Diffusiophoresis of a charged sphere in a necked nanopore

In an attempt to improve the performance of single-molecule nanopore based biosensors, we study theoretically the diffusiophoresis of a particle along the axis of a charged, necked nanopore, and the mechanisms involved. Numerical simulation is conducted by varying the geometry of the nanopore and its charged status, the particle position, and the background salt concentration to examine the particle behavior under various conditions and to gather necessary information for future device design. We show that the strength of the local concentration gradient, the charge density of the nanopore, and the presence of the nanopore wall yield complicated and interesting diffusiophoretic behaviors, which are informative to potential applications. ? 2013 American Chemical Society.