Assessment of 1/f noise associated with nanopores fabricated through chemically tuned controlled dielectric breakdown

Abstract

Recently, we developed a fabrication method—chemically‐tuned controlled dielectric breakdown (CT‐CDB)—that produces nanopores (through thin silicon nitride membranes) surpassing legacy drawbacks associated with solid‐state nanopores (SSNs). However, the noise characteristics of CT‐CDB nanopores are largely unexplored. In this work, we investigated the 1/f noise of CT‐CDB nanopores of varying solution pH, electrolyte type, electrolyte concentration, applied voltage, and pore diameter. Our findings indicate that the bulk Hooge parameter (αb) is about an order of magnitude greater than SSNs fabricated by transmission electron microscopy (TEM) while the surface Hooge parameter (αs) is ∼3 order magnitude greater. Theαs of CT‐CDB nanopores was ∼5 orders of magnitude greater than theirαb, which suggests that the surface contribution plays a dominant role in 1/f noise. Experiments with DNA exhibited increasing capture rates with pH up to pH ∼8 followed by a drop at pH ∼9 perhaps due to the onset of electroosmotic force acting against the electrophoretic force. The1/f noise was also measured for several electrolytes and LiCl was found to outperform NaCl, KCl, RbCl, and CsCl. The 1/f noise was found to increase with the increasing electrolyte concentration and pore diameter. Taken together, the findings of this work suggest the pH approximate 7–8 range to be optimal for DNA sensing with CT‐CDB nanopores.

Investigating protein translocation in the presence of an electrolyte concentration gradient across a solid‐state nanopore

“…The $${N_B}$$ decreased with decreasing C trans / C cis for positive bias (electrophoretic direction) and increased with decreasing C trans / C cis for negative bias (electroosmotic direction), as seen in Figure 4D. The activation of surface head groups can lead to higher noise properties since it has been previously shown that the surface Hooge parameter has a greater contribution to the overall noise when compared to the bulk Hooge parameter, further emphasizing the role of surface chemistry on the noise associated with nanopore devices [37,38]. Thus, one could expect that with increasing probability for electroosmotic transport direction (i.e., where surface groups are important), noise would also increase through nanopore surface contributions (Figure 4D).…”

Nanopore Data Analysis: Baseline Construction and Abrupt Change-Based Multilevel Fitting

“…Moreover, even when open-pore drift is absent, current fluctuations ( i.e. , noisy open-pore profiles) are not uncommon in most SSNs and become more apparent at higher applied voltages, as noted in our previous work. ,, The open-pore current drift due to pore enlargement (with time) could be largely negated with a window-based analysis, where the analysis is performed on equisized trace segments rather than on the entire trace itself . However, local and more pronounced open-pore fluctuations are more challenging and could easily lead to flawed event detection ( i.e.…”

Use of a solid‐state nanopore for profiling the transferrin receptor protein and distinguishing between transferrin receptor and its ligand protein

“…A nanopore was fabricated through a 30 ± 3 nm thick, silicon nitride membrane (NBPX5001Z‐HR, Norcada) using the chemically tuned controlled dielectric breakdown (CT‐CDB) method [25]. CT‐CDB is a modification of the well‐established CDB method that uses sodium hypochlorite (425044, Sigma‐Aldrich) during the fabrication process.…”