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|Mahamd||Last replied to at August 27, 2017, 11:40 am|
CMUT is a new technology for ultrasound transducer, some researchers believe CMUT will eventually replace piezo-ceramics in ultrasonic transducers, is it true or not?
Appreciate some clarifications.
|PJ||Last replied to at December 5, 2012, 3:46 pm|
CMUT is a new technology emerged around 10 years ago, using micro-machine technology to build ultrasound transducer. A basic CMUT transducer unit or a transducer cell is very similar to a drum, with a thin membrane electrode on top and other one on the bottom. When the two electrodes are charged the same, it will repel each other and when they are charged oppositely they will attract each other. By alternating the charge, a vibration of the membrane is achieve. On the other way, when pressure wave arrive on the membrane surface electrode, it will change the capacitance of the structure, or the charge, and thus give an electrical signal.
In air, CMUT ultrasound transducer shows great performance especially the sensitivity and bandwidth, however, just like a drum or guitar ring, once it is against a solid surface, the vibration will reduce dramatically. However for medical ultrasound, the wave has to be coupled into human tissue, and in this way, CMUT transducer will lose its sensitivity a lot. The sensitivity of CMUT ultrasound transducer is not as good as the piezoelectric ceramic based ultrasound transducer, especially today, composite material is very popular in ultrasound transducer.
Another disadvantage of the CMUT is that it need a DC voltage bias, which is inconvenient for the system design.
CMUT ultrasound transducer is based on semiconductor fabrication technology, and it is easier to integrate the switching or preamplifier circuit into it. This feature makes CMUT ultrasound transducer more attractive.