عنوان مقاله [English]
In the medical field, ultrasonic imaging is especially popular for its technological features, such as non-radioactive real-time acquisition, affordable equipment cost, and miniaturization capabilities in minimally invasive methods. However, in ultrasonic imaging, micromachined capacitive ultrasound transducers with consideration of various benefits such as ease of fabrication, integration with signal processing electronics, efficient performance, low impedance, and high transduction coefficient can be used for the high-frequency range of medical applications. In this paper, the mechanical and electrical behaviors of a capacitive micro ultrasonic transducer and the frequency bandwidth and sensitivity of the system are evaluated by consideration of scale effects. Moreover, the static deflection of the micro plate using COMSOL software and MATLAB script is extracted. To design an ultrasound transducer capable of producing high-resolution images, a micro capacitive structure using MEMS technology is required. In other words, in the development of medical devices including CMUTs, a range of the operating frequencies are crucial since this directly affects its resolution of images and applications. Consequently, in this work, in order to predict the mechanical behavior of this system accurately, the pull-in instability and frequency response of the diaphragm are investigated by considering the higher order gradients theory based on the Galerkin method. In fact, a simplified strain gradient elasticity analysis was used to analyze a circular micro-scale Kirchhoff plate, adding a role for intrinsic lengths in determining the behavior of the structure significantly. On the other hand, the pull-in voltage, resonance frequency, and the geometrical properties of the structure are the key parameters for designing a transducer. Hence, for a comprehensive study, the electrical features of the capacitive micro transducer including electromechanical coupling coefficient, output pressure, and sensitivity of the received signal are studied by considering the high-order gradients theory. An effective, simple and accurate modeling for a micro/nano structure is presented in this paper, which can be used for medical applications.