Ambient Vibration Energy Research Articles

Structural design and simulation analysis of a micro-silicon-based piezoelectric cantilever generator

The objective of this article is to simulate a piezoelectric cantilever beam generator with power harvesting from ambient vibration energy. This power device will act as the electrical energy supply of a micro-system, which can be used in inaccessible situations, to eliminate dependence on batteries. Optimization of the micro-silicon-based piezoelectric cantilever parameters was achieved by determining the most advantageous dimensions for the piezoelectric generator, while varying the beam length, width, thickness, proof mass weight and so on. The program also made sure that the piezoelectric cantilever beam structure’s natural frequency is equal to the desired input frequency from the ambient exciting vibration. In addition, a prototype miniature generator was fabricated with bulk silicon combined with etching.

3D Stack Integrated Triboelectric Nanogenerator for Harvesting Vibration Energy

The applications of a single‐layer triboelectric nanogenerator (TENG) may be challenged by its lower output current, and a possible solution is to use three‐dimensional (3D) integrated multilayered TENGs. However, the most important point is to synchronize the outputs of all the TENGs so that the instantaneous output power can be maximized. Here, a multi‐layered stacked TENG is reported as a cost‐effective, simple, and robust approach for harvesting ambient vibration energy. With superior synchronization, the 3D‐TENG produces a short‐circuit current as high as 1.14 mA, and an open‐circuit voltage up to 303 V with a remarkable peak power density of 104.6 W m−2. As a direct power source, it is capable of simultaneously lighting up 20 spot lights (0.6 W ea.) as well as a white G16 globe light. Furthermore, compared with the state‐of‐the‐art vibration energy harvesters, the 3D‐TENG has an extremely wide working bandwidth up to 36 Hz in low frequency range. In addition, with specific dimensional design, the 3D‐TENG is successfully equipped inside a ball with a diameter of 3 inches, using which 32 commercial LEDs are simultaneously lighted up via hand shaking, exhibiting great potential of scavenging the abundant but wasted kinetic energy when people play basketball, football, baseball, and so on.

Chaos in the fractionally damped broadband piezoelectric energy generator

Piezoelectric materials play a significant role in harvesting ambient vibration energy. Due to their inherent characteristics and electromechanical interaction, the system damping for piezoelectric energy harvesting can be adequately characterized by fractional calculus. This paper introduces the fractional model for magnetically coupling broadband energy harvesters under low-frequency excitation and investigates their nonlinear dynamic characteristics. The effects of fractional-order damping, excitation amplitude, and frequency on dynamic behaviors are proposed using the phase trajectory, power spectrum, Poincare map, and bifurcation diagram. The numerical analysis shows that the fractionally damped energy harvesting system exhibits chaos, periodic motion, chaos and periodic motion in turn when the fractional order changes from 0.2 to 1.5. The period doubling route to chaos and the inverse period doubling route from chaos to periodic motion can be clearly observed. It is also demonstrated numerically and experimentally that the magnetically coupling piezoelectric energy harvester possesses the usable frequency bandwidth over a wide range of low-frequency excitation. Both high-energy chaotic attractors and large-amplitude periodic response with inter-well oscillators dominate these broadband energy harvesting.

Optimization of Resonator Design for Vibration-Based Electromagnetic Energy Harvester

This paper presents an optimization on the resonator, which is one of the main components of electromagnetic energy harvester, using static structural analysis, stress analysis and modal analysis. The electromagnetic energy harvester is a vibration-based energy harvesting technology which has emerged as a solution for powering autonomous sensor nodes to increase their life span. Electromagnetic energy harvester acts as a transducer that converts ambient vibration energy to electrical power. An initial design of the resonator is developed and analyzed using ANSYS software. Static structural analysis and stress analysis have been performed to analyze different resonator designs to produce an optimum resonator model. Maximum static deflection under gravitation force was found to be 104.12 μm. Resonance frequency of the resonator was found to be 261.56Hz by using modal analyses. The selected resonator design was further modified to cater for wide-band frequency application as well as to have better performance. Four resonators with different beam lengths were combined in a model in order to operate at a wider frequency range. Five models were generated and the smallest frequency range is from 272 Hz to 299 Hz by model 5110_5410. The maximum power and minimum power that can be generated for this model is 135 μW and 93.9 μW respectively. The model 3910_4210 which has the highest frequency range generated a maximum power of 437 μW and minimum power of 270 μW at a frequency range of 422 Hz to 466 Hz.

