Net Electrophoresis of Particles in Microchannels with Multimodal Oscillatory Fields

Multimodal oscillatory fields with zero time average have recently been established to induce net electrophoretic drift of colloids, meaning that the direction of motion depends deterministically on which electrode is powered or grounded (Hashemi et al., PRE 2022). Here we explore this behavior experimentally in a microchannel geometry for a wide range of different electrolytes and electric field conditions. We observe a variety of behaviors, broadly consistent with a model predicated on asymmetric rectified electric fields (AREFs) as modified by the temporal symmetry breaking of the dual frequency modes. We discuss the implications for tunable particle manipulation by application of a multimodal field as an alternative to conventional DC fields.