Episode 4: Optical waveguide enables self-healing soft robotic system

In this podcast episode, MRS Bulletin’s Laura Leay interviews Rob Shepherd from Cornell University about an adaptive-responsive self-healing soft robotic system. Shepherd’s research team has developed waveguides made of self-healing polyurethane urea crosslinked with aromatic sulfide bonds. When this material is cut, relatively weak hydrogen bonds quickly form. Disulfide exchange then occurs and, although this takes longer than the formation of hydrogen bonds, results in much stronger bonding and so recovering much of the mechanical strength of the polymer. Light is transmitted down the waveguide and, when the material is cut or punctured, the signal is attenuated. The loss of signal can be acted on by the robot and it can change its pattern of movement until the strong disulfide bonds are formed. This self-healing material absorbs more light than previous versions of the polymer that couldn’t effect a chemical repair. This level of light absorption is actually useful as it makes the robot more sensitive to damage or deformation. This work was published in a recent issue of Science Advances.