Untethered, high-speed soft jumpers enabled by combustion for motions through multiphase environments

Abstract

Soft robots have been widely studied to accomplish multifunctional on-land tasks in recent years. Here, we develop a type of combustion-enabled soft jumpers that are able to move through multiphase media (e.g. water-air multiphase) with a high-speed of ∼6 times body length per second on average and up to ∼9 times body length per second at most while the driving time is less than 0.5 s. The reported soft jumpers are driven by extremely expandable silicon-rubber membranes resulted in the combustion of oxygen-propane mixed gas. Experiments are conducted to investigate the multiphase jumping response of the soft jumpers with respect to the premixed gas ratio r of the combustion. Both numerical and analytical models are developed to investigate the jumping response in terms of the gas amount A, the premixed gas ratio r and the water depth D W, and satisfactory agreements are obtained from the comparisons among the experimental, numerical and analytical results.