Ivan K. Schuller University of California-San Diego
Yvan Bruynseraede Catholic University of Leuven
Laura M. Lechuga IMM-CNM-CSIC
Ed Johnson Ion Optics, Inc.
F1: Physical I
Monday AM, November 27, 2006
Room 204 (Hynes)
9:30 AM - **F1.1
Importance of Nanosensors: Feynman's Vision and the Birth of Nanotechnology.
Jozef T. Devreese 1 2 Show Abstract
1 TFVS, Departement Fysica, Universiteit Antwerpen, Antwerp Belgium, 2 PSN COBRA, TU/e, Eindhoven Netherlands
10:00 AM - **F1.2
Nanostructured IR Materials for Small, Uncooled Cameras.
Gail Brown 1 Show Abstract
1 Materials Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States
A small, uncooled infrared detector array is being developed as one sensor for the Integrated Nanostructured Supersensor program. The main approach is to use type-II superlattices, composed of alternating thin layers of InAs and GaSb, as the basis for a high performance, uncooled photodiode covering the mid-infrared atmospheric window of 3 to 5 μm. The photodiodes require minimal applied voltages, and have very fast response times, suitable for widely distributed, small chip platforms. The focus is on the optimization of the superlattice design and growth in order to maximize the detector photoresponse. Systematic growth and characterization studies were performed to determine optimum superlattice designs suitable for mid-infrared detection. Recent studies have focused on short period superlattices designs with periods less than 50Å. Through precision molecular beam epitaxy, design changes as small as 3Å to the superlattice layers were studied. The effects of superlattice design and growth parameters upon the photoresponse spectra will be presented. In addition, a brief review of the present state-of-the-art for uncooled, and cooled, superlattice based mid-infrared detectors and arrays will be covered.
11:00 AM - **F1.3
Microcoil NMR for Lab-on-a-Chip Applications.
Aldrik Velders 1 3 , M. Gómez 1 3 , Henk Wensink 2 3 , Han Gardeniers 2 3 , David Reinhoudt 1 3 Show Abstract
1 SupraMolecular Chemistry & Technology, University of Twente, Enschede Netherlands, 3 MESA+ Institute for Nanotechnology, University of Twente, Enschede Netherlands, 2 BIOS, the Lab-on-a-Chip group, University of Twente, Enschede Netherlands
11:30 AM - **F1.4
Advances in Vapor Phase Explosives Detection: Laser Sensors, Photonic Bandgap Fibers, and RDX and TATP- Detection.
Aimee Rose 1 Show Abstract
1 , Nomadics, Inc, Cambridge, Massachusetts, United States
Nomadics FidoXT explosives detector is a thousand times more sensitive than any of its nearest competitors. Even with this success, we continually seek to improve sensitivity of our materials and devices as well as developing new materials with sensitivities to other explosives of interest. Recently, we demonstrated a 30-fold sensitivity gain in TNT vapor detection by quenching lasing action in conjugated polymers. Because stimulated emission can be halted by competitive decay processes, TNT-induced non-radiative decay of excited states increases the stimulated emission threshold in our materials and can even prevent it entirely. Attenuation of this signal when compared to the spontaneous (linear) emission response is inherently more sensitive since signal-to-noise of the emission measurements can be improved by orders of magnitude. In addition to this advance, photonic band gap (PBG) fibers are being developed as a substrate for fluorescence-based explosive sensing materials. PBG fibers have demonstrated unprecedented visible-light containment properties that promise enhanced sensitivity as well as engineering and design flexibility. The addition of PBG fibers to Nomadics AFP-based detection platform provides increased emission (signal) collection efficiencies while creating a more versatile and agile detection device. Finally, materials with sensitivities to other explosives of interest such as TATP and RDX are under development. Targeted materials, transduction mechanisms, and preliminary sensing results will be detailed.
12:15 PM - F1.6
Growth of Nearly Epitaxial Films of NaXCoO2 on Vicinal Cut SrTiO3 Substrates by PLD for Photon Sensor Applications.
Hanns-Ulrich Habermeier 1 2 , Lan Yu 1 2 , Yoshiharu Krockenberger 1 , Pengxiang Zhang 2 Show Abstract
1 Technology, Max-Planck-Institut FKF, Stuttgart Germany, 2 IAMPE, Kunming University of Science and Technology, Kunming China
The investigation of the physical properties of the NaxCoO2-system gained much interest, recently, mainly spurred by the rich physical phenomena caused by charge-, spin- and lattice interactions. They lead to superconductivity in hydrated Na0.3CoO2 and enhanced thermoelectric power. In this contribution we explore the possibility for using NaxCoO2 thin films as thermoelectric elements and possibly phonon sensors. Similar to previous work performed on YBCO and doped LaMnO3 thin films we are exploring the applicability of these materials as thin film thermoelectric devices. We have successfully prepared single phase NaxCoO2 [x= 0.51, 0.54, and 0.59] thin films on 5° miscut SrTiO3 single crystal substrates and analysed them by X-ray diffractometry and transport measurements. In addition to the structural analysis of these films we performed transport measurements along and perpendicular to the substrate tilt direction and determined the resistivity anisotropy as a function of temperature. The results are discussed within the frame of currently discussed models for the doping dependent transport properties and a strategy for the development of NaxCoO2 based thermoelectric as well as photon detection thin film devices will be developed.
12:30 PM - **F1.7
Active Signal Processing: A Counter-intuitive Approach to Enhancing Signal-to-Noise Ratio via Noise Injection.
Thomas George 1 Show Abstract
1 , Vialogy Corp., Altadena, California, United States
F2: Physical II
Monday PM, November 27, 2006
Room 204 (Hynes)
2:30 PM - F2.1
Microfabrication of PZT/SiO2/Si3N4 Piezoelectric Nanocantilever Sensors with Attogram Mass Detection Sensitivity
Zuyan Shen 1 , Wan Shih 1 , Wei-Heng Shih 1 Show Abstract
1 Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Piezoelectric microcantilever sensor (PEMS) offers the advantages of all-electrical, direct, in-situ chemical and biological detections. Binding of target analyte to the receptor on the cantilever surface decreases the PEMS’s resonance frequency, readily measurable electrically. Past studies showed that reducing the PEMS size can dramatically enhance the PEMS detection sensitivity. The key to small functioning PEMS is the piezoelectric layer. In an earlier study, we have developed a unique sol-gel process that produced lead zirconate titanate (PZT) films more than 1.5 micron thick that exhibited a dielectric constant of 1600. PZT/SiO2 PEMS 60 micron in length, 25 micron in width were then fabricated from the PZT film that exhibited 10^-15 g/Hz mass detection sensitivity (about the mass of a single virus). Recent studies have further improved the sol-gel process and produced PZT thin films that exhibited a dielectric constant of 1900 at a thickness less than 1 micron. With the improved PZT film, we fabricated PZT/SiO2/Si3N4 PEMS 15 micron in length and 14 micron in width with a 7 micron long, 4 micron wide SiO2/Si3N4 extension to enhance the mass detection sensitivity. The resonance frequencies of the current piezoelectric nanocantilever sensor (PENS) were in the range from hundreds KHz to several MHz. The detection sensitivity is calibrated by a 10 MHz Quartz Crystal Microbalance (QCM). The mass sensitivity of a 15 micron long PZT/SiO2/Si3N4 PEMS is shown to reach 10^-17-10^-18 g/Hz, smaller than the mass of a single virus or a few protein molecules.
2:45 PM - F2.2
Simulations of Sub-wavelength Metallo-dielectric Photonic Crystals for Gas Sensing.
Rana Biswas 1 , Srinivas Neginhal 1 , Changgeng Ding 1 , Irina Puscasu 2 , Martin Pralle 2 , Mark McNeal 2 , James Daly 2 , Anton Greenwald 2 , Ed Johnson 2 Show Abstract
1 Physics & ECpE, Iowa State University, Ames, Iowa, United States, 2 , Ion-Optics Inc,, Waltham, Massachusetts, United States
3:00 PM - F2.3
Multispectral Photonic Crystal Photo Sensor.
Juejun Hu 1 , Xiaochen Sun 1 , Ching-yin Hong 1 , Jean-Francois Viens 1 , Rupa Das 1 , Anuradha Agarwal 1 , Lionel Kimerling 1 Show Abstract
1 Microphotonics Center, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
3:15 PM - F2.4
NanoParticle Tracking Analysis – The Halo system.
