Power Harvesting Devices Research Articles

An AlScN Piezoelectric Micromechanical Ultrasonic Transducer-Based Power-Harvesting Device for Wireless Power Transmission.

Ultrasonic wireless power transfer technology (UWPT) represents a key technology employed for energizing implantable medical devices (IMDs). In recent years, aluminum nitride (AlN) has gained significant attention due to its biocompatibility and compatibility with complementary metal-oxide-semiconductor (CMOS) technology. In the meantime, the integration of scandium-doped aluminum nitride (Al90.4%Sc9.6%N) is an effective solution to address the sensitivity limitations of AlN material for both receiving and transmission capabilities. This study focuses on developing a miniaturized UWPT receiver device based on AlScN piezoelectric micro-electromechanical transducers (PMUTs). The proposed receiver features a PMUT array of 2.8 × 2.8 mm2 comprising 13 × 13 square elements. An acoustic matching gel is applied to address acoustic impedance mismatch when operating in liquid environments. Experimental evaluations in deionized water demonstrated that the power transfer efficiency (PTE) is up to 2.33%. The back-end signal processing circuitry includes voltage-doubling rectification, energy storage, and voltage regulation conversion sections, which effectively transform the generated AC signal into a stable 3.3 V DC voltage output and successfully light a commercial LED. This research extends the scope of wireless charging applications and paves the way for further device miniaturization by integrating all system components into a single chip in future implementations.

The magnetic field self-display system of coupler for wireless power transfer systems based on magnetic structure factor

The magnetic field surrounding wireless power transfer (WPT) systems is difficult for the general public to discern in practice. To address this problem, a system that only measures the current in the coils for transferring and receiving to get the coupler’s magnetic field strength at a specific geographic location in space is proposed. The system includes a current transformer, inductive power-harvesting device, rectifier module, voltage regulation module, microprocessor, AD module, and display module. Due to the fixed mechanical structure and position of the coupler when working, the calculation model of the magnetic field of the coupler is established, and the magnetic structure factor based on the mechanical structure of the coupler is defined. The system can obtain power and operate based on the inductive power harvesting principle without damaging the WPT system structure. It also can realize the convenient display of the magnetic field and avoid the dependence on professional instruments when measuring the magnetic field of the coupler. In addition, it is easy to implement in practice.

Time-dependent shape of bistable unsymmetric carbon fibers-epoxy thin laminates

Carbon fiber-epoxy thin laminates, manufactured adopting a [0/90] non-symmetric lay-up, are characterized by two stable curved shapes, so being bistable. These composite thin laminates are attracting great interest for their potential application as novel morphing structures and power harvesting devices in many engineering fields. The curvature changes of rectangular bistable plates were monitored at room temperature by a laser scanner system over a time span of 10 d. These changes were ascribed to the relaxation of thermal stresses over time. Anisotropic stress relaxation behavior was then studied looking at the matrix dominated properties, such as the transverse modulus in accelerated high temperature experiments and the moisture absorption. Then, a simple viscoelastic model was proposed together with a finite element analysis of the distortion arising from laminate cooling at the end of high temperature cure process. The experimental and numerical results showed that the transverse elastic modulus and the hygroscopic effect are the main factors affecting the shape relaxation of bistable laminates.

Improved Rectification and Osmotic Power in Polyelectrolyte-Filled Mesopores.

Ample studies have shown the use of nanofluidics in the ionic diode and osmotic power generation, but similar ionic devices performed with large-sized mesopores are still poorly understood. In this study, we model and realize the mesoscale ionic diode and osmotic power generator, composed of an asymmetric cone-shaped mesopore with its narrow opening filled with a polyelectrolyte (PE) layer with high space charges. We show that, only when the space charge density of a PE layer is sufficiently large (>), the considered mesopore system is able to create an asymmetric ionic distributions in the pore and then rectify ionic current. As a result, the output osmotic power performance can be improved when the filled PE carries sufficiently high space charges. For example, the considered PE-filled mesopore system can show an amplification of the osmotic power of up to 35.1-fold, compared to the bare solid-state mesopore. The findings provide necessary information for the development of large-sized ionic diode and osmotic power harvesting device.

