Hybrid PMUT realized using an innovative “Piezo-in-flex” technology

Piezoelectric micromachined ultrasonic transducers (pMUTs) are promising components that could address many applications. pMUTs are generally built using the microelectronic technologies and tools on silicon wafers to allow miniaturization, CMOS co-integration and high performance. Nevertheless, the technological realization can be time consuming, and the silicon material and processes are not always necessary for low frequency applications. In this paper, we report the study of a hybrid pMUT built using an innovative "Piezo-in-flex" technology based on the integration of piezoceramic actuators on a polymer material, in a cost effective way. Using an impedance-meter, the resonant frequency is measured at 21.75 kHz, in good agreement with the COMSOL simulation. At this resonant frequency, a pMUT displacement amplitude of 900 nm under 10 V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ac/peak-to-peak</inf> was measured using a laser vibrometer. Finally, a high acoustic pressure of 0.43 Pa is measured at 20 cm using a microphone. It opens the way of the realization of low cost conformable pMUT arrays.