Performance analysis and application of a hybrid electromagnetic-triboelectric nanogenerator for energy harvesting

In recent years, the possibility of harvesting the small-scale energies from the environment has been the subject of many scientific studies. Nanogenerators are emerging to be good candidates for converting the small-scale energies from the environment into electrical energy without need for battery. In this paper, a hybrid nanogenerator that integrates three different working mechanisms for conversion of mechanical energy into electrical energy is presented. The hybrid nanogenerator is composed of a zig-zag contact mode triboelectric nanogenerator (TENG), a sliding mode TENG and two electromagnetic generators (EMGs). Triboelectric surfaces are oppositely charged aluminium and Kapton layers for a zig-zag contact mode TENG and aluminium and PTFE layers for a sliding mode TENG. Aluminium layer is used as an electron donor, and also as an electrode. EMG unit is composed of two home-made copper coils and a neodymium magnet. All individual units are integrated into a two-piece acrylic shell. The whole device is of a compact, low-cost, and lightweight design. It has a size of 37 mm × 37 mm × 70 mm, which was optimized by modelling. Performance characterization verified the proposed hybrid nanogenerator as an efficient energy harvester. Output characteristics were tested under different loads (in a range from 10 kΩ to 100 MΩ). The maximum output voltage and current of the hybrid nanogenerator were estimated to be about 65 V and 15.25 μA, respectively. The maximum output power was 1.13 mW at 200 Ω. Charging performance analysis showed that the hybrid nanogenerator significantly enhanced the voltage level and charging speed of the tested capacitors in comparison with individual units. The hybrid nanogenerator charged 1μF capacitor to 9.1 V within 60 s. Individual units could simultaneously power at least 144 light-emitting diodes (LEDs). A hybrid signal could power at least 94 LEDs connected in series and at least 50 LEDs connected in parallel. Electrical energy produced by the hybrid nanogenerator was stored in a 47 μF capacitor bank and used to efficiently power a calculator.