Temperature Sensitive Flexible Optical Fiber Fluorescence Sensor for Wearable Health Monitoring

Optical temperature sensors with stretchability play a crucial role in the development of continuous, stable, and non-invasive wearable health monitoring systems. However, designing efficient and stretchable optical temperature sensors presents significant challenges. This study proposes a wearable optical temperature sensor based on flexible optical fibers, leveraging the temperature-sensitive properties of down-converted luminescent particles (ZnS:Mn). The flexible optical fibers, made from highly elastic polymers, can withstand tensile deformations of up to 250% and feature a core-cladding structure that effectively confines optical transmission. ZnS:Mn emits dual-wavelength light with distinct temperature dependencies, enabling stable temperature sensing through the intensity ratio. Experimental results demonstrate the sensor's exceptional temperature sensitivity, stability, and repeatability within the range of 7-80°C. Notably, the sensor also exhibits the ability to rapidly detect body temperature and recognize respiratory patterns. This work offers a promising solution for the development of advanced, personalized medical and wearable health monitoring devices.