Significantly Enhanced Power Generation from Extremely Low‐Intensity Magnetic Field via a Clamped‐Clamped Magneto‐Mechano‐Electric Generator

Abstract

battery maintenance and replacement will be practically infeasible. In addition, it is also challenging to recharge or replace batteries in harsh environments, such as the deep ocean and high air. In this regard, energy harvesting technology may be considered an ultimate solution to replace batteries, realize self-powered IoT components, and thus provide a long-term power supply for wireless sensor networks. [4,5] From the viewpoint of environmental pollution, the elimination of batteries, which are classified as "hazardous wastes," is also of great significance. [6] Among a large number of harvestable energy sources, like vibration, [7,8] radiation, [9,10] and magnetic/electric fields, [11,12] stray magnetic energy generated from power transmission cables, industrial machines, household appliances, etc., is technically favored because of the fixed frequency of 50 or 60 Hz and the ubiquitous distribution. [13][14][15][16] Coil devices based on electromagnetic induction principles are conventionally adopted to capture the ambient but wasted magnetic field energy. [13,17] However, the output power from compact coils is very limited in the case of low-frequency magnetic field energy harvesting. In contrast, magneto-mechano-electric (MME) generators are considered the most promising options to scavenge disused magnetic field energy. [12] The earliest design of a typical A magneto-mechano-electric (MME) generator that can harvest ambient magnetic noise plays a significant role in powering Internet of Things (IoT) sensor networks. However, it is still a challenge to capture sufficient energy and continuously drive IoT nodes from extremely low-intensity magnetic noise below 1 Oe. To circumvent the close dependence of the resonant frequency on the magnetic proof mass in conventional MME generators, a new clampedclamped (C-C) MME generator is proposed, that allows a much heavier magnetic mass to be attached at the beam center. Under weak magnetic fields of 0.48 and 0.96 Oe at 50 Hz, optimized output powers of 370 and 970 μW RMS , respectively are achieved, which shows an enhancement of ≈120% over that of cantilevered MME generators. The underlying mechanics are theoretically revealed by comparing the lumped parameters with a cantilevered MME generator and by calculating their deflection gain. Finally, it is demonstrated that the harvested energy from the proposed C-C MME generator from a 0.48 Oe magnetic field at 50 Hz is sufficient to continuously drive an IoT sensor without any additional intervals for recharging. It is believed that this work will open new possibilities for designing MME generators suitable for weak field energy harvesting.

Significant Output Power Enhancement in Symmetric Dual‐Mode Magneto‐Mechano‐Electric Coupled Resonators

“…Table 1 illustrates a comparison of the output power of the symmetric dual‐mode TFS‐MME energy harvester with those of recently reported MME energy harvesters operating in low frequency range. [ 1,10,12,17,20,21,23,28,30 ] It is clearly seen that the symmetric dual‐mode TFS‐MME energy harvester proposed in this work has an outstanding output performance with the highest normalized output power compared with state‐of‐the‐art MME devices even using extremely expensive piezoelectric single crystal. [ 10,12,20,21 ]…”

“…Table 1 illustrates a comparison of the output power of the symmetric dual-mode TFS-MME energy harvester with those of recently reported MME energy harvesters operating in low frequency range. [1,10,12,17,20,21,23,28,30] It is clearly seen that the symmetric dual-mode TFS-MME energy harvester proposed in this work has an outstanding output performance with the highest normalized output power compared with state-of-the-art MME devices even using extremely expensive piezoelectric single crystal. [10,12,20,21] Again, the enhanced output power of the energy harvester can be attributed to the amplified stress acted on one-pair piezoelectric ceramic pieces due to varying stiffness of the TFS, and strong mechanical coupling between two beams with symmetric dual-mode bending vibrations.…”

“…Chu et al proposed a clamped-clamped structured MME energy harvester, and it could produce an effective output power of 370 µW RMS under H ac of as low as 0.48 Oe. [23] Nevertheless, most designs today on MME energy harvesters including piezoelectric energy harvesters are based on a cantilever-beam structure system operating in its fundamental resonance-bending mode (single-mode), as shown in Figure 1ai,c. Considering the actual situation of only one end fixed, a considerable mechanical energy loss (i.e., clamp loss) at the clamped-end is inevitable due to the unbalanced clamp and the strong inertial force effect of the tip mass at the freeend during single-mode bending vibrations, [24,25] see Figure 1c.…”

Perovskite Piezoelectric-Based Flexible Energy Harvesters for Self-Powered Implantable and Wearable IoT Devices

“…Energy harvesting is a sustainable power source which can be utilized in wireless sensor networks (WSNs), mobile electronics and implantable and wearable IoT devices, eliminating the need for network-based energy, conventional batteries, cables and minimizing maintenance and ecological costs [ 9 ]. In energy harvesting, various energy conversion mechanisms have been investigated such as piezoelectric [ 10 , 11 ], pyroelectric [ 12 ], photovoltaic [ 13 ], triboelectric [ 14 ] and magneto-mechano-electric [ 15 ]. Of these, piezoelectric energy harvesters have received great attention in the scientific community since piezoelectric materials can precisely convert tiny mechanical/biomechanical movements such as muscle contraction/relaxation and cardiac/lung movements into electricity due to their high electromechanical coupling factor and piezoelectric coefficient [ 8 , 16 , 17 , 18 ].…”

Autonomous Resonance‐Tuning Mechanism for Environmental Adaptive Energy Harvesting

“…These tasks may be impossible in harsh environments, such as the outside walls of skyscrapers, deep undersea, and expansive forests. [ 5 , 6 , 7 ] Energy harvesting technology that captures unused ambient energy and converts it into usable electrical power can provide the most feasible solution for this problem. [ 8 , 9 , 10 ]…”