits over conventional alternatives such as gel shift, Western Blot, and comet assays. These devices were shown to sense damage-specific sensitivity thresholds on the order of femtomoles/nanograms of proteins with response times of seconds. These chips were subsequently implemented in the study of the anticancer agent beta-lapachone, which catalytically generates DNA damaging peroxide in the presence of overexpressed NAD(P)H:quinone oxidoreductase 1, a hallmark of many cancer cells. These electrochemical devices have shown real-time, selective response to drug-induced damage repair, demonstrating their utility in tracking environmental damage. Ongoing study will clarify the mechanism of selective cancer cell death induced by the DNA base-excision repair pathway.
11:00 AM - SM1.6.07
Extracting Kinetics and Thermodynamics of Helicase Binding with DNA Devices
Dimithree Kahanda 2 , Jason Slinker 2 , Kevin Du Prez 1 , Li Fan 1
2 Physics, University of Texas at Dallas, Richardson, Texas, United States, 1 Biochemistry, University of California, Riverside, Riverside, California, United States
Show AbstractHelicases, enzymes that separate two annealed strands of DNA or RNA, are involved in many critical cellular processes such as DNA replication, transcription, translation, recombination, DNA repair. Much remains to be understood about the comparative roles of the 31 non-redundant DNA helicases. Here, we utilize probe-modified DNA monolayers on multiplexed gold electrodes as a sensitive recognition element and morphologically responsive transducer of helicase binding. The electrochemical signals from these devices are highly sensitive to structural distortion of the DNA produced by the helicases.
We distinguished the details of DNA binding of three distinct XPB helicases, which belong to the Superfamily-2 of helicases. Clear changes in DNA melting temperature and duplex stability were observed upon helicase binding, shifts that could not be observed with the conventional UV-Visible absorption measurements. Binding dissociation constants were estimated in the range from 10-50 nM and correlated with observations of activity. These devices thus provided a sensitive measure of the structural thermodynamics and kinetics of helicase binding.
11:15 AM - SM1.6.08
Comprehensive Biosensor Integrated with a ZnO Nanorods FET Array for Selective Detection of Glucose, Cholesterol and Urea
Yoon-Bong Hahn 1 , Rafiq Ahmad 1
1 , Chonbuk National University, Jeonju Korea (the Republic of)
Show AbstractThe development of multiplexed nanoscale biosensors for simultaneous detection of multi-components still remains a major challenge at the nanotechnology frontier. It is well recognized that diabetes mellitus is a metabolic disorder resulting in an abnormal blood glucose level and activation of several metabolic pathways related to inflammation and apoptosis events. Cholesterol, another important biomolecule, with an increased level in blood can lead to heart diseases, stroke, coronary artery disease, arteriosclerosis, cerebral thrombosis, etc. In addition, urea in serum/blood/urine is important for the diagnosis of renal and liver diseases. To date, various types of advanced biosensor designs were proposed for the selective detection of a single component in the blood for the diagnosis and management of several diseases. Emphasizing on human health and clinical use point of view, there is an urgent requirement for the development of biosensor devices capable of simultaneous detection of clinically important biomolecules coupled with high sensitivity, excellent selectivity and fast response. In this work, inspired by the nanostructure and material benefits, for the first time, we reported a novel straightforward approach for the simultaneous detection of multicomponent (i.e. glucose, cholesterol and urea) with zinc oxide nanorods (ZnO NRs) based integrated field-effect transistors (FETs) array biosensor. Key to our sensor design is an integrated approach capable of selective and simultaneous detection of biomolecules without any interference in each sensor response. Further, the feasibility of the ZnO NRs FETs biosensor was assessed in mice and dog blood samples (normal, hypo- and hyper-glycemic).
