Patent ID: 8258674

Claim:
A surface acoustic wave sensor system, comprising: (a) a first piezoelectric device, comprising: (i) a first piezoelectric substrate; and (ii) a first electrode pattern disposed on the first piezoelectric substrate; wherein the first electrode pattern is spaced apart and defines a first detection region on a surface of the first piezoelectric substrate intermediate the first electrode pattern; wherein the first electrode pattern is configured to generate and detect a first surface acoustic wave signal that travels through the first detection region; and (b) a second piezoelectric device, comprising: (i) a second piezoelectric substrate, formed from a different piezoelectric material than the first piezoelectric substrate; and (ii) a second electrode pattern disposed on the second piezoelectric substrate; wherein the second electrode pattern is spaced apart and defines a second detection region on a surface of the second piezoelectric substrate intermediate the second electrode pattern; wherein the second electrode pattern is configured to generate and detect a second surface acoustic wave signal that travels through the second detection region; and wherein the sensor system is configured to detect a change in a physical condition between the first detection region and the second detection region by comparing the first surface acoustic wave signal to the second acoustic wave signal.