Force applied to a single molecule at a single nanogate molecule filter

Abstract

We have investigated the origin of molecule filtering system based on a chemical potential barrier produced by thermodynamically driven molecular flow in a nanoscopic space at nanogates. Single molecule tracking experiments prove that the highly localized potential barrier allows for selective manipulation of the target molecule. We propose the presence of a force, a few fN per molecule, to decelerate the molecule's movement at the nanogate, which is comparable to or larger than the force applied by conventional electrophoretic operation. The present force can be tuned by changing the nanogate width at the nanometre level. These findings allow us to propose an accurate design of novel devices for molecular manipulation on an ultra small scale using a very small number of molecules without any external biases.