| 摘要 |
PURPOSE:To obtain a sensor selectively responding to moisture and having high sensitivity and quick response, by forming a humidity-sensitive film comprising a porous glass membrane on a piezoelectric element through a membrane electrode. CONSTITUTION:For example, 2.5ml of a 2% ethanol solution of cellulose, 27ml or silicon tetraethoxide Si(OC2H5)4, 0.9ml of water and 0.5ml of 1.0N-HCl are mixed under stirring to prepare a uniform sol solution through hydrolysis. Next, a piezoelectric element wherein metal electrodes 4, 4 are formed to both surfaces of a quartz plate (quartz oscillator) 2 with oscillation frequency of 9.022MHz by vapor deposition is prepared and the sol solution is applied to the piezoelectric element so as not to expose both electrodes 4, 4 and allowed to stand to be solidified. Subsequently, the piezoelectric element is allowed to stand in a heating oven regulating to 500 deg.C and subjected to heating drying treatment for 5min to form a porous glass membrane 3 (void ratio; 30%) with a thickness of 7,000Angstrom . By this method, a sensor selectively responding to moisture and having high sensitivity and quick response is obtained.
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