High-frequency CMUT arrays with phase-steering for in vivo ultrasound imaging

Capacitive micromachined ultrasonic transducers (CMUTs) have prospective clinical applications in ultrasound diagnostics and therapy. We have modeled, fabricated, and characterized CMUT arrays suitable for intravascular and gastrointestinal use. The elements of the CMUT arrays are connected from the back side of the array by through-silicon-vias (TSVs) with a pitch of 25 μm. In the reported work, the presence of TSVs does not reduce the fill factor of the array. Two different membrane designs were fabricated, resulting in a resonance frequency in air of 35.6 and 41.0 MHz, respectively. The measurements were in good agreement with the simulated performance. The realized devices are promising for the fabrication of a 3D-ready and bio-compatible device, suitable for in vivo ultrasound applications.