Giant Pressure Output Efficiency of Capacitive Micromachined Ultrasonic Transducers Using Nano-Silicon-Springs

Abstract

Although lead-free capacitive micromachined ultrasonic transducers (CMUTs) feature wide bandwidth and high resolution in medical imaging, the weak pressure output efficiency by the small average displacement of the top plate causes narrow imaging depth and high driving voltage, which blur the merits. This paper introduces a nano-silicon-spring-embedded CMUT that improves the transduction efficiency, achieving giant pressure output efficiency at lower voltage due to increasing the average displacement of the plate movement. With the proposed brand new CMUT, the corresponding maximum pressure output at the surface was 1.1 MPa, with 5-cycle pulses of 4.7 MHz and 5 V-PP. The great pressure output efficiency was achieved as 220 kPa/V. With this giant transduction efficiency and low voltage operation, future work is to implement a portable and wearable ultrasonic device with the nano-silicon-spring-embedded CMUT.