Optimized design of CMUT with hexagonal membranes

Abstract

A Capacitive Micro-machined Ultrasonic Transducer (CMUT) with hexagonal membrane is constructed to work as a transmitter and compared to a CMUT with circular membrane. In this paper, three desirable combination of circular and hexagon are analyzed to select the dimensions for hexagonal shaped CMUT. Capacitive Micro-machined Ultrasonic Transducer (CMUT) is a micro constructed transducer used both as transmitter for generating ultrasonic waves and as receiver to modulate the electrical capacitance of the capacitive transducer. It can be fabricated with many geometries especially circular, square, rectangular, and hexagon. Circular CMUTs offers optimum performance in terms of deflection with DC, deflection of biased membrane with AC bias, resonant frequency, capacitance and deflection along frequency but for array formation the wafer area is wasted. A CMUT with hexagonal membrane gives an ultrasonic signal of constant amplitude with less deflection of membrane within the cavity and the outside environment. Stationary analysis is carried out with electro-mechanics for discussing the capacitance change of CMUT. The collapse or pull in voltage of hexagon CMUT is found to be high and increases the bandwidth of CMUT. The absolute percent difference of resonant frequency is observed to be 2.3 % with dimensions selected from the COH configuration of the CMUT.