Salt Gradient Improving Signal-to-Noise Ratio in Solid-State Nanopore

As the single molecule detection tool, solidstate nanopores are being applied in more and more fields, such as medicine controlled delivery, ion conductance microscopes, nanosensors, and DNA sequencing. The critical information obtained from nanopores is the signal collected, which is the ionic block current caused by the molecules passing through the pores. However, the information collected is, in part, impeded by the relatively low signal-to-noise ratio of the current solid-state nanopore measurements. Here, we report that using a salt gradient across the nanopore could improve the signal-to-noise ratio when molecules translocate through Si3N4 nanopore. Furthermore, we demonstrate that the improved signal-to-noise ratio is connected with not only the value of surface charge but also that of a salt gradient between cis and trans sides of the nanopore.