Article: Zhao, H; O’Brien, K.; Li, S.; and Shepherd, R.; “Optoelectronically Innervated Soft Prosthetic Hand via Stretchable Optical Waveguides”, Science Robotics, 1 (1)
Abstract: Because of their continuous and natural motion, fluidically powered soft actuators have shown potential in a range of robotic applications, including prosthetics and orthotics. Despite these advantages, robots using these actuators require stretchable sensors that can be embedded in their bodies for sophisticated functions. Presently, stretchable sensors usually rely on the electrical properties of materials and composites for measuring a signal; many of these sensors suffer from hysteresis, fabrication complexity, chemical safety and environmental instability, and material incompatibility with soft actuators. Many of these issues are solved if the optical properties of materials are used for signal transduction. We report the use of stretchable optical waveguides for strain sensing in a prosthetic hand. These optoelectronic strain sensors are easy to fabricate, are chemically inert, and demonstrate low hysteresis and high precision in their output signals. As a demonstration of their potential, the photonic strain sensors were used as curvature, elongation, and force sensors integrated into a fiber-reinforced soft prosthetic hand. The optoelectronically innervated prosthetic hand was used to conduct various active sensation experiments inspired by the capabilities of a real hand. Our final demonstration used the prosthesis to feel the shape and softness of three tomatoes and select the ripe one.
Acknowledgments: We thank A. Ruina for input on the soft finger design. We also thank our group mates B. Peele, C. Larson, and J. Pikul for support and help during the experiments. Funding: This work was supported by the Air Force Office of Scientific Research under award number FA9550-15-1-0160. Part of the study was performed at the Cornell NanoScale Facility, a member of the National Nanotechnology Coordinated Infrastructure, which was supported by the NSF (grant ECCS-1542081), and the Cornell Center for Materials Research Shared Facilities, which was supported through the NSF Materials Research Science and Engineering Centers program (DMR-1120296).