11:30 AM - SM1.6.09
Non-Enzymatic Glucose Sensor Using Graphene Based Structure
Mahmoud Sakr 1 , Mohamed Serry 1
1 , The American University in Cairo, New Cairo Egypt
Show AbstractNon-enzymatic glucose sensors have shown excellent stability, sensitivity and selectivity when compared to enzymatic sensors. We introduce a new structure using graphene based schottky diode (graphene-metal-semiconductor junction) in glucose sensing applications by oxidation and reduction of glucose molecules on the surface of Pt-thin film and enhancement of current in presence of graphene layers on the surface of Pt. It was noticed by increasing Pt-thickness, the higher graphene growth, the higher the output current values (15µA for 50nmPt at 10mM glucose). In addition, sensitivity of the structure was tested by varying glucose concentrations between 2-15mM. Furthermore, Electrochemical measurements demonstrated glucose molecules adsorption and desorption on the surface of the structure when prepared in phosphate buffer saline (pH=7.4). Besides, selectivity test has shown the selectivity of the structure toward glucose molecules in presence of other solutions i.e. NaCl, KCl, sucrose, Na2SO4, urea and H2O2. Theoretical modeling by using tight binding and first principles confirmed glucose molecules adsorption and diffusion through the surface of graphene and charge density due to glucose oxidation and formation of gluco-lactone molecules as noticed from density functional theory, the binding energy is -0.27 eV. Moreover, charge distribution is noticed at the interface between glucose and Pt-Graphene layers. The physisorption interaction between graphene and Pt results in shifting fermi-level position and p-doping graphene so, oxidation of glucose molecules on the surface of the structure will change the local electric field distribution and the variation in schottky barrier height (SBH) in Pt/n-Si will result in detectable current changes due to molecules adsorption. This structure can be useful in future sensing applications i.e. gas sensors and electro-chemical sensors.
11:45 AM - *SM1.6.10
Solution-Gated Organic Thin-Film Transistors for High-Performance Biosensors
Feng Yan 1
1 , Hong Kong Polytechnic University, Hong Kong China
Show AbstractSolution-gated transistors have shown promising applications in biosensors due to the high sensitivity, low working voltage and the simple design of the devices. Solution-gated transistors normal have no gate dielectric and the gate voltages are applied directly on the solid/electrolyte interfaces or electric double layers near the channel and the gate, which lead to very low working voltages (about 1 V) of the transistors. On the other hand, the devices can be easily prepared by solution process or other convenient methods because of the much simpler device structure compared with that of a conventional field effect transistor with several layers. Many biosensors can be developed based on the detection of potential changes across solid/electrolyte interfaces induced by electrochemical reactions or interactions. The devices normally can show high sensitivity due to the inherent amplification function of the transistors. Here, I will introduce several types of biosensors studied by our group recently, including DNA, glucose, dopamine, uric acid, cell, and bacteria sensors, based on solution-gated organic electrochemical transistors. The biosensors show high sensitivity and selectivity when the devices are modified with functional nano-materials (e.g. graphene, Pt nanoparticles) and biomaterials (e.g. enzyme, antibody, DNA) on the gate electrodes or the channel. Furthermore, the devices are miniaturized successfully for the applications as sensing arrays. It is expected that the solution-gated organic transistors will find more important applications in the future.
12:15 PM - *SM1.6.11
Materials and Devices for Brain-Machine Interfaces
Mohammad Reza Abidian 1
1 , University of Houston, Houston, Texas, United States
Show AbstractRecent advances in nanotechnology have generated wide interest in applying nanomaterials for neural prostheses. An ideal neural interface should create seamless integration into the nervous system and performs reliably for long periods of time. As a result, many nanoscale materials not originally developed for neural interfaces become attractive candidates to detect neural signals, stimulate neurons, and regenerate axons. I have extensive experience in application of polymeric nanobiomaterials for neural interface technology, particularly in the areas of neural recording, nerve regeneration, and drug delivery. In this seminar, I will introduce state-of-the-art neural interface technologies with an emphasize on electroactive biomaterials for neural engineering, in particular for neural tissue regeneration, drug delivery to brain tumor, and neurochemical sensing.