Bob Carr 1 Show Abstract
1 Research, NanoSight Ltd, Salisbury, Wiltshire, United Kingdom
A new technique for nanoparticle sizing that allows visualisation of nanoscale particles in liquids on an individual basis is described. The technology comprises a metallised optical element illuminated by laser beam at the surface of which deeply sub-micron (nanoscale) particles in suspension can be directly visualised, sized and counted in real time using only a conventional optical microscope fitted with a low cost camera and a dedicated analytical software package.
F3: Chemical I
Monday PM, November 27, 2006
Room 204 (Hynes)
4:30 PM - **F3.1
Mechanism of Chemical Sensing by Thin Film Resistive Metallophthalocyanine Sensors.
Forest Bohrer 1 , Amos Sharoni 2 , Corneliu Colesniuc 2 , Jeongwon Park 1 , Andrew Kummel 1 , Ivan Schuller 2 , William Trogler 1 Show Abstract
1 Chemistry, University of Calif. San Diego, La Jolla, California, United States, 2 Physics, University of Calif. San Diego, La Jolla, California, United States
Thin film chemiresistive sensors with fast response times and low power demands are of interest for use in rapid, portable detection of gas phase toxins. Standoff detection of acetylcholinesterase inhibitors, which are used as both warfare agents (Sarin, Soman) and pesticide are of interest. In this work cobalt phthalocyanine (CoPc) is explored as a sensor of organophosphates (dimethyl methylphosphonate, DMMP) and other volatile organics. The sensitivity and selectivity of CoPc is examined by analyzing the interactions of CoPc thin films (50-150 nm) with various organic vapors, and the synthesis of new functionalized CoPc molecules is undertaken to improve selectivity. Conductivity in MPc films arises from hole charge carriers and it is strongly influenced by oxygen doping. Charge injection from oxidation of MPcs by O2 has been shown to yield EPR active adducts of MPc+ and O2-. Previous studies of gas interactions with MPc thin films have focused primarily on oxidizing gases, such as ozone and NOX, which increase sensor conductivity. The interaction of MPcs with electron pair donor gases, such as ammonia, have the opposite effect, as film conductivity decreases. This behavior suggests that metal-analyte coordination strength and analyte ligand properties determine sensor response. To test this hypothesis the effects of donor ability on analyte interaction with CoPc thin films and various analytes were studied by monitoring the time-dependent direct current response (% current change) at constant voltage. Results show that the donor number of an analyte has a profound influence on the sensor response, and that CoPc films are more sensitive to strongly basic analytes than weaker ones, as ranked by the Gutmann donor number scale. The kinetics of interaction between the sensor and analyte were determined to be first order. The sensor recovery kinetics correlates with the donor number of the analyte, which is consistent with stronger bases forming more stable coordination complexes to CoPc. The role of dopant oxygen on sensor response and recovery was explored by exposing the sensors to identical doses of DMMP in dry air and in nitrogen. A two site binding model involves rapid (minutes) analyte binding to open metal coordination sites of the MPc surface molecules, which serve as hole traps and decrease conductivity. Prolonged analyte exposure causes slower (hours)displacement of oxygen from occupied binding sites, which decreases conductivity by destroying charge carriers. This research was funded by AFOSR MURI F49620-02-1-0288.
5:30 PM - **F3.3
Concentration, Manipulation, and Detection of Chemical Analytes using Porous Photonic Crystals Based on Silicon.
Michael Sailor 1 Show Abstract
1 Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, United States
Chemical reactions of nanostructured multilayers of porous silicon will be described. Electrochemical and chemical modification reactions designed to improve the sensitivity, specificity, or stability of the porous Si films will be described. Use of the materials as remote, low power microsensors for chemical toxins and pollutants will be discussed.
Ivan K. Schuller University of California-San Diego
Yvan Bruynseraede Catholic University of Leuven
Laura M. Lechuga IMM-CNM-CSIC
Ed Johnson Ion Optics, Inc.
F4: Chemical II
Tuesday AM, November 28, 2006
Room 204 (Hynes)
9:45 AM - F4.1
A CMOS Single Chip Chemical Sensor for Volatile Organic Compound Detection.
Bo Li 1 , Sarah Bedair 1 , Jessica Cooper 2 , Suresh Santhanam 1 , Lawrence Schultz 3 , Jay Snyder 4 , Richard McCullough 2 , Lee Weiss 3 , Gary Fedder 1 , David Lambeth 1 Show Abstract
1 Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 2 Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 3 Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 4 National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, Pennsylvania, United States
The development of a low cost, low power and portable device for detection and identification of volatile organic compounds (VOCs) is needed for various applications such as homeland security and monitoring of agriculture, medical, and manufacturing environments. CMOS MEMS technology has many advantages for making such sensors. It provides single chip integration of sensing devices and CMOS interfacing circuitry with smaller device sizes and power consumption. In this work, a CMOS-MEMS based single chip sensor array composed of chemiresistors have been fabricated and studied. Polythiophene polymers functionalized with varying chemical structures are used for sensing materials which has been demonstrated to be able to detect and discriminate between VOCs in our previous work. The device was fabricated with a 0.35 micron BiCMOS technology (Jazz Semiconductor). Post processes are utilized to expose the aluminum electrode array and electroless plate Au thin film on top of aluminum to provide ohmic contact to conductive polymers. The whole sensor chip contains 16 chemiresistors with on-chip multiplexer and readout electronics with a total chip size of 1.8 × 2.5 mm2. A custom designed ink-jet printing system was used to accurately deposit multiple polymer solutions on to the chemiresistor electrode arrays. The device has been tested for its sensing performance to various VOCs.
10:00 AM - F4.2
Chemical Sensing Mechanisms of Organic Transistors and Novel Techniques for Analytes Identification
Richard Yang 1 2 , William Trogler 2 , Andrew Kummel* 2 Show Abstract
1 Material Science and Engineering, UC San Diego, La Jolla, California, United States, 2 Department of Chemistry and Biochemistry , UC San Diego, La Jolla, California, United States
Organic chemically sensitive field-effect transistors (ChemFETs) have shown detection limits to parts per billion (ppb) to gases such as NO2. However, their chemical sensing mechanisms are still not well understood in literature. We have developed a basic understanding of the enhancement of sensitivity and selectivity of ChemFETs compared to chemoresistive sensors made from the same sensing material. Low-voltage operating CuPc thin-film transistors have been fabricated for the sensing studies. On these devices, we have observed that the sensitivity and selectivity can be tuned by the gate voltage. Furthermore, at low gate voltage, the ChemFET sensitivity is found to be dominated by analyte induced changes in the threshold voltage; however, at high gate voltage, the sensitivity is dominated by analyte induced changes in the mobility. We are proposing a unified sensing model to explain these phenomena: analytes absorbed by CuPc films displace surface bound oxygen molecules and create trap states and fixed charge. Therefore, analytes can be differentiated based on how they alter the density of fixed charge and the activation energy of the trap states. Transient spectroscopic techniques are being developed to identify analytes in time and frequency domains. From our variable temperature study of charge transport properties of CuPc ChemFETs, we have observed two distinct trap energies associated with interface and bulk traps respectively. These trap states are responsible for transient currents induced by gate voltage pulses. Each analyte interacted with these two populations of trap states may provide a unique signature for chemical analytes.
10:15 AM - F4.3
Nanostructured Conducting Polymers for Radio Frequency-Based Chemical Sensors.
Lintao Cai 1 , Alexey Kovalev 1 , Matthew Bray 1 , Douglas Werner 1 , Theresa Mayer 1 Show Abstract
1 Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States
Nanostructured conducting polymers (NCPs) were synthesized using chemical and electrochemical methods to obtain nanofiber, nanotube, and porous thin films of polyaniline (PANI), polypyrrole (PPY), and poly(3,4-ethylenedioxythiophene) (PEDOT) for radio frequency (RF) based chemical sensors. Comparisons of the electrical properties of 1–4 μm thick NCP films were made at DC using an interdigitated electrode structure and at radio frequencies (RF) using a cavity resonator. The DC and RF conductivity of each CP was found to be very sensitive to film morphology and porosity, with the porous materials providing the highest on-state conductivity and dynamic range of those investigated (e.g., 50 S/cm to 10-6 S/cm). In all cases, we found a direct correlation between changes in the DC and RF conductivity measured at frequencies between 1.5 and 20 GHz during exposure to chemical analytes such as HCl and NH3. The nanoporous structure of these films enabled a rapid response between the high and low conductivity states of the CP (e.g., less than 60 sec at 100 ppm NH3 for 3 μm thick PANI) despite the relatively thick layers, which are required for RF sensing applications. These DC and RF measurements show that NCP films can be incorporated into future wireless chemical sensor networks.
