Bioinspired Miniature Ionic Power Pack Using Stacked Liquid Marbles for Muscle Stimulation

Inspired by the electrogenic mechanism, a miniature ionic power pack based on liquid marbles (LMs) is developed that overcomes ion-migration rates constraint in traditional systems. This stacked LM power source utilizes droplets encapsulated with hydrophobic powders composed of Brazilian palm wax, stearic acid, and hydrophobic magnetite, optimized for mechanical robustness, stability, and rapid activation. Upon near-infrared activation, the LMs merge within 1 s, enabling efficient and reliable activation. The system demonstrates enhanced ion-transport and superior performance, achieving an open-circuit voltage of 290 mV, a short-circuit current of 150 µA, and a power density of 275 W·m⁻ 3 , outperforming conventional gel-based systems by factors of 1-, 70-, and 23-fold, respectively. Scalability is validated through series and parallel configurations, supporting diverse biomedical applications. As a proof of concept, the LM power pack is successfully applied in electrical stimulation therapies for medical treatment chips and sports rehabilitation, showcasing its potential for compact, biocompatible, and efficient bioelectronic systems.