High sensitivity fiber-optic temperature sensor based on PDMS glue-filled capillary

A high sensitivity fiber-optic sensor based on temperature-sensitive material is proposed and demonstrated experimentally. The sensor consists of single-mode fiber (SMF), silicon capillary tube (SCT) and polydimethylsiloxane (PDMS) film, where the PDMS glue is filled into the SCT and s a temperature-sensitive medium sensing cavity is formed at the end of the SMF. Due to its high thermal expansion and thermo-optic effects, the sensor structure is more sensitive response to the change of ambient temperature. The experiment results demonstrate that the maximum temperature sensitivity of our proposed sensor is 3.449 nm/°C in temperature range of 34–48 °C, and the linearity of fitting curve is 99.9%. Compared with the same structure but filled with ultraviolet (UV) glue, the PDMS-based sensor not only has much higher temperature sensitivity, but also has better stability and repeatability. For the new type of sensor composed of optical fiber microstructure and sensitive material, the proposed sensor structure can increase the measurement temperature range. The sensor structure is simple to fabricate, stable in structure, and possessing good repeatability, which has great potential applications in the temperature sensing fields.