Broadband Vibrational Energy Harvesting Based on a Triboelectric Nanogenerator

Vibrations in living environments are generally distributed over a wide frequency spectrum and exhibit multiple motion directions over time, which renders most of the current vibration energy harvesters unpractical for their harvesting purposes. Here, a 3D triboelectric nanogenerator (3D‐TENG) is designed based on the coupling of the triboelectrification effect and the electrostatic induction effect. The 3D‐TENG operates in a hybridization mode of conjuntioning the vertical contact‐separation mode and the in‐plane sliding mode. The innovative design facilitates harvesting random vibrational energy in multiple directions over a wide bandwidth. An analytical model is established to investigate the mechano‐triboelectric transduction of 3D‐TENG and the results agree well with experimental data. The 3D‐TENG is able to harvest ambient vibrations with an extremely wide working bandwidth. Maximum power densities of 1.35 W m‐2 and 1.45 W m‐2 are achieved under out‐of‐plane and in‐plane excitation, respectively. The 3D TENG is designed for harvesting ambient vibration energy, especially at low frequencies, under a range of conditions in daily life and has potential applications in environmental/infrastructure monitoring and charging portable electronics.

A micromachined low-frequency piezoelectric harvester for vibration and wind energy scavenging

To efficiently scavenge ambient vibration energy and wind energy at the same time, a low-frequency piezoelectric harvester was designed, fabricated and tested. A lumped-parameter model of the cantilevered piezoelectric energy harvester with a proof mass was established and the closed-form expressions of voltage and power on a resistance load under base acceleration excitation were derived. After effects of the lengths of the proof mass and electrodes on output power were analyzed, a MEMS harvester was optimally designed. By using aluminum nitride as piezoelectric layer, a MEMS energy harvester was fabricated with bulk micromachining process. Experimental results show that the open-circuit frequency of the MEMS harvester is about 134.8 Hz and the matched resistance is about 410 kΩ. Under the harmonic acceleration excitation of ±0.1 g, the maximum output power is about 1.85 µW, with the normalized power density of about 6.3 mW cm−3 g−2. The critical wind speed of the device is between 12.7 and 13.2 m s−1 when the wind direction is from the proof mass to the fixed end of the cantilever. The maximum output power under 16.3 m s−1 wind is about 2.27 µW.

Design and analysis of a 2D broadband vibration energy harvester for wireless sensors

This paper presents a design for a novel vibration energy harvester using a magnetoelectric (ME) transducer, which is efficiently applicable in two-dimensional (2D) motion and over a range of vibration frequencies. This harvester adopts a circular cross-section cantilever rod to extract the ambient vibration energy because of its ability to host accelerations in arbitrary motion directions. Moreover, the magnetic interactions between the magnets and the ME transducer will lead to the nonlinear oscillation of the rod with increased frequency bandwidth. The influences of the nonlinear vibration factor and magnetic field distribution on the electrical output and bandwidth of the harvester are investigated to achieve optimal vibration energy harvesting performances. The experimental results showed that, the harvester was sensitive to the vibration with arbitrary in-plane directions. With an acceleration of 0.6g (where g=9.8ms−2), it had the working bandwidths of 4.2Hz, 2.6Hz, 2.3Hz, 2.5Hz and 3.2Hz, and the output powers of 0.6mW, 0.49mW, 0.33mW, 0.5mW and 0.56mW at the in-plane excitation angles of−90°, −45°, 0°, 45° and 90°, respectively.

Triboelectric Nanogenerator for Harvesting Vibration Energy in Full Space and as Self‐Powered Acceleration Sensor

A spherical three‐dimensional triboelectric nanogenerator (3D‐TENG) with a single electrode is designed, consisting of an outer transparent shell and an inner polyfluoroalkoxy (PFA) ball. Based on the coupling of triboelectric effect and electrostatic effect, the rationally developed 3D‐TENG can effectively scavenge ambient vibration energy in full space by working at a hybridization of both the contact‐separation mode and the sliding mode, resulting in the electron transfer between the Al electrode and the ground. By systematically investigating the output performance of the device vibrating under different frequencies and along different directions, the TENG can deliver a maximal output voltage of 57 V, a maximal output current of 2.3 μA, and a corresponding output power of 128 μW on a load of 100 MΩ, which can be used to directly drive tens of green light‐emitting diodes. Moreover, the TENG is utilized to design the self‐powered acceleration sensor with detection sensitivity of 15.56 V g‐1. This work opens up many potential applications of single‐electrode based TENGs for ambient vibration energy harvesting techniques in full space and the self‐powered vibration sensor systems.

