Nanometer-Scale-Resolution Multichannel Separation of Spherical Particles in a Rocking Ratchet with Increasing Barrier Heights

We present a nanoparticle size-separation device based on nanofluidic rocking Brownian motor. It features ratchet-shaped electrostatic particle potential with increasing barrier heights along the transport direction. The sharp drop of current height is exploited to separate suspension into multiple subpopulations. By solving Fokker-Planck equation, we show that physics separation mechanism governed by energy landscape under forward tilt ratchet. For given geometry and sorting duration, applied force thus only tunable parameter increase resolution. experimental conditions 3.5 V voltage 20 s sorting, predict resolution approximately $2$ nm, supported data for separating spherical gold particles nominal diameters 80 100 nm.