As a noval 2D ultrasonic transducer array, what are the advantages of CMUT array compared with the original 2D piezoelectric ceramic transducer array? Let's take a look at a paper: Citation 1, Omer Oralkan from Stanford University tested the performance of CMUT by experimentally comparing the CMUT transducer with the piezoelectric ceramic transducer. CMUT is compared with 2D piezoelectric ceramic transducer.

Disadvantages of 2D piezoelectric ceramic transducer:

It's difficult to create a lot of matrix elements, complex connection. Grating lobe: In order to reduce the grating lobes, the spacing of array elements must be smaller than wavelength of the acoustic wave  (Sound speed is 1540m/s, frequency is 5MHz, wavelength is 308 um. 10 MHZ, 154 um. High frequency, high detection accuracy.) This small size limits the transmitting energy and reduces the receiving sensitivity of piezoelectric ceramic materials, making it difficult to achieve a large dynamic range.

Advantages of CMUT:

Better bandwidth. High sensitivity. Easy to manufacture. Small size, low noise. It can also be integrated with CMOS IC packaging.

In this paper, CMUT with diameter 36um and 400US *400um piezoelectric transducer are used for experiments. The following figure shows the sensitivity comparison between PZT and CMUT. Compared with the CMUT model of 200% Cp (parasitic capacitance), PZT has an advantage only around the central frequency of 3MHz. Parasitic capacitance can be reduced by integrating the receive amplifier into the CMUT chip.

Compared with the SNR, PZT has an advantage only near the center frequency of 3MHz.