A bio-inspired, soft-bodied jumper

Some species of fly larvae and nematodes achieve rapid locomotion by forming loops with their bodies, latching their heads and tails, and storing elastic energy by pressurizing their soft bodies, until rapidly releasing the energy to power a jump, even without legs. Here, we model the mechanics of curved expanding bodies to understand the forces generated against a latch and the energetics that govern jumping. We then present a gall midge inspired soft-bodied jumper inspired by the incredible feats of these larvae and nematodes that emulates this jumping strategy through thermally induced volumetric expansion and mechanical latching. The robot is constructed from a silicone-alcohol composite that expands under Joule heating from an embedded nichrome wire, and is secured by a polyimide latch that enables elastic energy storage and sudden release. With a mass of 150 mg and length of 13 mm, the soft-bodied jumper reaches take-off velocities up to 1.82 m sand a jumping power density up to 1274 W kg, rivaling the performance of its biological counterparts, and demonstrating one of the highest-performing soft-bodied latch-mediated spring actuation (LaMSA) systems. Together, the model and physical system illustrate a simplified soft-bodied LaMSA mechanism, showing how the interplay of elastic energy storage and rapid release enables high-speed, impulsive motion in small-scale synthetic systems.