A Curled Piezoelectric Cantilever for Two Dimensional Vibration Energy Harvesting

To harvest ambient vibration energy of different directions, a micromachined vibration energy harvester which can harvest two-dimensional vibration energy was proposed. The harvester is composed of a curled piezoelectric cantilever, a proof mass and the substrate. One end of the cantilever is fixed onto the substrate and the other end is connected with a proof mass. It is the residual stress of micromachining processes that causes the cantilever to curl. A proof-of-concept prototype of the two-dimensional vibration energy harvester was assembled and tested to evaluate the performance. Experimental results show that the vibration direction with the highest energy scavenging efficiency changed with the frequency of the ambient vibration. The vibration energy of any direction in the neutral plane of the curled cantilever can be harvested by using the first two natural vibration modes of the prototype.

Design and Analysis of a Vibration-Based Magnetoelectric Energy Harvesting Device

An energy harvester is presented to harvest ambient vibration energy using a cantilever beam and multiple Terfenol-D/PMN-PT/Terfenol-D laminate magnetoelectric transducers. The harvester uses eight magnets to make up a magnetic circuit arranged on the free end of the cantilever beam. The magnetic circuit can produce a high gradient magnetic field space. The multiple transducers are placed at the high magnetic field gradient position to make the best use of the magnetic field produced by the magnets. The nonlinear vibration and electrical-output performances of the harvester at resonance are analyzed. The theoretical results indicate that the prototype can produce a load power of 7.619 mW, which is sufficient to supply low consumption wireless sensor nodes.

Trends of MEMS-Based Vibration Energy Harvester

Micro vibration energy harvesters have received much attention due to their potential application of low power wireless sensor networks and embedded systems. This paper studies three mechanisms to scavenge the ambient vibration energy, discusses the power management circuit and the application of the converter, investigates the prospective development and ongoing challenges in MEMS-based vibration energy harvester.

Topology optimization of a cantilevered piezoelectric energy harvester using stress norm constraints

Vibrational piezoelectric energy harvesters are devices which convert ambient vibrational energy into electric energy. Here we focus on the common cantilever type in which an elastic beam is sandwiched between two piezoelectric plates. In order to maximize the electric power for a given sinusoidal vibrational excitation, we perform topology optimization of the elastic beam and tip mass by means of the SIMP approach, leaving the piezoelectric plates solid. We are interested in the first and especially second resonance mode. Homogenizing the piezoelectric strain distribution is a common indirect approach increasing the electric performance. The large design space of the topology optimization approach and the linear physical model also allows the maximization of electric performance by maximizing peak bending, resulting in practically infeasible designs. To avoid such problems, we formulate dynamic piezoelectric stress constraints. The obtained result is based on a mechanism which differs significantly from the common designs reported in literature.

Harvesting the Vibration Energy

Ambient energy can in many situations not only augment battery life in autonomous devices, but enable the whole functionality of such devices. Harvesting of ambient energy in any available form is hence very desirable. From available sources of ambient energy, solar and vibration energy are now prevalent forms of harvested energy. Several transduction mechanisms exist for transformation of mechanical energy of ambient vibrations into electric energy. Electromagnetic Transduction seems to be proper mechanism for harsh conditions thanks to its simplicity and robustness. There are many issues though, that need to be worked out yet. This paper proposes basic overview of ambient energy sources, describtion of vibration energy harvesting mechanisms and identifies common limitations in designs of electromagnetic vibration energy generators.

Modelling and Simulation of MEMS Electret Vibration-Driven Energy Harvesters

To solve the problem of feeding the remote microsystems the electret microgenerators powering by the energy of ambient micro vibrations were analyzed. The numerical modeling of all the operation modes of these generators was performed not taking into account the certain design of mechanical part of their operation. This approach allows one to analyze generator operation in the full range of possible parameters, such as generation frequency, load, capacitance modulation depth and electret polarization value. The cases of out-of-plane vibrations as well as the lateral (in-plane) shift of the capacitor plates were investigated. Basing on the results of numerical modeling of all the operation modes of electret generators the analytical expressions for maximum generated power were derived. The performed analysis has shown that for the range of low frequency vibrations (10-100 Hz) the power density could be increased by two orders of magnitude compared with known prototypes

Design of a Bimorph Piezoelectric Energy Harvester for Railway Monitoring

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from <TEX>$2.06m/s^2$</TEX> base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