12:45 PM - SM1.6.12
Gramicidin A and Alamethicin Bioprotonic Devices for Controlling H+ Flow
Zahra Hemmatian 1 2 , Scott Keene 2 , Erik Josberger 2 , Takeo Miyake 2 , Carina Arboleda 2 , Marco Rolandi 1 2
1 Department of Electrical Engineering, University of California Santa Cruz, Santa Cruz, California, United States, 2 Department of Materials Science and Engineering, University of Washington, Seattle, Washington, United States
Show AbstractIn biological systems, most of the communication between cells is mediated by membrane proteins and ion channels that passively allow or actively control the flow of ions and small molecules across the cell membrane. A bioelectronic device in which ion channels control ionic flow across a lipid bilayer with an applied voltage should therefore be ideal for interfacing with biological systems. Here, we demonstrate a biotic-abiotic bioprotonic device in which Pd contacts actively regulate proton (H+) flow across a supported lipid bilayer (SLB) incorporating the ion channel Gramicidin A (gA) and the voltage gated ion channel Alamethicin (ALM). This is the first time that H+ conducting channels have been integrated with Pd/PdHx H+-conducting contacts and that the H+ current flowing through these channels has been directly measured and controlled. This work opens the door to integrating more complex H+ channels such as bacteriorhodopsin at the Pd contact interface to produce responsive biotic-abiotic devices with increased functionality.
SM1.7: Neural/Cellular Interfacing and Stimulation
Session Chairs
Magnus Berggren
Rylie Green
Nick Melosh
Thursday PM, April 20, 2017
PCC North, 100 Level, Room 121 A
2:30 PM - *SM1.7.01
Massively Parallel Electrode Arrays as Neural Interfaces
Nick Melosh 3 , Mina Hanna 3 , Abdul Obaid 3 , Jun Ding 2 , Andreas Schaefer 1
3 Materials Science and Engineering, Stanford University, Stanford, California, United States, 2 , Stanford University, Stanford, California, United States, 1 , Francis Crick Institute, London United Kingdom
Show AbstractTransitioning from small numbers of neural recording electrodes to the hundreds of thousands necessary to capture even a small fraction of a region’s neural activity presents significant challenges to current brain interface approaches. Despite significant recent advances in planar cortical recording arrays, high channel count depth electrodes for stimulation or recording sub-surface regions in the brain are still lacking. Here we take a different approach to achieve high electrode counts, creating bundles of ten to one hundred thousand insulated microelectrodes, each of which can be a separate channel. Since the electrical properties and insertion of these types of microwires (~10-25 um diameter) are well known there is good confidence they can be inserted into the brain and record or stimulate neural activity. Here we show scaling and operation of these arrays as neural interface devices, and discuss the opportunities and challenges massively parallel systems provide.
3:00 PM - SM1.7.02
Conducting Polymers Thin Films and Nanoparticles for Optical Control of Animal Behavior
Maria Rosa Antognazza 1 , Giovanna Barbarella 2 , Claudia Tortiglione 2 , Fabio Benfenati 1 , Guglielmo Lanzani 1
1 , Istituto Italiano di Tecnologia, Milano Italy, 2 , National Research Council, Bologna Italy
Show AbstractUse of light for selective and spatio-temporally resolved control of animal specific functions is emerging as a valuable alternative to standard electrical methods, able to overcome many current limitations. Several strategies have been proposed, mainly exploiting photoactive mediators nearby or within the animal tissues: photo-isomerizable or photo-cleavable compounds, infrared neural stimulation, genetic expression of sensitive probes.
Here, we propose the use of organic semiconductors as efficient, versatile and biocompatible optical transducers, suitable for in vivo applications. In more detail, we report on poly-hexylthiophene (P3HT)-based materials in form of (a) thin films; (b) nanoparticles.
We fabricated a fully flexible, organic retinal prosthesis made of conjugated polymers layered onto a silk fibroin substrate. The long-term biocompatibility was extensively assessed by implanting the device in the sub-retinal space of rat animal models. Moreover, electrophysiological and behavioral analyses revealed a significant and persistent recovery of light-sensitivity and visual acuity up to 6 months after surgery.
We synthesized P3HT nanoparticles, with excellent colloidal stability in aqueous solution and optimal in vitro bio-compatibility. We then explored their use as photo-actuators in animal models of Hydra Vulgaris. We show that uptake of organic nanoparticles leads to specific light-activated effects, on both a behavioral and a molecular level. Possible photo-stimulation mechanisms will be critically discussed.
