Prevention of Dielectric Breakdown of Nanopore Membranes by Charge Neutralization

Abstract

To achieve DNA sequencing using a solid-state nanopore, it is necessary to reduce the electric noise current. The noise current can be decreased by reducing the capacitance (C) of the nanopore device. However, we found that an electric-charge difference (ΔQ) between the electrolyte in one chamber and the electrolyte in another chamber occurred. For low capacitance devices, this electric-charge imbalance can lead to unexpectedly high voltage (ΔV = ΔQ/C) which disrupted the membrane when the two electrolytes were independently poured into the chambers. We elucidated the mechanism for the generation of initial defects and established new procedures for preventing the generation of defects by connecting an electric bypass between the chambers.

High fidelity moving Z-score based controlled breakdown fabrication of solid-state nanopore

“…It was found the Joule heating could break the Si-N bonds at the pore aperture area [35,51,52]. There are works showing the formation of multiple nanopores during the nanopore enlargement [33,48,53,54]. However, the possibility of additional breakdown at other locations in our experiment is not likely due to the behavior seen in figure 5(B), which strongly indicates the single pore enlargement through the Joule heating around the exiting nanopore.…”

Integrated solid-state nanopore platform for nanopore fabrication via dielectric breakdown, DNA-speed deceleration and noise reduction

“…Figure 2 provides a schematic diagram of the solid-state device with a layer of nanometre-sized beads on the SiN membrane from the cis side. The solid-state substrate for nanopore fabrication (see Supplementary Figure S4 ), the bead layer and the polyimide layer were prepared as previously reported 33 35 38 . Nanopore fabrication via the MPVI procedure was performed in situ under typical conditions (1 M KCl aqueous solution with Tris-EDTA buffer, 10 mM Tris, 1 mM EDTA, pH 7.5).…”

“…Figure 7a presents the PSD curve of each device, and these curves clearly depict the reduced noise spectra of the polyimide device and the bead-polyimide device across the entire frequency regime. The device capacitance arising from the surface area exposed to the electrolyte solution governs the typical ionic current noise at high frequency 38 . The noise arising from the device capacitance was calculated to be 1000 pF for the bare device and 50 pF for the polyimide-coated device and bead-polyimide-coated device.…”

“…Two chambers ( cis and trans chambers) were formed in a custom flow cell. We recently determined that an electric charge difference between the chambers generates defects in the membrane, particularly when the capacitance of the substrate is less than 100 pF 38 . To prevent initial defects, the charge difference was neutralized using an electric bypass channel connected to both chambers.…”

“…In addition to the above challenges, a nanopore system requires the reduction of the ionic current noise to improve the signal-to-noise ratio, particularly in the high-frequency range (e.g., 1 MHz). The device capacitance arising from the surface area exposed to the solution dominates the high-frequency noise 38 . To decrease the surface area of the device, an insulating layer (e.g., poly(dimethylsiloxane) or polyimide) was also integrated into our device.…”