Synchronous oscillatory electro-inertial focusing of synthetic and biological particles

The 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 drug delivery. Here, we present experimental results on the focusing of synthetic and biological particles using synchronous oscillatory electro-inertial flow in a microfluidic device. By varying the phase difference between the oscillatory flow and AC electric field, we show that the focusing efficiency and the focusing positions of microparticles can be controlled. Specifically, we are able to focus 1-micron polystyrene particles or bacteria within a microfluidic channel of only 2 cm in length. Furthermore, this technique is suitable for preserving the viability of biological particles, including epithelial cells, 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 physical properties, such as size and zeta potential.