Fabrication of 128+128 Element Row-Column Addressed 2D CMUT Arrays on a Borosilicate Glass Substrate Using Anodic...

Row-column addressed 2D ultrasonic transducer arrays require fewer connections compared to their fully addressed counterparts. This allows easier integration with electronics and convenience for high frame rate imaging. High frequency operation is required to resolve finer features during small animal imaging. The real-time monitoring of cardiac flow patterns required for early detection of cardiovascular diseases in mice used in preclinical research is challenging due to their small size and high heart rate. A high-frequency 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 128+128-element row-column (RC) addressed 2D CMUT array with a broadband frequency response. The fabricated devices have a center frequency of 12.4 MHz and a fractional bandwidth of 92% in immersion. Isolation of the sealing location by etching trenches into the silicon top plate led to elimination of dielectric breakdown related device failure at the sealing location. Use of a borosilicate glass substrate and metallization of the top electrode resulted in uniform pressure and symmetric behavior in orthogonal biasing configurations. The device was used for plane-wave imaging while digitally switching scan planes, volumetric imaging and for vector flow imaging of a rotating disk phantom.