Nanopore Fabrication via Transient High Electric Field Controlled Breakdown and Detection of Single RNA Molecules

Abstract

The fabrication of nanopores through a dielectric breakdown method, achieved by simple, low-cost desktop setups, has promoted the research of solid-state nanopore sensing. This paper reports a method for fabricating nanopores. This method uses transient high electric field controlled breakdown (THCBD) to form electric-field-dependent nanopores with different diameters in the order of milliseconds. By manipulating a micropipette with a high electric field to establish the meniscus contact with the SiN x membrane, nanopores can be formed through an “auto-brake” fabrication process. Compared with the traditional dielectric breakdown, THCBD can greatly shorten the breakdown time and form pores of different sizes under higher electric fields without causing additional damage to the SiN x membrane. The nanopores formed by this method can be successfully used to detect two types of RNA molecules. One is transfer RNA from yeast extract and the other is a synthetic RNA oligonucleotide fragment (rArArArArArArArArArArArA).

In situsolid-state nanopore fabrication

“…This has previously been done using a micropipette filled with electrolyte to contact the top of the membrane. 126,165 Performing CBD by applying the breakdown voltage between the electrolyte in the pipette and a backside reservoir resulted in pore formation localised to the area where the meniscus contacts the membrane (B1 mm in diameter). Controlling the pipette position using a micromanipulator enabled the creation of high density arrays of nanopores thus significantly increasing the number of biosensing experiments that can be performed per membrane.…”

Localized Nanopore Fabrication via Controlled Breakdown

“…Such localized changes of material could be introduced by dielectric thinning, temperature differences, oxide defects, or other properties that locally increase in conductivity. This section will discuss the approaches that assist the formation of nanopores in a specific region, including laser-assisted breakdown [ 86 , 88 , 89 , 144 ], pre-thinning [ 150 ], local high electric field [ 151 , 152 ], and local liquid contact [ 153 , 154 , 155 , 156 ].…”

“…The micromanipulator makes it possible to repeat the CBD process many times per membrane, therefore enabling the fast preparation of nanopore arrays. Based on this principle of pipette tip positioning, Yin et al developed a transient high-electric-field controlled breakdown (THCBD) [ 151 ] by applying a high voltage before establishing the liquid contact ( Figure 5 d). Their work demonstrates that pore-forming time is inversely dependent on the applied voltage, while pore diameters have a linear relationship with breakdown voltage.…”

Localised solid-state nanopore fabrication via controlled breakdown using on-chip electrodes

“…To overcome this issue, several CBD techniques have been developed that enable control over the nanopore position. These have included using an atomic force microscope tip to apply the voltage [42,43], thinning a region of the membrane prior to breakdown [44], and confining the electrolyte on one side of the membrane [45][46][47]. These techniques have been used to integrate nanopores with on-chip structures such as microfluidics [48] and microwells [49].…”