Synchronous oscillatory electro-inertial focusing of biological particles

Manipulation of microparticles and living cells using active and passive techniques in microfluidic devices is useful for a variety of applications including filtration of contaminants, flow cytometry, and microfluidic mixing. Here, we present experimental results on the focusing of biological particles including bacteria and epithelial cells using synchronous oscillatory electro-inertial flow in a microfluidic device. By varying the phase difference between an oscillatory flow and AC electric field, we show that the focusing efficiency and the focusing positions of bioparticles can be controlled. Specifically, we are able to focus E. coli bacteria (1 μm) in a short channel of only 2 cm in length. Furthermore, this technique is suitable for preserving the viability of bioparticles, including epithelial cells (70 μm), due to the low shear stress experienced in the device. These results show that synchronous oscillatory electro-inertial microfluidics offers novel capabilities for manipulating microscale biological particles based on their size and surface properties, such as zeta potential.