Enhancement of a Label-free Dielectrophoretic Cell Sorter with an Integrated Impedance Detection System

We present a miniaturized CMOS impedance detector integrated within a dielectrophoretic microfluidic device for label-free separation, enabling the sorting and counting of particle suspensions in a fully electrical manner. This approach makes possible a truly portable system for cell sorting and analysis. Towards this end, the design of ad hoc coplanar electrodes for impedance sensing, supported by numerical simulations, is illustrated. The validation of the system with 10 m polystyrene beads is reported. A USB-controlled single-chip lock-in demodulator allows high-throughput counting of resistive peaks of 1% amplitude, with a signal-to-noise ratio >10 and with a time resolution of 200 s.