Enhanced current phenomenon in nanocrystalline graphite nanopore

In the realm of nanopore sensing, one of the most fundamental questions that needs to be answered is how ions are transported through nanochannels. The changes in current caused by the molecule moving through the nanopores provide us with useful information about the size, conformation, and charge of the test substance. In this context, we have fabricated a nanometer-sized pore in a suspended nanocrystalline graphite membrane and found that when negatively charged deoxyribonucleic acid (DNA) molecules pass through the pore, the current increases. Using the Navier–Stokes and Poisson–Nernst–Planck coupling models, we calculated the current reduction due to the steric hindrance effect of DNA molecules, as well as the current increase due to the enhanced ion concentration in nanopores, which is attracted by DNA surface charges. The results from these studies provide a new nanopore material for basic and applied nanofluidic research and reveal that the electroosmotic flow plays a role in driving DNA transport and generating conductive events due to polarization effects. This finding not only expands our understanding of the physical principles governing DNA–nanopore interactions but also holds promise for advancing the sensitivity and specificity of nanopore-based molecular detection.