Layered SiO2 / LiNbO3 / Si SH-SAW Biological Sensor for Operation in Water

SummarySurface Acoustic Wave (SAW) sensors have raised an interest for biological sensing applications. Operation in water requires exploiting Shear Horizontal SAW (SH-SAW), which however suffer from losses due to radiation in the substrate. Therefore, we adopt here a resonator structure consisting in a LiNbO
3
layer bonded to a Si substrate and covered by a thin SiO
2
layer to provide electrical insulation when in contact with water. The resonator operates at 378 MHz and its quality factor was evaluated in air/water operation with a Q
water
of 280.