Particle Size Determination in Impedance Flow Cytometry Using Measured Opacity

Microfluidic electrical flow cytometry is a popular method to study a wide variety of biological cell properties. Unfortunately, when using coplanar electrodes, this method is sensitive to positional differences of passing particles or cells. In this work we present a novel compensation method to account for the particle position in a coplanar electrode setup using the measured electrical opacity. We demonstrate an accurate size discrimination of 5, 6 and 7 µm polystyrene beads irrespective of their position using the measured electrical opacity making use of the variation of electrical field strength with height in the channel. Thus, only two electrodes are required, which is favorable for microfluidic devices with size limitations.