High-temperature resistive hydrogen sensor based on thin nanoporous rutile TiO2 film on anodic aluminum oxide

Chi Lu, Zhi Chen

Research output: Contribution to journalArticlepeer-review

116 Scopus citations


Thin titanium oxide (TiO2) films were prepared through electron-beam evaporation of titanium metal on substrates followed by oxidizing and sintering at 600 °C in flowing oxygen. The thicknesses of the as-deposit metal films were 25 nm, 50 nm and 100 nm. The phase of the TiO2 converted from the thermal oxidation was detected to be rutile. Nanoporous anodized aluminum oxide (AAO) and plain thermal silicon oxide on top of a commercial silicon wafer were used as substrates to support the TiO2 thin layer. A pair of interdigit platinum electrodes with a spacing of 5 μm was fabricated on the TiO2 thin films by photolithography. At 500 °C, the samples showed different sensing behaviors to hydrogen concentration levels ranging from 5 ppm to 500 ppm, with nitrogen as the background gas. It was found that the sensitivity was significantly enhanced by the increased specific surface area of the TiO2 thin film due to the shaping of the porous AAO substrate. The performance of the sensor based on the TiO2 film converted from 25-nm-thick Ti on the porous AAO substrate, which has the largest specific surface area among all the other samples, was featured by a conductance change of 25-90 times and considerable resolution for 5 ppm to 500 ppm H2, as well as very fast response and recovery (the time delay to reach or retreat to half of the maximum stable signal, t50%, was always no more than 10 s). The rutile-phased thin TiO2 film on AAO is proven to be a promising high-temperature hydrogen sensor with satisfactory performance, excellent durability, and ideal compatibility to micro-miniaturization.

Original languageEnglish
Pages (from-to)109-115
Number of pages7
JournalSensors and Actuators, B: Chemical
Issue number1
StatePublished - Jun 18 2009

Bibliographical note

Funding Information:
This work was supported by the Department of Energy (DE-FG26-04NT42171) and National Science Foundation (ECS-0609064). The authors would like to thank Mr. Zhifang Fan for his help in photolithography, Dr. Young-Sik Song for his help in the SEM works, and Mr. Ye Sun and Mr. Wenzhong Li for their help in the XRD.


  • AAO
  • High-temperature
  • Hydrogen sensor
  • Rutile
  • Thin film
  • TiO

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry


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