3-Dimensional broadband energy harvester based on internal hydrodynamic oscillation with a package structure

Energy harvesting techniques which convert ambient waste energy into usable electrical power have emerged with the increased energy demand and rapid growth of self-powered systems. Among them, the triboelectric nanogenerator (TENG), which utilizes contact-electrification, has attracted a great deal of attention owing to its high output energy, good cost-effectiveness, and simple fabrication process. Here, the TENG harvesting ambient mechanical energy based on internal hydrodynamic oscillation (Hy-TENG), is demonstrated. The Hy-TENG shows an output voltage and current of 22 V and 1.45 mu A, respectively, under vibration of 5 Hz. The maximum instantaneous power density is 26.5 mW/m(2). By utilizing water in the mechanical energy harvesting process, several powerful advantages are also guaranteed due to the shape adaptability of water. First, both a wide bandwidth and a low resonance frequency are verified, which are advantageous for applications based on human motion. These frequency response characteristics indicate the strong potential of the Hy-TENG in actual environments. Furthermore, the Hy-TENG is highly scalable, as water can easily be restored to its initial state without a mechanical conversion apparatus. Finally, Hy-TENG harvesting 3-dimensional random motion (3-D Hy-TENG) is developed with a simple design based on the easily shape-transformable characteristic of water. Additionally, enhanced endurance against environmental factors and mechanical damage can be expected based on the packaged structure and on the non-destructive water-solid contact. (C) 2015 Elsevier Ltd. All rights reserved.