Low Cross Sensitivity Fiber-Optic MEMS Pressure Sensor for Water Depth Measurement

Abstract

To address the demand for high-precision depth detection in intelligent monitoring and sensing applications for the ocean environment, this letter presents a fiber-optic Fabry-Perot (FP) micro-electro-mechanical systems (MEMS) water depth pressure sensor. Its core is a miniaturized FP cavity fabricated via anodic bonding of borosilicate glass and silicon, which ensures robustness and enables wafer-scale production. Experimental results demonstrate a high pressure sensitivity of −68.99nm/MPa over 0.1-1.1MPa (equivalent to 10-110m water depth). When integrated with a high-resolution interrogation system, centimeter-level depth resolution is achieved. The sensor demonstrates a repeatability error of 0.18%Full scale (FS) and stability better than 0.21%FS. Furthermore, owing to the matched thermal expansion coefficients of the bonded materials, the sensor exhibits low temperature cross sensitivity, with a temperature sensitivity of only 0.43nm/°C over the -10-40°C range, ensuring reliable operation in varying temperatures. This work provides a competitive solution for developing high-reliability, low cost optical water depth pressure sensors suitable for marine environments.