Dielectrophoretic Microfluidic Switching for Lab on a Chip Applications
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1004-P08-04
Dielectrophoretic Microfluidic Switching for Lab on a Chip Applications Lisen Wang1 and Abraham Philip Lee1,2 1 Biomedical Engineering Department, University of California, Irvine, 3120 Nature Science II, Irvine, CA, 92697 2 Department of Mechanical and Aerospace Engineering, University of California, Irvine, Irivne, CA, 92697
ABSTRACT Dielectrophoresis switching with vertical microelectrodes in the side wall of microchannel have been designed, fabricated and tested. With appropriate electrode design, lateral DEP force can be generated so that one can position particulates along the width of the channel. A set of interdigitated electrodes in the side wall of the microchannels is used for the generation of non-uniform electrical field to introduce DEP force to repel or attract beads/cells to the sidewalls. A countering DEP force is generated from another set of electrodes patterning on the opposing side walls. These DEP forces can be adjusted by the voltage and frequency applied. By manipulating the coupled DEP forces, the particles flowing through the microchannel can be positioned at different equilibrium points along the width direction and continue to flow into different outlets. The objects of interest can be switched to desired channel outlets in the flow with no need of any moving parts and the down-stream channel can be more than three outlets. Experimental results for switching cells to two outlets and polystyrene microbeads to five outlets have been achieved. The effect of the geometry and flow rate on the performance of the switching was studied and an analytical solution for the optimal design and operation of DEP electrode arrays has been derived from the proposed model. INTRODUCTION The field of microfluidic lab-on-a-chip aims to develop an integrated platform with multiple functions typically for applications in chemical or biological analysis systems[1, 2]. Traditional sample preparation steps are usually labour intensive and time consuming, while microfluidic systems provide the opportunities for integrating the entire analysis on a single platform. The ultimate goal using microfluidic chips is to integrate functional components to accomplish all the sample preparation steps. In a general microfluidic platform, the object of interest is usually the biological constituents. For chemical analysis, different chemical reagents need to be injected into the microfluidic channel or be sent to different channel branches with
precisely controlled volume. A microfluidic switch is usually needed to regulate the fluids and its constituents in the microfluidic networks. Different microfluidic switching techniques have been developed for controlling the flow in microchannel. Active flow control units have been integrated in the channel outlet branches to introduce back pressure to stop the flow in some outlet and direct to others. Magnetohydrodynmic(MHD) switch [3]with MHD pumps at the two outlets of the Y junction have been demonstrated for switching electrolyte solution by Lorenz force. Cheng and
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