Power Response of a Muscle Actuator Driven by a Regenerative, Enzymatic Pressurization Mechanism

Inspired by the characteristics of biological muscles, rubber muscle actuators (RMAs) are lightweight and compliant structures that deliver high power/weight ratios and are currently under investigation for use in soft robotics, prosthetics, and specialized aircraft. RMA actuation is accomplished by inflating the structure’s air bladder, which results in the contraction of the muscle. In this proceedings paper, we describe the use of gaseous products from enzymatically-catalyzed reactions to pressurize and drive the motion of RMAs. Specifically, this paper details the power envelope of RMAs driven by the urease-catalyzed production of CO₂, under dynamic loading conditions. The use of enzymatically catalyzed, gas-producing reactions is advantageous for powering RMAs, as these systems may be self-regulating and self-regenerating. Reaction design parameters for sizing the gas source to RMA power requirements and power envelope results are reported for gas-powered actuator dynamics tested on a linear motion test assembly. The power response to increasing loads reflects the partial pressure over the reaction slurry; therefore, the chemistry and reactor scale affect the entire structure’s efficiency. We outline the reactor space-time design constraints that facilitate a tailored power response for urease catalyzed gas generation sources.