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Engineering the Invisible

The members of Nanoscale Science and Engineering Center are developing new materials and devices at nanometer scales to address emerging research and developing needs in national security, sensing and diagnostics, biomedical imaging, drug and vaccine development, cancer treatment, environmental and renewable energy applications.

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  • Event: Physics Colloqium
  • seminar: Curvature-Induced Dielectrophoresis for Particle and Cell Manipulations in Microfluidic Devices Abstract Dielectrophoresis (DEP) is a powerful tool that has been widely used to manipulate (e.g., focus, trap, concentrate, and sort) particles and cells in microfluidic devices. Traditional electrode-based DEP (eDEP) arises from the non-uniform high-frequency AC electric field between pairs of electrodes that are fabricated within a microchannel. This method suffers from the problems of fabrication complexity and electrode fouling etc. Such problems are significantly mitigated in the so-called insulator-based DEP (iDEP) devices, where both AC and DC electric fields can be applied through the electrodes that are positioned virtually outside a microchannel. However, in-channel insulating obstacles such as hurdles, posts, and ridges are required to create the electric field gradients. The locally amplified electric field around these micro-obstacles may cause adverse effects on both the sample and the device due to potential Joule heating and particle clogging issues. Our group has recently developed a new method that exploits the curvature of insulating walls for a diverse electrical control of particle and cell motions in microfluidic devices. Due to the variation in path length for electric current, the electric field becomes inherently non-uniform within a microchannel corner. Thus induced DEP can generate both a crossstream and a counter-stream particle motion, which are second-order function of the electric field and are superimposed to the linear electrokinetic motion for flexible particle manipulations. In this talk I will present our recent results on the dielectrophoretic focusing, trapping, concentration, and separation of particles and cells in curved microchannels and microfluidic reservoirs with applications to lab-on-a-chip systems. Biosketch Dr. Xuan is currently an assistant professor of mechanical engineering at Clemson University. He received his PhD degree from the Department of Mechanical and Industrial Engineering at University of Toronto in 2006 and Bachelor of Engineering degree from University of Science and Technology of China in 1995. He also got a Doctor of Engineering degree on Physical Electronics from Shanghai Institute of Technical Physics in 2000. Dr. Xuan’s research interests cover micro/nanofluidics fundamentals and lab-on-a-chip applications. He has published over 50 journal papers in this area with an H-index of 18.