Polymer-Layered Optical Wearable (PLOW) for Healthcare Applications: Temperature and Stretching Monitoring.

Thermal and stretching characteristics are crucial variables in healthcare, robotics, and human-machine interaction applications. Here, we present a single-mode fiber-based, balloon-shaped, single- and dual polymer-layered optical wearable (PLOW) system that can sense both temperature and stretching. These two types of PLOWs are compared in terms of their detection performance across all criteria. Dual polymer-based systems have a substantial temperature sensitivity of -1.39 nm/°C, while single polymer ones show a sensitivity of -0.18 nm/°C. The increased sensitivity is attributed to the higher thermo-optic coefficient of the bipolymer (polymer jacket and PDMS) encasing. In terms of stretching sensing, single PLOWs beat dual ones for both longitudinal and lateral stretching due to the large change in shape variable at the same extrusion pressure in single PLOWs. The fast temporal response, high-temperature tolerance, long-term stability, and stretching sensitivity of both PLOWs make them ideal for real-time monitoring of skin temperature, wrist pulse, voice recognition, and different mechanical stimuli. These measures are critical for correctly assessing invasive human health parameters. We believe that these technologies will hold tremendous promise in wearable optical systems, with applications ranging from healthcare to humanoid robotics.