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Experimental, theoretical, and finite-element simulation investigations of the pressure-driven translocation of nanoparticles across a conical-shaped glass nanopore membrane (GNM) are presented. The translocation of the particles is experimentally analyzed by measuring the shape of transient pulses when current flowing between two Ag/AgCl electrodes, located on opposite sides of the GNM, is momentarily interrupted as a particle passes through the nanopore. Asymmetric triangular-shaped resistive pulses are observed for the translocation of 120 nm radius particles through a 210 nm radius GNM at a transmembrane pressure between −2 and −160 mmHg. A linear dependence is observed between the particle translocation frequency and the applied pressure. Analytical theory and finite-element simulation for pressure-driven flow through a conical-shaped pore were developed to compute the volumetric flow rate, the position-dependent particle velocity, and the particle translocation frequency. The translocation frequencies computed from theory and simulation as a function of pressure were found to be in agreement with experimental observations. The particle translocation pulse shape was also computed by a combination of finite-element simulation with a dynamic nanoparticle trajectory calculation. Surprisingly, the simulations demonstrate that pulse widths are nearly independent of the nanopore radius. The independence of pulse width on nanopore size is a consequence of both the solution velocity and the width of the electrical sensing zone increasing in proportion to the orifice radius for conical-shaped pores.
Lan et al. (Mon,) studied this question.