Patent ID: 7816837

Claim:
A surface acoustic wave sensor for detecting the minute mass applied to a surface acoustic wave element on the basis of the change in frequency using an SH-type surface acoustic wave, the surface acoustic wave sensor comprising: a rotated Y-cut LiTaO 3 substrate having Euler angles of (0°, 120° to 140°, 0°±5°); electrodes, principally containing Au, and arranged on the LiTaO 3 substrate to excite a surface acoustic wave; and a reaction membrane, bound to a target substance or a binding substance bound to the target substance, covering the electrodes arranged on the LiTaO 3 substrate; wherein the electrodes have a normalized thickness of about 3.0% to about 5.0%, the normalized thickness being determined by normalizing the thickness of the electrodes by the wavelength of the surface acoustic wave; the surface acoustic wave element is a resonator type surface acoustic wave element; and the electrodes include at least one interdigital electrode and reflectors arranged on both sides of the at least one interdigital transducer in a direction of propagation of a surface acoustic wave.