F5: Biosensing I
Tuesday AM, November 28, 2006
Room 204 (Hynes)
11:00 AM - **F5.1
Integrated Nucleic Acid Based Biosensor.
Carl Batt 1 , Nathaniel Cady 2 , Scott Stelick 1 , Clarissa Lui 1 , Matthew Kennedy 1 , Viktor Koltko 1 Show Abstract
1 Food Science, Cornell University, Ithaca, New York, United States, 2 Albany NanoTech, SUNY Albany, Albany, New York, United States
11:30 AM - **F5.2
Mechanical Characterization of Stimulus-responsive Hydrogels Based on Genetically Engineered Proteins for Actuation and Drug Delivery Applications.
Nitin Chopra 1 , Santoshkumar Khatwani 1 , Elizabeth Moschou 1 , Leonidas Bachas 1 , Sylvia Daunert 1 Show Abstract
1 Chemistry Department, University of Kentucky, Lexington, Kentucky, United States
12:00 PM - **F5.3
Detection of Cancer Using Nanostructured Arrays.
Andrew Kummel 1 , Manuel Ruidiaz 2 , Maria Cortes-Mateos 2 , Forest Bohrer 1 , Jian Yang 1 , Davorka Messmer 2 , Bradley Messmer 2 , Sarah Blair 2 , Jessica Wang-Rodriguez 2 , Sadik Esener 2 , Ivan Schuller 2 , William Trogler 1 Show Abstract
1 Dept. Chem., University of California-San Diego, San Diego, California, United States, 2 UCSD Moores Cancer Center, UCSD, La Jolla, California, United States
Multiple randomized prospective trials with greater than ten year follow-up have proven that breast conservation therapy (BCT) has equal survival efficacy compared to mastectomy in treating early stage breast cancer. However, obtaining a negative margin in localized excision with primary breast conservation therapy is challenging. Despite improved pre-operative imaging techniques, such as breast MRI and ultrasound, many studies report positive margin rates of 25-50% for partial mastectomy even in early stage breast cancer patients. The gold standard for achieving negative margins is to evaluate multiple intra-operative frozen sections of the excised tumor margin. This is economically unfeasible and performing multiple frozen sections on small lesions will compromise the specimens available for histological evaluation on permanent section. Pathologists have used touch preparations of the margins to limit the tissue utilized; this technique involves scraping cells off the edge of the specimen onto a slide to assess for the presence of tumor cells at the margin. However, the utility of this technique alone is limited by the pathologist’s expertise in cytology and technical difficulties related to artifacts produced by the air drying process. Therefore, there is a strong need for a real time cancer detection system to optimize BCT. We are developing a cancer cell microarray and proximity camera; the cancer cells will be directly transferred to the sensor by touching the margin of the excised breast tissue, thereby limiting the air drying artifact and providing a real-time assay for the presence or absence of cancer cells. This system combines characterization of cells based on size and shape with a focused proteomic array based on the alterations in the expressions of several protein markers in breast cancer cells. The goal is to integrate the cell array with a microlens arrays for imaging onto a CMOS imaging chip. Fabrication of a efficient array involves (a) patterning substrates with both reactive and non-reactive regions which are optically transparent, (b) using air-stable high density surface bonding so the arrays have a long shelf life, (c) careful spacing of the fluorophores from any materials which induce quenching, (d) identification of cellular phenotypes from core samples to train algorithms for cancer cell detection.
12:30 PM - F5.4
Nano Sensor Arrays for Cancer Detection
Krithika Kalyanasundaram 1 , P. Gouma 1 Show Abstract
1 Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook, New York, United States
This paper focuses on the use of arrays of nanosensors of metal oxides for measuring gases released from cancerous cell lines. Head space analysis of four different cancer cell lines namely- skin, pancreas, lung and colon, have been carried out using highly selective arrays of nanostructured tungsten trioxide based sensors in an electronic nose configuration. The sensors were fabricated using the sol-gel technology. Distinct signatures of the signal obtained from the respective cell cultures allowed for the differentiation of the cancer type involved. These highly sensitive and selective nano-metal oxide sensor arrays provide a promising technology for cancer detection.
F6: Biosensing II
Tuesday PM, November 28, 2006
Room 204 (Hynes)
2:30 PM - **F6.1
Silicon-based Photonic Bandgap Structures for Biosensing.
Philippe Fauchet 1 Show Abstract
1 ECE, University of Rochester, Rochester, New York, United States
3:00 PM - **F6.2
Plasmonic & Nanophotonic Biosensors.
Sadik Esener 1 Show Abstract
1 , University of California - San Diego, San Diego, California, United States
4:00 PM - F6.3
Magnetoplasmonics Nanobiosensors for High Sensitivity Interrogation.
Laura Lechuga 1 , Borja Sepulveda 1 , Jose Miguel Garcia-Martin 1 , Rebecca Asenjo 1 , Antonio Garcia-Martin 1 , Juan Gonzalez-Diaz 1 , Alfonso Cebollada 1 , Gaspar Armelles 1 , Roy Clarke 2 , Divine Kumah 2 , Rosa Alejandra Lukaszew 3 , Jonathan Skuza 3 Show Abstract
1 Instituto de Microelectronica de Madrid (IMM-CNM), CSIC, Tres Cantos, Madrid Spain, 2 , University of Michigan, Ann Arbor, Michigan, United States, 3 , University of Toledo, Toledo, Ohio, United States
We have recently developed a novel Magnetooptical Surface Plasmon Resonance (MOSPR) Sensor which can improve the sensitivity of the conventional Surface Plasmon Resonance (SPR) sensors1. This MOSPR sensor arises from the combination of the Surface Plasmon Resonance in thin metallic layers and the magneto-optic (MO) activity of ferromagnetic metallic materials. Such combination generates a large enhancement of the MO effects closely localized at the surface plasmon resonance.The sensor uses Co/Au multilayers of nanometric thicknesses as transducers, a prism-coupling configuration and p-polarized light to excite the surface plasmon, rotating magnets or magnetic coils to apply a modulating magnetic field, and detects the magnetooptic effects of the reflected light as a function of the angle of incidence. A large and sharp enhancement of the MO effect is produced at the angle of incidence in which SPR is excited and, likewise the conventional SPR sensors, the enhancement shifts to higher (lower) angles when the refraction index of the adjacent dielectric medium increases (decreases). Therefore, the local variations of refractive index produced within the evanescent field of the surface plasmon can be detected measuring, in real time, the changes of the MO effects of the reflected light.The layers are prepared by physical methods as sputtering and molecular beam epitaxy. Before using them as sensors, a complete characterization of the transducer has been carried out: the structure (XRD, TEM), the morphology (AFM, SEM), the magnetic (SQUID and Kerr magnetometry) and magneto-optic (Kerr spectroscopy) properties have been carefully analyzed.The experimental characterization of the MOSPR sensor has shown an increase in the limit of detection in a factor of three in changes of refractive index and in the adsorption of biomolecules as compared to the standard SPR sensors. An improvement of the limit of detection up to one order of magnitude can be achieved by an adequate combination of the magnetic-metallic layers and by decreasing the noise of the experimental set-up.In a further innovation, the thin layer of the magneto-optic transducer could be composed by magnetic nanostructures (2D or 3D) embedded in a noble metal matrix. The incorporation of magneto-optical elements tailored on the nanometer scale into the nanooptical structures can even improve the sensitivity limit due to the localisation of the magnetoplasmonic effect. B. Sepúlveda, A. Calle, L. M. Lechuga, and G. Armelles. Highly sensitive detection of biomolecules with the magneto-optic Surface Plasmon Resonance sensor. Optics Letters. 31(8), 1085-1087, 2006
4:15 PM - F6.4
The Role of Small Nanoparticle Aggregates in the Effective Design of Surface Enhanced Raman Biosensors
Li-Lin Tay 1 , Qingyan Hu 1 , Matthew Noestheden 1 , Jeff Fraser 1 , John Pezacki 1 Show Abstract
1 , National Research Council, Ottawa, Ontario, Canada
Surface enhanced Raman spectroscopy (SERS) is among one of the fastest growing plasmonic based biosensing techniques. Its single-molecule sensitivity and chemical specificity of the local environment of the nanoprobe renders it a very attractive platform for the target-specific detection. In the label-free SERS biosensors, it is necessary to rely on binding specificity between the functionalized nanoprobe (Ag or Au colloidal nanoparticles (NP), for example) and the targeted species. On one hand, surface functionalization helps to stabilize these NPs by forming a mono-dispersed system and prevents catastrophic aggregation. However, one must also understand that the ultra high SERS activities (or SERS “hot sites”) are generated through the capacitive field enhancement of two-coupled NPs (dimer) or small aggregates of NPs. Although the field enhancement factor from an individual NP is significant, it may not provide the necessary sensitivity required by many biosensors. In this study, silver NP functionalized with terminal hydrazide was employed to specifically target ketone-incorporated surface proteins over-expressed on the membrane of the transfected HeLa cells. The NP-labeled HeLa cells were then fixed and desiccated in ambient condition before subjected to optical, Raman and scanning electron microscopy (SEM). Confocal Raman imaging of the transfected HeLa cells shows a wide distribution on the number of SERS hot sites per cell. On average, approximately 6 – 12 SERS hot sites were observed per cells. Optical diffraction limit, obviously, restricts one to correlate the observed SERS signal to the morphology of SERS NPs. The large atomic number contrast between the Ag-NP and cell surface enables excellent contrast and resolution of the NPs under SEM. SEM showed that most of the NPs on the cell surfaces are in the form of small NP aggregates. In particular, the dimerized NPs are the most common form of NP aggregates. Although it is also possible to locate a single Ag NP on the cell surface, it is much less common than the aggregated clusters. We have located cells decorated with various types of NP aggregates under SEM and carried out optical and Raman microscopy of these selected cells. This correlation study shows that exceptionally intense SERS signals were obtained from both aggregated and dimerized NPs. In contrast, no detectable SERS signal was obtained from the single NP monomers. Moreover, SEM imaging performed after Raman mapping showed very localized damages to cell surface immediately beneath and adjacent to the NP aggregates. We will present results from SEM and SERS correlation studies and discuss the importance in designing the appropriate nanoprobes for SERS based biosensor platform.
