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

An ultra-sensitive sensor, based on two Fabry-Perot interferometers (FPIs), has been realized for temperature and pressure sensing. A polydimethylsiloxane (PDMS)-based FPI was used as a sensing cavity, and a closed capillary-based FPI 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, showing a great Vernier effect.