Oscillatory electro-inertial microfluidics for tunable particle manipulation

Conventional microfluidic techniques that make use of only one force (i.e., passive or active) for particle manipulation are limited in their abilities by their low throughput or lack of tunability when it comes to complex heterogeneous samples. To overcome these limitations, the emerging field of multiphysics microfluidics integrates two or more techniques on a single device either as cascaded connections or by physical coupling. However, the richness and complexity of multiphysics microfluidic phenomena have not been thoroughly investigated or understood. Here, we present results on the electro-inertial migration of particles in coupled synchronous oscillatory pressure-driven and electrokinetic flows. Using our apparatus, oscillatory flows create an "infinite" channel length enabling the investigation of electro-inertial migration velocity and focusing positions of a range of synthetic and biological particles. We quantify the migration velocity based on relevant system parameters such as particle size, oscillatory flow frequency and amplitude, and electrokinetic mobility. By doing so, we contribute to the comprehension of fundamental mechanisms underlying electro-inertial lift and establish a versatile platform for complex particle manipulation.