Hybrid energy harvester with simultaneous triboelectric and electromagnetic generation from an embedded floating oscillator in a single package

Highlights: • A new structural design of mechanical energy harvester is proposed based on triboelectric-electromagnetic hybrid mechanism. • A floating oscillator with core magnet and polymer clothes responds to external vibration to activate both the triboelectric nanogenerator component and the electromagnetic generator component. • Validity of the hybridization is deeply discussed and operations of commercial electronic systems are demonstrated. Hybridization of two energy harvesters with different mechanisms in one device is a fascinating idea, but a rational design of a hybrid energy harvester for practical applications is challenging. In this work, a floating oscillator-embedded triboelectric-electromagnetic (FO-TEEM) generator is proposed. A triboelectric nanogenerator (TENG) component and an electromagnetic generator (EMG) component independently but simultaneously produce power using the shared floating oscillator. This floating oscillator-based configuration enables versatile energy harvesting capability, excellent size scalability, self-packaged structure, and operation at frequencies in the sub-10 Hz range. Under sinusoidal vibrations with 7.5 Hz frequency, the TENG and the EMG components produced normalized output power of 130 W/kg m³ and 128 W/kg m³, respectively. The charging characteristics were analyzed to design an effective operation scenario. From experimental results, it was found that the TENG component provides consistent charging characteristics, while the EMG component provides fast charging speed. The hybrid device provides both advantages. Using stored electrical energy collected from the FO-TEEM generator, commercial products were successfully powered including an LED lamp, a portable fan, wireless illuminance sensor system, and charging of a smart phone.