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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/fnoise 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. Theαsof CT‐CDB nanopores was ∼5 orders of magnitude greater than theirαb, which suggests that the surface contribution plays a dominant role in 1/fnoise. 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/fnoise was also measured for several electrolytes and LiCl was found to outperform NaCl, KCl, RbCl, and CsCl. The 1/fnoise 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.
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False negative and false positive free nanopore fabrication via adaptive learning of the controlled dielectric breakdown
We investigate the current transport characteristics in the electrolyte-dielectric-electrolyte structure commonly used in the in-situ controlled breakdown (CBD) fabrication of solid-state nanopores. It is found that the stochastic breakdown process could lead to fidelity issues of false positives (an incorrect indication of a true nanopore formation) and false negatives (inability to detect initial nanopore formation). Robust and deterministic detection of initial physical breakdown to alleviate false positives and false negatives is critical for precise nanopore size control. To this end, we report a high fidelity moving Z-Score method based CBD fabrication of solid-state nanopore. We demonstrate 100% success rate of realizing the initial nanopore conductance of 3±1 nS (corresponds to the size of 1.7±0.6 nm) regardless of the dielectric membrane characteristics. Our study also elucidates the Joule heating is the dominant mechanism for electric field-based nanopore enlargement. Single DNA molecule sensing using nanopores fabricated by this method was successfully demonstrated. We anticipate the moving Z-Score based CBD method could enable broader access to the solid state nanopore-based single molecule analysis.
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- Award ID(s):
- 1710831
- PAR ID:
- 10095722
- Date Published:
- Journal Name:
- Transducer 2019
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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