Polydimethylsiloxane-Assisted Surface Plasmon Resonance–Based Temperature Sensor

Abstract

Since the important applications in multiple fields, research on temperature sensors based on surface plasmon resonance (SPR) technology is receiving increasing attention. Therefore, a SPR-based temperature sensor consisting of temperature-sensitive material of polydimethylsiloxane (PDMS) and titanium dioxide (TiO₂) forming a bi-layer silver structure has been proposed and investigated in this work. As a solid medium with a high thermo-optic coefficient, the PDMS can significantly improve the temperature sensitivity of the sensor. By adjusting the thickness of each layer of the TiO₂-Ag-TiO₂-Ag-PDMS sensing structure, the optimal thickness combination of the structure can be obtained. The thickness of the TiO₂ layer between two silver layers and the thickness of the PDMS layer can adjust the position of the resonance angle. Adding a monolayer of WS₂ upon the PDMS layer can further improve the sensitivity. With an incident with monochromatic light at 632.8 nm, the maximum sensitivity of the structure in the range of 275–360 K and 321–360 K is − 0.094°/K (air) and − 0.129°/K (ethanol), respectively, maintaining high linearity in the range of 310–340 K. The temperature sensitivity also remains high linearity at wavelengths of 620 nm and 680 nm. The proposed sensor structure exhibits excellent sensitivity and figures of merit in the field of sensing temperature.