Ultra-stretchable elastomeric suspended-core optical fibers for wearable sensing applications.

Stretchable optical fibers are emerging as a promising platform for wearable sensing applications, owing to their exceptional flexibility, high sensitivity, and inherent immunity to electromagnetic interference. Although current research primarily concentrates on conventional step-index configurations, microstructured optical fibers (MOFs) with precisely engineered architectures offer unprecedented design flexibility and functional versatility. Nevertheless, the fabrication of such advanced fiber structures poses significant technical challenges. This study introduces a demonstration of an elastomeric suspended-core MOF fabricated using styrene-ethylene-butylene-styrene (SEBS) through the preform-to-fiber thermal drawing process, achieving precise geometrical and dimensional control of the fiber structure. The fabricated fiber demonstrates remarkable performance characteristics, including low optical transmission loss (0.0621 dB/cm at 550 nm wavelength), mechanical robustness sustaining up to 500% strain, and superior optomechanical sensitivity under both normal pressure (0-10 N) and bending deformation (0°-90°). These attributes collectively validate its suitability for advanced wearable sensing applications. As a proof of concept, we demonstrate the elastic MOF's versatile applications across three domains: (1) robotic tactile sensing that discriminates surface textures via characteristic light attenuation, (2) high-accuracy data gloves for finger joint flexion tracking in gesture recognition, and (3) real-time respiratory monitoring with reliable breathing rate detection. The integration of SEBS-based elastomeric properties with enhanced optomechanical responsiveness creates a multifunctional platform for next-generation optical sensors in intelligent robotics, human-machine interfaces, and biomedical monitoring systems.