Translocation of charged particles through a thin micropore under pressure-driven flow

Abstract

We report the effects of a particle surface charge during translocation through a thin micropore based on the simulation and experiments. The translocation of carboxylated and nonfunctionalized polystyrene beads through a fabricated micropore was measured. To compare the translocation behaviors of a particle with/without surface charge under the same driving force, we used a pressure-driven method low bias voltage. We then analyzed the signals with two factors: the translocation time and blocking current. Based on the analysis, we found that, at a low flow rate, the translocation time was largely dependent on the surface charge of the particles. More importantly, we found an unusual phenomenon that the flow rate can affect the blocking current, and the level of effect was significantly determined by the particle's surface charge. To understand this phenomenon, we suggest a plausible mechanism considering the effect of the convective flow on the counterion flux and FEM results.