High temperature compatible aluminum nitride resonating strain sensor

Aluminum nitride (AlN) is a promising material for harsh environment sensing applications due to its piezoelectric effect and mechanical stability at high temperatures. In this work, AlN double-ended tuning forks (DETF) are presented as a transduction element to measure mechanical loads by observing the resonance frequency shift. The fabrication process of the MEMS devices including the bonding step to a steel parallel is described. Device operation is demonstrated for strain sensing up to 91 °C and operation of the transducer without applied strain is demonstrated up to 570 °C.