4:30 PM - F6.5
Biosensing Array of Gold Nanoparticles Immobilized above Gold Surface.
Kazuma Tsuboi 2 , Kotaro Kajikawa 1 2 Show Abstract
2 PRESTO, JST, Saitama Japan, 1 Department of Electronics and Applied Physics, Tokyo Institute of Technology, Yokohama Japan
Arrayed biosensing dots composed of surface immobilized gold nanospheres (SIGNs) were fabricated above a planner gold surface using the SAM films used as a spacer. Two kinds of fabrication methods were examined: (i) patterning of the spacer SAM film that forms cross-linkage from the gold surface to the gold nanoparticles. (ii) patterning of a SAM film with microholes, followed by deposition of the spacer to form the cross-linkage. In both cases, the ordered microdots of gold nanoparticles were successfully formed, and they were probed with optical second-harmonic microscopy. Since the resonance condition of localized surface plasmons (LSPs) produced in the SIGN system is sensitive to the refractive index adjacent to the nanospheres, the SIGN system acts as an affinity biosensors. Two kinds of sensing methods were adopted to monitor a change in the LSP resonance condition: one is a reflectivity measurement of blue ray and the other is a second-harmonic generation (SHG) measurement. Both methods provide sensitive biosensor systems.
4:45 PM - F6.6
Charge Transfer Provides an Integrated Approach to Biosensor Materials.
Frank Hernandez 1 , Pahan Godakumbera 1 , Vivekanand Shete 1 , Roselyne Lichuma 1 , David Benson 1 Show Abstract
1 Chemistry, Wayne State University, Detroit, Michigan, United States
Charge transfer has been used to measure ligand-protein interactions with three materials. Our initial studies have used emission intensity changes in various sized and material semiconducting nanoparticles to monitor ligand-protein interactions. The method involves electron/charge transfer from tetraammine(5-maleimido-1,10-phenanthroline)ruthenium(II) complex cation (complex 1), attached to a surface tethered protein, to a semiconducting nanoparticle exciton. Since charge transfer can also be detected electrochemically, the ability of the same reagents to adsorb to Au electrodes for electrochemical biosensing was examined. The complex 1-tethered proteins that were attached to semiconducting nanoparticles can also be immobilized to mercaptopropylsilanized glass surfaces and monitored by single molecule spectroscopy. Finally, complex 1 has also been substituted for other maleimide-functionalized complexes with different redox thermodynamics. This combined experimental/material approach (fluorescence intensity, fluorescence lifetime, square wave voltammetry, and single molecule fluorescence trajectories) provides a mechanistic proposal of surface reactions that occur for biosensor function. The electron/charge transfer process injects one electron from complex 1 into a set of orbitals on the surface of the material. This electron/charge transfer can occur by tunneling thourgh up to four monolayers of ZnS passivation. This approach is significant, in that the same complex 1 mondified protein, or aptamer, can be attached to three different materials and provide three different signal outputs. The mechanism and integration of these biosensors will be discussed.
5:00 PM - F6.7
Measuring the Intracellular Environment with Fluorescent Nanosensors: New Delivery Methods and Sensing Mechanisms.
Jonathan Aylott 1 Show Abstract
1 School of Pharmacy, University of Nottingham, Nottingham United Kingdom
Techniques to measure the composition of the intracellular environment are important in elucidating the mechanisms of cell function and understanding cellular behaviour. Developments in the field of nanosensors may provide some solutions to enable quantification of analytes in the cellular environment, overcoming disadvantages, such as cell destruction and lack of spatial localisation, associated with the current methods of choice. The small size of the nanosensors, typically <100 nm, allows many sensors to be introduced to a single cell with minimal physical perturbation of the cell. The nanosensors discussed in this paper are prepared using microemulsion polymerization techniques and consist of one or more sensing components co-immobilised in an inert optically transparent matrix; polyacrylamide or sol-gel. The nanosensor matrix imparts two primary advantages; the sensing dye is protected from interfering species in the intracellular environment whilst simultaneously the cell is protected from any cytotoxic effects of the sensing components. Nanosensors selective to glucose, oxygen, zinc and calcium have previously been prepared and characterised in terms of dynamic range, selectivity, reversibility and response time. Challenges remain to extend the range of analytes that can be measured and improve the delivery methods used to introduce these nanosensors to cells. The use of the cell-penetrating peptide, TAT, conjugated to the nanosensor surface will be demonstrated as a delivery vector. While the application of distance dependent FRET techniques will show how nanosensors can be tuned to increase the number of analytes that can be detected.
5:15 PM - F6.8
A Self-Contained, Nano-Gap Biomolecule Impedance Sensor with Fluidic Control System.
Huinan Liang 1 , Wook Jun Nam 1 , Stephen Fonash 1 Show Abstract
1 , Center for Nanotechnology Education and Utilization, The Pennsylvania State University, University Park, Pennsylvania, United States
A sub-50nm bio-molecular direct electrical-detection structure integrated with micro- and nano-fluidic systems has been constructed. It is based on a full analysis, design and fabrication approach, which addresses noise, sensitivity, and integration issues. These devices are composed of integrated microfluidic channels in PDMS and nanofluidic channels in silicon oxide. These in turn are all integrated with a nano-gap sensing structure which may have metallic or semiconducting electrodes, as needed in an application. The microfluidic channel in PDMS provides access to the nanofluidic channel feeding the nano-gap sensing structure. By using the microfluidic channel configuration for interfacing with the outside world, effective and active fluid flow and exchange through the nanofluidic channel is achieved. A result of our design and optimization analysis is our being able to reduce background noise from the electrical double layer. We provide a demonstration of the bio-molecular sensing capabilities of our device by using the carboxyl-amino group interaction and a nano-gap structure with gold electrodes. First, probe molecules with amino groups are infused through the fluidic system to the nano-gap and are self-assembled onto the gold electrodes via thiolate bonding. Then target molecules with terminating carboxyl groups are infused to bind with the probe molecules. Impedance changes are measured electrically at each infusion and binding step using an Agilent 4284A impedance analyzer thereby detecting the appearance of each molecule type as it passes through the system. We are able to detect about 15% impedance changes with the carboxyl-amino binding occurrence. This successful, real-time electrical detection of the common carboxyl-amino binding process shows the potential detecting applications of our structure for other bio-molecules.
