Theory and analysis of electrode size optimization for capacitive microfabricated ultrasonic transducers

Theoretical analysis and computer simulations of capacitive microfabricated ultrasonic transducers indicate that device performance can be optimized t hrough judicious patterning of electrodes. The conceptual basis of the anal ysis is that electrostatic force should be applied only where it is most ef fective, such as at the center of a circular membrane. If breakdown mechani sms are ignored, an infinitesimally small electrode with an infinite bias v oltage results in the optimal transducer, A more realistic design example c ompares the 3-dB bandwidths of a fully metalized transducer and a partially metalized transducer, each tuned with a lossless Butterworth network. It i s found that the bandwidth of the optimally metalized device is twice that of the fully metalized device.