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An Agilent ENA5061B vector network analyzer (VNA) has been used for impedance measurement and the resonance and anti-resonance values from the imaginary impedance curve were used to determine the electromechanical coupling co-efficient. The measured resonant frequency of 19.3 MHz using a Polytec™ laser Doppler vibrometer (Polytec™ MSA-500) is in excellent agreement with the 3-D FEA simulation result using IntelliSuite™. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wire bonding. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. The agreements of both results are excellent which verifies that fringing field effects exist in the device operation.Įxperimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. Three dimensional modeling is carried out to accurately capture the characteristic behavior of the device.

The analytical prediction has been validated with the finite element method simulation results through PZFlex. Effects of the variation in membrane thickness, gap separation, and membrane radius on membrane displacement are investigated.

Circular membrane approximation model has been considered. Mason’s modeling techniques are used to evaluate the membrane displacement. To determine the equivalent capacitance of the device, the capacitances of the membrane, gap and silicon nitride insulating layer are associated in series. The capacitance value of the device is evaluated based on Younes Ataiiyan’s method. CMUT is used as a medical imaging component which can be an important module for sustainable healthcare system.

This paper models the fringing field effects in a capacitive micromachined ultrasonic transducer (CMUT) structure for determining the sensitivity of the device.