Laser-induced graphene-based moisture generators for scalable integration and self-powered respiration monitoring

Moisture-enabled generators (MEGs) generate electricity through moisture-induced interfacial and ionic process, yet their practical deployment is still restricted by the modest output of a single unit and the difficulty of large-scale integration. Here, we report an electrochemically coupled, laser-induced-graphene-based moisture electric generator (L-MEG), in which the redox reactions of an active Al top electrode operate synergistically with moisture-induced ionic transport, thereby providing an additional ionic source and electrochemical driving force. The bottom laser-induced-graphene (LIG) electrode, directly patterned on a flexible polyimide (PI) substrate through laser engraving, enables scalable fabrication and supports series and parallel integration with negligible loss. A single L-MEG unit delivers a stable voltage above 1.1 V for more than 120 h under ambient conditions. Upon integration, the assembled L-MEG modules reach output voltages above 10 V, which directly illuminate a commercial LED without any intermediate energy storage. Moreover, taking advantage of its intrinsic humidity sensitivity, the L-MEG further serves as a passive respiration sensor. Through their characteristic frequency and amplitude signatures, with dominant frequencies ranging from 0.19 to 1.50 Hz, L-MEG simultaneously resolves three respiratory patterns including normal, rapid, and deep breath, together with two respiration sites including mouth and nose, providing a battery-free and reliable route toward continuous physiological monitoring.