Design and Fabrication of 128+128 Element Row-Column Addressed CMUT Arrays for Monitoring Murine Cardiac Flow Patterns

Cardiovascular disease (CVD) is a leading cause of death. As human and rodent hearts have very similar morphologies and developmental processes, mice are excellent models for the study of CVDs and their treatments. Real-time monitoring of cardiac flow patterns required for studying CVD development in mice is challenging due to their small size and high heart rate (>600 bpm in adults). A high-resolution, high-frame-rate plane-wave vector-flow imaging approach is needed to overcome this hurdle and decode the relation between blood flow and cardiac mechanics. To this end, we designed a row-column (RC) addressed 128+128-element 2D CMUT array with a broadband frequency response. The fabricated devices had a center frequency of 12.8 MHz and a fractional bandwidth of 92% in immersion. Isolation of the sealing location by etching trenches into the silicon top plate led to improved device reliability. Use of a borosilicate glass substrate and metallization of the top electrode resulted in symmetric row and column behavior. The functionality of the arrays was demonstrated in plane-wave imaging while switching between orthogonal scan planes.