Field effect modulated nanofluidic diode membrane based on Al2O3/W heterogeneous nanopore arrays

Abstract

We developed Al2O3/W heterogeneous nanopore arrays for field effect modulated nanofluidic diodes. They are fabricated by transferring self-organized nanopores of anodic aluminium oxide into a W thin film. The nanopores are ∼20 nm in diameter and 400 nm in length. After mild oxidation, approximately 10 nm WO3 grows on the surface of W, forming a conformal and dense dielectric layer. It allows the application of an electrical field through the surrounding W electrode to modulate the ionic transport across the entire membrane. Our experimental findings have potential applications in high throughput controlled delivery and electrostatic sorting of biomolecules.

Hidden Nanobubbles in Undersaturated Liquids

“…For example, nanoporous membranes have been used to explore diodelike effects. 60 Here, the one-end pore on a hydrophobic substrate was built (see Figure 4b), and its ability to stabilize concave nanobubbles in the undersaturated liquid was then confirmed by our constrained LDFT simulation (Figure 4e). …”

Logic Functions with Stimuli‐Responsive Single Nanopores

“…The electrochemical signals can be provided by the external electrodes and by recirculating small vol-umes of fresh solutions. [7,[27][28][29][79][80][81][82][83][84][85][86] Other practical issues not considered here are the stability and durability after several cycles, [19,71] the significant noise-to-signal ratio, [8,63] and the mass-transport limitations that may appear at high frequency pulses. [63,79,85] In this context, the cigar-shaped pore of Figure 3 permits a convenient external reconfiguration, [75,76] because of Figure 2.…”

“…Integration of several pores in a series arrangement can allow multiple sensing and actuating processes. Figure 2 suggests an experimental realization for the enabled OR (EnOR) function, in which a simple binary output (current) can be obtained from different combinations of chemical, thermal, and electrical [21], [22], [41], [43], [65], [66], [67], [70], [83] Optical UV light and photo-labile groups [48], [68], [69], [70], [71], [72] inputs. The currents are estimated from the individual pore conductance values.…”

“…Chemicals pH and carboxylic groups [1], [32], [34], [70] pH and amino groups [15] pH and amino/carboxylic group in bipolar diode [42] pH and amino/carboxylic group in bipolar transistor [33] pH and amphoteric groups [16], [75] pH and phosphonic groups [37] pH-sensitive polymer brushes [45] Ca 2 + and carboxylic groups [38], [80] pH and DNA chains [17], [36], [ [44], [70] temperature and pH-sensitive polymer brushes [46], [47] Electrical gate potential and field effect nanopores [21], [22], [41], [43], [65], [66], [67], [70], [83] Optical UV light and photo-labile groups [48], [68], [69], [70], [71], [72] inputs. The currents are estimated from the individual pore conductance values.…”

“…[28,77] Although organic materials offer a wide range of chemical functionalization options, [2,27,70] other practical realizations should also be possible with solid-state nanopores, because of the possibility to fabricate different heterostructures with the available pattern-transfer processes. [21,22,65,[81][82][83]…”