Flexible and Stretchable Optical Waveguide Tactile Sensor for 3-Axial Force Sensing

Tactile sensing is essential for precise manipulation and ensuring safety by providing real-time feedback on external forces and interactions. However, conventional tactile sensors struggle to maintain flexibility, accuracy, and reliability when applied to complex or flexible surfaces. To address these limitations, we present a novel, fully flexible optical waveguide sensor capable of 3-axial force sensing by detecting variations in light intensity within intersecting optical channels. This work includes a comprehensive theoretical analysis and modeling of optical waveguide mechanisms, focusing on intrinsic, extrinsic, and intersection losses, thereby establishing a foundation for optimizing sensor design and minimizing these losses. The sensor’s performance was validated through experiments involving various deformation modes, including stretching, bending, and pressing, achieving a resolution of 0.0073 N and a hysteresis of 4.76%. To model the relationship between applied forces and light intensity loss, we employed an artificial neural network, which achieved an error margin of 0.10058 N (R² = 0.98472) in force prediction. The combination of high performance, flexibility, and accuracy makes this sensor a promising solution for tactile sensing in advanced applications such as flexible systems and soft robotics.