A novel approach to determining piezoelectric properties of nanogenerators based on PVDF nanofibers using iterative finite element simulation for walking energy harvesting

This study presents the experimental characterization and finite element investigation of a piezoelectric nanogenerator based on electrospun poly(vinylidene difluoride) (PVDF) nanofibers walking energy harvesting applications. The piezoelectric response of nanogenerator device was experimentally evaluated under low frequency cyclic impacts using PiezoTester. The impact test was then simulated and the obtained experimental applied force-time curve is implemented into the finite element model as the impactor external force. Based on mentioned procedure, a novel iterative finite element simulation was then introduced to determine the piezoelectric properties of PVDF nanofibers to avoid any redundant experiments. The experimental voltage-time was compared with voltage time obtained from optimized finite element model and a reasonable agreement was achieved between the numerical and experimental curves. Thereinafter, as a case study, a PVDF nanofibers nanogenerator integrated foam (PNIF) was simulated to use as an energy harvester in the shoe insole. The validated finite element model was then constructed to optimize the PNIF elasticity modulus to reach the maximum efficiency of energy harvester during human walking. The results showed that the best efficiency of the energy harvesting is achieved for 211.27 kPa PNIF modulus, which can generate 15.1 V. These results lead to the establishment of engineering design rules in the industrial scale for wearable power harvesting devices in the footwear industry.

Performance of a Solar Thermoelectric Power-Harvesting Device Based on an All-Glass Solar Heat Transfer Pipe and Gravity-Assisted Heat Pipe with Recycling Air Cooling and Water Cooling Circuits

For the purpose of collecting solar radiation for energy conversion and utilization and improving the output performance of thermoelectric power-generation components, a new solar thermoelectric conversion device based on an all-glass solar heat transfer pipe and gravity-assisted heat pipe with recycling air cooling and water cooling circuits is designed. The uniqueness of the device lies in the combination of gravity-assisted heat pipes with excellent thermal conductivity and a direct air-cooled mode, a fin-cooled mode, and two solar-driven water-cooling modes with different flow rates. Based on the structure, the device can realize four separate output modes and multiple composite output modes and has practical significance for meeting different load power requirements, such as wireless sensors and electronics. Under a state of regular illumination from 3.14 × 104 lx to 10.04 × 104 lx, with one thermoelectric power generator (TEG) in one mode, the peak output voltage and power values of the device in single-output mode range from 183.1 mV to 370.7 mV and 33.5 mW to 137.2 mW, respectively, proving the feasibility of the proposed device. The energy supply of the above structure is completely obtained from the natural environment, and this aspect provides a high reference value for the cross-research of natural environment energy utilization and thermoelectric energy-conversion technology.

Stress relaxation in asymmetric bistable composites: Experiments and simulations

In the last years, bistable composite structures are finding interest in several aeronautical applications such as power harvesting devices or morphing applications on very small aircraft/drones, not needing servo-activated control systems. Residual stresses, developed upon cooling after curing, leads to warped the composite laminates. Several batches of unsymmetrical and unbalanced [0°/90°] laminates were cured in an autoclave according to a standard temperature cycle, following the pre-preg supplier suggested curing cycle. In order to increase the thermal stresses (and hence the bistability phenomenon), these laminates were removed from the autoclave immediately after the curing reaction and rapidly cooled down at room temperature not applying the indicated cool rate between 2 and 5 °C min−1. During storage at room temperature, thermal stresses changed over time, indicating that asymptotic stress relaxation occurs. The first part of this work looks at residual stress characterization of bistable composite plates measuring the changes of shape observed during room temperature annealing. Rectangular plates were produced and the bistable geometric shapes were accurately assessed using a laser scanner system over several days, in order to monitor the curvature changes due to stress relaxation. Then phenomenological viscoelastic predicting models were proposed for a quick estimate for the strain/stress relaxation phenomenon. The loss of bistability was demonstrated with the help of numerical simulation and experimental testing. The final goal was to gain a better knowledge of the relation between processing and final shape of bistable laminates, in order to make them suitable for application on small air vehicles.

