Ultra-sensitive temperature and pressure sensor based on PDMS-based FPI and Vernier effect

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An ultra-sensitive sensor, based on two Fabry–Perot interferometers (FPIs), has been realized for temperature and pressure sensing. A polydimethylsiloxane (PDMS)-based FPI 1 was used as a sensing cavity, and a closed capillary-based FPI 2 was used as a reference cavity for its insensitivity to both temperature and pressure. The two FPIs were connected in series to obtain a cascaded FPIs sensor, showing a clear spectral envelope. The temperature and pressure sensitivities of the proposed sensor reach up to 16.51 nm/°C and 100.18 nm/MPa, which are 25.4 and 21.6 times, respectively, larger than these of the PDMS-based FPI 1 , showing a great Vernier effect.