Multi-directional Vibration Energy Harvesting Research Articles

Design of a Two-Degree-of-Freedom Mechanical Oscillator for Multidirectional Vibration Energy Harvesting to Power Wireless Sensor Nodes.

Converting otherwise wasted kinetic energy present in the environment into usable electrical energy to power wireless sensor nodes, is a green strategy to avoid the use of batteries and wires. Most of the energy harvesters presented in the literature are based on the exploitation of a one-degree-of-freedom arrangement, consisting of a tuned spring-mass system oscillating in the main direction of the exciting vibration source. However, if the direction of excitation changes, the efficiency of the harvester decreases. This paper thus proposes the idea of a curved cantilever beam with a two-degree-of-freedom arrangement, where the two bending natural frequencies of the mechanical resonator are designed to be equal. This is thought to lead to a configuration design that can be used in practical circumstances where excitation varies its direction in the plane. This, in turn, may possibly lead to a more effective energy-harvesting solution to power nodes in a wireless sensor network.

A piezo-electromagnetic hybrid multi-directional vibration energy harvester in freight trains

Rail freight systems are widely acknowledged for their operational efficiency across various nations. However, a prevailing limitation lies in the absence of power supply within standard freight wagons, impeding the installation of essential sensors to monitor train operation. This paper provides an innovative solution to this issue, where a novel device is developed to harvest vibration energy from freight trains to power operational condition monitoring sensors. The proposed device integrates a piezoelectric energy harvester with an electromagnetic counterpart, utilizing a spring-mass structure to capture vibration energy and transfer it to cantilever beams through magnetic coupling. A cantilever beam with variable width and a distinctive “checkmark” shape is employed to ensure even stress distribution to enhance piezoelectric material efficiency. The optimal spatial configuration between magnets and coils, as well as inter-magnet spacing, is determined through finite element analysis and empirical testing. Experimental results under the excitation with a frequency of 9.5 Hz and a vertical amplitude of 2 mm show the hybrid harvester can generate a maximum power of 3.276 mW. This hybrid energy harvesting system has the potential to provide dependable power to electronic components, including temperature sensors and accelerometers, crucial for monitoring rail freight train operations.

Design, modelling and experimental verification of a tunable electromagnetic generator for multi-directional vibration energy harvesting

Design, modelling and experimental verification of a tunable electromagnetic generator for multi-directional vibration energy harvesting

Triboelectric Nanogenerator with a Rotational Freestanding Mode for Multi-directional Vibration Energy Harvesting

Triboelectric Nanogenerator with a Rotational Freestanding Mode for Multi-directional Vibration Energy Harvesting

Spherical Magnetoelastic Generator for Multidirectional Vibration Energy Harvesting.

Vibration is a common, usually wasted energy, and an attractive target for sustainable electricity generation. In this work, we introduce a new working mechanism to the vibration energy harvesting community by contributing a spherical magnetoelastic generator (S-MEG), which permits multidirectional vibration and is highly adaptable to many natural oscillation frequencies, exhibiting a resonant frequency of 24 Hz and a relatively wide working bandwidth of 15 Hz in the low-frequency range. It also features a low internal impedance of 70 Ω, which can respectively deliver a maximum short-circuit current density of 7.962 A·m-2 and a power density of 15.1 mW·m-2. To demonstrate the capability of S-MEG for ambient vibration energy harvesting, a 220 μF commercial capacitor was successfully charged to 2 V within 25 s, sustainably driving wearable bioelectronics for multiple physiological information monitoring. It could also harvest multidirectional vibration energy from both hand-shaking and bicycle-riding, generating approximately 2.5 mA and 6 mA alternating current from the motions, respectively, even with heavy perspiration or on a rainy day without the need for encapsulation. In summary, this work brings forth an appealing platform technology to the community of vibration energy harvesting, holding a collection of compelling features, including high current density, low inner impedance, intrinsic waterproofness, and scalability for large-scale vibration energy harvesting.

A mosquito-inspired self-adaptive energy harvester for multi-directional vibrations

In this paper, a new concept of direction self-adaptive energy harvesting is put forward for multi-directional vibrations, and a novel direction self-adaptive piezoelectric energy harvester (DSPEH) is explored by introducing a self-adaptive rotation mechanism into the cantilever beam inspired by mosquito wings to validate the new concept. Different from the conventional piezoelectric energy harvester (PEH), the proposed DSPEH has an additional rotation degree of freedom obtained by the rotation unit to realize self-adaptive rotation passively without any manual intervention or power supply. Working principle and theoretical analysis of the proposed DSPEH are conducted and a prototype is fabricated to demonstrate the concept. The energy harvesting performance of the proposed DSPEH is investigated under sweeping frequency and harmonic excitation, and the key parameters affecting the energy harvesting efficiency, such as damping parameters and mass eccentricity coefficient, are analyzed in detail. Simulation and experimental results are in good agreement. Owning to the characteristic of self-adaptive rotation, the most attractive feature of the proposed DSPEH is not simply the ability to realize multi-directional vibration energy harvesting, but the capability of achieving stable and high voltage output levels in multi directions, which is fundamentally distinct from the conventional PEH and other multi-directional energy harvesters. The average output voltage is 30% higher than that of the conventional PEH. Compared with other multi-directional energy harvesters, the proposed DSPEH also has higher energy harvesting efficiency.

