AlN/ZnO/LiNbO3 packageless structure as a low-profile sensor for on-body applications

Surface acoustic wave (SAW) devices are widely used as filters or resonators for mobile communications or radars applications. However, the velocity of the wave can be very sensitive to physical parameters of the environment (temperature, strain...), which allows the device to be used as a sensor. SAW devices are passive (batteryless) and wireless, but are often bulky due to the package. To dramatically reduces their profile, it is possible to use a Wave-guiding Layer Acoustic Wave (WLAW) structure, which consists of a low velocity layer between two higher velocity layers. These structures have the potential to be ultra-thin and conformable and thus could be used for flexible on-body biomedical applications. This work investigates the AlN/ZnO/LiNbO₃ structure as a candidate for a WLAW temperature sensor.