Enhanced Nanoparticle Sensing in a Highly Viscous Nanopore

Abstract

AbstractSlowing down translocation dynamics is a crucial challenge in nanopore sensing of small molecules and particles. Here, it is reported on nanoparticle motion‐mediated local viscosity enhancement of water‐organic mixtures in a nanofluidic channel that enables slow translocation speed, enhanced capture efficiency, and improved signal‐to‐noise ratio by transmembrane voltage control. It is found that higher detection rates of nanoparticles under larger electrophoretic voltage in the highly viscous solvents. Meanwhile, the strongly pulled particles distort the liquid in the pore at high shear rates over 103 s−1 which leads to a counterintuitive phenomenon of slower translocation speed under higher voltage via the induced dilatant viscosity behavior. This mechanism is demonstrated as feasible with a variety of organic molecules, including glycerol, xanthan gum, and polyethylene glycol. The present findings can be useful in resistive pulse analyses of nanoscale objects such as viruses and proteins by allowing a simple and effective way for translocation slowdown, improved detection throughput, and enhanced signal‐to‐noise ratio.