An Electroactive Binder in the Formulation of IGZO Ink to Print an IGZO‐Based Rectifier for Harvesting Direct Current (DC) Power from the Near Field Communication (NFC) Signal of a Smartphone

AbstractFormulating a high‐performing semiconducting ink is crucial toward printing a diode for constructing a direct current (DC) power harvesting device, consisting of an antenna, a diode, and a capacitor, that can rectify the coupled weak near field communication (NFC) (13.56 MHz) signal (<1.5 Vpp) generated from smartphones. To achieve such performance, indium gallium zinc oxide (IGZO)‐based semiconducting ink is formulated by developing an electroactive binder, poly(4‐styrene sulfonic acid). By reducing the turn‐on voltage and providing a good rheological characteristic for printing metal insulator semiconductor‐Schottky diodes on plastic film, the newly formulated IGZO ink is able to print a rectifier that can harvest DC voltage with 50% efficiency from the coupled 13.56 MHz signal (NFC) of a smartphone.

Antimony Oxide-Doped 0.99Pb(Zr0.53Ti0.47)O3–0.01Bi(Y1−xSbx)O3 Piezoelectric Ceramics for Energy-Harvesting Applications

The effects of doping antimony oxides (Sb2O3/Sb2O5) on the ferroelectric/piezoelectric and energy-harvesting properties of 0.99Pb(Zr0.53Ti0.47)O3–0.01BiYO3 (PZT–BY) have been studied. The feasibility of doping Sb2O3 and Sb2O5 into the PZT–BY ceramics has also been compared by considering factors such as sintering condition, grain size, density, and electrical properties etc. This work discusses a detailed experimental observation using Sb2O3, because Sb2O5 is relatively expensive and does not follow the stoichiometric reaction mechanism when doped in PZT–BY. The Sb2O3-doped specimens were well sintered by oxygen-rich sintering and reached a maximum density of 99.1% of the theoretical value. X-ray diffraction (XRD) analysis showed a complete solid solution for all the specimens. Scanning electron microscope (SEM) observation revealed that the addition of Sb2O3 inhibits grain growth, and exhibits a denser and finer microstructure. The 0.1 moles of Sb2O3-doped ceramic shows a sharp decrease in the dielectric constant (ε33T = 690), while the piezoelectric charge constant (d33) and electromechanical coupling factor (kp) maintained high values of 350 pC/N and 66.0% respectively. The relatively higher value of d33 and lower ε33T of the 0.99Pb(Zr0.53Ti0.47)O3–0.01Bi(Y0.9Sb0.1)O3 ceramic resulted in an optimum value of piezoelectric voltage constant (g33 = 57.4 × 10−3 Vm/N) and a high figure of merit (d33 × g33 = 20075 × 10−15 m2/N). These values are high compared to recently reported works. Therefore, Sb2O3-doped PZT–BY ceramic could be a promising candidate material for the future study of power-harvesting devices.

Ultra-long vertically aligned lead titanate nanowire arrays for energy harvesting in extreme environments

Recent research has shown that nanowire arrays can be fabricated into power harvesting devices that convert ambient vibrations to electrical power. These devices, however, are limited to low temperature environments due to material constraints. To solve this problem, this paper offers a route to obtain a nanowire energy harvester that is capable of operating at extreme temperatures. This is achieved by developing a method to synthesize vertically aligned arrays of ultra-long lead titanate nanowires and fabricating them into an energy harvester. Performing power characterization measurements of the device in a temperature-controlled environment illustrates useful power generation at temperatures up to 375°C. This work offers a new method for the fabrication of extreme temperature device thereby offering a significant advancement in the field of energy harvesting by demonstrating energy production in extreme environments where previous systems would fail.

