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

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 46; no. 6; pp. 1364 - 1374
• Main Authors: Bozkurt, A., Ladabaum, I., Atalar, A., Khuri-Yakub, B.T.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.1999; Institute of Electrical and Electronics Engineers
• Subjects: Acoustic devices; Acoustics; Biomembranes; Circuits; Computer simulation; Devices; Electric potential; Electrodes; Electrostatics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Impedance; Networks; Optimization; Pattern analysis; Patterning; Performance analysis; Physics; Silicon; Transducers; Transduction; acoustical devices for the generation and reproduction of sound; Ultrasonic transducers; Design; Dimensioning; Electrodes; Finite element method; Capacitive transducer; Equivalent circuit; Miniaturization; Modeling; Ultrasonic transducer; Optimization
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/58.808859

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