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.

Intrinsic fractional noise in nanopores: The effect of reservoirs

“…35 It also allows to probe efficiently the effect of different pore geometries. 48 The mapping has great potential to reduce the cost of simulating large reservoirs and probe further effects on nanoporous transport. For example, the mapping could easily be extended to the investigation of more varied geometries, adsorption within the pore 35 or equilibrium reactions at boundaries mimicking electrodes.…”

Review—Nanopipette Applications as Sensors, Electrodes, and Probes: A Study on Recent Developments

“…The increase in the current is caused by the increased conductivity due to the surface charge of the analyte 49 where similar behavior is also observed for other conical nanopores. 1 Even for the same analyte, pulse responses can differ depending on the salt concentration. 57 A variety of analytes can be detected by utilizing nanopipettes for resistive-pulse sensing including DNA, 58 proteins, 59 antibodies, 30 cancer biomarkers 31 and nanoparticles.…”

“…By analyzing the magnitudes, shapes, or frequency of these current-pulses, we can obtain information on the size, shape, or charge of the analyte. 1 The ion current rectification on the other hand is based on the preferential ionic flow under applied voltage and can be explained as the asymmetrical response in the current-potential (I-V) curves. 2 Besides the geometry, this phenomenon is mostly dependent on the surface charge of the nanopore and the electrical double layer (EDL).…”

Solid-State Nanopore for Molecular Detection

“…Such extreme sensitivity originates from the nanometer scale pore where the target molecules are slightly smaller than the pore diameter [11]. To date, several detection strategies were developed such as resistive pulse sensing [12], tunneling current detection [13] and optical detection [14]. Among them, label-free resistive pulse sensing has been gaining prominence which was originated from Coulter counter [15] for the counting and sizing of particles suspended in an electrolyte through a micrometer-sized hole.…”