Theoretical investigations of energy harvesting efficiency from structural vibrations using piezoelectric and electromagnetic oscillators

Conversion of ambient vibrational energy into electric power has been the impetus of much modern research. The traditional analysis has focused on absolute electrical power output from the harvesting devices and efficiency defined as the convertibility of an infinite resource of vibration excitation into power. This perspective has limited extensibility when applying resonant harvesters to host resonant structures when the inertial influence of the harvester is more significant. Instead, this work pursues a fundamental understanding of the coupled dynamics of a main mass-spring-damper system to which an electromagnetic or piezoelectric mass-spring-damper is attached. The governing equations are derived, a metric of efficiency is presented, and analysis is undertaken. It is found that electromagnetic energy harvesting efficiency and maximum power output is limited by the strength of the coupling such that no split system resonances are induced for a given mass ratio. For piezoelectric harvesters, only the coupling strength and certain design requirements dictate maximum power and efficiency achievable. Since the harvesting circuitry must "follow" the split resonances as the piezoelectric harvesters become more massive, the optimum design of piezoelectric harvesters appears to be more involved than for electromagnetic devices.

A retrofitted energy harvester for low frequency vibrations

Piezoelectric-based energy harvesting is an efficient way to convert ambient vibration energy into usable electric energy. However, its output power drops steeply with reducing excitation frequency. To improve the harvesting performance at low frequencies, a multi-impact harvester is proposed in this paper. The proposed design consists of a hung mass and two stiff piezoelectric cantilever beams. A series of impacts between the mass and cantilever beams are involved during the vibration of the mass, which triggers high frequency vibrations on the cantilever beams. Four equations of motion corresponding to different system statuses are presented to simulate the vibration of the harvester. Based on the linear piezoelectric theory, a distributed-parameter electromechanical model is used for the bimorph cantilever beam and its output power is calculated. For comparison, a conventional cantilever-beam-based harvester and a single-impact harvester are introduced and their output powers are also calculated. Under the same sinusoidal excitation, the modeling result shows that the power of the proposed harvester is more than three times larger than the ones from the conventional cantilever beam harvester and the single-impact harvester. The multi-impact harvester also occupies less space than the conventional one. A parametric study is presented in this paper for the multi-impact harvester considering different external resistances, hung masses, cantilever beam thicknesses and excitation frequencies.

Design of piezoelectric energy harvesting devices subjected to broadband random vibrations by applying topology optimization

Converting ambient vibration energy into electrical energy by using piezoelectric energy harvester has attracted a lot of interest in the past few years. In this paper, a topology optimization based method is applied to simultaneously determine the optimal layout of the piezoelectric energy harvesting devices and the optimal position of the mass loading. The objective function is to maximize the energy harvesting performance over a range of vibration frequencies. Pseudo excitation method (PEM) is adopted to analyze structural stationary random responses, and sensitivity analysis is then performed by using the adjoint method. Numerical examples are presented to demonstrate the validity of the proposed approach.

The Output Character Analysis of the Piezoelectric Cantilever Power Generator for Ambient Vibration Harvesting

High output power can be obtained by optimizing the piezoelectric battery structure parameters. Several piezoelectric battery prototypes with dimensions around 30mm×8mm×1mm have been set up to test the power from ambient vibration harvesting. Output power generation of 130 µW at 93.2 Hz is obtained for a typical device with cantilever beam width 8mm. The test results are consistent with the theory analysis and indicate that a piezoelectric battery for ambient vibration energy harvesting is a promising electric power source for wireless sensors nodes with micro-power consumption.

Development of a Vibration Powered Micro Generator and its Application to Harvest the Vibration Energy of the KRI KKP-811’s Engine

Vibration energy harvesting has been receiving a considerable amount of interest as a means of powering wireless sensors and low-power devices. In this paper, an energy harvester is presented to convert ambient mechanical vibration into electrical energy employing magnetoelectric generator. The harvester uses single magnet-spring attached on the coil. When the harvester is excited, the magnet moves relative to the coil, undergoes magnetic field variations and produces a power output. To obtain a maximum power output, the mass of magnet is varied. The magnetoelectric generator with various masses of magnets was tested by a harmonic exciter with various frequencies and amplitudes. The one with maximum power output was then applied to harvest the ambient vibration energy of KRI KKP-811’s Engine. The results show that this prototype can harvest maximum energy of 2μW when it is placed at the base/foundation of the engine.