Pressure Driven Non-monotonic Gating in Tunable Polydimethylsiloxane Nanopores Regulates DNA Translocation.

Abstract

Achieving dynamic control of the size of solid-state nanopores remains a significant challenge in single-molecule sensing. In this work, a flexible PDMS (polydimethylsiloxane) nanopore (3.9 μm thick) was fabricated by focused ion beam (FIB) milling and subjected to an applied transmembrane hydrostatic pressure in a KCl electrolyte, enabling real-time modulation of its aperture. The flexible PDMS nanopore exhibits nonmonotonic deformation in response to external pressure: initial constriction at low pressure, followed by re-expansion at higher pressure, with the smallest pore diameter achieved at an intermediate pressure. Leveraging this "constriction-dilation" gating behavior, we systematically regulated λ-DNA translocation─observing maximized ionic current blockade amplitude, prolonged dwell time, and optimal event frequency at the intermediate pressure regime. Furthermore, compared to a conventional rigid silicon nitride (SiN) nanopore, the flexible PDMS nanopore exhibited substantially reduced baseline current noise and enhanced signal-to-noise ratio (SNR), attributed to its low dielectric constant and mechanical stability. This work combines dynamic mechanical tuning and low-noise soft-material characteristics to realize a single-molecule detection platform with high sensitivity and selectivity for flexible, tunable nanopore sensing in DNA analysis and other biomolecular measurement applications.