Abstract
This work proposes to develop a CMOS (complementary metal oxide semiconductor) capacitive ultrasonic sensor chip that can be jointly operated with an acoustic lens system to achieve fast 3-D photoacoustic imaging. Compared to conventional piezoelectric technology, capacitive transducers have a wider bandwidth and can be miniaturized and fabricated in a dense array to provide better imaging quality. Different from our previous approach that requires a long acquisition time to measure the complete waveform of each sensor for 3-D image reconstruction, the new scheme only has to detect the peak amplitude of a waveform. This paper reports the characterization of the fabricated sensors, which shows the sensors have a resonant frequency near 3.5 MHz and the peak detection errors are typically within 10% for test signals from 1 to 10 MHz with the amplitude from 50 to 400 mV. © 2014 The Authors. Published by Elsevier Ltd.