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A research team from the Department of Mechanical Engineering and Automation at the Chinese University of Hong Kong (CUHK) recently developed a Self-Powered Wireless Sensing Electronic Sticker (SWISE).
SWISE can convert the energy of the finger touch on the electronic sticker into electromagnetic wave signals for wireless transmission without batteries and wires. Taking advantage of flexible, ultra-thin and long and efficient transmission distance, SWISE can promote the development of intelligent sensing and remote control technologies. The results were published in the internationally renowned journal Scientists progress, and the research team will cooperate with technology companies to bring related smart products to market.
In addition, the team invented a new triboelectric nanogenerator (TENG) that has a much higher output power than the existing TENG. This invention may pave the way for the use of TENG to power household electrical appliances and provide an alternative renewable energy option.
Wireless detection electronic sticker
The development of the Internet of Things (IoT) is the key to building a smart city, in which sensors act as the eyes and ears of the IoT system. These sensors are responsible for collecting physical variables such as temperature, pressure, speed and converting them into electronic signals for analysis. Some researchers have predicted that there will be billions of sensor nodes connected to IoT in the next few years, forming a network of physical information detection.
However, traditional wireless detection and transmission technology still requires several independent modules for detection, signal modulation, transmission, power source and management, which makes the whole system bulky and rigid, with high power consumption and high cost. This undoubtedly limits the application scenarios for wireless sensing technology and increases maintenance costs and difficulties.
The research team led by Prof. Zi Yunlong, Assistant Professor in the Mechanical Engineering and Automation Department of CUHK, designed a smart electronic sticker SWISE, combining the four functional modules of traditional wireless detection systems into one unit. .
SWISE is a soft and flexible electronic film (the thinnest is only 95m, which is less than the width of two human hair), which generates a displacement current during the discharge process to achieve self-wireless detection. powered based on triboelectric nanogenerator (TENG) technology.
SWISE has three layers, where the middle one is a metal film with two electrodes, and the outside is composed of a tribo-charge layer and a substrate layer. When the finger slides over the tribo-charge layers of SWISE to generate tribo-charges, a discharge effect will be generated, which converts the kinetic energy of the movement of the finger into electromagnetic signals. The research team proved that the signal can travel long distances (up to 30 meters) without an external power supply.
Multipoint sensing capability, which can be achieved by distinguishing signals generated from different design parameters, allows sensors to be widely applied in different scenarios in smart city. Thus, the research team has designed devices with various parameters, for example by modifying the inductance of the device, so that SWISE can generate signals with different characteristics and spectra, which widens its fields of application.
The wireless software keyboard and wristband shown in videos 1 and 2 can transmit four different signals 1, 2, 3 and 4, respectively. SWISE is also expected to be used in smart clothing, robotics, medical treatments, human-machine interfaces, body area sensor networks and virtual reality in the future.
In addition, the research team is exploring the potential of SWISE for gas detection. They found that the spectra of the electromagnetic signal generated by the displacement current will vary slightly when the composition of the gas between the two electrodes of the metal film is changed.
Using artificial intelligence (AI) and deep learning technologies, they were able to distinguish the signal characteristics of ten different combinations of gas composition and concentration (including argon, carbon dioxide, helium, nitrogen and air in general), with a recognition accuracy of 98.5%.
The team repeatedly tested the SWISE detection system and its applications, such as wireless software keyboards and smart bracelets. The results fully proved that it has enormous potential for application in wireless detection and remote control. It is expected to promote the evolution of smart sensing and remote control technologies and the development of smart city in Hong Kong.
This project was funded by the Hong Kong SAR Government Research Grants Council Career Start Program, General Research Fund, Hong Kong SAR Innovation and Technology Fund, and the Tencent academic relations program.
New triboelectric nanogenerator with high output power
TENG allows SWISE to generate displacement current during the discharge process to achieve self-powered wireless detection. Not only a touch of the finger can generate energy by TENG. Mechanical movements in the environment, such as water waves, wind, rain droplets, and biomechanical movements can also be harvested by TENG to produce clean, renewable energy. However, the TENG suffers from two fundamental limitations: low load transfer and high output impedance, which results in low output power and limited application.
Recently, Professor Zi and his team developed an oppositely charged transistor-type triboelectric nanogenerator (OCT-TENG) capable of delivering an instantaneous power density greater than 10 MW / m2 at a low frequency of around 1 Hz, well above previous reports.
To demonstrate the high performance of this new invention, the team turned on a 180W commercial light using an OCT-TENG device, as well as a wirelessly powered 30W vehicle LED bulb. These results set a record for the high power output of TENG. The related output was published in the prestigious journal of Nature Communication.