According to statistics, floods that occurred between 2000 and 2019 caused economic losses of approximately US$651 billion worldwide. Therefore, exploring scientific and advanced flood risk management solutions has great economic value and social significance. Due to the sudden and random nature of extreme events, flood alarm systems must have the ability to detect hydrological data in a timely manner in order to achieve reliable flood response. However, current flood alarm systems generally rely on commercial batteries, which limits the intelligent development of disaster prevention planning and maintenance costs . Therefore, developing new power supply methods for flood alarm systems is the key to achieving timely and efficient alarms.
Beijing Institute of Nanoenergy and Systems, Chinese Academy of Sciences Academician Wang Zhonglin , Researcher Jiang Tao et al. reported a self-powered smart buoy based on friction nanogenerator (TENG) for water wave energy collection and Flood alarm . The spherical TENG device with four spiral units is integrated with the charge excitation module (CEM) to improve the electrical output. The output current and output power of can reach 15.09 mA and 24.48 mW, which are 250.5 and 4 times higher than , respectively. Based on this CEM-integrated TENG, the author constructed a self-powered smart buoy and successfully implemented a water level alarm system and a mobile phone water level information exchange system. This work extends the application of TENG to the field of water wave energy collection and provides a new strategy for flood early warning. The research was published in Advanced Functional Materials in a paper titled "Self-Powered Intelligent Buoy Based on Triboelectric Nanogenerator for Water Level Alarming."
[Design of self-powered flood alarm system]
The self-powered smart buoy mainly consists of three parts: TENG, CEM, and functional circuit. TENG is used to collect water wave energy and convert mechanical energy into electrical energy; CEM is integrated with TENG to improve its electrical output and drive the back-end functional circuit to work effectively; the functional circuit is used to realize water level information detection and signal transmission. Therefore, the buoy can be powered by the water wave energy in the working environment to achieve information detection and risk warning in the working environment. The TENG unit is made of silicone material and formed into a spring shape through 3D printing technology, and is pasted on both sides with copper foil as electrodes and PET film as the dielectric layer. Under the action of external force, the TENG unit is compressed and elongated, achieving contact and separation of the electrode and dielectric layer, causing opposite charges to accumulate on their respective surfaces, and ultimately realizing the conversion of mechanical energy into electrical energy. Considering the randomness of wave conditions in flood environments, the author assembled four TENG units in the form of regular tetrahedrons inside acrylic spherical shells. This design can adapt to water wave energy collection in different directions, improving structural flexibility and energy conversion efficiency.
Figure 1 Design of self-powered flood alarm system
Figure 2 Integration of TENG unit and CEM
[Electrical output performance of spherical TENG device]
After integrating CEM, the output current of a single TENG unit is increased from 4.0 µA to 4.3 mA, correspondingly The transferred charge increases from 38.5 nC to 2.9 µC. In order to not be restricted by the direction, the author constructed four TENG units in the form of a regular tetrahedron into a spherical TENG device, and measured its electrical output performance under water waves simulated on a six-degree-of-freedom platform. As the load resistance increases from 10 Ω to 20 kΩ, the current decreases from 15.09 to 0.10 mA, and the power reaches a maximum value of 24.48 mW when the matching resistance is 680 Ω. At the same time, the power density of the device can be calculated as 11.4 W m-3. The integration of CEM greatly increases the capacitance of the TENG, causing its equivalent internal impedance to decrease accordingly. Therefore, the matching resistance of the output power is significantly reduced. The author compared the short-circuit current and maximum power with the results before integrating CEM. The results showed that the current and power were increased by 250.5 times and 4.0 times respectively, highlighting the enhanced effect of CEM on electrical output performance.
Figure 3 Electrical output performance of spherical TENG device
[Application Demonstration]
Based on the powerful wave energy collection capability of TENG, the author successfully demonstrated the self-powered water level alarm system. First, the TENG unit in the spherical device is connected in parallel through the CEM and the rectifier bridge .Then, a 470 µF capacitor is used to store electrical energy and power the functional circuit to form a self-powered smart buoy. The initial water level is 25 cm, while the water level sensor switch is set to 35 cm. As the water level continues to rise, the spherical TENG device is triggered by water waves, converting mechanical energy into electrical energy and storing it in a capacitor. After a precharge time of 20 s, the transmitter voltage can be charged to 3 V. When the water level reaches 35 cm, the water level sensor switch is turned on, the signal transmitting unit works, and the LED alarm light is lit. In addition, the author also constructed a water level information exchange system between a self-powered smart buoy and a mobile phone. When the water level reaches a certain height, the system can transmit water level information to the mobile phone. When the water level exceeds the warning value, the mobile phone will automatically make a call and send a text message containing GPS information to the emergency contact.
Figure 4 Application demonstration of self-powered flood alarm system
Summary: The author reported a self-powered smart buoy based on TENG, which can realize functional applications by collecting water wave energy in its working environment, breaking the limitations of commercial electricity consumption . The maximum output current and output power of the CEM-integrated spherical TENG reached 15.09 mA and 24.48 mW, respectively. With its high electrical output performance, the authors successfully demonstrated a water level alarm system and a mobile phone water level information exchange system. This self-powered smart buoy provides a new strategy for flood early warning and has application potential in the Internet of Things, disaster prevention and other fields.
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Original link:
https://onlinelibrary.wiley.com/doi/10.1002/adfm.202205313
Source: Frontiers of Polymer Science
