Effects of Asymmetric Nanopore Geometries on Nanoparticle Sensing Using Track-Etched Nanopore Membranes

Abstract

Resistive pulse sensing, based on the Coulter Counter principle, is an important assay for sensing and separation processes to detect/discriminate several types of particles in various mediums. In such a set-up, attaining the signal from the smaller particles can be hard compared to larger particles. In this work, we focus on the critical role of pore shape on signal precision. We have simulated hourglass and cigar shaped nanopores to study the sensitivity for small particles. We have considered the translocation of 120 nm diameter particle by altering the surface charge as -0.001 C/m2, -0.007 C/m2 and -0.015 C/m2 under the applied potential between -0.3 V and -1 V with 0.1 increments. We have compared the signals in different concentration for identical-sized particles with varying surface charges. Comparison of pulse magnitudes and normalized current changes obtained from each pore shapes have shown that the cigar shaped pore yields more prominent signals for smaller sized particles than the hourglass pore. The results reveal that the hourglass shaped pore provides higher sensitivity than cigar shaped to discriminate the smaller particles and the hourglass pore might be preferable for nanopore sensor applications.