Single-channel multi-core fiber sensor for finger bending detection based on composite calibration

Accurate and real-time sensing of finger motion is essential for applications in wearable electronics, human-machine interaction, and rehabilitation monitoring. In this study, we propose a single-channel multi-core fiber sensor system for finger bending detection, integrating thermal diffusion technology with a composite calibration mechanism based on dual-wavelength multi-core fiber Bragg gratings. A thermal diffusion-fabricated coupler is used to combine multiple fiber Bragg grating signals from different cores into a single optical channel, significantly reducing hardware complexity and enhancing system compactness. To further improve sensing precision and stability, the composite calibration strategy based on dual-wavelength multi-core fiber Bragg gratings effectively compensates for errors arising from structural packaging and cross-sensitivity. Experimental results demonstrate that the sensor achieves accurate and stable multi-parameter decoupling, with excellent repeatability and low crosstalk. The proposed design enables high integration, flexible fabrication, and reliable performance, offering a scalable and efficient solution for next-generation wearable optical fiber sensing systems.