Ivan K. Schuller University of California-San Diego
Yvan Bruynseraede Catholic University of Leuven
Laura M. Lechuga IMM-CNM-CSIC
Ed Johnson Ion Optics, Inc.
Wednesday AM, November 29, 2006
Room 204 (Hynes)
9:30 AM - **F7.1
Integration of Nanophotonics Biosensors in Lab-on-a-chip Microsystems.
Andreu Llobera 1 , Jose del Rio 1 , Borja Sepúlveda 1 , Ana Calle 1 , Francisco Blanco 2 , Kepa Mayora 2 , Carlos Domínguez 1 Show Abstract
1 , Centro Nacional de Microelectrònica, Bellaterra Spain, 2 MEMS Department, IKERLAN S.Coop, Mondragón Spain
The progressive demand for the detection of very low concentrations of (bio)chemical substances has speed-up the development of a large variety of biosensors. Among them, photonic biosensors based on evanescent wave detection, and specially the interferometric ones, have demonstrated its outstanding properties as an extreme high sensitivity for the direct measurement of biomolecular interactions in real time and in label-free schemes. A scaling down of the photonic biosensors towards nanometer-size structures has allowed a significant increase of their sensitivity. Concretely, using evanescent-wave sensing, Mach-Zehnder interferometers with nano/micro dimensions have shown sensitivities of 7.10-6 in the refractive index , which means a sensitivity close to the picomolar level in protein detection and ability to discern single-nucleotide variations in DNA strands .Nevertheless, these results have been obtained using a conventional optical bench and macrofluidics set-ups. The next step towards a complete photonic “lab-on-a-chip” microsystem is the definition of all the required components on a single platform, and at the same time meeting the requirements of cost, disposability and portability. The photonic biosensor microsystem we are working on will be assembled by developing the following parts: (i) micro/nano sensors fabricated with standard silicon technology. The excellent optical quality of the silicon-derived materials, together with the robustness of the technology make them the most suitable for defining the micro/nano sensors, (ii) a microfluidic cartridge monolithically integrated with the sensor and with the corresponding tube connections. This component is mainly fabricated in epoxy-type polymers (as SU-8) due to its structural and chemical stability. An hybrid silicon-polymer integrated structure is presented as the optimal configuration for biosensing applications, (iii) robust immobilisation and regeneration protocols for the biological receptor on the sensor waveguide surface (iv) CMOS photodetectors (also defined with standard P-I-N silicon technology), electronic (either analogic or also integrated on the same substrate) & software control (v) final integration and packaging, which also include the peristaltic pumps, injection pumps and the reservoirs. F.Prieto et al. Nanotechnol. 14, 907-912. 2003.  F.J. Blanco et al. EUROPT(R)ODE VIII. Tübingen (Germany) 2006
10:00 AM - **F7.2
ICx Technologies Approach to Sensor Integration: An Evolutionary Process to the ``Tri-corder".
David Cullin 1 Show Abstract
1 , ICx Technologies, Washington, District of Columbia, United States
11:00 AM - **F7.3
Sensing of Interface Processes with the QCM-D and Nanoparticle Plasmon Techniques.
Christoph Langhammer 1 , Elin Larsson 1 , Alexandre Dmitriev 1 , Igor Zoric 1 , Bengt Kasemo 1 Show Abstract
1 Applied Physics, Chalmers University of Technology, Gothenburg Sweden
F8: Novel Detection Schemes I
Wednesday AM, November 29, 2006
Room 204 (Hynes)
11:45 AM - **F8.1
Interfacing Neurons with Si Micro-electronics.
Gustaaf Borghs 1 Show Abstract
1 NEXT, IMEC, Leuven Belgium
12:15 PM - **F8.2
A Semiconductor-based Field-effect Platform for (Bio-)Chemical and Physical sensors: From Capacitive EIS Sensors and LAPS over ISFETs to Nano-scale Devices.
Michael Schoening 1 , Maryam Abouzar 1 , Torsten Wagner 1 , Niko Naether 1 , David Rolka 1 , Tatsuo Yoshinobu 3 , Joachim Kloock 1 , Monika Turek 1 , Sven Ingebrandt 2 , Arshak Poghossian 1 Show Abstract
1 Laboratory for Chemical Sensors and Biosensors, Aachen University of Applied Sciences & Research Centre Juelich, IBN, Juelich, NRW, Germany, 3 Department of Electrical Engineering, Tohoku University, Sendai Japan, 2 Research Centre Juelich, Institute of Bio- and Nanosystems, Juelich, NRW, Germany
The coupling of semiconductor field-effect devices (FED) together with chemical and biological recognition elements, like functional intelligent materials, biomolecules and living cells, represents an attractive platform for the creation of different bio-/chemical sensors, multi-parameter analysis systems and bio-chips. In this work, recent developments and current activities of (bio-)chemically modified FEDs, scaling down from capacitive EIS (electrolyte-insulator-semiconductor) sensors and LAPS (light-addressable potentiometric sensor) over ISFETs (ion-sensitive field-effect transistor) to nanostructures, that have been realised in our laboratory, will be presented. Selected examples of application of FEDs for the detection of physical parameters in liquids will be discussed, too.Two strategies integrate FEDs into a flow-through cell: A modular concept has been applied to develop an ISFET-based multi-parameter system (in this system, the ISFET as an originally (bio-)chemical sensor also serves as a physical sensor), while a capacitive EIS sensor and LAPS, respectively, have been integrated into a flow-through set-up as monolithic part of a micro-machined cell fabricated by combining Si and SU-8 technology. The realised devices have been utilised for the detection of different (bio-)chemical (pH, K+, heavy metals, penicillin, organophosphorus pesticides, alliin and cyanide) and physical (temperature, flow velocity, flow direction, diffusion coefficient and liquid level) parameters. In addition, a cleaning-in-place suitable non-glass “unbreakable” EIS pH-sensor for process control in food industry, a handheld 16-channel pen-shaped “chip-card” LAPS with integrated signal processing for multi-sensor applications as well as for the visualisation of a test sample injected into the microchannel, and (bio-)chemical sensors based on a porous Si will be presented.Furthermore, with the aim to realise DNA arrays and protein chips with a direct electrical readout for a fast, simple and low-cost analysis, capacitive EIS sensors and ISFETs have been investigated for DNA-hybridisation detection as well as to monitor the layer-by-layer adsorption of polyelectrolytes. Hence, a new approach for the label-free detection of charged biomolecules based on measurements of the ion-concentration redistribution within the intermolecular spaces or in a molecular layer using FEDs will be discussed.With the aim of future development of nano-devices for detecting single biomolecules, the possibility of a simple preparation of different self-aligned nanostructures (nano-gap, nano-channel, nano-electrodes, nano-FEDs, etc.) by scaling down from micro- to nano-pattern using conventional photolithography and layer-expansion technique will be experimentally demonstrated. The introduced technique might allow to prepare structures even below 10 nm at both the laboratory and mass-production level.
F9: Novel Detection Schemes II
Wednesday PM, November 29, 2006
Room 204 (Hynes)
2:30 PM - **F9.1
Carbon Nanotube Based Biosensors.
Ernest Mendoza 1 , Jahir Orozco 2 , Victor Puntes 1 , Cecilia Jimenez 2 , Cesar Fernández-Sánchez 2 Show Abstract
1 , Institut Catala de Nanotecnologia, Bellaterra, Barcelona, Spain, 2 , Centro Nacional de Microelectrónica de Barcelona, Bellaterra, Barcelona, Spain
3:00 PM - **F9.2
Brownian Motion Approach to Biosensing: Prospects for Chimeric Phage.
Samuel Bader 1 2 Show Abstract
1 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States, 2 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States
4:00 PM - F9.3
Integrated Biosensor Based on Butt-coupled Optical Waveguide Microcantilever Arrays.
