Viscosity and Conductivity Tunable Diode-like Behavior for Meso- and Micropores.

Abstract

Rectifying pores, which transport ions mainly in one direction blocking the ionic flow in the other, were shown to be important in the preparation of chemical sensors, components of ionic circuits, and mimics of biological channels. Ionic rectification has been shown with various engineered systems, but pores with similar opening diameters often rectify to a various uncontrolled extent. In this Letter we present a system of single meso-pores, whose current-voltage curves and rectification can be tuned with great precision via viscosity and conductivity gradients of solutions placed on both sides of the membrane. The mechanism of rectification is based on electroosmotically induced flow, which fills the entire volume of the pore with a single solution from either side of the membrane. The highly predictable rectifying system can find various applications, including measuring viscosity of unknown media and tuning electrokinetic passage of particles.