Generating electricity from friction: A new breakthrough by scientists in the study of green energy sources
Unlike familiar green energy sources such as hydrogen, solar power or wind power, the friction-based generator – TENG – can recover mechanical energy from vibrations, wind, ocean waves, bodily movements or even human breath, converting them into electricity to power electronic devices, sensors or Internet of Things (IoT) systems. Essentially, TENG operates based on two fundamental physical effects: triboelectrification and electrostatic induction. When two materials (one prone to donating electrons and one prone to receiving electrons) come into contact and then separate, opposite charges form and remain on their surfaces; when the two electrodes are connected to an external circuit, a useful electric current is generated. Research into electrode materials and suitable TENG structural designs that can exploit environmental mechanical oscillations will enable the creation of self-powered devices.
TENG was first introduced in 2012 by Professor Zhong Lin Wang and colleagues at the Georgia Institute of Technology (Georgia Tech, the US). In a paper published in the journal Nano Energy titled “Flexible triboelectric generator” (2012) and a 2014 US patent (“Triboelectric Nanogenerator”), the authors described the mechanism of electricity generation from the contact and separation of two materials with different triboelectric properties. Today, TENG has become a vibrant global research field involving hundreds of research groups worldwide, producing thousands of international publications each year, including many in leading journals. Various applications have been tested, such as power-generating walkways, self-powered biomedical devices, IoT equipment and systems harnessing wave energy.
Applications of TENG for green energy, self-powering, IoT, robotics, smart sports, etc. (Source: J. Luo, Z. L. Wang, https://doi.org/10.1002/eom2.12059)
In June 2022, VAST President approved the independent project “Research, fabrication and investigation of properties of several materials and triboelectric generation structures (TENG)” (Code: DL0000.08/22-24), led by the Graduate University of Science and Technology. The project was headed by Prof.Dr. Phan Ngoc Minh, with significant contributions from Assoc.Prof.Dr. Le Trong Lu and several scientists from the Institute of Materials Science and the Centre for High Technology Research and Development. This was the first project at VAST focusing on triboelectricity, marking the initial step toward establishing a new research group and direction in the field of green energy.
3D-printed device for fabricating TENG electrode materials (self-developed at the Institute of Materials Science)
TENG structure of 13 × 13 cm² capable of generating electricity under small vibrations applied to the electrode surface
The research team successfully fabricated various material systems for use as electrodes in triboelectric generators, notably the PHMG–GA–PVA system synthesised from Polyhexamethylene guanidine hydrochloride (PHMG), Polyvinyl Alcohol (PVA) and Glutaraldehyde (GA). The 13 × 13 cm² triboelectric generator produced using 3D-printing technology and the above materials delivers a peak voltage of 664.5 V, a short-circuit current of 116.8 µA, a tapping–releasing force of 10 N and a frequency of 1 Hz. The team’s research on PHMG-TENG is novel and achieves far superior electricity-generation performance compared with many previously reported polymers. The fabricated TENG system produces stable current after 360,000 tapping cycles, demonstrating high durability and long-term stability of the material.
TENG structure of 13 × 13 cm² operating stably after 360,000 tapping cycles at 1 Hz, producing an electrical source with a voltage of 665 V and a current of 116.8 µA
In addition, the team developed a CS–PHMG–GA material system for TENGs (CS stands for Chitosan), capable of generating a peak voltage of nearly 1.5 kV and a power output of 12 mW at a 10 MΩ load. This material shows outstanding electricity-generation efficiency, capable of operating across a wide humidity range (40%–90%) and frequency range (1–20 Hz), and exhibits strong antibacterial properties: eliminating almost all E. coli and S. aureus bacteria in just 60 seconds. This result opens a new research direction for antibacterial triboelectric generators (antibacterial-TENG) as well as friction-based generators applicable in textile technology (textile-TENG), etc.
The research team successfully fabricated a triboelectric generator consisting of four parallel tapping structures, producing a rectified output voltage of 288 V, a peak voltage pulse of 680 V, a peak current pulse of 340 µA and a power output of 0.23 W. The system operates stably for more than 10,000 cycles and is capable of lighting nearly 100 LED bulbs. The fabricated generator can supply energy for sensors, IoT systems or self-powered devices operating in harsh environments. This is a step closer to practical application, opening prospects for powering sensors and standalone wireless monitoring systems without the need for batteries.
According to the evaluation of the VAST-level Acceptance Council: This is the pioneering TENG project at the unit, opening a new research direction in triboelectric energy. The project received high recognition for its creativity in material development, its combination of high electricity-generation efficiency, stable durability in humid environments, and excellent antibacterial properties – all factors enhancing the practical value of the device. The achievements not only demonstrate the research team’s capability but also open new pathways for the field of green energy. In the time to come, the research team will continue to optimise the surface structure of materials, integrate energy-storage capability and develop practical applications such as IoT-TENG, textile-TENG integrated into fabrics and clothing, or buoy-TENG – smart buoy systems using wave energy to measure marine parameters, etc.
Translated by Phuong Huyen
Link to Vietnamese version
