3‐D Printable Living Hydrogels as Portable Bio‐energy Devices

Harnessing engineered living materials for energy application represents a promising avenue to sustainable energy conversion and storage, with bio-batteries emerging as a pivotal direction for sustainable power supply. Whereas, the realization of miniaturized and portable bio-battery orchestrating off-the-shelf devices remains a significant challenge. Here, this work reports the development of a miniaturized and portable bio-battery using living hydrogels containing conductive biofilms encapsulated in an alginate matrix for nerve stimulation. These hydrogels, which can be 3-D printed into customized geometries, retained biologically active characteristics, including electroactivity that facilitates electron generation and the reduction of graphene oxide. By fabricating the living hydrogel into a standard 2032 battery shell with a diameter of 20 mm, this work successfully creates a miniaturized and portable bio-battery with self-charging performance. The device demonstrates remarkable electrochemical performance with a coulombic efficiency of 99.5% and maintains high cell viability exceeding 90% after operation. Notably, the electricity generated by the bio-battery can be harnessed for nerve stimulation to enable precise control over bioelectrical stimulation and physiological blood pressure signals. This study paves the way for the development of novel, compact, and portable bio-energy devices with immense potential for future advancements in sustainable energy technologies.