A Conformal Ultrasound Transducer Array Featuring Microfabricated Polyimide Joints

摘要

Due to their increased angular coverage around body surfaces, conformal ultrasound transducers may potentially provide increased signal acquisition relative to rigid medical ultrasound probes and eliminate the need for mechanical scanning. This paper describes a novel, high efficiency, and robust conformal ultrasound transducer array based on a flexible substrate of silicon islands joined together using polyimide joints. The array incorporated diced bulk lead zirconate titanate (PZT) mounted atop the silicon islands as its piezoelectric material for its desirable electromechanical coupling factor and high piezoelectric coefficients. Parylene thin films deposited over the array reinforced the bendable joints, encapsulated the metal film interconnects, and formed, in conjunction with the silicon, an acoustical match between the PZT and soft tissue. Eight element linear arrays were fabricated with a pitch of 3.5 mm, operating at a center frequency of 12 MHz with a 6dB bandwidth of 27%. The robustness of the transducer was demonstrated by iterative bending around a 1 cm diameter cylinder, and the durability of the electrical traces and the frequency performance was measured using a vector network analyzer. This paper presents a robust, durable conformal ultrasound array with the versatility to scale to enable new applications in diagnostic ultrasound imaging.