Damping and stiffening forces of a squeeze film between two plates

This paper presents the analysis of the squeeze film effect on the MEMS power harvesting devices. The effect of the squeeze film has been represented by the damping effect in previous studies. Our goal, however, is to quantify the stiffening effect, which affects the resonance frequency of the squeeze film and the oscillator system. The finite difference method for rectangular geometries is applied to solve the nonlinear isothermal Reynold’s equation for the squeeze film. The approach is validated by theoretical results for small squeeze numbers. The stiffening effect actually appears as a negative added mass. The damping effect obtained from numerical solutions matches perfectly with the equivalent damping formula derived from the analytical formula. The dynamic response of sinusoidally forced oscillator involving one squeeze film is obtained numerically in order to demonstrate the stiffening effect of the squeeze film. Three main parameters are considered: the initial gap of the squeeze film, the excitation amplitude, and the excitation frequency. The relationship between the amplitude of the steady-state sinusoidal response and the excitation frequency is determined. Numerical results demonstrate that the squeeze film gives rise to both a shift in the resonance frequency at small amplitude oscillations and amplitude dependence of the resonance frequency known as nonlinear hardening. These effects are both observed in experiments.

Nanofiber alignment tuning: An engineering design tool in fabricating wearable power harvesting devices

Piezoelectrics are one of the most important materials used for harvesting energies. Several piezoelectric nanostructures have been used to construct nanogenerators (NGs). Nanofibers made by piezo-polymers, especially polyvinylidene fluoride (PVDF) because of their high flexibility, biocompatibility, and low cost, have shown wonderful growth as the key materials for NGs. Despite these favorable properties, fabricated nanofibrous devices still has low efficiency and many studies have been conducted to characterize and improve the performance of the PVDF nanofibers. Here we tried to fabricate PVDF NG device based on align nanofibers to improve the NGs output, using two different methods rotary collector and applying magnetic field. Characteristics of these structures are evaluated utilizing X-ray diffraction, Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. Electrical response of fabricated samples is measured through utilization of an impedance analyzer at room temperature. Results demonstrate that crystalline structure increases in both methods but sample fabricated by rotary collector in magnetic field has more improvement in their outputs. This result shows that in addition to the crystalline structure, nanofibers alignment and arrangement play important roles in piezoelectric properties of sample, as well as NG efficiency. These results teach us to establish engineering design rules for wearable power harvesting devices.

Piezoelectric electrospun nanofibrous energy harvesting devices: Influence of the electrodes position and finite variation of dimensions

Having control on the specific area of power harvesting devices is the main controllable parameter in their fabrication. Hence, in this paper, at first a piezoelectric nanofiber is made with different dimensions and all kinds of function tests including X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry are implemented thereon. After ensuring accurate …… responses from the device, some kinds of forces like concentration impact and distributed impact and tension creation by applying bending force are applied on the fabricated device in the laboratory. To assess the effect of electrode position, electrodes were placed in five modes within the samples and the output voltage was recorded with regard to applied forces type. The results indicated that an increase in specific area of nanofibrous mats in devices absolutely resulted in an increase in electric output, but the electric output reduced consequently when it normalized to the specific area of nanofibrous mats. These results imply promising approaches, as an enhanced efficiency energy-scavenging interface, for designing and fabricating various wearable self-powered electrical devices and systems.

Rotary-type electromagnetic power generator using a cardiovascular system as a power source for medical implants

Power-harvesting devices have received attention as power supplies for implantable medical devices. Power-harvesting technologies can overcome the limitation of a battery, such as limited battery lifetime and repeated surgical interventions. However, micropower generators do not meet the energy requirements of medical implants such as neural recording, implantable hearing aids, and implantable wireless sensors. They require an electrical power from 1 to 10 mW. This paper introduces an electromagnetic power generator using blood flow and blood pressure to drive an implanted medical device. The fabricated power generator, which is composed of a tiny rotor with magnets and external coils with ferrite cores, operates within a wide blood pressure range from 6.75 to 54.75 mmHg. In addition, the total volume and weight of the generator are 3.16 cc and 24 g, respectively. Using animal and mock-up tests, we verified the ability of the self-powered device to drive the medical implants. In the animal test, we utilized a blood pump to control the blood flow and blood pressure. The generator generated a maximum electrical power of 3.4 mW (conversion efficiency of 1.04%) at a blood pressure drop of 54.75 mmHg and blood flow of 2.68 L/min.

