Modulated Laser‐Assisted Nanopore Fabrication With Ammonium Sulfate for Single‐Molecule Sensing

Nanopore sensing provides a label‐free platform for single‐molecule analysis. To achieve reliable solid‐state nanopore sensing, however, it is essential to optimize appropriate nanopore fabrication methods, as variations in pore diameter, geometry, surface state, and fabrication residues can affect molecular discrimination capability. Here, we report a temporally modulated CW laser‐assisted dielectric breakdown method for facilitating in‐situ fabrication of nanopores in silicon nitride membranes, coupled with ammonium sulfate electrolytes to improve sensing performance. Systematic characterization revealed that temporally modulated CW laser minimizes contamination/debris formation during pore fabrication and yields improved nanopore sensing. Streaming‐potential measurements and interfacial ion‐transport simulations suggest that ammonium‐containing electrolytes modify the SiN nanopore interface by promoting NH 4 + adsorption on the inner pore surface as well as SO 4 2− ions, thereby enhancing DNA–pore interactions. This effect slowed a subset of DNA translocation events, enabling longer dwell‐time observations and differentiation between poly(dA) and poly(dC) blockade populations. Furthermore, aptamer‐assisted detection enabled detection of Scp1‐bound aptamer complexes under conditions where the protein alone tended to clog the pore. The Scp1–aptamer complex showed prolonged dwell times compared with those of free aptamers, even under 0.14 M KCl. Together, these results demonstrate that integrating our approach provides an improved approach for high‐performance single‐molecule nanopore detection.