Asymmetric nanopore rectification for ion pumping, electrical power generation, and information processing applications

Single-track, asymmetric nanopores can currently be functionalised with a spatially inhomogeneous distribution of fixed charges and a variety of pore tip shapes. Optimising the asymmetric nanopore characteristics is crucial for practical applications in nanofluidics. We have addressed here this question for three cases based on different input/output chemical and electrical signals: (i) ion pumping up a concentration gradient by means of a periodic, time-dependent bias potential, (ii) information processing with a single nanopore acting as the nanofluidic diode of a logic gate, and (iii) electrical energy harvesting using a nanopore that separates two solutions of different salt concentrations. The results show the nanopore characteristics (size, shape, and charge distribution) that should be optimised for each application. In particular, the control of the pore tip size and charge appears to be crucial in all cases because it is in this narrow region where the interaction of the ions and the pore surface occurs, and this will eventually determine the nanodevice performance.