Ultrasound sensors have been widely used in various applications such as medical imaging, industrial inspection, and non-destructive testing. Ultrasound sensors usually use piezoelectric ultrasound transducers to convert acoustic pressure energy into electrical signals based on piezoelectric materials. They can detect a wide range of ultrasound frequencies and are widely used. However, the sensitivity and dynamic range of the sensors are fixed and as a result, they can suffer signal saturation or low sensitivities. In addition, the manufacturing of the sensors requires several manual steps which result in high costs. We introduce a new type of optical ultrasound sensor using silicon photonic waveguides combined with a MEMS cantilever membrane. The optical ultrasound sensor is highly sensitive, and its sensitivity and dynamic range are tunable. Our sensor combines the advantages of both silicon photonics and MEMS to provide a new approach to measuring ultrasound. Silicon photonics uses the light interference effect to precisely measure the location of the MEMS membrane. The sensor consists of a silicon photonics waveguide that is integrated with a cantilever MEMS structure. The MEMS cantilever is designed to be highly sensitive to mechanical vibrations, including ultrasound signals. The resonant frequency of the sensor can be adjusted by controlling the dimensions of the cantilever. MEMS and silicon photonic devices are highly compact and can be integrated with other devices on a single chip, making them well-suited for a wide variety of fields and can be fabricated using standard semiconductor fabrication techniques, so they can be manufactured at a relatively low cost. 

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- D. J. Choi, S. W. Nam, M. G. Lim, Y. J. Park, M. J. Her, D. U. Kim, H. J Seong, S. Han**, and J. S. Yu**, "Optical Ultrasound Sensor Based on Silicon Photonic MEMS Cantilever with Tunable Dynamic Range", 2023 IEEE 18th International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), 2023