Cover Image

The cover image is based on the Technical Note A highly sensitive magnetic configuration-based triboelectric nanogenerator for multidirectional vibration energy harvesting and self-powered environmental monitoring by Minseok Park et al., https://doi.org/10.1002/er.7003.

A Liquid-Metal-Based Freestanding Triboelectric Generator for Low-Frequency and Multidirectional Vibration

There are a lot of vibrational energies, which are low frequency, multidirectional, and broadband, in the nature. This creates difficulties for devices that aim at harvesting vibration energy. Here, we present a liquid-metal-based freestanding triboelectric generator (LM-FTG) for vibration energy harvesting. In this device, the fluidity of liquid is used to increase sensitivity to vibration for better low-frequency response and multidirectional vibration energy harvesting capability. The freestanding power generation mode is able to increase power generation stability. Experiments show that the bandwidth of LM-FTG can almost cover the entire sweep frequency range, and a 10 μF capacitor can be charged to 6.46 V at 7.5 Hz in 60 s by LM-FTG. In particular, 100 LEDs are illuminated in the low-frequency environmental experiment successfully. The proposed LM-FTG can work in low frequency with large working bandwidth, which provides an effective method for energy harvesting of low-frequency and multidirectional vibrations.

A highly sensitive magnetic configuration‐based triboelectric nanogenerator for multidirectional vibration energy harvesting and self‐powered environmental monitoring

A highly sensitive magnetic configuration‐based triboelectric nanogenerator for multidirectional vibration energy harvesting and self‐powered environmental monitoring

An ultralow frequency, low intensity, and multidirectional piezoelectric vibration energy harvester using liquid as energy-capturing medium

Herein, a piezoelectric vibration energy harvester (PVEH) using liquid as an energy-capturing medium is proposed to simultaneously achieve ultralow frequency, low intensity, and multidirectional vibration energy harvesting in a horizontal plane, which is difficult to realize using traditional PVEHs. The proposed harvester comprises a cylindrical container with a certain liquid, a piezoelectric cantilever beam, ropes, and floater-lever arrays. The experimental results indicate that the proposed harvester with a single floater-lever can generate 9.8 μW under an ultralow frequency (2.6 Hz) and a low intensity vibration excitation (0.03 g), and the normalized power density is 8.89 μW/(cm3 g2 Hz). Under a multidirectional vibration excitation (360° in the horizontal plane) with frequencies below 3 Hz and an acceleration of 0.03 g, the two proposed harvesters with three and four floater-levers indicate a maximum output power (Pmax) deviation of 24.92% and 28.31%, respectively, and an angle bandwidth of 360° (using 2/2Pmax as the standard). All the experimental results indicate that the proposed PVEH is highly promising as an energy supply of wireless sensor networks distributed in ultralow frequency, low intensity, and multidirectional applications.

A goblet-like non-linear electromagnetic generator for planar multi-directional vibration energy harvesting

A novel electromagnetic energy harvester for in-plane multi-directional vibrations is developed by letting a magnetic ball move on a two-dimensional surface which is generated from the rotation of a one-dimensional bi-stable potential curve. A goblet-like structure is designed to keep the ball on the nonlinear potential surface. Due to the special symmetric configuration, in-plane excitations from any direction can equivalently force the motion of the magnetic ball and thus produce electricity in the coils on the outer surface of the structure. Meanwhile, the good features of nonlinearities on bandwidth extension are preserved. Continual circular motions were observed for a wide frequency range. The operation bandwidth could reach a high value of 8 Hz and simultaneously the maximum power of 7.649mW was captured in experiments under a harmonic excitation of 1 g, corresponding to a normalized power density of 72.5 µW cm−3 g−2. In particular, the proposed harvester showed good performance for low frequency vibrations and is especially suitable for human body energy harvesting. With the harvester attached to the ankle, 1.4mW was obtained when walking at 5 km h−1. Notably, the method can be applied to other one-dimensional potential portraits for constructing the corresponding two-dimensional potential surface.

