Characterization of Photonic Temperature Sensors by Comparative Human Body Measurements Using Waveguide Bragg Grating and Microring Resonator-Based Sensors

Human body temperature is an important indicator of physical health. Waveguide Bragg grating (WBG)- and microring resonator (MRR)-based polymer optical waveguide temperature sensors provide alternative methods for monitoring the human body temperature. In this study, optical waveguide temperature sensors, with a combination of polymethylmethacrylate (PMMA) and polydimethylsiloxane (PDMS) for the formation of waveguide structures, are designed and fabricated via a polymer-based fabrication process to achieve real-time temperature measurements in situ. We experimentally characterized and compared the sensor thermal properties within the temperature range of 35 °C–40 °C. Based on the results from our study, the WBG and MRR temperature sensors had high-sensitivity properties. The temperature sensitivity coefficient of the WBG temperature sensor was −177.6 pm/°C and that of the MRR temperature sensor was −0.03035 mW/°C. The error of these two temperature sensors did not exceed 0.1 °C. These sensors show great promise as basic sensing elements in optical waveguide sensor applications for the early detection and monitoring of heat-related illnesses.