Design and fabrication of SAW pressure, temperature and impedance sensors using novel multiphysics simulation models

• Temperature, pressure and impedance SAW sensors were fabricated and characterized.
• Multiphysics models were used to design and simulate the complete structures.
• Fabrication protocol was designed for this particular technology.
• Sensors results for accuracy, repeatability and reproducibility characteristics are presented.

Surface acoustic wave (SAW) devices have been shown to be suitable for many applications. Some of these applications are temperature, pressure and impedance-based sensors. In this study, we investigate the performance of a SAW resonator as temperature and pressure sensors, and a reflective differential delay line (RDDL) structure as an impedance sensor. The SAW sensors were designed using a proposed FEM-based multiphysics model on COMSOL® and fabricated using photolitography over a 128° YX LiNbO3 substrate for an operation frequency of 65 MHz. Using a vector network analyzer (VNA), the devices were characterized; frequency shifts on the S11 parameter of resonators were observed depending on the applied external pressure and temperature changes, and amplitude variations for impedance changes in the case of RDDL. The experimental results were compared with simulation data. The evaluated sensitivities were 87.81 ppm/°C, 0.9 ppm/kPa and 0.0023 dB/Ω.