Review of Imprinted Polymer Microrings as Ultrasound Detectors: Design, Fabrication, and Characterization

Detectors play a vital role in ultrasound sensing and imaging applications. With the rapid development of photoacoustic imaging technology in recent years, novel ultrasound detectors based on optical methods have gained increased attention, among which the imprinted polymer microring is a representative one. This review covers the device design, fabrication, and characterization, with an emphasis on how the imprinting-based fabrication methodology benefits the device performance, which further facilitates photoacoustic imaging and sensing applications. By carefully designing and fabricating the imprint mold, the imprinted polymer microring has a quality factor on the order of $10^{5}$ at 780 nm. The device has advantages such as wide acoustic bandwidth response from dc to 350 MHz at -3 dB, low noise equivalent detectable pressure, wide acceptance angle, and so on. The polymer microring has been successfully employed in applications such as photoacoustic imaging and real-time terahertz pulse detection.