Flexible dual-core optical waveguide with variable contact-induced losses for quasi-distributed tactile sensing

Optical waveguide tactile sensors, essential for measuring contact forces, have gained significant attention in recent years due to their high sensitivity, resistance to electromagnetic interference, and potential for distributed tactile sensing. In this study, we propose a flexible dual-core optical waveguide tactile sensor, which features a uniform polydimethylsiloxane (PDMS) core for force measurement, and a flat fluorinated polymethyl methacrylate (PMMA) core that interacts with a gradient loss-inducing contactor for position discrimination. Experimental results show that, when an equivalent normal force is applied at different locations along the waveguide, the PDMS core generates a consistent signal, while the fluorinated PMMA core exhibits varying responses based on the contact position. This distinctive behavior allows for the decoupling of force magnitude and location. The sensor demonstrated a spatial resolution of 4 mm and a dynamic range of 0-6 N. To showcase its practical application, we integrated the sensor onto the finger of a robotic gripper and the rear of a robotic manipulator, enabling object localization and the detection of external pressure on the robotic hand. The sensor's high flexibility and quasi-distributed tactile sensing capabilities make it promising for applications in intelligent robotics.