Flexible AlScN based PMUT arrays for conformal and wearable ultrasound

Abstract

Flexible transducers address the limitations of conventional rigid ultrasound probes for wearable applications, such as the continuous monitoring of vital organs. In this work, we demonstrate the first flexible micromachined ultrasound transducer array based on AlScN piezoelectric film. Using flat panel display compatible technology which enables the manufacturing of large-aperture arrays we demonstrate a piezoelectric transducer with an active area of 1.5x1.5 cm2. The rigid glass substrate is removed and replaced by a flexible acoustic backing layer. Optimizations on thickness, mechanical rigidity, and acoustic properties of the backing material were performed to maximize the flexible transducer performance leading to transmit sensitivity of 3.8 kPa/V at 1.8 MHz and capable of acoustic imaging functionalities