Conical Nanotubes Synthesized by Atomic Layer Deposition of Al2O3, TiO2, and SiO2 in Etched Ion-Track Nanochannels

Abstract

Etched ion-track polycarbonate membranes with conical nanochannels of aspect ratios of ~3000 are coated with Al2O3, TiO2, and SiO2 thin films of thicknesses between 10 and 20 nm by atomic layer deposition (ALD). By combining ion-track technology and ALD, the fabrication of two kinds of functional structures with customized surfaces is presented: (i) arrays of free-standing conical nanotubes with controlled geometry and wall thickness, interesting for, e.g., drug delivery and surface wettability regulation, and (ii) single nanochannel membranes with inorganic surfaces and adjustable isoelectric points for nanofluidic applications.

Solid-state and polymer nanopores for protein sensing: A review

“…[42], 2021, American Chemical Society (g) sketch of nanopipette pulling [79] and (h) SEM image of a nanopipette. (i) sketch of track-etching technique Vt and Vn are the speed of chemical etching inside the irradiated zone and bulk material respectively (j) replica of conical nanopore obtain by TiO2 deposition by atomic layer deposition [80] (k) FESEM image of "bullet-like" shape nanopore, Reproduced with permission [81], 2009, Elsevier…”

“…Figure 1: (a) Sketch of SiN nanopore drilled using electron or ion beam Reproduced with permission [78], 2017, Elsevier (b) TEM image of a SiN nanopore.Illustration of classical (c) and laser-assisted (d) dielectric breakdown and the distribution of defects inside the SiN film (e) and (f) respectively, Reproduced with permission[42], 2021, American Chemical Society (g) sketch of nanopipette pulling[79] and (h) SEM image of a nanopipette. (i) sketch of track-etching technique Vt and Vn are the speed of chemical etching inside the irradiated zone and bulk material respectively (j) replica of conical nanopore obtain by TiO2 deposition by atomic layer deposition[80] (k) FESEM image of "bullet-like" shape nanopore, Reproduced with permission[81], 2009, Elsevier…”

Regulating Nonlinear Ion Transport through a Solid-State Pore by Partial Surface Coatings

“…Compared with chemical ways of surface modification with soft organic monolayers, physical approaches such as sputtering is a convenient method to coat nanopores with hard dielectric thin films. In the previous literature, various coating materials (SiO 2 , , HfO 2 , , ZnO, , TiO 2 , , and Al 2 O 3 , ) were employed to study the effect of controlling mass and ion transport. Herein, we qualitatively examine the coating materials and patterns of a dielectric layer on solid-state nanopores.…”

Highly Rectifying Conical Nanopores in Amorphous SiO2

“…One major challenge in current nanopore technology is to combine the high throughput rates that nanopores in ultrathin membranes provide with highly asymmetric transport properties characteristic of long, conical nanopores. [38][39][40] Furthermore, translating the performance of single pores to multipore systems without losing performance has proven to be challeng-ing. 19,41 Different techniques like e-beam lithography, 42 ion beam sculpting, 21 e-beam drilling using a transmission electron microscope, 43 focused ion beam drilling, 44 dielectric breakdown 45 or laser-assisted pulling 46 can only be used to fabricate a single or few nanopores and thus lack the scalability that many applications require.…”