Tunable, multi-modal, and multi-directional vibration energy harvester based on three-dimensional architected metastructures

Conventional vibration energy harvesters based on two-dimensional planar layouts have limited harvesting capacities due to narrow frequency bandwidth and because their vibratory motion is mainly restricted to one plane. Three-dimensional architected structures and advanced materials with multifunctional properties are being developed in a broad range of technological fields. Structural topologies exploiting compressive buckling deformation mechanisms however provide a versatile route to transform planar structures into sophisticated three-dimensional architectures and functional devices. Designed geometries and Kirigami cut patterns defined on planar precursors contribute to the controlled formation of diverse three-dimensional forms. In this work, we propose an energy harvesting system with tunable dynamic properties, where piezoelectric materials are integrated and strategically designed into three-dimensional compliant architected metastructures. This concept enables energy scavenging from vibrations not only in multiple directions but also across a broad frequency bandwidth, thus increasing the energy harvesting efficiency. The proposed system comprises a buckled ribbon with optional Kirigami cuts. This platform enables the induction of vibration modes across a wide range of resonance frequencies and in arbitrary directions, mechanically coupling with four cantilever piezoelectric beams to capture vibrations. The multi-modal and multi-directional harvesting performance of the proposed configurations has been demonstrated in comparison with planar systems. The results suggest this is a facile strategy for the realization of compliant and high-performance energy harvesting and advanced electronics systems based on mechanically assembled platforms.

A Piezo-Electromagnetic Coupling Multi-Directional Vibration Energy Harvester Based on Frequency Up-Conversion Technique

Harvesting vibration energy to power wearable devices has become a hot research topic, while the output power and conversion efficiency of a vibration energy harvester with a single electromechanical conversion mechanism is low and the working frequency band and load range are narrow. In this paper, a new structure of piezoelectric electromagnetic coupling up-conversion multi-directional vibration energy harvester is proposed. Four piezoelectric electromagnetic coupling cantilever beams are installed on the axis of the base along the circumferential direction. Piezoelectric plates are set on the surface of each cantilever beam to harvest energy. The permanent magnet on the beam is placed on the free end of the cantilever beam as a mass block. Four coils for collecting energy are arranged on the base under the permanent magnets on the cantilever beams. A bearing is installed on the central shaft of the base and a rotating mass block is arranged on the outer ring of the bearing. Four permanent magnets are arranged on the rotating mass block and their positions correspond to the permanent magnets on the cantilever beams. The piezoelectric cantilever is induced to vibrate at its natural frequency by the interaction between the magnet on cantilever and the magnets on the rotating mass block. It can collect the nonlinear impact vibration energy of low-frequency motion to meet the energy harvesting of human motion.

A two-dimensional energy harvester with radially distributed piezoelectric array for vibration with arbitrary in-plane directions

Piezoelectric vibration energy harvesters have attracted much attention in the last decades due to their great potential application in powering various ultra-low-power sensors/actuators in the ambient environment. Many works have been presented to improve the energy conversion efficiency and broaden the operating bandwidth. One purpose of these studies is to harvest vibration energy with a specific excitation direction. However, a vibration source in a practical environment may from different directions. In this article, a piezoelectric vibration energy harvester with the radially distributed piezoelectric array is proposed to scavenge two-dimensional vibration energy. Meanwhile, we introduce a new concept, named angle bandwidth, to describe the ability of harvesting two-dimensional vibration energy. The theoretical analysis and the simulation results indicate that this harvester can scavenge vibration energy with arbitrary in-plane directions using the arc-shaped radially distributed piezoelectric array on a flexible cylinder. The experimental results show that this new design has large angle bandwidth, and the angle bandwidth increases from 87.5° to 106.3° when increasing the number of polyvinylidene fluoride elements from one to four. Also, the angle bandwidth of piezoelectric array in series is always larger than that in parallel. Overall, the present two-dimensional piezoelectric vibration energy harvester has the potential for a higher multi-directional vibration energy harvesting efficiency than a traditional cantilever-shaped piezoelectric vibration energy harvester. It also can be used as a self-powered vibration direction sensor.

Broadband and three-dimensional vibration energy harvesting by a non-linear magnetoelectric generator

Vibration, widely existing in an ambient environment with a variety of forms and wide-range of scales, recently becomes an attractive target for energy harvesting. However, its time-varying directions and frequencies render a lack of effective energy technology to scavenge it. Here, we report a rationally designed nonlinear magnetoelectric generator for broadband and multi-directional vibration energy harvesting. By using a stabilized three-dimensional (3D) magnetic interaction and spring force, the device working bandwidth was largely broadened, which was demonstrated both experimentally and theoretically. The multidirectional vibration energy harvesting was enabled by three identical suspended springs with equal intersection angles, which are all connected to a cylindrical magnet. Numerical simulations and experimental results show that the nonlinear harvester can sustain large-amplitude oscillations over a wide frequency range, and it can generate power efficiently in an arbitrary direction. Moreover, the experimental data suggest that the proposed nonlinear energy harvester has the potential to scavenge vibrational energy over a broad range of ambient frequencies in 3D space.