UC San Diego

Advances in reversible adhesives have proven critical in accomplishing novel robotic locomotion and manipulation tasks. However, reversible adhesives using previously reported methods have limited performance dependent on the surface type (i.e., surface roughness) to which they are being applied, and the surrounding environment (i.e., underwater). Bioinspiration, in which concepts from nature inspire synthetic designs, has furthered the development of provocative reversible adhesives. For this dissertation, I explored the topic of fish-inspired reversible adhesives to advance robotic manipulation and locomotion capabilities in wet and submerged environments. Specifically, I focused on the clingfish, an intertidal fish that attaches to rocky surfaces using a suction disc while sustaining high pull-off forces. This impressive ability makes the clingfish an ideal model organism for the development of bioinspired adhesives. I performed investigations into the micro- and macro-scale components of the biological suction disc that are responsible for attachment. I analyzed the contribution of mesoscale surface structures using a custom algorithm to automate their detection and characterization. I applied the conclusions regarding the roles of each biological component to develop bioinspired suction discs that were capable of attaching to widely variable substrates while sustaining high pull-off forces. To minimize the need for active control of adhesion, I investigated the design parameters necessary for the suction discs to directionally adhere. By tuning their material and geometric characteristics, I developed discs that demonstrated morphological computation to achieve anisotropic adhesion in a wet environment. The morphologically programmed discs were applied to underwater locomoting robots, while minimizing the complexity of control. I lastly applied my conclusions regarding the impact of mesoscale surface structures of the clingfish to develop biomimetic textures to resist shear disturbances. I investigated the dependency of design parameters, such as stiffness, of the textures on the surface properties of the objects to be manipulated. The biomimetic textures were applied to the challenge of manipulating wet, delicate surfaces, with an explicit application to surgical manipulation. I lastly coupled the benefits of surface texturing and suction to develop a robotic manipulator to achieve a stable grasp of wet and lubricated objects against axial and shear disturbances. Overall, the exploration of fish-inspired adhesives presented in this dissertation yielded novel robotic capabilities when applied to the areas of manipulation and locomotion.