A Thermodynamic Consideration on the Mechanism of Ultrasensitive Moisture Sensing by Amorphous Silica

Y. Tsukahara, Toshihiro Tsuji, T. Oizumi, S. Akao, N. Takeda, Kazushi Yamanaka

Research output: Contribution to journalArticle

Abstract

We detected the change in the phase velocity of surface acoustic waves propagating along the amorphous silica layer on a spherical single-crystal quartz due to the very small amount of moisture at less than 1μmol·mol-1 in the ambient N 2 gas. This was made possible for the first time because this system, called a ball SAW moisture sensor, was extremely sensitive. The measured phase velocity changed as a function of moisture density and temperature and was fitted strikingly well with a thermodynamic model assuming that dissociated H + and OH - dissolved into the amorphous silica layer at room temperature.

Original languageEnglish
Article number108
JournalInternational Journal of Thermophysics
Volume38
Issue number7
DOIs
Publication statusPublished - 2017 Jul 1

Keywords

  • Ball SAW sensor
  • Humidity
  • Hygrometer
  • Trace moisture

ASJC Scopus subject areas

  • Condensed Matter Physics

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