Microfabricated ultrasonic transducers monolithically integrated with high voltage electronics

Abstract

Capacitive microfabricated ultrasonic transducers (cMUTs) recently produced clinical-quality images, and have the potential to enable true 3D ultrasound. Much has been written about the value of integrating cMUTs with electronics, and some early work has been published (Eccardt, P.-C. et al., 1996; Noble, R.A. et al., 2002). The paper describes monolithic integration of high-quality imaging cMUTs with analog switching electronics. The switching circuitry used has the same voltage limitations as commercial multiplexing chips (200 V/sub PP/). Water tank results demonstrate that cMUTs integrated with controlling switches are fully-functional when the capacitance and resistance of the switch are inserted into the cMUT model. The results further demonstrate no measurable effect of the switch on the radiation pattern of the acoustic elements. This verifies the viability of aperture control and channel multiplexing with monolithically integrated electronics. In the short term, such integration can allow for reconfigurable apertures, arrays with many elevation rows, and optimal preamplification. it also represents a step towards a practical 2D matrix transducer, due to the density of its integration and the freedom to optimize separately the cMUT and the integrated electronics.