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Development of QCM humidity sensors using anodized alumina film
Author(s) -
Yamamoto Nobuo,
Yamaguchi Tomiharu,
Hara Kazuhiro
Publication year - 2019
Publication title -
electronics and communications in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.131
H-Index - 13
eISSN - 1942-9541
pISSN - 1942-9533
DOI - 10.1002/ecj.12218
Subject(s) - quartz crystal microbalance , materials science , humidity , anodizing , relative humidity , thin film , quartz , dew point , crystal (programming language) , deposition (geology) , nanoporous , analytical chemistry (journal) , composite material , aluminium , chemistry , adsorption , nanotechnology , chromatography , meteorology , paleontology , physics , organic chemistry , sediment , computer science , biology , programming language
Humidity sensors based on QCM (quartz crystal microbalance) have been developed using an anodized alumina thin‐film as a sensing material. An aluminum thin‐film is deposited on a silver‐coated quartz crystal by electron beam deposition and is anodized in an acid solution. The resultant alumina film is porous. The resonant frequency gradually decreases from 5% to 94% relative humidity (RH) and steeply changes near 100% RH. This result shows that the sensor can be used as a dew‐point sensor as well as a humidity sensor. The response times to the humidity changes from 27% to 59% RH and from 59% to 27% RH are less than 5 s. The sensor shows reversible response to some gases such as ethanol, toluene, and acetone vapors in addition to airborne particles such as pollen.