Concept Of Energy Harvesting Research Articles

PENDEXE: A novel energy harvesting concept for low frequency human waistline

We report a novel concept of harvesting energy from low frequency and low force human gait movement from a device attached at the waistline. Due to the rather low characteristic frequencies of the human gait it is difficult to harvest energy piezoelectrically from such movement. The concept reported here uses a pendulum to exploit kinetic energy available from walking and jogging and later converting it into electrical energy by using compliant piezoelectric unimorphs. The pendulum with a fundamental frequency of approximately 2Hz is directed to excite the piezoelectric unimorphs at their natural frequency of 50Hz by a mechanical frequency up-conversion technique. The maximum power output is nearly 300μW. The concept, fabrication of novel rotor-pendulum based harvesting unit and experimentation are discussed in detail.

Myocardial Cell Pattern on Piezoelectric Nanofiber Mats for Energy Harvesting

The paper presents in vitro contractile myocardial cell pattern on piezoelectric nanofiber mats with applications in energy harvesting. The cell-based energy harvester consists of myocardial cell sheet and a PDMS substrate with a PVDF nanofiber mat on. Experimentally, cultured on specifically distributed nanofiber mats, neonatal rat ventricular cardiomyocytes are characterized with the related morphology and contraction. Previously, we have come up with the concept of energy harvesting from heart beating using piezoelectric material. A bio-hybrid energy harvester combined living cardiomyocytes, PDMS polymer substrate and piezoelectric PVDF film with the electrical output of peak current 87.5nA and peak voltage 92.3mV. However, the thickness of the cardiomyocyte cultured on a two-dimensional substrate is much less than that of the piezoelectric film. The Micro Contact Printing (μCP) method used in cell pattern on the PDMS thin film has tough requirement for the film surface. As such, in this paper we fabricated nanofiber-constructed PDMS thin film to realize cell pattern due to PVDF nanofibers with better piezoelectricity and microstructures of nanofiber mats guiding cell distribution. Living cardiomyocytes patterned on those distributed piezoelectric nanofibers with the result of the same distribution as the nanofiber pattern.

Characterization of piezoelectric material for micro thermal harvesters

This paper presents the first realizations of a novel concept for thermal energy harvesting at micro scale. The devices proposed here are based on a two-step transduction combining thermo-mechanical and piezoelectric conversion. In this contribution, we present for the first time results on micro fabricated structures with integrated piezoelectric layers, focusing mainly on the characterization of the piezoelectric material. The process flow to get a bilayered bistable structure is briefly described, highlighting the way how to control the initial deflection. The characterization of the piezoelectric thin film is presented then. The e31,f coefficient is measured in both sensor and actuator mode and is found to be equal to -0,91 C.m−2 in both configurations. This value, close to the state-of-the-art, is very promising for the future thermal harvesting applications. Finally the buckling of a structure actuated by a voltage was observed and the corresponding displacement measured by laser interferometry.

Inductive Energy Harvesting for Rotating Sensor Platforms

An inductive energy harvesting concept for structures rotating in proximity to a stationary body is proposed. The performance of such devices is studied analytically and numerically, and an experimental proof of concept is presented, demonstrating energy output density of 1 mW/cm3 from a typical geometry and rotation scale. The proposed approach may be suitable for powering retrofitted wireless sensors on engine bodies and also on rotating parts where complex stator-rotor wiring solutions would otherwise be required.

Pyroelectric Energy Scavenging Techniques for Self-Powered Nuclear Reactor Wireless Sensor Networks

Recent advances in technologies for harvesting waste thermal energy from ambient environments present an opportunity to implement truly wireless sensor nodes in nuclear power plants. These sensors could continue to operate during extended station blackouts and during periods when operation of the plant’s internal power distribution system has been disrupted. The energy required to power the wireless sensors must be generated using energy harvesting techniques from locally available energy sources, and the energy consumption within the sensor circuitry must therefore be low to minimize power and hence the size requirements of the energy harvester.Harvesting electrical energy from thermal energy sources can be achieved using pyroelectric or thermoelectric conversion techniques. Recent modeling and experimental studies have shown that pyroelectric techniques can be cost-competitive with thermoelectrics in self-powered wireless sensor applications and, using new temperature cycling techniques, have the potential to be several times as efficient as thermoelectrics under comparable operating conditions. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, is outlined. This paper outlines the modeling of cantilever and pyroelectric structures and single-element devices that demonstrate the potential of this technology for the development of high-efficiency thermal-to-electrical energy conversion devices.

Energy harvesting for the implantable biomedical devices: issues and challenges.

