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Research

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FIG. 1: Standard CMUT cell cross section

Our Research

Capacitive micromachined ultrasound transducers (CMUTs) have recently emerged as an alternative to piezoelectric transducers, offering advantages such as wide bandwidth, ease of fabricating large arrays, and integration with supporting electronic circuits. CMUT technology can produce the type of integrated catheter arrays and external probes enabling advanced 3-D imaging. A CMUT is simply a device with two plate-like electrodes biased with a DC voltage and driven with an additional AC signal to harmonically move one of the plates. The main components are the cavity, the membrane, and the electrode. Using common integrated circuit (IC) fabrication processes, a capacitor cell appears as a metallized membrane (top electrode) suspended above a heavily doped silicon substrate (bottom electrode), as shown in Fig. 1. An insulating layer is included to prevent the two electrodes from shorting in case of contact. A single transducer element uses many small capacitor cells connected in parallel. By organizing transducer elements in different geometries, any array shape is possible.