Microfluidic Potentiometric Cytometry for Size-Selective Micro Dispersion Analysis

Impedance-based microfluidic cytometry has proven its potential for applications in point-of-care tests and clinical diagnosis. In this work, we have developed a three-electrode microfluidic potentiometric cytometry system for robust cell size and concentration measurement. A pair of planar electrodes applies a constant voltage drop as a sensing electrode detects the potential changes caused by particle translocation events through a microchannel. The microchannel geometry was optimized based on numerical simulation to provide signal amplitudes of particles independent of cross-sectional position as well as buffer conductivity. Additionally, the signal amplitude shows non-linear characteristics with respect to particle diameter, enabling stem cell selective counting without further signal processing. Experimental results from measurements of the concentration of polystyrene particles as well as stem cells in a stromal vascular fraction (SVF) showed good agreement with manual hemocytometry (error < 2.1%). The developed system is applicable to point-of-care cell, bacteria, and microparticle analyses for global health and environmental monitoring.