Electromechanical finite element modelling for dynamic analysis of a cantilevered piezoelectric energy harvester with tip mass offset under base excitations

A new electromechanical finite element modelling of a vibration power harvester and its validation with experimental studies are presented in this paper. The new contributions for modelling the electromechanical finite element piezoelectric unimorph beam with tip mass offset under base excitation encompass five major solution techniques. These include the electromechanical discretization, kinematic equations, coupled field equations, Lagrangian electromechanical dynamic equations and orthonormalized global matrix and scalar forms of electromechanical finite element dynamic equations. Such techniques have not been rigorously modelled previously by other researchers. There are also benefits to presenting the numerical techniques proposed in this paper. First, the proposed numerical techniques can be used for applications in many different geometrical models, including micro-electro-mechanical system power harvesting devices. Second, applying tip mass offset located after the end of the piezoelectric beam length can result in a very practical design, which avoids direct contact with piezoelectric material because of its brittle nature. Since the surfaces of actual piezoelectric material are covered evenly with thin conducting electrodes for generating single voltage, we introduce the new electromechanical discretization, consisting of the mechanical and electrical discretized elements. Moreover, the reduced electromechanical finite element dynamic equations can be further formulated to obtain the series form of new multimode electromechanical frequency response functions of the displacement, velocity, voltage, current and power, including optimal power harvesting. The normalized numerical strain node and eigenmode shapes are also further formulated using numerical discretization. Finally, the parametric numerical case studies of the piezoelectric unimorph beam under a resistive shunt circuit show good agreement with the experimental studies.

Development of piezoelectric energy harvesting modules for impedance-based wireless structural health monitoring system

This paper reports smart wireless sensor node for Structural Health Monitoring (SHM) that is capable of operation with energy harvesting systems using piezoelectric materials. A large amount of research has focused on utilizing the impedance method for structural health monitoring but these studies required expensive and bulky impedance analyzers, which are unsuitable for field deployment. Piezoelectric materials can be used as mechanisms to transfer ambient vibrations into electrical energy that can be stored and used to power other devices. In this study, three types of piezoelectric materials were evaluated experimentally for use as power harvesting devices. In general, the power produced by the vibrations of piezoelectric devices is low, meaning that the equipment powered by the device cannot be operated effectively. Therefore, a time delay circuit and reset IC chip was used to improve the efficiency of the electrical power generated. The experimental results were used to estimate the efficiency of these devices and identified the feasibility of their use in practical applications.

Power harvesting systems design for railroad safety

Railroad crossings represent a significant danger in railroad transportation systems. Each year thousands of accidents occur that involve trains and other vehicles at unprotected railroad crossings, resulting in hundreds of fatalities and injuries. Additionally, derailments occur on average once every 6 h across the United States due to mechanical failures and improperly maintained track, endangering property and lives. The lack of electrical infrastructure in remote areas is a primary barrier impeding the installation of safety enhancements such as warning light systems and track health monitoring sensors that could reduce the frequency of such accidents. Providing on-demand power by harvesting energy from deflecting railroad track during the passage of trains is a promising approach compared with the cost of installing electrical power lines or the lack of robust solar and/or wind power solutions. This paper discusses the design and development of several power harvesting devices capable of scavenging power from the vertical deflection of railroad track. The design of a cam-based generator device driven by the train wheels is also discussed. Simulation and testing results on these devices are also presented in this paper.

