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Tuesday, Feb 26, 2013

8:30 AM9:30 AM Goergen Hall 101

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BME Seminar Series: Blanca H. Lapizco-Encinas - Assoc. Prof., Chemical and Biomedical Engineering, RIT

Dynamic Particle Manipulation in Microfluidic Devices Employing Dielectrophoresis


Dielectrophoresis (DEP) is the motion of particles in due to polarization effects in nonuniform electric fields; this electrokinetic transport mechanism has a great potential for the manipulation of a wide array of bioparticles, ranging from biomolecules to microorganisms. DEP can be carried out employing DC and AC electric fields. The majority of the studies on DEP have employed arrays of microelectrodes, however, employing microelectrodes has some drawbacks such as high cost and loss of functionality due to fouling. Insulator-based dielectrophoresis (iDEP) is an attractive alternative, since it employs arrays of insulating structures, instead of electrodes, to create nonuniform electric fields; resulting in inexpensive and robust devices.

This seminar presents the use of DC-iDEP and AC-iDEP for the manipulation and concentration of different types of particles (inert particles and cells). Microchannels containing arrays of cylindrical insulating posts were employed to trap, sort and concentrate particles. Experiments were performed by introducing a sample of the particles into the microchannel, and then applying an electric potential (DC o AC) across the insulating structures array, creating regions of higher and lower electric field intensity, i.e,. dielectrophoretic traps, where the particles were dielectrophoretically immobilized. The dielectrophoretic response of the particles was recorded in the form of videos and pictures. The effect of operating conditions such as microchannel geometry, magnitude of the applied potential, properties of the particles and suspending medium were studied by using a mathematical model built with COMSOL. Successful trapping of the different types of particles was achieved, demonstrating the versatility of iDEP as a technique to be used with DC or AC electric fields.