Pellicular Morphing Surfaces for Soft Robots

Soft structures in nature endow organisms across scales with the ability to drastically deform their bodies and exhibit complex behaviors while overcoming challenges in their environments. Inspired by microstructures found in the cell membranes of the Euglena family of microorganisms, which exhibit giant changes in shape during their characteristic euglenoid movement, this letter presents the design, fabrication, and characterization of bio-inspired deforming surfaces. The result is a surface of interconnected strips, that deforms in 2-D and 3-D due to simple shear between adjacent members. We fabricate flexible polymeric strips and demonstrate three different shapes arising out of the same actuation by imposing various constraints. We characterize the strips in terms of the force required to separate them and show that the bio-inspired cross section of these strips enables them to hold up to 8 N of force with a meagre 0.5 mm of material thickness, while still being flexible to deform. Further, the design of a soft robot module, with an actively deformable surface has been presented, which replicates the mechanism of shape change seen in the Euglena. This letter shows the potential for this new form of shape morphing surface in realizing bio-mimetic soft robots exhibiting large changes in shape.