Researchers at China’s Tsinghua University have demonstrated a flexible, stretchable optical fiber that uses light signals from embedded upconversion nanoparticles to act as a biocompatible temperature sensor (Adv. Funct. Mater., doi: 10.1002/adfm.201902898). The team believes that the fiber could offer an interesting platform for the development of real-time wearable temperature sensors for personal health care, as well as for applications in robotics.
To be practical, wearable sensors need to be sufficiently flexible to bend and stretch with the twists and turns of their human wearers. The development of such supple materials for wearable temperature sensors has already made a fair amount of progress in the electronic realm, with research teams looking at various mechanically flexible nanomaterials such as carbon nanotubes and polymer composites.
But the Tsinghua University researchers note that such materials tend to include metal components that reduce their biocompatibility—and whose effectiveness in the real world might be compromised by electromagnetic interference. Optical fiber offers a possible alternative that can overcome some of these problems. Yet conventional fibers, made of silica or glass, fall short on the flexibility requirement.