Bendable Polymer-Based High-Frequency pMUTs on Transparent SU8 and Polyimide Substrates

This paper presents the fabrication of two bendable pMUTs on SU8 and polyimide substrates, which offer transparent and biocompatible features. The pMUT on the polyimide substrate, with a thickness of 50 μm, is highly bendable with a 5 mm bending radius, whereas 300 μm thick robust pMUT on transparent SU8 shows partial bendability with a bending radius of 25 mm. Furthermore, the pMUTs on SU8 and polyimide substrates reported in this paper benefit from low actuation voltage levels of 10 V and high underwater resonance frequencies of 12 MHz and 4 MHz, respectively, which are beneficial for high-resolution medical imaging applications.