Patent ID: 8841817

Claim:
A surface acoustic wave sensor comprising: a substrate arranged at a surface of a measurement subject which is a measuring object of both a strain and a temperature, at least a part of the substrate being made of a piezoelectric material; a first electrode arranged at a top surface of the substrate to oscillate or receive a surface acoustic wave; a second electrode arranged at the top surface of the substrate to receive or reflect the surface acoustic wave oscillated by the first electrode; a propagation portion placed at the top surface of the substrate between the first electrode and the second the electrode to transmit the surface acoustic wave from the first electrode toward the second electrode; a phase detection device detecting a phase of the surface acoustic wave oscillated by the first electrode and a phase of the surface acoustic wave received or reflected by the second electrode; and a frequency detection device detecting a resonant frequency of the first electrode, wherein a first area placed at a bottom surface of the substrate directly under the propagation portion is fixed to the measurement subject, and a second area placed at the bottom of the substrate directly under both the first electrode and the second electrode is not fixed to the measurement subject.