Aerosol Jet Printing of Piezoelectric Surface Acoustic Wave Thermometer

Abstract Surface acoustic wave (SAW) transducers are a subclass of micro-electromechanical systems (MEMS) that generate an acoustic emission when electrically stimulated. These transducers can also convert surface strain into readable electrical signals. By monitoring variations in scattering parameters, a SAW device can detect physical properties of host structures and external factors like temperature. Traditional fabrication of SAW transducers requires labor- and cost-intensive subtractive processes that produce large volumes of hazardous waste. This study utilizes an innovative aerosol jet printer to fabricate SAW transducers by directly writing consistent, high-resolution, silver comb electrodes onto a Y-cut LiNbO3 piezoelectric substrate. The printed, two-port, 20 MHz SAW transducers were validated as a thermometer, which exhibited excellent linearity and repeatability from 25 °C to 200 °C. Sensitivities of the printed SAW thermometer are -96.9×10-6 °C-1 and -92.0×10-6 °C-1 when operating in pulse-echo mode and pulse-receiver mode, respectively. These results highlight a repeatable path to additively manufacture compact and high-frequency SAW transducers.