Kirill Zinoviev 1 , Jose Antonio Plaza 1 , Victor Cadarso 1 , Carlos Dominguez 1 , Laura M. Lechuga 1 Show Abstract
1 , National Microelectronics Centre, Cerdanyola del Valles, Barcelona, Spain
Microcantilever sensors for biomolecular recognition proceed from the microcantilevers used in atomic force microscopy. The principle of their operation is based on the bending induced in the cantilever when a biomolecular interaction takes place on one of its surfaces. In this way, microcantilevers translate the molecular reaction into a nanomechanical motion, which is commonly detected using optical or piezoresistive read-out. In order to achieve highly integrated microsystem with microcantilever transducers, we have recently introduced a new type of read-out technique. The technique is represented by a new generic sensing probe based on microcantilevers acting as optical waveguides operated in visible range. The principle of operation is based on the sensitivity of energy transfer between two butt coupled waveguides to their misalignment with respect to each other. This new technique can be considered as an alternative to the known methods used for read-out of nanomechanical response of microcantilevers to external force exerted on them. With the proposed method, sub-nanometer displacement of cantilever free end can be registered with a conventional photodetector. Real-time parallel monitoring of several channels can be realized because no preliminary alignment or adjustment, except for light coupling, is required. The fabricated cantilever arrays have 20 cantilevers. Each of them is 200 mm long, 40 mm wide, and 500 nm thick with a spring constant of 0.050 N/m. A subnanometer resolution in the cantilever deflection has been observed experimentally. Fabrication of the sensor was done using standard microelectronics technologies. The cantilevers are made of thermal silicon dioxide, transparent in visible range. This material was found to be suitable for the fabrication of flat rectangular waveguide cantilevers with less than one micron initial displacement, what allowed fabricating them aligned with respect to the output waveguides.For biosensing applications, a selective immobilisation of the biological receptor only on one side of the optical cantilever must be achieved. The well-known immobilisation chemistry on gold layer, normally used for biological immobilisation, can not be used due to absorption of light propagating along the cantilever if a gold layer is deposited. For that reason, two different approaches have been explored: (i) a nano ink-jet deposition of the bioreactive layer, and (ii) to use a protective layer on one side of the cantilever, which is eliminated after the immobilisation. This new device has shown good performances for biosensing and offers an interesting approach for further integration in lab-on-a-chip microsystems.
4:15 PM - F9.4
Microcapillary Condensation in Anodic Alumina Nanopores.
Felix Casanova 1 , Anne Ruminski 2 , Chang-Peng Li 1 , Igor Roshchin 1 , Michael Sailor 2 , Ivan Schuller 1 Show Abstract
1 Physics, University of California, San Diego, La Jolla, California, United States, 2 Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, United States
4:45 PM - F9.6
WITHDRAWN 11/16/06 Understanding Conduction Mechanisms in Nano-Structures.
Victor Gehman 1 , Karen Long 1 , Francisco Santiago 1 , Kevin Boulais 1 , Alfredo Rayms-Keller 1 Show Abstract
1 Code B20, Naval Surface Warfare Center, Dahlgren Division, Dahlgren, Virginia, United States
WITHDRAWN Wednesday 11/293:45 pmF9.6
5:00 PM - F9.7
Ultimate Nanoprobing in UHV: Four independent Scanning Tunneling Microscopes Navigated by High Resolution UHV SEM.
Markus Maier 1 Show Abstract
1 R&D, Omicron NanoTechnology GmbH, Taunusstein, Hessen, Germany
5:15 PM - F9.8
Thermal and Pressure Sensing by Chemoreceptive MOS Transistors (CνMOS) with PVDF Coating.
Blake Jacquot 1 , Nini Munoz 1 , Edwin Kan 1 Show Abstract
1 Electrical and Computer Engineering, Cornell University, Ithaca, New York, United States
F10: Poster Session
Wednesday PM, November 29, 2006
Exhibition Hall D (Hynes)
9:00 PM - F10.1
Integration of Functional Polymers for Sensor Applications.
Kyung Choi 1 Show Abstract
1 , Bell Labs, Lucent Technologies, Murray Hill, New Jersey, United States
9:00 PM - F10.10
Tuning of Interparticle Interactions in DNA-Nanoparticle Assemblies for Integrated Biosensing Application
Stephanie Lim 1 , Lingyan Wang 1 , Chuan-Jian Zhong 1 Show Abstract
1 Chemistry, State Univ. of New York at Binghamton, Binghamton, New York, United States
Molecularly-engineered nanoparticles have attracted growing interest because of their potential applications in biological sensing, catalysis, drug delivery, tissue repair, immunoassay, cell separation, and medical imaging. The key to such applications is the ability to tune or alter the interparticle interactions in the nanoparticle assemblies in ways favoring the desired interactions, which is especially important for integrated biosensors in biochip format. We are developing a new approach to tuning and altering the interparticle interactions in DNA-mediated assemblies of gold nanoparticles by manipulating the complimentary binding and the reaction temperature. Reversible assembly and disassembly of DNA-mediated assemblies of gold nanoparticles have been demonstrated by application of this approach. Importantly, the tailoring and reconstitution of the constituents in the DNA-gold nanoparticle assembly are demonstrated to be viable in terms of particle size and composition (e.g., alloy or magnetic nanoparticles). This demonstration has significant implications to the design of novel responsive DNA-nanoparticle nanostructures for integrated biosensing applications.
9:00 PM - F10.11
Atomic resolution AFM on NaCl at 5 K using the QPlus sensor
Markus Maier 1 , Andreas Bettac 1 , Michael Wittmann 1 , Albrecht Feltz 1 Show Abstract
1 R&D, Omicron NanoTechnology GmbH, Taunusstein, Hessen, Germany
Over many years, low temperature STM has been established as an advanced imaging and spectroscopy tool in various scientific fields. However, the creation and investigation of nano-structures on insulating surfaces pushes AFM as an alternative and complementary imaging technique. Ideally, the used AFM probe should simultaneously or alternatively work in STM and STS modes and not compromise on performance. Based on a proven LT STM platform, we have integrated a QPlus [1,2] sensor for atomic resolution AFM while maintaining ease of use and level of STM performance. Especially at low temperatures and related spatial constraints, this self-sensing AFM technique is an ideal and easy to handle alternative to cantilever based optical detection.The QPlus sensor employs a quartz tuning fork for force detection in non-contact AFM operation mode. One prong of the tuning fork is fixed while the SPM probe tip is mounted to the second prong. It thus acts as a quartz lever transforming it's oscillation into an electrical signal as a result of the piezo-electric effect. The used feedback signal is based on frequency shift originating from tip-sample force interaction. A dedicated pre-amplification technique ensures distance control based on the pure vibrational signal with perfect separation of the tunnelling current when working on conducting samples. In addition, extremely low signals require the first amplification stage to be very close to the sensor, i.e. to be compatible with low temperatures. Measurements on Si(111) 7x7 show that tunnelling current and vibrational signal are clearly separated. In addition, benchmark measurements on NaCl with a typical corrugation of approx. 10pm prove that resolution on insulation samples is competitive to best cantilever based AFM results.
9:00 PM - F10.12
Wafer Scale Fabrication of Nanoscale 12 Point Probes with TiW Electrodes.
Lauge Gammelgaard 1 , Mette Balslev 2 , Jesper Hansen 2 , Peter Petersen 2 , Peter Bøggild 1 Show Abstract
1 Department of Micro- and Nanotechnology, Technical University of Denmark, Lyngby Denmark, 2 , Capres A/S, Lyngby Denmark
The linear four-point probe is a standard technique for measuring resistivity on semiconductors and a range of other materials. By sourcing a current through two tips and measure the voltage potential drop across two tips, the resistivity can be computed for homogeneous materials, with near elimination of contact resistance. This technique has been demonstrated to work successfully on the microscale with four-point probes comprised of four individual Au coated SiO2 cantilevers and has been used for investigations on a range of materials [1-3]. This technology has a lower limit of 1 micrometer in terms of pitch. Moreover, there are other important applications where a smaller pitch would be highly advantageous, including low RA magnetic tunnel junction stacks, and carbon nanotubes. We have realized wafer scale fabrication of 4 and 12 point probes with a probe pitch down to 250 nm with electrodes made of TiW (10/90 w.t %). The electrodes are placed on a microscale SiO2 cantilever with a spring constant of around 0.5 N/m making it comparable to a contact mode AFM cantilevers and conveniently allowing for self-aligning of the probe tips to the sample surface. Having more than four electrodes on the probes allows us to select electrode combinations with different pitch during measurements with the same probe thereby making it possible to extract information on the depth profile of the resistivity. The choice of electrode material is critical; absence of an insulating oxide, good conductivity, good wear resistance and CMOS compatibility are some of the most important properties. Compared to Au (2 µΩcm), TiW has a higher resistivity of around 40 µΩcm (bulk value). This is however an acceptable trade-off, since TiW does not oxidize and it is in contrary to Au CMOS compatible. Finally TiW is more wear resistant and harder. We were able to sputter TiW films with a surface roughness of 4-7 nm on wafer scale, to facilitate good electrical electrode-surface contact. Measurements made with a current of 10 μA on an Indium Tin Oxide (ITO) surface showed a value of Rsquare of 90 Ω/square in good agreement with the expected value of 80-100 Ω/square given by the supplier of the ITO film. References C. L. Petersen, T. M. Hansen, P. Bøggild, A. Boisen, O. Hansen and F. Grey Scanning microscopic four-point conductivity probes Sensors and Actuators A, 96, 53 (2002) P. Bøggild, F. Grey, T. Hassenkam, D. R. Greve, T. Bjørnholm. Direct measurement of the microscale conductivity of conjugated polymer monolayers.Adv. Mat. 12, 947 (2000) S. Hasegawa, I. Shiraki, T. Tanikawa, C. L. Petersen, T. M. Hansen, P. Boggild, and F. Grey Direct measurement of surface-state conductance by microscopic four-point probe method J. Phys.: Condens. Matter 14 8379-8392 (2002)
9:00 PM - F10.13
Fabrication and Characterization of Single TiO2 Nanotube Nanosensor.
