Patent ID: 8436509

Claim:
A shear-horizontal surface acoustic wave sensor, comprising: a piezoelectric substrate, a unidirectional transmitting interdigital transduce on the substrate that primarily excites shear-horizontal waves on the substrate, a guiding layer on the substrate that has a lower shear velocity than the substrate for confinement of the shear-horizontal wave therein as a guided Love wave, a sensing region on the guiding layer, and a unidirectional receiving interdigital transducer that detects the guided Love wave that is transmitted through the sensing region, wherein the unidirectional transmitting and receiving transducers each comprise an electrode-width-controlled single-phase unidirectional transducer (EWC-SPUDT) comprising at least one EWC-SPUDT cell, each EWC-SPUDT cell comprising a λ/8 excitation electrode finger and λ/8 and λ/4 reflection electrode fingers, and wherein the finger spacings are optimized to excite or detect shear-horizontal waves that are in-phase along the length of each transducer in the presence of the guiding layer and the sensing region.