Multimodal soft optical waveguide sensor with microstructured core-cladding interface for human-robot interaction

Increasing demands for human-robot interaction (HRI) highlight the need for safe and reliable sensing mechanisms. Soft optical waveguide sensors, offering intrinsic compliance, immunity to electromagnetic interference, and electrical safety, present a promising solution. However, existing designs face challenges with bidirectional sensing and high computational costs. This paper proposes a multimodal soft optical waveguide sensor with a microstructured core-cladding interface (MOWMI) that detects bidirectional bending angles using a single core. Optimal microstructure roughness is determined by monitoring normalized intensity changes within the sensing range ( − 90° to 90°) for three pitch values (300, 600, 1800 μm) to achieve anisotropic response. Additionally, three colored core blocks (red, green, blue) provide cues for local pressure, supporting use as an HRI interface. MOWMI enables simultaneous sensing of bending direction, angle, and local contacts using a simple thresholding algorithm with low computational cost. Integration into a wrist wearable demonstrates teleoperation with minimal interference to human motion.