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

Abstract

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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>r</mml:mi> </mml:math> of the combustion. Both numerical and analytical models are developed to investigate the jumping response in terms of the gas amount <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>A</mml:mi> </mml:math> , the premixed gas ratio <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>r</mml:mi> </mml:math> and the water depth <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>D</mml:mi> <mml:mrow> <mml:mtext>W</mml:mtext> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> , and satisfactory agreements are obtained from the comparisons among the experimental, numerical and analytical results.