Self-powered wireless environmental monitoring system for in-service bridges by galloping piezoelectric-triboelectric hybridized energy harvester

The energy harvesting technology for the ubiquitous natural wind enables a desirable solution to the issue of distributed sensors in the bridge environmental sensing Internet of Things (IoT) system being restricted to conventional energy supply. In this work, a self-powered system based on a compact galloping piezoelectric-triboelectric energy harvester (GPTEH) is developed to achieve efficient wind energy harvesting. The GPTEH is constructed on the prototype of a cantilever structure with piezoelectric macro-fiber composite (MFC) sheets and a rectangular bluff body with triboelectric nanogenerators (TENGs). Through a special swing-type structural design with iron blocks inside the bluff body, the GPTEH exhibits preferable aerodynamic behavior and excellent energy conversion efficiency, compared to conventional cantilever kind of piezoelectric wind energy harvester (PWEH). The GPTEH also demonstrates the capability of high output power density (PEH of 23.65 W m-2 and TENG of 1.59 W m-2), superior response wind speed (about 0.5 m s-1), and excellent long-term stability (over 14000 cyclic tests). Furthermore, a power management system is developed to efficiently utilize the output energy from GPTEH to power the sensors and wirelessly transmit environmental data to the terminals. The proposed GPTEH powered system exhibits a great potential for the bridge environmental monitoring and IoT technologies.