Abstract
To conduct burst-echo imaging with air-coupled capacitive micromachined ultrasonic transducers (CMUTs) using the same elements in transmission and reception, this work proposes a dedicated and integrated front-end circuit board design to build an imaging system. To the best of the authors’ knowledge, this is the first air-coupled CMUT burst-echo imaging using the same elements in transmission and reception. The reported front-end circuit board, controlled by field programmable gate array (FPGA), consisted of four parts: an on-board pulser, a bias-tee, a T/R switch and an amplifier. Working with our 217 kHz 16-element air-coupled CMUT array under 100 V DC bias, the front-end circuit board and imaging system could achieve 22.94 dB signal-to-noise ratio (SNR) in burst-echo imaging in air, which could represent the surface morphology and the three-dimensional form factor of the target. In addition, the burst-echo imaging range of our air-coupled CMUT imaging system, which could work between 52 and 273 mm, was discussed. This work suggests good potential for ultrasound imaging and gesture recognition applications.
Highlights
In recent years, air-coupled ultrasonic testing technology has played a significant role in the medical [1] and aerospace [2] industries, human–computer interaction (HCI) [3] and other fields, owing to the advantages of being noncontact and noninvasive [4]
Compared to traditional piezoelectric ultrasonic transducers, capacitive micromachined ultrasonic transducers (CMUTs) with wide bandwidth, good acoustic matching with air, fabricated high-density arrays and integration with front-end circuits are suitable for air-coupled ultrasonic applications [5,6,7,8]
This paper reported a dedicated and integrated front-end circuit board controlled by a fieldelements, this paper reported a dedicated and integrated front-end circuit board controlled by a programmable gate gate array (FPGA)
Summary
Air-coupled ultrasonic testing technology has played a significant role in the medical [1] and aerospace [2] industries, human–computer interaction (HCI) [3] and other fields, owing to the advantages of being noncontact and noninvasive [4]. Air-coupled CMUTs have been studied in a variety of applications for a long time. Designed an air-coupled CMUT that had its −6 dB bandwidth improved from 1% to 2.5% for ultrasonic transit-time detection. Previous applications of air-coupled CMUTs did not use the same CMUT element to transmit and receive ultrasonic waves. CMUTs, leading to a low signal-to-noise ratio (SNR), which impedes imaging applications in air. The main includeinclude low receiving sensitivity of CMUTs and noise by the T/R switch switch in the receiving both greatly reducing of the echo signal. CMUT imaging using the the same transmission and result demonstrated the thefeasibility feasibilityofofair-coupled air-coupled imaging using same transmission reception elements, suggesting good potential in ultrasound imaging and gesture recognition and reception elements, suggesting good potential in ultrasound imaging and gesture recognition applications in in the the future
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