NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
A Method for Fabricating Conductometric Gas Sensors of Metal Oxide Nanotubes Formed in Porous Aluminum Oxide Membranes
Published
Author(s)
Reit Artzi-Gerlitz, Kurt D. Benkstein, David L. Lahr, Joshua L. Hertz, Christopher B. Montgomery, John E. Bonevich, Stephen Semancik, Michael J. Tarlov
Abstract
We describe a general, simple strategy for fabricating conductometric gas sensors from metal oxide nanotubes formed in nanoporous aluminum oxide membranes. In this approach, the aluminum oxide membrane serves as both a template for growth of the sensing nanotubes and a scaffold to support the nanotubes and electrical contacts made to the ends of ensembles of nanotubes for sensing measurements. Two significant advantages of this sensing architecture are: 1) analyte molecules are constrained to enter the interior of the nanotubes thereby maximizing sensitivity; and 2) metal contacts for conductometric measurements are easily and reproducibly established at the ends of ensembles of nanotubes. We demonstrate a proof-of-concept for this approach with the fabrication and gas-sensor testing of WO3 nanotube-based conductometric devices. To make these devices, WO3 nanotubes were first formed in the pores (diameter ≈ 200 nm, length ≈ 60 μm) of alumina membranes by sol-gel deposition. Thin film Au electrical contacts (≈ 50 nm) were then deposited at an oblique angle on the top and bottom of the WO3-coated membranes so as to maintain the open pore structure of the nanotubes and to enable conductometric sensing measurements along the length of the nanotube assemblies. The resulting nanotube sensor assemblies were able to detect both oxidizing (nitrogen dioxide) and reducing (methanol) gases at sensor operating temperatures ≤ 200 °C, and exhibited electrical sensing responses two to three orders of magnitude greater than a planar WO3-film sensor. The enhanced sensitivity is attributed to the large surface area presented by the interior of the nanotube assemblies.
Citation
Advanced Materials
Volume
136
Issue
1
Pub Type
Journals
Keywords
anodized aluminum oxide, gas sensor, nanotube, NO2, sol-gel, tungsten-oxide
Citation
Artzi-Gerlitz, R.
, Benkstein, K.
, Lahr, D.
, Hertz, J.
, Montgomery, C.
, Bonevich, J.
, Semancik, S.
and Tarlov, M.
(2009),
A Method for Fabricating Conductometric Gas Sensors of Metal Oxide Nanotubes Formed in Porous Aluminum Oxide Membranes, Advanced Materials
(Accessed October 12, 2025)