A theoretical and experimental investigation of power harvesting using the NiMnGa martensite reorientation mechanism

Magnetic shape memory alloys (MSMAs) can exhibit the shape memory effect when there is a magnetic field in the vicinity of a material point. The microstructure of the MSMAs is comprised of tetragonal martensite variants, each with their preferred internal magnetization orientation. Starting from a random variant orientation, the application of a large enough magnetic field will cause the variants to reorient so that the internal magnetization vectors align with the external field. Then, keeping the magnetic field constant and adding a variable compressive stress in a direction normal to that of the magnetic field, some or all of the martensitic variants may rotate into a stress preferred state. As the variants reorient, the internal magnetization vectors rotate, and the material’s magnetization changes. For power harvesting and sensing applications, the change in magnetization induces a current in a pickup coil placed around the MSMA specimen, resulting in an output voltage at its terminals according to Faraday’s law of inductance. This paper focuses on the evaluation of the voltage output, both experimentally and numerically, in an attempt to assess the ability of a MSMA thermodynamic based constitutive model, used in conjunction with Faraday’s law of induction, to predict the variant reorientation induced voltage output. Assessing the accuracy of the predicted voltage is beneficial for the design of both MSMA based power harvesting devices and MSMA based displacement sensors.

Tackling global electricity shortage through human power: Technical opportunities from direct or indirect utilizations of the pervasive and green human energy

With the energy and environmental problems becoming increasingly serious, human power, as a pervasive, renewable, mobile and environment friendly energy, draws more and more attention over the world. In this paper, the most basic features of human power are presented. The currently available human power harvesting theories and devices are briefly reviewed and compared. Further, direct or indirect utilization of human power in daily life, especially transportation and home appliances, such as human-powered car, watercraft, aircraft, washing machine and television etc. are summarized. Considering that the total energy from an individual is rather limited, as previously focused by most of the former works, it is conceived in this paper that an important future for large scale use of human powers lies in the efficient conversion, collection and storage of such energy from discrete people and then use it later on as desired. With the huge amount of energy gathered, the application category of human power would be significantly expended. Starting from this point, three technical ways towards efficiently utilizing human power are sketched, which are termed as human-powered grid (HPG), human-powered charger (HPC) and human-powered storage (HPS), among which, HPG is capable of collecting the electric power produced by each individual at different regions and thus can supply unique and flexible power to the customers covered in the area, without relying on the conventional electricity grid. The HPC can then charge various kinds of electrical devices instantly by a human driven generator which converts human power into electricity. Finally, the HPS can store electricity in time for later use. In this way, even for the devices requiring electricity that is strong enough, the collected human power can also serve as its reliable energy source. Meanwhile, utilization of human power becomes rather convenient and timely which guarantees its practical value. It is expected that with further research and increasing applications, human power could partially relieve the current global electricity shortage and environmental issues via its pervasive contribution.

Wireless links for global positioning system receivers

Given an object, its positioning in the space is a main concern in structural monitoring and a required feedback in structural health monitoring, structural control and robotics. In addition, to make the sensor unit wireless is a crucial issue for advanced applications. This paper deals with the exploitation of wireless transmission technology to long-term monitoring GPS (Global Positioning System) receivers - like the Leica GMX 902 and the Leica GRX 1200-pro. These GPS receivers consist of five parts: antenna, receiver, user client computer, interface and power supply. The antenna is mounted on the object to be monitored and is connected with the receiver by a coaxial-cable through which the radio frequency signals are transmitted. The receiver unit acquires, tracks and demodulates the satellite signals and provides, through an interface which in this paper is made wireless, the resulting GPS raw data to the user client computer for being further processed by a suitable positioning algorithm. The power supply reaches the computer by a wired link, while the other modules rely on batteries re-charged by power harvesting devices. Two wireless transmission systems, the 24XStream and the CC1110, are applied to replace the cable transmission between the receiver and the user client computer which up to now was the only market offer. To verify the performance and the reliability of this wireless transmission system, some experiments are conducted. The results show a successful cable replacement.