Untethered artificial muscles powered by wearable sweat-based energy generator

A sustainable power source is essential for soft artificial muscle to achieve untethered actuation, typically driven by rigid and bulky batteries that severely restrict their applications. Herein, a wearable sweat-based energy generator (SEG) is designed to directly power up a soft artificial muscle for establishing a self-powered conjunct system. The generator generates electricity from sweat based on the redox reaction, which shows a maximum power density of 18.3 μw cm⁻² at a resistance of 0.3 kΩ with a small amount of sweat (0.2 mL). It is sufficient to activate the artificial muscles. Next, the sweat generator is integrated with artificial muscle to present an autonomously powered actuator, resulting in a bending motion based on converting electricity into movement by the electroactive polymer poly(vinylidene fluoride-hexafluoropropylene) (PVDF(HFP)) containing LiCl liquid. This autonomously powered artificial muscle can imitate finger motion, bionic flowers, and a self-powered gripper to manipulate tiny objects. Moreover, integrating artificial muscle and electromyogram sensors with sweat-based energy generators may have potential application values in repairing damaged muscle with closed-loop sensing and treatment. Thus, this autonomously powered artificial muscle can be of great interest for soft robotics, the biomedical field, and biomimetic devices.