Probing Material Properties via a pair of Piezoelectric Micromachined Ultrasound Transducers

SummaryUltrasonic methods have been widely employed for non-destructive testing and characterization of materials. This work investigates the potential of employing micromachined ultrasonic transducers in this context. Piezoelectric Micromachined Ultrasound Transducers (PMUTs) were used in a 5-layer acoustic model (PMUT-medium-specimen-medium-PMUT) to evaluate the feasibility of material characterization in air. A transmitter PMUT was electrically actuated to project ultrasonic waves through the air-sample-air interface before being incident on a receiver PMUT. The modulation of the amplitude at the receiver PMUT is then correlated to the specimen material type, which showed a clear distinction between metallic and polymeric materials. However, materials of a similar nature were not immediately distinguishable. The experimental findings are complemented by numerical simulations. These findings reinforce the feasibility of PMUTs to be deployed for non-destructive assessment of materials.