Facile fabrication of nanofluidic diode membranes using anodic aluminium oxide

Abstract

Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al(2)O(3)/SiO(2) (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al(2)O(3) (positive) and SiO(2) (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion.

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

“…24 The process is described in Figure S1 of the supplemental material. 25 Briefly, 200 nm W was deposited on a freestanding low stress SiN membrane followed by an annealing process ( Figure S2 in the supplemental material 25 ).…”

Ion current rectification effect of porous graphene membrane

“…The similar works about rectification effect of ion current based on other kind nanochannels or nanopores have also been carried out. For example, the alumina/silicon dioxide hetero-structured solid state nanopore membrane was used to study the rectification effect at relatively high electrolyte concentrations and the rectification coefficient was in the range of 1 to 7 [17]. The glass nanopipettes were modified with polyethyleneimines (PEIs) and the related ion current rectification was studied [14].…”

Application of a bipolar nanopore as a sensor: rectification as an additional device function

“…In this case, the main charge carrier is the anion (Cl − ) and the sensor works on the basis of the increasing Cl − current caused by the increased accumulation of Cl − attracted by the positive analyte ions into the binding region. There are well-established techniques for the fabrication of bipolar pores from chemical treatment to atomic layer deposition [15,16,17,18].…”