SURFACE ACOUSTIC WAVE SENSOR

摘要

A surface acoustic wave sensor for detecting or quantitatively determining a subject of the object of detection by measuring the variation of frequency due to mass load. The sensor comprises a surface acoustic wave element and a reactive film formed on the surface acoustic wave and has an enhanced sensitivity by the improvement of the structure of the surface acoustic wave element itself. The surface acoustic wave sensor (1) utilizes a surface acoustic wave of SH type and comprises a rotation Y cut LiTaO3 substrate having an Euler angle of (0°, 0° to 18°, 0°±5°) or (0°, 58° to 180°, 0°±5°), a surface wave exciting electrode (3) formed on the LiTaO3 substrate (2) and containing Au as the main component, and a reactive film (4) so formed on the LiTaO3 substrate as to cover the surface wave exciting electrode (3) and bondable to the substance to be detected or a bonding substance bondable to the substance to be detected. The film thickness normalized with the wavelength of the interdigital electrode (3) is in the range from 0.8 to 9.5%.