The development of implanted devices is essential because of their direct effect on the lives and safety of humanity. This paper presents the current issues and challenges related to all methods used to harvest energy for implantable biomedical devices. The advantages, disadvantages, and future trends of each method are discussed. The concept of harvesting energy from environmental sources and human body motion for implantable devices has gained a new relevance. In this review, the harvesting kinetic, electromagnetic, thermal and infrared radiant energies are discussed. Current issues and challenges related to the typical applications of these methods for energy harvesting are illustrated. Suggestions and discussion of the progress of research on implantable devices are also provided. This review is expected to increase research efforts to develop the battery-less implantable devices with reduced over hole size, low power, high efficiency, high data rate, and improved reliability and feasibility. Based on current literature, we believe that the inductive coupling link is the suitable method to be used to power the battery-less devices. Therefore, in this study, the power efficiency of the inductive coupling method is validated by MATLAB based on suggested values. By further researching and improvements, in the future the implantable and portable medical devices are expected to be free of batteries.

A review of piezoelectric vibration energy harvesting techniques

In this paper, recent published techniques for vibration energy harvesting with piezoelectric materials have been summarized. The various techniques described are classified in terms of linear and nonlinear vibration energy harvesters, harvesting electrical circuits, large scale vibration energy harvesting concept. The focus is on linear vibration energy harvester but with multiple resonant mode models. The paper concluded with an overview of vibration energy harvesting techniques that aim to maximize the extracted power and the future utilization of the vibration energy harvester.

The effect of noise on the response of a vertical cantilever beam energy harvester

An energy harvesting concept has been proposed comprising a piezoelectric patch on a vertical cantilever beam with a tip mass. The cantilever beam is excited in the transverse direction at its base. This device is highly nonlinear with two potential wells for large tip masses, when the beam is buckled. For the pre‐buckled case considered here, the stiffness is low and hence the displacement response is large, leading to multiple solutions to harmonic excitation that are exploited in the harvesting device. To maximise the energy harvested in systems with multiple solutions the higher amplitude response should be preferred. This paper investigates the amplitude of random noise excitation where the harvester is unable to sustain the high amplitude solution, and at some point will jump to the low amplitude solution. The investigation is performed on a validated model of the harvester and the effect is demonstrated experimentally.

A Simplified Process of PMN-PZT Energy Harvester Based on Flammable Materials

With the increasing demand of auxiliary power unit in portable electronic devices, the concept of renewable energy harvesting near human surrounding environmental circumstance arouses an interest. As the field of microelectromechanical system (MEMS) has advanced, a clear need for the integration of materials other than silicon and its compounds into micromachined transducers has emerged. Piezoelectric materials are high energy density materials that scale very favorably upon miniaturization and that has led to an ever-growing interest in piezoelectric films for MEMS applications. However, conventional powder processing and machining cannot meet the requirement of such fine ceramic structure. Advanced technologies such as those using lasers and soft PDMS modeling method have been available for micro-patterning of ceramics but are not viable for large-scale production. It is difficult and time-consuming to pattern fine scale ceramics. In this paper, we fabricated simple process of MEMS based energy harvester by employing the flammable materials with PMN-PZT micro-pillar structure. The optimum aspect ratio of thickness/length for the ceramic pillar dielectric properties and micro-structure will be discussed.

On the Role of Nonlinearities in Vibratory Energy Harvesting: A Critical Review and Discussion

The last two decades have witnessed several advances in microfabrication technologies and electronics, leading to the development of small, low-power devices for wireless sensing, data transmission, actuation, and medical implants. Unfortunately, the actual implementation of such devices in their respective environment has been hindered by the lack of scalable energy sources that are necessary to power and maintain them. Batteries, which remain the most commonly used power sources, have not kept pace with the demands of these devices, especially in terms of energy density. In light of this challenge, the concept of vibratory energy harvesting has flourished in recent years as a possible alternative to provide a continuous power supply. While linear vibratory energy harvesters have received the majority of the literature's attention, a significant body of the current research activity is focused on the concept of purposeful inclusion of nonlinearities for broadband transduction. When compared to their linear resonant counterparts, nonlinear energy harvesters have a wider steady-state frequency bandwidth, leading to a common belief that they can be utilized to improve performance in ambient environments. Through a review of the open literature, this paper highlights the role of nonlinearities in the transduction of energy harvesters under different types of excitations and investigates the conditions, in terms of excitation nature and potential shape, under which such nonlinearities can be beneficial for energy harvesting.