Dongkyu Cha 1 , Bongki Lee 1 , Jiyoung Kim 1 , Moon Kim 1 , Sanghee Won 2 , HyunJung Shin 2 , Jaegab Lee 2 , Myungmo Sung 2 Show Abstract
1 MSE, university of texas at dallas, Richardson, Texas, United States, 2 Advanced Materials Engineeering, Kookmin University, seoul Korea (the Republic of)
9:00 PM - F10.14
Single Bacterial Spore Detection with Integrated Magnetoelastic Particle Sensor on a Microfluidic Chip.
Jiehui Wan 1 , Shin Horikawa 1 , Jong Wook Hong 1 , Valery Petrenko 2 , Bryan Chin 1 Show Abstract
1 Material Engineering, Auburn University, AUBURN, Alabama, United States, 2 Department of Pathobiology, Auburn University, Auburn, Alabama, United States
9:00 PM - F10.15
Modeling of Nanogap Capacitors Used for Impedance Characterization of Living Cells.
Divya Pamaraj 1 2 , Wanda Zagozdzon-Wosik 1 2 , John Miller 3 2 , Rohith Ramaprasad 1 , Joe Charlson 1 Show Abstract
1 Electrical and Computer Engineering Department, University of Houston, Houston, Texas, United States, 2 Texas Center for Superconductivity, University of Houston, Houston, Texas, United States, 3 Physics Department, University of Houston, Houston, Texas, United States
Nano-gap MOS capacitors were studied to evaluate their limitations in applications of dielectric spectroscopy in living cells. The purpose was to optimize the design of a transducer to avoid interfacial polarization at the electrodes, which leads to frequency dependence thus causing misinterpretation of the measured sample impedance, which has its own dependence on frequency. We studied nanogap capacitors using CoventorWare software for their design and operation. Silicon IC technology was selected for designing processes in which we could limit electric double layer impedance by precisely controlling dielectric thickness of the capacitors in the range of 17 to 150 nm. The working capacitance was defined by lateral oxide etching of a comb-like capacitor structures, thus ensuring high perimeter to area ratio. Restrictions known from CMOS circuits regarding oxide leakage current, which depends on geometry and increases with the gate area were taken into account. System level module Architect, which allows for Behavior Design was first used to create comb like nanogap capacitor arrays. Our focus in analyses was on the frequency dependence of sample impedance. By performing parametric and sensitivity simulations using Saber we could identify critical parameters of the design that are important in delivering maximum response of the cell suspension acting as a capacitor dielectric. Transferring the design from Architect to a 2-D layout editor and 3-D model to Designer allowed for structure visualization with all layers. Analyzer with its multi-physics numerical capability and visualization of the obtained results was used to further tune the design. For validation purposes we fabricated several capacitors according to the simulated design parametes. Highly doped n+ polysilicon with metallization and n+ implanted Si substrate were acting as capacitor’s electrodes. Encapsulation completed the fabrication process. Capacitors were characterized, compared and used for impedance measurements of living cell suspensions. Advantages and limitations of nanogap arrays as BIOMEMS will be discussed.
9:00 PM - F10.16
Optical Properties of Zn0.46Cd0.54Se/ZnCdMgSe Multiple Quantum Wells for Infrared Photodetector Applications.
Xuecong Zhou 1 , Shengkun Zhang 1 , Hong Lu 2 , Aidong Shen 2 , Wubao Wang 1 , C y Song 3 , H c Liu 3 , B b Das 1 , Maria Tamargo 2 , Robert Alfano 1 Show Abstract
1 Physics/Institute for Ultrafast Spectroscopy and Lasers, The City College of New York, New York, New York, United States, 2 Chemistry, The City College of New York, New York, New York, United States, 3 Institute for Microstructural Sciences, National Research Council, Ottawa, Ontario, Canada
9:00 PM - F10.2
C-V Characteristics of Porous Gate MIS Capacitors with Nano-structured Carbon Nitrides for Micro Humidity Sensors
Sung Pil Lee 1 , Sung Yeop Kim 1 , Jigong Lee 1 Show Abstract
1 Electronic Engineering, Kyungnam University, Masan, Kyungnam, Korea (the Republic of)
9:00 PM - F10.3
Development of Double-cantilever Infrared Focal Plane Arrays: Fabrication and Post-process Curvature Modification
Shusen Huang 1 , Xin Zhang 1 Show Abstract
1 , Boston University, Boston, Massachusetts, United States
Uncooled double-cantilever infrared focal plane arrays (FPAs) have the potential of reaching a noise-equivalent temperature difference (NETD) approaching the theoretical limit and thus have gained increasing interest. Each pixel of the device consists of two overlapping bimaterial cantilevers that deflect in opposite directions as their temperature rises due to the absorption of incident infrared radiation. This paper reports recent progress in the development of these double-cantilever FPAs, including fabrication and post-process curvature modification. The fabrication process of microbolometer FPAs was performed by using a surface micromachining module with two sacrificial layers of polyimide. The use of spin-on polyimide allows not only an all-dry final release step overcoming stiction problems, but also complete compatibility with deposition and patterning of infrared structural layers, i.e., plasma-enhanced chemical vapor deposited SiNx and electron beam Al in this work. The as-fabricated FPAs are curved because of the imbalanced residual stresses in the bimaterial cantilevers. Proof-of-concept experiments of post-process curvature modification are then performed. The deflection of the single-cantilever microbolometer is significantly reduced by 10-min rapid thermal annealing (RTA) treatment at 325°C. However, the deflection directions of double-cantilever structures are reversed after the RTA treatment at 375°C. Results of RTA experiments on top cantilevers are summarized, demonstrating that when the annealing temperature increases the cantilevers’ curvature becomes less upward as expected. In summary, we successfully fabricate double-cantilever microbolometers using a surface micromachining module with polyimide as sacrificial materials, demonstrating that RTA is a valid method for post-process curvature modification of cantilever infrared focal plane arrays.
9:00 PM - F10.5
A Phenomenological Approach to Studying the Correlation Between Particle Size and the Sensitivity of Metal Oxide Sensors
Andrew Dougherty 1 , Bruce Patton 1 Show Abstract
1 Physics, The Ohio State University, Columbus, Ohio, United States
There has been a lot of effort expended in the study of the responses of metal oxide sensors to the presence of various gases. The ability of these sensors to withstand harsh conditions make them of particular interest for industrial applications and internal combustion engines [1-4]. The sensing mechanism is thought to be the changing thickness of a charge depletion layer around the outside of the metal oxide particles. The theory predicts a sharp increase in sensitivity when the depletion layer extends throughout the material . This has lead to interest in creating particles, films, and structures with dimensions small compared to the Debye length [1-4].
A phenomenological approach, the Integrated Reaction Conduction (IRC) model [4,7], was used to predict the effect of varying particle sizes on sensor responses. The particle sizes were chosen so that both partially and fully depleted grains were modeled. The grains become depleted when their radius is less than twice the Debye length . The IRC was also used to show what gas reactions were most important on the surface of the metal oxide particles. Different reaction kinetics can lead to different predicted responses, which may disqualify certain reaction candidates as the dominant force driving the sensing mechanism [4,7]. Finally, the IRC was used to probe information about the microstructure of the sensing surface. As sintering increases the fraction of open necks the effective medium used must change, allowing for the IRC to help determine the amount of sintering present in the oxide layer [4,7]. Other models were used to address the response times of the sensors. These covered the diffusion of gases into the interiors of porous materials, among other things. The models used depended upon the nanostructure of the material.