3:15 PM - SM1.7.03
Magnetothermal Multiplexing with Magnetic Nanoparticles
Michael Christiansen 1 , Jun Sang Moon 1 , Ritchie Chen 1 , Simone Schuerle 1 , Qi Ge 2 , Polina Anikeeva 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 , Singapore Institute of Technology and Design, Singapore Singapore
Show AbstractResearch on biomedical applications of magnetic nanoparticles has increasingly sought to demonstrate noninvasive actuation of a variety of cellular processes and material responses using heat dissipated by the particles in the presence of an alternating magnetic field. These approaches intend to noninvasively couple an external, electronically controlled electrical circuit to responsive biological or materials systems. Here, we theoretically motivate and experimentally demonstrate a technique to selectively couple one type of magnetic material to the external circuit at a time, offering a form of multiplexed stimulation. By modeling particle heating outside the traditional domain of validity of linear response theory, we elaborate a strategy for identifying magnetic nanoparticles that can be selectively heated at distinct alternating magnetic field conditions. Using custom made alternating magnetic field setups, independent heating of multiple nanoparticles is demonstrated in both solid and liquid matrices. Specific applications, including selective stimulation of nearby brain regions, multiplexed drug release, and multi-stage shape memory response from polymer composites are discussed.
3:30 PM - SM1.7.04
Can Electroceutical pH Modulation Affect Neuronal Excitability?
Xenofon Strakosas 1 , John Selberg 1 , Zahra Hemmatian 1 , Noah Christie 1 , Marco Rolandi 1
1 , University of California Santa Cruz (UCSC), Santa Cruz, California, United States
Show AbstractEpilepsy is a chronic condition of the brain marked by reoccurring seizures. Seizures occur when neurons inside specific brain regions fire all together simultaneously. This increased excitability results in faulty signaling that manifests in uncontrollable motions. Targeted treatment to the closest proximity of the brain epileptic regions is preferred over drug inhalation. This can be achieved by devices that can stimulate neurons, deliver drugs and locally control the pH. Acidosis is known to terminate epileptic seizures. Naturally, acidocis occurs by the increased production lactic acid and carbon dioxide during seizures or by increasing the levels of CO2 in the brain during breathing. However, breathing CO2 is not a practical way to treat epilepsy. Local pH changes can be achieved by bio-protonic devices. We present electrodes of palladium nanoparticles (protodes) able to change the pH in buffer conditions. Because of their high surface to volume ratio, palladium nanoparticles improve the proton injection resulting in modulation of pH in physiological media. As a proof of principle, we integrated brain slices with our platform and performed electrophysiological recordings under electroceutical pH modulation.
3:45 PM - SM1.7.05
A Nerve-on-a-Chip Platform to Facilitate the Design of Peripheral Nerve Interfaces
Sandra Gribi 1 , Mathis Lamarre 1 , Diego Ghezzi 1 , Stephanie Lacour 1
1 , Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne Switzerland
Show AbstractPeripheral nerves are often interfaced with cuff-based and microchannel-based nerve implants so that neural activity may be stimulated, inhibited and/or recorded. In vivo evaluation of these interfaces is mandatory but often time-consuming, and focused on single implant design. In vitro studies can provide further design freedom to the bioelectronic engineer, but neuron cultures do not replicate accurately in vivo, in-nerve conditions.
In order to overcome these restrictions, we developed a microchannel electrode platform for stimulating and recording from explanted nerve roots in a dish. The fabrication method of the platform enables to easily vary electrodes’ design parameters and materials, while the use of explanted nerve roots leads to immediate recording from bundles of axons and from a large number of samples. Furthermore the microchannel electrode design enables high signal-to-noise ratio recording of individual single-fiber action potential (SFAP).
