An integrated Ring CMUT array for endoscopic ultrasound and photoacoustic imaging

This work presents our preliminary results on developing an integrated quad-ring CMUT array for endoscopic ultrasound and photoacoustic imaging. We have designed and fabricated a ring capacitive micromachined ultrasonic transducer (CMUT) array composed of 512 elements distributed among four concentric rings each having 128 elements. The operational frequency of each ring was chosen to achieve a similar pressure beam profile for all the rings. The device's inner and outer diameters measure 5.0 and 10.1 mm, respectively. The CMUT array was integrated with custom front-end ICs using a quartz fan-out board. This bench-top assembly allowed connection to a single ring (i.e., 128 elements) at a time. Thus far, we have built assemblies with connections to the two outer rings. We have successfully demonstrated real-time volumetric imaging with these assemblies using nylon wire phantom and metal spring phantom.