A flexible piezoelectric micromachined ultrasound transducer

Abstract

A novel flexible piezoelectric ultrasound transducer based on MEMS technology is studied, which can be used in medical imaging with the advantage of conformal contact with skin surfaces. The device was based on MEMS-technology and fabricated on a composite substrate of polyimide and biomedical-grade PDMS. DRIE was used to etch the polyimide film into an array pattern for placing the bulk PZT dices. The whole device was packaged by biomedical-grade PDMS for conformal contact with the body surface. A 4 × 4 array was fabricated with element size of 1 mm. The transducer worked in d₃₁ mode at a resonant frequency of 2 MHz and an electromechanical coupling factor of 0.21. The variance of resonant frequency of the array elements was less than 3%. The resonant frequency was unchanged after bending for one hundred cycles or wrapping around a 1 cm diameter cylinder.