Gating of Nanopores: Modeling and Implementation of Logic Gates

Nanoporous and nanofluidic structures can be coated with metal and insulating layers deposited on the pore surface: when an electrolyte solution is in contact with the internal insulating layer, well-defined ionic conductance levels could be tuned by applying a gate potential to the external metallic layer. We study theoretically the dependence of the effective gate potential at the insulating layer/solution interface with the applied gate potential at the metallic surface as well as the change of the nanopore conductance with the gate potential for different electrolyte solution concentrations and nanopore radii. We solve the Poisson-Boltzmann equation to obtain the electrical potential distribution in the two regions of the pore cross-section, the insulating layer, and the inner pore solution. The model provides estimations of the effective nanopore surface charge density that could be achieved by gating the nanopore (this charge determines the nanopore selectivity in practical cases). As an application, we have shown that NOR and NAND logic gate schemes based on input and output electrical signals could be implemented by exploiting the gating of the nanopore conductance.