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Tutorial SM01—Microfluids and Microfluidic Devices

Apr 13, 2020
01:30 PM - 05:00 PM
PCC North, 200 Level, Room 221 A

Instructors: Dorian Liepmann, University of California, Berkeley; Bingcheng Lin, Dalian Institute of Chemical Physics, Chinese Academy of Sciences; D. Sakthi Kumar, Toyo University

Micro-Electromechanical Systems (MEMS)-based sensors have enormous potential for both portable and distributed applications, for example Smart Dust, which is a great example. Biological and biomedical need has been a major driver for development of new types of sensors that inherently need to work with fluids. Small sensors require small samples, which are easier to acquire and are ideal for wearable or implantable biomedical systems. This situation has led to the development of microfluidics, which describes both the fluid mechanics necessary for design and the fabrication techniques for small fluid-based systems.

Over the last 20 years, biomedical microdevices or BioMEMS have evolved in several areas. The original devices were silicon-based systems very similar to standard MEMS. Later the introduction of soft lithography using silicone-type materials as well as plastics made it possible for numerous laboratories to investigate and develop microfluidic systems. Now 3D printing has made structures that are more complex possible. In all these cases, merely shrinking existing large-scale devices has not been an effective approach for the creation of successful microsystems. In order to make devices that work well and efficiently, it is necessary to design the systems in a way that exploits the behavior of fluid flows at small scales. In general, this means laminar flows because of the inherently low Reynolds Numbers, but they tend to behave in counterintuitive ways that make design challenging. Similarly, the presence of large molecules such as DNA, cells, or small beads can also interact with the flow. 3D printed fluid systems tend to be a little larger than photolithographically fabricated devices, which means that they can operate in a transitional flow regime that permits the formation of vortical flow due to the increased inertia of the fluid. These more complex fluid flows can accelerate mixing or separate different cells.

Finally, a sensor system has to be able to provide a measurement of some aspect of the sample. Techniques to measure the concentration or even existence of a substance or analyte include fluorescence imaging, transducing the effects of a chemical reaction, or measuring a flow property. ELISA combines the first two techniques. Often, the signal is very small because the sample volume is very low. It then becomes critical to increase the concentration of the analyte or amplify its signal while maintaining reasonable signal to noise.

The tutorial sessions will introduce an overview of the history of BioMEMS materials and fabrication processes. Then the fundamentals of microfluidics will be presented focused on the designing microfluidic systems. This will include application of scaling analyses. The effects of two phases, for example molecules and particles, on the dynamics of the system will be discussed along with the appropriate nondimensional numbers needed to predict the overall behavior of the flow. A similar discussion of the effects and uses of increasing the size of the flow channels in 3D printed devices will be given. After the microfluidic section, the tutorial will switch focus to measurement techniques that can be used in BioMEMS devices including optimization of the signal to noise for accurate measurements. Lastly, current systems and applications will be presented and discussed.

1:30 pm
History of BioMEMS and Fabrication Processes

Dorian Liepmann, University of California, Berkeley

2:00 pm
Fundamentals of Microfluidic Design

Dorian Liepmann, University of California, Berkeley

3:00 pm BREAK

3:30 pm
Nanotechnology for Microfluidics and Advanced Sensors

D. Sakthi Kumar, Toyo University

Microfluidic devices are getting a lot of attraction in their use as an intermediate step between in vitro and in vivo conditions because they can mimic and simulate in vivo conditions. Currently, work is progressing to construct microfluidic devices, having many organs, implanted using multiple cell lines, and in other ways to develop “Human on a Chip,” which may be able to obtain the physiology of an individual human being as such, will enable work toward personalized precision medicine, and can be used for many advanced drug-related experiments. Based on this concept, the area of microfluidics is rapidly evolving into a sophisticated technology that may cater to the futuristic need for point-of-care (POC) devices and human-on-chip (HOC) systems with integrated sensors for autonomous and specific applications in biomedical, chemical, food or environmental research. Futuristic application of the HOC system can be visualized to integrate it to Artificial Intelligence (AI) thus providing information about potential threats to health conditions at a very early stage, which can transform the field of medicine. This may be the next development sought after by the medical community.