A Handheld 128+128 Row-Column Addressed CMUT Array Probe: System Design and Phantom Validation

Row–column (RC) addressed arrays offer an attractive route to compact and versatile high frame-rate ultrasound systems by reducing channel count while retaining volumetric imaging capability. In this work, we introduce a handheld 128+128 element RC-addressed capacitive micromachined ultrasonic transducer (CMUT) probe, integrating custom electronics for high-voltage switching and low-noise amplification. The probe supports multiple imaging modes through flexible biasing schemes: one approach uses a selected elevational aperture thickness with an adjustable step size to sequentially acquire orthogonal slices that can be reconstructed into high-resolution 3D volumes, while another approach employs orthogonal transmit–receive (TX–RX) operation to capture the entire volume in a single acquisition with greatly reduced imaging time. The performance of both modes was validated using a 3D-printed spiral phantom with 0.2 mm wall thickness, demonstrating volumetric rendering of complex structures. The aperture-based method achieved superior resolution, while the orthogonal approach provided rapid volumetric coverage. These results establish the handheld RC-addressed CMUT probe as a versatile platform for next-generation high-frame-rate volumetric ultrasound imaging, with particular relevance to preclinical applications such as in-vivo mouse cardiac imaging.