The nerve-on-a-chip platform is prepared as follows: 8 platinum thin film electrodes are patterned on glass (pitch: 1mm) and encapsulated in a PDMS microchannel (100 x 100 µm2 cross-section, 10 mm length) thereby defining 100 x 300 µm2 electrode contacts. The chip is immersed in Hanks’ balanced salt solution kept at 37°C. Nerve roots are explanted from adult rats, and dissected to obtain strands of diameter in the 100 µm to 500 µm range. The microelectrodes are wired to standard electrophysiology hardware for stimulation and recordings. The platform allows for the tracking of SFAP propagation with varying amplitude (15 to 140 µV) as well as back propagating SFAP. By slowly increasing the current, we obtained SFAPs, multi-unit and compound action potentials, leading to a diversity of signals close to in vivo nerve activity.
We successfully implemented the nerve-on-a-chip platform to detect the velocity and direction of propagation of SFAPs. We developed a velocity calculation algorithm and evaluated its performance using recordings of 22 different SFAPs. The algorithm successfully detected all the SFAPs as well as their direction of propagation. Velocities were obtained in the 0 to 80 m/s range and correlated with SFAP amplitudes.
Next we used the platform to evaluate the inhibition of neural activity using a conjugated polymer (P3HT:PCBM). The polymer was coated inside the microchannel and locally heated using a narrow light beam. Upon green light illumination, we observed clear silencing of nerve compound action potentials.
The nerve-on-a-chip platform provides a straightforward interface with nerve strands, and offers an exciting avenue for improved nerve neuroprosthesis.
4:30 PM - SM1.7.06
Hybrid Nanosheets for Biomimetic Neural Interfaces
Sami Nazib 1 , Aneesha Kondapi 1 , Francesca Cavallo 1
1 , University Of New Mexico, Albuquerque, New Mexico, United States
Show AbstractWe developed a laboratory model which mimics neural microenvironment and at the same time allows: (i) extra-cellular recording from single neurons; (ii) optical imaging; (iii) controlled application of mechanical strain; (iv) optical stimulation/silencing of single cells. This advanced neural interface will enable a plethora of fundamental studies in electrophysiology, neuromechanobiology and optogenetics.
Specifically, we fabricated a microfluidic channel network formed by an inorganic and device-grade nanosheet on a compliant substrate. Briefly, hybrid SiO2/graphene nanosheets are transferred to a compliant substrate. Ordered arrays of 3D channels are then are obtained by guided self-assembly of the supported films under compressive strain. This process yields 3D scaffolds comprising an array of graphene electrodes to record neural activity, and an insulating coating, namely SiO2. A similar process was used to obtain channels formed by optically emitting nanosheets (i.e., SiO2 embedding Si nanocrystals) and graphene electrodes. The compliant substrate is a blend of elastomer- and gel-like polydimethylsiloxane, with an elastic modulus ranging from ~20 to 80 kPa, i.e., closely matching the natural microenvironment of neurons. The cross-sectional size of the 3D scaffolds is scaled to match the diameter of neurites so that the biological cell and the nanosheet are in close contact. Our design allows cultured neurons to live in a 3D and compliant environment, such as the one they naturally experience. Furthermore, guided confinement of neurites in microchannels which embed interfacing devices allows controlling/probing neural activity with high specificity and high signal-to-noise ratio. The close proximity between the interfacing devices and the neurites in a 3D microchannel will potentially inhibit formation of glial scars, thereby ensuring that a stable and reproducible coupling exists between devices and neurites. Structural characterization of the fabricated devices is performed by optical and electron microscopy. The integrity of the graphene electrodes after processing is confirmed by 2D micro-Raman mapping. Functional characterization of the graphene electrodes is performed by two-probe measurements. Optical emission in the visible range is acquired from Si-nanocrystals/SiO2 nanosheets via photoluminescence spectroscopy.