Where appropriate, first principles techniques and experimental observations are used to fix parameters in the model. A comparison of the phenomenological techniques are made with more fundamental approaches. The Debye length and sensitivity predictions of all methods are compared with actual experimental data. Also, sensor responses are predicted and tested. Correlations between the two are discussed, and an evaluation of the phenomenological models' ability to describe the responses of the metal oxide sensors is presented.References
1) M. E. Franke, T. J. Koplin, U. Simon: Small 1 (2006) 36-50.
2) H. Meixner, U. Lampe: Sensors and Actuators B 33 (1996) 198-202.
3) B. T. Marquis, J. F. Vetelino: Sensors and Actuators B 77 (2001) 100-110.
4) B. Chwieroth: Design and Modeling of Metal Oxide Gas Sensors: Ph.D. thesis, The Ohio State University (2001).
5) N. Barsan, U. Weimar: Journal of Electroceramics 7 (2001) 143-167.
6) N. Yamazoe, G. Sakai, K. Shimanoe: Catalysis Surveys from Asia 7 (2003) 63-75.
7) B. Chwieroth, B.R. Patton, Y. Wang: Journal of Electroceramics 6 (2001) 27-41.
9:00 PM - F10.6
An Ultra-high Sensitive Hydrogen Sensor based on a Single Pd Nanowire
Minhong Jeun 1 , Eunsongyi Lee 1 , Kyoung-il Lee 1 , Wooyoung Lee 1 Show Abstract
1 Department of Materials Science and Engineering , Yonsei University , Seoul Korea (the Republic of)
Pd nanostructures such as nanowires, nanochains, and nanotubes have recently attracted considerable interest due to the possibility of hydrogen sensor applications. The commercial hydrogen sensors are primarily types of hot wires, oxide (nitride)-semiconductor thick films, or Schottky barrier diodes. In general, these sensors have high sensitivity whereas they must be heated to approximately 400 °C for proper sensing operation. However, in recent years, Pd nanostructures were found to detect hydrogen gas at room temperature as well as to be highly sensitive and to respond fast. In the present work, we report on a novel approach to fabrication of an ultra-high sensitive hydrogen sensor using on a single Pd nanowire. Arrays of Pd nanowires (d = 20 – 200 nm) were grown by electrodeposition of an anodized aluminum oxide (AAO) template into nanochannels from an aqueous plating solution of 0.034 M PdCl2 and 0.1 M HCl. The Pd nanowires were liberated from the electroplated AAO by dissolution in a solution of 2% HF and immersed into IPA (isopropyl alcohol). The Pd nanowires were dispersed by applying a drop of IPA containing the nanowires onto a SiO2 substrate with patterned outer Au electrodes. The inner micron-scaled Au electrodes connecting the Pd nanowires with the outer electrodes were fabricated by electron beam lithography and lift off process. An individual Pd nanowire with d = 200 nm was found to operate as a hydrogen sensor in the concentration range 0.02 – 4 % at room temperature by measuring the electrical resistance change in the nanowire. In particular, the Pd nanowire was found to be able to detect hydrogen gas down to the lowest concentration of 0.02 % (200 ppm) reported in the literatures due to the highly sensitive surface activity of the Pd nanowire. The sensitivity (ΔR/R) of the Pd nanowire was determined to be 0.26 % and 15 % for the concentrations of 0.02 % and 4 %, respectively. The variation of the resistance in the nanowire was observed to be reproducible for cycles of absorption and desorption of hydrogen to the Pd nanowire in a few tens of second. When the Pd nanowire is exposed to hydrogen, (1) hydrogen molecules are absorbed on the surface of the Pd nanowire (α phase) (2) absorbed hydrogen molecules are dissociated into hydrogen atoms which diffuse into the Pd interstitial sites, and (3) react with Pd atoms to form Pd-hydride (PdHx, β phase). The resistivity of PdHx is higher then pure Pd, since hydrogen atoms play a role as additional scattering sources. The power consumption of the Pd nanowire sensor for hydrogen detection was also found to be ultra low as a few tens of nW. In this work, a hydrogen sensing device based on a single Pd nanowire is of great importance, since it permits a new evaluation of important issues related to the mechanism of hydrogen detection. The effects of surface roughness and diameters of the single Pd nanowires on the hydrogen sense will be discussed.
9:00 PM - F10.7
Optical Humidity Sensor Using Europium Luminescence.
Astrid Knall 1 , Martin Tscherner 1 , Christian Konrad 2 , Alessandro Bizzarri 2 , Volker Ribitsch 2 3 , Franz Stelzer 1 , Georg Uray 3 Show Abstract
1 Institute for Chemistry and Technology of Organic Materials, Graz University of Technology, Graz Austria, 2 Institute of Chemical Process Development and Control, Joanneum Research, Graz Austria, 3 Institute of Chemistry, Karl-Franzens University Graz, Graz Austria
The quenching of europium luminescence by water is utilized by severalgroups to determine the number of water molecules coordinated toLanthanide ions in the first coordination sphere . Bymonitoring the luminescence lifetime of europium(III) salts dissolvedin ionic liquids, the reversibility of the quenching reaction has beenproven . Moreover, it has been shown that the luminescencelifetime of Eu(III) chloride and perchlorate decreases with increasingamounts of water, both in the gaseous  and liquid state.Herein, a simple optical sensor for the determination of relativehumidity based on europium luminescence lifetime is presented.Incorporation of europium (III) into different polymer matricescombined with layer-forming application techniques yielded sensing layers. By fluorescence spectroscopy, sensor spots could be investigated in different humidity concentration environments. It can be shown that the luminescence is reversibly quenched by adding water vapour to a nitrogen atmosphere surrounding the sensing layer.Due to the non-invasive and non-destructive natureof this method for water vapour sensing a wide range of applicationscan be addressed.Sensitivity, cross-selectivity, response times and matrix effectsthereon will be discussed.1) Supkowski, R.M. and W.D. Horrocks, Inorg. Chim. Acta, 2002, 340, 44-48.2) Billard, I., et al., Eur. J. Inorg. Chem., 2004(6), 1190-1197.3) Petushkov, A.A., S.M. Shilov, and V.N. Pak, Tech. Phys. Lett., 2004, 30(11), 894-896.4) Lis, S. and G.R. Choppin, Anal. Chem., 1991, 63(21), 2542-2543.
9:00 PM - F10.8
Ferroelectric Modulation of 2-D Photonic Crystal Emission for Gas Detection.
Anton Greenwald 1 , Irina Puscasu 1 , Mark McNeal 1 , Edward Johnson 1 , James Daly 1 , Martin Pralle 1 , Yasmin Afsar 1 Show Abstract
1 , Ion Optics, Inc., Waltham , Massachusetts, United States
We have developed a single chip MEMS device for infrared spectroscopic sensing of vapors based on the use of photonic crystal (PC) emission.  A thin filament emits IR radiation limited to a narrow band by PC coating formed by lithography. The light passes through vapors to be sensed and is re-imaged on the filament where the PC now acts a preferential absorber. Optical absorption is detected as a temperature change. Pulse heating the filament increases signal to noise ratio but our device cannot operate at a frequency greater than 2 Hz Replacing the dielectric of the PC with ferroelectric material that can be electrically modulated at high frequency could increase device sensitivity. However, the change in wavelength shift or polarization with applied electric field is small. We will report initial experimental results for applied fields both normal and parallel to the surface. - “Photonic Crystals Enable Infrared Gas Sensors Irina Puscasu*, Ed Johnson, Martin Pralle, Mark McNeal, Jim Daly, and Anton Greenwald , presented at SPIE conference symposium on “Nanoengineering: Fabrication, Properties, Optics, and Devices”, Denver, CO (2004), SPIE Proc. v5515, p.58 (2004).
9:00 PM - F10.9
Multi-walled Carbon Nanotube based Aromatic Hydrocarbon Sensor
Sudhaprasanna Padigi 1 , Ravi Kiran Kondamareddy 1 , Vindhya Kunduru 1 , Shalini Prasad 1 Show Abstract
1 Electrical and Computer Engineering, Portland State University, Portland, Oregon, United States