Hybrid Cell Structure for Wideband CMUT: Design Method and Characteristic Analysis

Abstract

Capacitive micromachined ultrasonic transducer (CMUT) is an ultrasonic transducer based on the microelectromechanical system (MEMS). Wideband CMUT has good application prospects in ultrasonic imaging, ultrasonic identification, flow measurement, and nondestructive testing due to its excellent characteristics. This paper studies the method of increasing the bandwidth of the CMUT, proposes the structure of the wideband CMUT with a hybrid cell structure, and analyzes the design principles and characteristics of the wideband CMUT structure. By changing the cell spacing and the number of cells of different sizes composing the CMUT, we analyze the simulation of the effect of the spacing and number on the CMUT bandwidth, thereby optimizing the bandwidth characteristics of the CMUT. Next, the selection principle of the main structural parameters of the wideband CMUT is analyzed. According to the proposed principle, the CMUT in the air and water are designed and simulated. The results prove that both the air and water CMUT meet the design requirements. The design rules obtained in this paper can provide theoretical guidance for the selection of the main structural parameters of the wideband CMUT.

Research on Broadband Matching Method for Capacitive Micromachined Ultrasonic Transducers Based on PDMS/TiO2 Particles

“…It has significant advantages that traditional piezoelectric transducers do not have, such as a simple and flexible structure, high sensitivity, high electro-mechanical conversion efficiency, high resolution, wide bandwidth, and good consistency. It also has the potential to easily form large arrays and integrate with electronic devices [10][11][12][13][14][15][16][17][18]. In addition, it can match better with the acoustic transmission medium be-cause its diaphragm has a lower acoustic impedance [19,20], providing favorable conditions for ultrasonic imaging.…”