(128e) Electrokinetic Colloid and Micro-Vortex Dynamics in Heterogeneous Nano-Slot Devices

Understanding the electrokinetic interaction between colloidal particles and a nanochannel is of particular interest in the field of micro- and nano-fluidics and may play an important role in biomolecular detection. At relatively high-voltages, wherein concentration-polarization (CP) and electro-convective vortices emerge, the interaction complexity is further increased. Here we study the colloid dynamics in the vicinity of a heterogeneous nanoslot device wherein field-focusing effects and geometrically modulated interface significantly affect the CP and vortices due to both Dukhin’s electro-osmosis of the 2^nd kind and Rubinstein’s electro-convective instability. In particular, trapping of colloids at the nanoslot entrance and their accumulation due field-focusing gradient effects within the diffusion layers is addressed.