Correcting off-axis effects in an on-chip resistive-pulse analyzer

A resistive-pulse analyzer is a device that utilizes measurements of the electrical resistance of a solution-filled pore to determine the size of particles that pass through the pore. The relation between particle size and changes in the pore’s resistance is complicated by particles that travel off the central axis of the pore. Here, we present data taken using a microfabricated pore and latex colloids that illustrates the effects of off-axis particles, and propose an algorithm for removing those effects from the data. We show that the ability to remove off-axis effects increases the precision of devices that transport particles through the pore with a pressure-driven flow relative to those that use electrophoretic flow.