Impedance measurement technique for high-sensitivity cell detection in microstructures with non-uniform conductivity distribution.

Particle detection in microstructures is a key procedure required by modern lab-on-a-chip devices. Unfortunately, state of the art approaches to impedance measuring as applied to cell detection do not perform well in regions characterized by non-homogeneous physical parameters due, for example, to the presence of air-liquid interfaces or when the particle-electrode distance is relatively high. This paper presents a robust impedance measurement technique and a circuit for detecting cells flowing in microstructures such as microchannels and microwells.