Flexural ultrasonic transducers (FUTs) are a promising route for a new generation of adaptive ultrasonic sensors, for applications including flow and proximity sensing. One major limitation is that the FUT’s resonance frequencies and dynamics are highly sensitive to environmental conditions including temperature, and variations in plate geometry. There are hence barriers to wider in-situ operation in industrial applications. To address these challenges, the shape memory alloy Nitinol is used to fabricate the FUT plate. The rationale is that the tuneable Young’s moduli of Nitinol can be used to tune FUT resonance, with the capacity to achieve resonance frequency stability approaching 80°C. Furthermore, Nitinol’s shape memory effect can be used to recover a deformed FUT plate structure, showing the potential for remote repair of sensors. Here, a pair of Nitinol flexural ultrasonic transducers (NFUTs) were fabricated to be used in transmit-receive. The dynamics were measured via electrical impedance analysis, laser doppler vibrometry and acoustic microphone techniques. Two sensors produced using our approach displayed differences in series resonance of 0.82%, 0.24%, and 1.04% respectively, for the first three fundamental vibration modes. Resonance stability with increasing temperature was characterised, where resonance shifts as low as 0.96% were measured, towards 80°C. The key novelty of this study is the characterisation of a FUT with a Nitinol plate, where two FUTs with closely matched dynamics can be achieved. Practical application challenges are discussed, where NFUTs can feature in a new generation of environmentally robust, in-situ measurement sensors
