A Light Waveguide Bending Sensor with a High Sensing Range and High Sensitivity

The optical waveguide bending sensor offers numerous advantages, including high sensitivity, compact size, immunity to electromagnetic interference, corrosion resistance, and biocompatibility. These attributes have led to its extensive adoption in robotics systems. This study introduces a highly sensitive optical waveguide bending sensor with a wide range. Structural optimizations are implemented in the standard waveguide system to minimize interference from ambient light and unwanted deformation. The responses of four core materials to different curvatures and bending angles are thoroughly examined. The experimental findings confirm the efficacy of the cladding modifications and reveal distinct sensitive ranges for each material. Building on the results from single-core waveguides, a tri-core waveguide is developed to broaden the sensor's sensitive range from less than 60° to 120°, resulting in over a 30% reduction in the error of bending angle sensing compared to single-core waveguides. Additionally, the sensor's ability to monitor joint angles is demonstrated through evaluations performed on the wrist and ankle joints.