SAFT imaging using immersed capacitive micromachined ultrasonic transducers

Micromachined ultrasonic transducers (cMUTs) capable of operating in immersion mode have been designed and fabricated. As with previously reported airborne results, these immersable transducers possess extremely wide bandwidths, with operation typically ranging from low MHz extending beyond 10 MHz in water. Such wide bandwidths are of interest for many imaging applications. A range of transducer arrays have been fabricated with individual element sizes ranging from 200 μm - 1 mm. The transducers are fabricated using an electronics-compatible micromachining process, which would allow analogue front-end electronics and transducers to be implemented on the same silicon substrate. Results will be presented from small aperture synthetic line arrays of cMUT receivers, which have been used in conjunction with a series of piezoelectric sources to allow images to be presented of reflective targets. The data is processed using a 2D Synthetic Aperture Focussing Technique (SAFT) algorithm.