Role of Nanopore Geometry in Particle Resolution by Resistive-Pulse Sensing

Abstract

Nanopores as resistive pulse sensors can effectively detect single-particles of several types including molecules without the need of labelling. Although pore geometry has a significant role in the formation of the obtained signals, it has been investigated relatively little. In the present study, we run simulations to consider the effects of pore geometry and compare conical, cigar and hourglass shaped pores at the conditions where both the resistive and conductive pulses occur in the conical pore. We examine the pulse magnitudes in relation to variations in size and charge for spherical particles. We also compare the pore geometries for when the particles pass through an off-axis trajectory, close to the pore wall. The results show that distorting the conical shape into an hourglass or a cigar shape can significantly enhance the sensing capability of the nanopore. We show that at identical conditions, the hourglass pore only generates resistive pulses unlike the other two geometries. In the absence of the conductive pulses, the hourglass pore is robust to the variations in the particle charge and its pulse magnitudes are less affected by the particle trajectory than the cigar pore. The comparison shows that the hourglass pore may yield the best performance for size discrimination purposes. On the other hand, the conductive pulses carry valuable information and accordingly, by the aid of conductive pulses, the cigar pore can outperform the other geometries for the detection of charged particles.