CMUT ring arrays for forward-looking intravascular imaging

The paper describes an annular CMUT ring array designed and fabricated for the tip of a catheter used for forward-looking intravascular imaging. A 64-element, 2-mm average diameter array was fabricated as an experimental prototype. A single element in the array is connected to a single-channel custom front-end integrated circuit for pulse-echo operation. In conventional operation, the transducer operates at around 10 MHz. In the collapsed regime, the operating frequency shifts to 25 MHz and the received echo amplitude is tripled. The SNR is measured as 23 dB in a 50-MHz measurement bandwidth for an echo signal from a plane reflector at 1.5 mm. We also performed a nonlinear dynamic transient finite element analysis for the transducer, and found these results to be in good agreement with experimental measurements, both for conventional and collapsed operation.