Analysis and Characterization of Soft-Lithography-Compatible Parallel-Electrode-Sensors in Microfluidic Devices

Microfluidic devices integrated with Coulter sensors have been widely used in counting and characterizing suspended particles. The electrodes in these devices are mostly arranged in a coplanar fashion due to a simple fabrication process and leads to non-uniform electric fields confined to the floor of the microfluidic channel. We have recently introduced a simple fabrication method that can effortlessly create parallel electrodes in microfluidic devices built with soft-lithography. In this paper, we theoretically and experimentally analyze the developed parallel-electrode Coulter sensor and compare its sensitivity with that of the Coulter sensor built on conventional coplanar electrodes. Both our simulation results and experiments with cell suspensions show that parallel-electrode Coulter sensor can provide as much as ~5× sensitivity improvement over conventional coplanar electrodes.