Highly Sensitive Pressure Sensors Based on Fabry–Perot Interferometers and Vernier Effect

Based on the traditional Vernier effect (TVE) and harmonic Vernier effect (HVE) mechanisms, this paper studies high-sensitivity pressure sensors made by parallelling a sensing element of Fabry-Perot interferometer (FPI), FPIs, based on silicone gel (Sg) thin film, and a capillary-based reference element, FPIr. In the range of 0-0.3 Mpa, three sensing FPIswere fabricated and tested with sensitivity range of 4.07 - 6.75 nm/Mpa. The affection of the thickness of the Sg film to the response to pressure was discussed. Three FPIrwere fabricated for parallelling to the three FPIsto form four TVE or HVE-based sensors showing pressure sensitivity in the range of 51.26-197.06 nm/Mpa with good linearity. These sensors are of low temperature crosstalk. The highest sensitivity of theses sensors is about 48.41 times higher than that of a single FPIs. It can be seen that, for the same harmonic order, the detuning is decreased, the M-factor and sensitivity are significantly improved. Experimental results shows that manufacturing difficulty of 1stHVE-based sensors has been significantly reduced for no need of precise control of cavity length of FPIrand FPIs. According to the sensitivity requirements in actual situations, these proposed pressure sensors, have potential applications in different scenarios, such as healthcare, environmental monitoring, aerospace, and geological exploration.