Ion-beam sculpting at nanometre length scales

Precise control of the size and noise of solid-state nanopores using high electric fields

“…While biological pores offer greater sensitivity and often lower noise properties, they are limited to very specific operational conditions due to the fragility of the supporting lipid bilayer, and by their fixed size to study very small molecules, such as single-stranded DNA. Solid-state nanopores, on the other hand, are a promising alternative as they offer increased durability, size and shape tuning ability, and are naturally suited for integration with wafer scale technologies [3,4]. Typically drilled in thin (10-50 nm) insulating membranes using a tightly focused beam of electrons in a transmission electron microscope (TEM) [5], the resultant pore diameter and shape can be controlled by adjusting the beam parameters used in the fabrication process [6,7] or by subsequent treatment with a scanning electron microscope (SEM) [8].…”

Atomic Layer Deposition to Fine-Tune the Surface Properties and Diameters of Fabricated Nanopores

“…[1][2][3][4] But despite the stability, tunability, and other potential advantages that fabricated solid state nanopores may offer, the ion beam, electron beam, or chemical etch fabrication conditions used to create nanopores usually yield uncharacterized and possibly unfavorable surface properties that can interfere with the pore's sensing abilities.…”

“…[2][3][4] Ion beam sculpting employing feedback control has been used to fabricate such nanopores in thin silicon nitride membranes. 2 To respond to single molecules in a high throughput, selective, and sensitive manner, the properties of both the membrane and the nanopore must be carefully selected. For example, the surface properties of the pore and its immediate surroundings should not repel the molecules that are to be detected, and the limiting aperture of the pore must have a diameter large enough to allow the molecules to translocate, but small enough to optimize signal response to the molecules' presence.…”

“…The final product was a nanopore in a ∼5-40 nm thick film of Si 3 N 4 across one end of the 200 nm-long FIB channel. 2 In general, the pore thickness was proportional to the pore diameter. For example, the thickness, or length, of a 5 nm diameter pore was about 5 nm.…”

Detection of DNA Sequences Using an Alternating Electric Field in a Nanopore Capacitor

“…An external electric bias V ex is applied across the membrane to drive a single DNA strand back and forth through the pore, while the electric potentials induced by the DNA motion are independently recorded at the top and bottom layers (electrodes) of the capacitor membrane, V top and V bot , respectively. Nanometer-diameter pores in such membranes have already been manufactured, [19][20][21] and the voltage signals resulting from the translocation of DNA strands through such pores have been recorded. 22 In particular, measurements have recently been reported using a single DNA molecule trapped in a nanopore of a 3.4 nm×4.2 nm cross section in a MOS capacitor with an area of 10 μm×10 μm and a gate dielectric nominally 2 nm thick.…”