Green and flexible pMUT based on transparent piezoelectric chitosan thin film

The development of piezoelectric biomaterials able to combine biocompatibility, flexibility and environmental sustainability is imperative for the development of sustainable and compliant devices for health and environment applications. Additionally, a tailored manufacturing protocol that meets the constraints of biomaterials is required to increase the device's processability and performance. This work presents a novel flexible piezoelectric micromachined ultrasound transducer (pMUT) based on piezoelectric-enhanced and biocompatible chitosan thin film whose tunable fabrication approach makes the device adaptable to configurations that span from planar millimetric arrays until optical fiber-based endoscopes with a footprint smaller than
$500\ \mu\mathrm{m}$
. The device was tested underwater to evaluate its ultrasound sensing ability in a physiological environment.