Enzyme-powered soft robots: Harnessing biochemical reaction for locomotion

Abstract

Enzymes have been known as “renewable resources” in cellular processes (in vivo) for more than a century, and are applied in a wide range of fields, including pharmaceuticals and food, particularly through in vitro approaches. This study explored using an enzymatic reaction as the power source for soft robots (here, robots fashioned from silicone). Soft robots powered by pneumatic pressure deform flexible materials in response to internal pressure changes, thereby inducing robot motion. Traditionally, the primary operational principle involved controlling internal pressure using a compressor, creating challenges related to device enlargement, weight, and electric power consumption. Here, as an alternative, we operated a pneumatically driven soft robot by applying the O2 gas generated from decomposition of H2O2 catalyzed by the ubiquitous enzyme catalase. The generation of O2 gas was influenced by the catalase concentration, H2O2 concentration, and the supply-rate of H2O2. Operational tests on a silicone-rubber soft arm suggested controllability of its velocity and number of operational cycles by modifying the enzymatic reaction conditions. Our findings demonstrate the utility of the catalase-catalyzed reaction as a power source for soft robots, thereby showcasing novel prospects for enzyme applications.