Enhanced Impedance Flow Cytometry via Acoustic-Driven Microparticle Focusing in Microchannels

This work presents a new microparticle focusing technique for Impedance Flow Cytometry (IFC) affected by acoustic excitation in a microchannel with air pockets. Particle focusing is achieved by utilizing the secondary flow generated by the vibration to alter the trajectories of particles in microchannels. Different excitation frequencies are used to drive the vibration of a gas-liquid interface and two particle focusing modes are achieved under different excitation frequencies. The impedance measurement is performed downstream to verify its applicability to IFC. The results indicate that when particle focusing is present, there is a significant reduction in the standard deviation of impedance changes caused by 10 μm microspheres, dropping from 0.0096 mV to 0.0021 mV compared to non-oscillating conditions.