Electrically gated nanoporous membranes

We propose a novel nanoporous membrane platform which allows for low-power electrical control of diffusion of charged molecules through field-effect gating for smart drug delivery systems. An applied gate voltage controls the electrical potential in the nanochannel resulting in either enrichment or exclusion of charged molecules. Molecules with the same polarity as the channel potential are excluded from the nanochannel due to electrostatic repulsion, whereas molecules with opposite charge are enriched due to electrostatic attraction. Therefore, the diffusive flow of the charged molecules can be controlled by a single gate voltage without the need for any other driving mechanism provided the molecule of interest is charged. An anodic aluminum oxide (AAO) membrane with 40 nm pore diameter was functionalized by sputtering an electrically conductive chromium (Cr) layer which acts as the gate electrode. The resulting pore diameter was decreased to 25 nm after the deposition, which is expected to balance the tradeoff between electrical gate control and diffusion rate.