Origin of Nonequilibrium 1/f Noise in Solid-State Nanopores

Nanopore devices are applied in many fields like molecule sensing and DNA sequencing, and the detection precision is primarily determined by the 1/f noise. The mechanism of 1/f noise in nanopores is still not clearly understood, especially the nonequilibrium 1/f noise in rectifying nanopores. Hereby, we propose that the 1/f noise in solid-state nanopores is originated from the electrolyte ions trapping-detrapping process on the inner surface of the nanopores, which can nonlinearly affect the ion number inside the rectifying nanopore due to the specific ion enrichment/depletion effect. Our model can not only quantitatively explain the nonlinear dependence of 1/f noise on the applied voltage, i.e., the nonequilibrium 1/f noise, for current rectifying nanopores, but also give a unified explanation on the influences of the electrolyte concentration, pH value, and the geometry of the nanopore. According to the model, we find a new flattening phenomenon of1/f noise in conical nanopores, and it is further confirmed by our experimental results. Our research can be helpful to understand and reduce 1/f noise in other nanopore devices, especially where the enrichment or depletion of ion exists.