5:00 PM - SM1.7.08
Single Cell Intracellular Changes in Real Time during External Stimulation
Amy Gelmi 1 , Spencer Crowder 1 , Maria Joah Cruz 1 , Alexis Pena 1 , Ali Maziz 2 , Edwin Jager 2 , Molly Stevens 1
1 , Imperial College London, London United Kingdom, 2 , Linkoping University, Linkoping United Kingdom
Show AbstractThe control of stem cell fate via external stimulation is a vital contribution to the advancement of tissue engineering for regenerative medicine, and there are many external factors at play when cells interact with biomaterials[1]. Highly sensitive real-time characterisation using Atomic Force Microscopy (AFM) and micro-Raman spectroscopy (RMS) of living human mesenchymal stem cells (hMSC) elucidates the cellular response and mechanisms during applied external electrical stimulation. Real-time characterisation using AFM can directly measure single cell elasticity changes due to mechanics such as reorganisation of the cytoskeleton, and RMS of living cells can determine the progression changes in biomolecular composition. The external stimulation is provided by biocompatible conductive polymer electrodes, which are capable of electrical and mechanical stimulation.
The hMSC are able to successfully adhere and spread on the conductive polymer electrodes, with no adverse effects, over long time periods (14 days)[2,3]. A biphasic pulse stimulation is applied to the conductive polymer electrodes with the cultured cells in a live cell arrangement in order to deliver the external stimulation to the cells, whilst also simultaneously performing AFM and Raman measurements. Initial experiments demonstrate changes in the elasticity of hMSCs was observed during and post-stimulation.
Using conductive polymer actuating microchips [4] we are also able to deliver both electrical and mechanical stimulation to individual hMSC. Direct electrical or mechanical stimulation combined with cell modulus measurements and cell biochemistry spectra is a novel type of measurement in understanding the immediate response of living cells to external stimulation, and how this response may be appropriated to control stem cell fate. Once these response mechanics are better understood, the process can be improved and finely-tuned, creating a more efficient approach to tissue engineering via ‘smart’ biomaterials.
[1] S. W. Crowder, V. Leonardo, T. Whittaker, P. Papathanasiou, M.M. Stevens, Cell Stem Cell 2016, 18, 39
[2] A. Gelmi, M. K. Ljunggren, M. Rafat & E.W.H. Jager, J. Materials Chemistry B, (2)24, 2014
[3] A. Gelmi, C. Puckert, M. K. Ljunggren, M. Rafat, and E. W. Jager, RCS Advances, (6) 67, 2016
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5:15 PM - SM1.7.09
Interface Investigation of 3D-Structured Organic Semiconductors with Electrogenic Cells for Biosensing Applications
Francesca Santoro 1 , Yoeri van de Burgt 2 3 , Scott Keene 2 , Bianxiao Cui 1 , Alberto Salleo 2
1 Chemistry, Stanford University, Stanford, California, United States, 2 Material Science and Engineering, Stanford University, Stanford, California, United States, 3 Mechanical Engineering, Eindhoven University of Technology, Eidhoven, California, United States
Show AbstractInterfacing OECT’s with ionic barriers and biological systems holds considerable promise not only for building sensitive biosensors and diagnostic tools, but also for recording biological process in live cells and neurons. In fact, organic transistors or multi (organic) electrode arrays can record action potentials from electrogenic cells as well as send electrical stimuli to trigger certain electrical patterns within cells. Traditional devices are planar, and a cleft between cells and device typically forms, affecting the recorded signal quality. Recently, 3D modifications of the electrode surface have been successfully proposed for traditional metal electrodes. Here, we present a novel patterning method using a direct-write femtosecond laser process, to create well-defined micro patterns into PEDOT:PSS films. The direct-write technique is straightforward and does not involve complicated lithography or etching steps while the ultrafast nature of the process ensures a high resolution and low impact. Electrogenic cells can sense 3D cues inducing spatially guided outgrowth and stretching. Furthermore, we investigate the effective interface of electrogenic cells by using an innovative heavy metal staining/embedding procedure for scanning electron microscopy (SEM) and in situ focused ion beam (FIB) sectioning. For the first time, we are able to resolve the cellular membrane adhering on to the organic film with 20 nanometer resolution. By comparing SEM investigations with impedance spectroscopy performed on functionalized PEDOT:PSS films, we can both effectively visualize the point contacts of the cell membrane on to the 3D PEDOT structures as well as provide an estimate of the resulting electrical contact resistance and capacitance of the cleft. These in vitro morphological studies represent the first step towards a 3D implantable organic electrodes.