| 摘要 |
PURPOSE:To enable measurement in a gas containing a large quantity of moisture and having low insulating properties, etc., by coating an external exposed surface in a filmy metallic electrode formed onto a piezoelectric element with an electrical insulating film. CONSTITUTION:A sensor element having a pair or filmy electrodes 3 on a piezoelectric element 2 and shaping a chemical composition sensitive film 4 on at least one electrode 3 is formed. A quartz oscillator or Rochelle salt is used as the element 2, and a metallic thin-film consisting of gold, silver, etc., is employed as the filmy electrode 3 and applied onto both surfaces of the element through evaporation or sputtering. A plasma polymerization organic acid containing an ammonium group, etc., is used as the sensitive film 4 on the electrode 3, or a glass film through an alkoxide solution method is employed as a glass thin-film on the electrode. The external exposed surfaces of the metallic electrodes 3 are coated with electrical insulating films 5, thus allowing measurement at the time of immersion into a gas or a liquid containing a large number of moisture and having low insulating properties.
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