China
Africa
Explore chapters and articles related to this topic
Recent Advances in Capacitive Micromachined Ultrasonic Transducer Imaging Systems
Published in Troy Farncombe, Krzysztof Iniewski, Medical Imaging, 2017
Albert I. H. Chen, Lawrence L. P. Wong, John T. W. Yeow
Compared to a PZT transducer, the vibrating membrane of a CMUT is substantially thinner. As a result, a CMUT experiences a much higher damping that leads to a wider bandwidth, or less ringing. Imagine if ringing effect was significant in our ears, we would be hearing echoes and distorted sounds constantly and be unable to appreciate a symphony and clearly distinguish between notes! In short, it is extremely important to have a wider bandwidth in order to resolve spatially.*
The design and optimization of transimpedance amplifier capacitance detection circuit
Published in Amir Hussain, Mirjana Ivanovic, Electronics, Communications and Networks IV, 2015
Linfeng Mu, Wendong Zhang, Changde He, Chenyang Xue
CMUT is a device based on a capacitive structure, which benefits from electrostatic forces. These forces are created between two electrodes separated from each other by a very small gap and is used to transmit and receive acoustic waves at ultrasonic frequencies (Cetin & Ahmet 2011).
RF MEMS, FBAR, and CMUT
Published in J. David, N. Cheeke, Fundamentals and Applications of Ultrasonic Waves, 2017
CMUT (capacitive micromachined ultrasonic transducers) are capacitive transducers produced by MEMS technology. They have many desirable qualities including low cost, high volume manufacture, miniature, high performance, and ease of integration with ICs.
An alN-based piezoelectric micromachined ultrasonic transducer with a double-beam suspended structure
Published in Journal of the Chinese Institute of Engineers, 2022
Yihsiang Chiu, Li Wang, Dan Gong, Yang Yang, Weili Wang, Nan Li, Shenglin Ma, Yufeng Jin
A much lower electromechanical conversion efficiency for the conventional bulk piezoelectric transducer is caused by poor acoustic coupling (Oralkan et al. 2003). This issue can be overcome by miniaturizing the capacitive micromachined ultrasonic transducer (CMUT) using integrated circuit technology. On the other hand, a tiny capacitive air gap underneath transducer is required for sensible ultrasonic reception, restricting the displacement of membrane and hence leading to a lower propagatable sound pressure level (SPL). Therefore, high voltage (>100 V) and big air gap are needed for the CMUT to generate a large vibration amplitude. By contrast, piezoelectric micro-machined ultrasound transducers (PMUT), which make use of the piezoelectric effect independent of a direct current (DC) polarization voltage can be utilized in the same way. The process of fabrication is more straightforward than that of the CMUT. Meanwhile, the PMUT exhibits a displacement from elastic supporting layer and actuating membrane deflection due to the piezoelectric effect. Lead zirconate titanate (PZT) (Baborowski et al. 2003), zinc oxide (ZnO) (Li et al. 2017), and aluminum nitride (AlN) are serveral piezoelectric materials that are commonly used. In particular, PZT is frequently applied in medical imaging due to its extraordinary piezoelectric coefficient. Moreover, the integration of ZnO MEMS into circuits is complicated by the diffusion of Zn ions, which results in contamination of the CMOS circuit. Although it is possible to integrate ZnO MEMS devices into circuits, Zn ions usually diffuse, which easily induces CMOS circuits contamination. Furthermore, ZnO devices are associated with higher power dissipation attributed to their high conductivity. In contrast, AlN is processed at low temperature, which is beneficial for post-CMOS compatible fabrication with a lower residual stress, compared with other materials (Smyth, Sodini, and Kim 2017; Shelton et al. 2009).