High reliability microfluidic biosensor for single cell impedance cytometry

This paper presents a microfluidic biosensor for micro particles and cells differentiation using cytometry. It is based on Electrical Bio-impedance Spectroscopy and able to perform cell by cell characterization at high flow rate. Sensing area is centered in platinum coplanar microelectrodes integrated in a 20×10 μm microchannel. Operating in laminar flow conditions, it permits to highly reduce risk of cell aggregation and focused cells and particles during measurement to improve reliability. Simulations by finite element method were performed to determinate fluid velocity profile along the channel and the effect of cell shifting during characterization. Comparison with measurement show that particles were correctly focused during measurement with a position shift less than 1μm. Measurement performed on 6 μm calibrated beads, demonstrate the possibility to determine precisely the microparticles size with an error less than 2%. Measurements performed with yeast cells, red blood cells compared to calibrated beads validate the possibility to use our sensor to detect very small dimensional changes of cells and particles, the precision being function of their impedance response.