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Watch Your Step! You might be generating Electricity!

Watch Your Step! You might be generating Electricity!

Technology News |
By Wisse Hettinga



Three-dimensional graphene (3DG) foam as an active layer in triboelectric nanogenerators (TENGs) and as an energy harvesting power source for autonomous sensors

Researchers from the University of the West of Scotland together with Integrated Graphene Ltd. and Albasense Ltd, have studied the effect of using three-dimensional foam in triboelectric nanogenerators.

From the results as published in Sciencedirect:

 

Mechanical energy is one of the most abundant and versatile energy sources available in nature. In the case of humans, one could easily understand that our daily actions could produce energy from milliwatts to a few watts. For that to happen, we need to find a high efficiency technology capable of transforming mechanical energy – currently wasted in the environment – into useful electrical energy essential to power not only small IoT electronic devices and sensors but also more power-hungry apparatus, e.g., electric cars, and drones. Triboelectric nanogenerators (TENGs) have been proposed as promising technology to harvest mechanical energy from low frequency vibrations (0.1–10 Hz). Since the first publications on TENGs in early 2012, their characteristics and fundamentals have been thoroughly studied. Those investigations included TENGs for self-powered sensing platforms [9], theoretical working principle of TENGs, giant energy harvesting from ocean waves (so-called blue energy) [11], role of TENGs on IoT devices, and power management of TENGs. Despite the number of publications, and advantages offered by TENG devices, the technology is still the subject of intense investigation, aiming to address drawbacks of this promising energy harvesting technology. These include high internal impedance (from MΩ to GΩ depending on the material and structure), low durability, limited short-circuit current (nA to μA), structural changes (material deterioration and degradation over time), and post-stress conditions.

A series of comprehensive measurements have been carried out to test the output characteristics of 3DG-TENG under cyclic mechanical stimulus, capable of operating TENG in contact-separation mode at different frequencies, gap distances between electrodes, and applied pressures. The triboelectric response of 3DG-TENG (with an effective surface of 16 cm2) showed maximum open-circuit voltage (Voc) and short-circuit current (Isc) of 400 V and 105.7 μA respectively when stimulated at 3 Hz (contact-separation frequency) and 70 mm (optimum gap distance). Under the same conditions, a maximum output power (Pout) of around 10.37 W/m2 is produced using an external load resistance of 40 MΩ; this is an order of magnitude lower resistance than that needed with other graphene based TENG variants. 3DG-TENG exhibited great stability in the output characteristics with 15,000 cyclic mechanical stimuli and a retention percentage in Pout above 95%. This is a significant improvement with respect to other carbon based TENG`s, which show enhanced deterioration of TENG performance due to material transfer between electrodes and plastic deformation of triboelectric materials. Simulations of TENG Voc using distance dependent model determined high triboelectric charge densities in the range of mC/m2. Here, we also demonstrate the potential of 3DG-TENG as an energy supply for energy storage devices, and as an active layer in an autonomous pressure sensing platform for anonymous room occupancy monitoring in smart buildings.

 

Find the full research report

The research team:

Emma Keel: Conceptualization, Methodology, Software, Validation, Investigation, Formal analysis, Writing – original draft. Ammara Ejaz: Methodology, TENG characterisation; Michael McKinlay: TENG modelling and Formal analysis. Manel Pelayo: TENG characterisation and Formal analysis. Marco Caffio: Supervision, Project administration. Des Gibson: Supervision, Project administration, Writing – review & editing. Carlos García Núñez: Methodology, Formal analysis, Supervision, Visualization

 

 

 

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