Microfluidic device with asymmetric electrodes for cell and reagent delivery

We present the design and fabrication of a micro-electromechanical system (MEMS) device for cell and particle delivery using a combination of AC electrokinetic fluidic flow and negative dielectrophoresis (DEP) force. An array of interdigitated asymmetric microelectrode pairs were used in the planar device. The electrodes produced a net charge in the surrounding fluid, generating an AC electrokinetic fluidic motion. A non-uniform electric field with low actuation frequency from the microelectrode pairs resulted in a negative DEP force, which was responsible for pushing delivery particles away from sedimentation. The experimental results showed that the flow velocity increased rapidly from 267 μm/min to 394 μm/min when the applied frequency was increased from 10 kHz to 70 kHz for a cell-suspending medium buffer solution with a conductivity of 4.7 μS/cm. A maximum delivery velocity of 801 μm/min was obtained when the buffer conductivity was increased to 47 μS/cm with an actuation frequency of 100 kHz.

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