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(a) The simplified model of the magnet and the iron core; (b) the diagram of the dipole model; (c) the comparison of model results and FEM simulation; (d) the comparison of test and theoretical results.
Source publication
In this study, the performance of an electromagnetic vibration energy harvester (EM-VEH) based on micro-electro-mechanical systems 3D coils was presented theoretically and experimentally. The VEH employs two 3D coils and E-shape iron cores inserted into the coils to reduce the magnetic leakage and to improve the output power. In this structure, the...
Citations
In this study, we conducted a systematic exploration of a micro-electromagnetic vibration energy harvester with a bi-magnet structure and microelectromechanical systems 3D coils. First, we establish a physical model of stiffness and damping characteristics based on the superposition principle for the bi-magnet structure which has also been verified experimentally. Then, we investigate the influence of magnet gap and air gap on the stiffness and the magnetic flux change rate, mainly focusing on the distance and the potential barrier between the two potential wells. Finally, we fabricate and assemble the bi-magnet VEH prototype and tested the output performance under 1 and 6g excitation, which correspond the intra-well vibration and inter-well vibration, respectively. The tested results show that under 1g excitation, the prototype can output 155.38 μW power with 32 Hz half-power bandwidth and 4939.06 μW·Hz integrated power, which are obviously higher than those for mono-magnet under same excitation. When the excitation raises to 6g, the output power is improved to 362.98 μW with the half power bandwidth and integrated power enhanced to 56 Hz and 9289.96 μW·Hz, respectively. The tested results also prove that the structure proposed in this study can significantly enhance the output performance compared with a mono-magnet structure and other published data.
The evolution of artificial intelligence of things (AIoT) drastically facilitates the development of a smart city via comprehensive perception and seamless communication. As a foundation, various AIoT nodes are experiencing low integration and poor sustainability issues. Herein, a cubic-designed intelligent piezoelectric AIoT node iCUPE is presented, which integrates a high-performance energy harvesting and self-powered sensing module via a micromachined lead zirconate titanate (PZT) thick-film-based high-frequency (HF)-piezoelectric generator (PEG) and poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) nanofiber thin-film-based low-frequency (LF)-PEGs, respectively. The LF-PEG and HF-PEG with specific frequency up-conversion (FUC) mechanism ensures continuous power supply over a wide range of 10-46 Hz, with a record high power density of 17 mW/cm3 at 1 g acceleration. The cubic design allows for orthogonal placement of the three FUC-PEGs to ensure a wide range of response to vibrational energy sources from different directions. The self-powered triaxial piezoelectric sensor (TPS) combined with machine learning (ML) assisted three orthogonal piezoelectric sensing units by using three LF-PEGs to achieve high-precision multifunctional vibration recognition with resolutions of 0.01 g, 0.01 Hz, and 2° for acceleration, frequency, and tilting angle, respectively, providing a high recognition accuracy of 98%-100%. This work proves the feasibility of developing a ML-based intelligent sensor for accelerometer and gyroscope functions at resonant frequencies. The proposed sustainable iCUPE is highly scalable to explore multifunctional sensing and energy harvesting capabilities under diverse environments, which is essential for AIoT implementation.
In recent years, self-powered energy harvesting technology has been widely studied, which may provide supplementary power for wireless sensing networks with low power consumptions. The energy harvester could reduce the use of conventional power supply of batteries, and even eliminate the challenge of battery replacement for large scale networks. In this review, the fundamentals and theories of energy conversion from mechanical vibration to electrical current via variable capacitor are introduced, followed by the discussion of frequency bandwidth broadening, structural parameters, such as surface potential, initial air gap, and stopper heights, as the aspects for controlling squeeze-film air damping force and the output power. Representative examples of the design optimizations of vacuum operating pressure and perforated holes on bottom electrode are presented. Also, special electret processing and built-in corona needles for enhanced space charge stability and self-recharging capability are briefed. This review can provide the research community with a better understanding of the MEMS-compatible electrostatic vibration energy harvester, and further facilitate its development for future potential applications. 2022-0089
