Integrated thermal management-sensing-actuation functional artificial muscles

Abstract

Electrothermal-driven polymer fiber-based artificial muscles with helical or twisted structures are promising due to their low cost and high energy density output. However, the current cooling methods for these muscles, such as natural cooling or cold-liquid baths, limit their actuation frequency, especially for large-diameter artificial muscles, posing a technical barrier to their broader application. In this study, we developed an advanced tubular fluidic pump by introducing carbon nanotube electrodes, achieving pumping capabilities over 2 times that of conventional electrodes. We integrated this pump with tubular fiber artificial muscles, creating fluid pump-cooled electrothermal artificial muscle systems with parallel and series configurations. This integration reduced cooling time to about one-ninth of the original and increased mechanical energy output power density by 3 times, expanding the effective actuation frequency range by 3.5 times. Additionally, to effective control artificial muscle actuation, we incorporated a resistive sensing layer directly onto the surface of the artificial muscles, enabling position monitoring. On the application front, we demonstrated the potential of these artificial muscles in thermally responsive functional composite materials, deformable mechanical components, and bionic origami wrist joints.