Chemical sensor utilizing a surface transverse wave device

A surface transverse wave device suitable for use as a sensor in a liquid, said device comprising:

• a piezoelectric substrate having a sensing surface;
• at least one transducer attached to said piezoelectric substrate for converting applied electric signals into acoustic signals in said piezoelectric substrate;
• a surface trapping structure, having dielectric material, for trapping acoustic waves in the substrate at the sensing surface of said substrate;
• and
• a chemically reactive layer that reacts with a class of solutes to be detected in said liquid;
• wherein said piezoelectric substrate has a composition and crystal cut such that said at least one transducer couples substantially only into shear horizontal acoustic waves, whereby this device exhibits a much greater sensitivity than a SAW device of comparable dimensions and arrangement of said at least one transducer.

A surface transverse wave device suitable for use as a sensor in liquids, said device comprising:

• a nonpiezoelectric substrate having a sensing surface;
• a surface trapping structure for trapping acoustic waves in the substrate at the sensing surface of said substrate;
• a chemically reactive layer that reacts with a class of solutes to be detected in said liquid;
• and
• means for converting an electrical signal into an acoustic signal that is trapped at the sensing surface of said nonpiezoelectric substrate.