A concept for energy harvesting from quasi-static structural deformations through axially loaded bilaterally constrained columns with multiple bifurcation points

A major obstacle limiting the development of deployable sensing and actuation solutions is the scarcity of power. Converted energy from ambient loading using piezoelectric scavengers is a possible solution. Most of the previously developed research focused on vibration-based piezoelectric harvesters which are typically characterized by a response with a narrow natural frequency range. Several techniques were used to improve their effectiveness. These methods focus only on the transducer’s properties and configurations, but do little to improve the stimuli from the source. In contrast, this work proposes to focus on the input deformations generated within the structure, and the induction of an amplified amplitude and up-converted frequency toward the harvesters’ natural spectrum. This paper introduces the concept of using mechanically-equivalent energy converters and frequency modulators that can transform low-amplitude and low-rate service deformations into an amplified vibration input to the piezoelectric transducer. The introduced concept allows energy conversion within the unexplored quasi-static frequency range (≪1 Hz). The post-buckling behavior of bilaterally constrained columns is used as the mechanism for frequency up-conversion. A bimorph cantilever polyvinylidene fluoride (PVDF) piezoelectric beam is used for energy conversion. Experimental prototypes were built and tested to validate the introduced concept and the levels of extractable power were evaluated for different cases under varying input frequencies. Finally, finite element simulations are reported to provide insight into the scalability and performance of the developed concept.

CURRENT WAYS TO HARVEST ENERGY USING A COMPUTER MOUSE

This paper deals with the idea of an energy harvesting (EH) system that uses the mechanical energy from finger presses on the buttons of a computer mouse by means of a piezomaterial (PVF2). The piezomaterial is placed in the mouse at the interface between the button and the body. This paper reviews the parameters of the PVF2 piezomaterial and tests their possible implementation into EH systems utilizing these types of mechanical interactions. The paper tests the viability of two EH concepts: a battery management system, and a semi-autonomous system. A statistical estimate of the button operations is performed for various computer activities, showing that an average of up to 3300 mouse clicks per hour was produced for gaming applications, representing a tip frequency of 0.91 Hz on the PVF2 member. This frequency is tested on the PVF2 system, and an assessment of the two EH systems is reviewed. The results show that fully autonomous systems are not suitable for capturing low-frequency mechanical interactions, due to the parameters of current piezomaterials, and the resulting very long startup phase. However, a hybrid EH system which uses available power to initiate the circuit and eliminate the startup phase may be explored for future studies.

Piezoelectric energy harvesting from hybrid vibrations

The concept of harvesting energy from ambient and galloping vibrations of a bluff body with a triangular cross-section geometry is investigated. A piezoelectric transducer is attached to the transverse degree of freedom of the body in order to convert these vibrations to electrical energy. A coupled nonlinear distributed-parameter model is developed that takes into consideration the galloping force and moment nonlinearities and the base excitation effects. The aerodynamic loads are modeled using the quasi-steady approximation. Linear analysis is performed to determine the effects of the electrical load resistance and wind speed on the global damping and frequency of the harvester as well as on the onset of instability. Then, nonlinear analysis is performed to investigate the impact of the base acceleration, wind speed, and electrical load resistance on the performance of the harvester and the associated nonlinear phenomena that take place. The results show that, depending on the interaction between the base and galloping excitations, and the considered values of the wind speed, base acceleration, and electrical load resistance, different nonlinear phenomena arise while others disappear. Short- and open-circuit configurations for different wind speeds and base accelerations are assessed. The results show that the maximum levels of harvested power are accompanied by a minimum transverse displacement when varying the electrical load resistance.

Modeling of Piezoelectric Energy Harvesting from Freely Oscillating Cylinders in Water Flow

A concept of energy harvesting from vortex-induced vibrations of a rigid circular cylinder with two piezoelectric beams attached is investigated. The variations of the power levels with the free stream velocity are determined. A mathematical approach including the coupled cylinder motion and harvested voltage is presented. The effects of the load resistance, piezoelectric materials, and circuit combined on the natural frequency and damping of the vibratory system are determined by performing a linear analysis. The dynamic response of the cylinder and harvested energy are investigated. The results show that the harvested level in SS and SP&PS modes is the same with different values of load resistance. For four different system parameters, the results show that the bigger size of cylinder with PZT beams can obtain the higher harvested power.

Incident flow effects on the performance of piezoelectric energy harvesters from galloping vibrations

In this paper, we investigate experimentally the concept of energy harvesting from galloping oscillations with a focus on wake and turbulence effects. The harvester is composed of a unimorph piezoelectric cantilever beam with a square cross-section tip mass. In one case, the harvester is placed in the wake of another galloping harvester with the objective of determining the wake effects on the response of the harvester. In the second case, meshes were placed upstream of the harvester with the objective of investigating the effects of upstream turbulence on the response of the harvester. The results show that both wake effects and upstream turbulence significantly affect the response of the harvester. Depending on the spacing between the two squares and the opening size of the mesh, wake and upstream turbulence can positively enhance the level of the harvested power.

Design, fabrication and characterization of an inductive human motion energy harvester for application in shoes

The concept of energy harvesting has been in the focus of research for more than two decades now and with the continuous device miniaturization and reduction in power consumption of the electronics it has become a viable power source for mobile systems. The increasing desire for mobility and longevity in terms of battery life has eventually led to wearable systems, i.e. electronic circuits with their power supply which are being integrated into textiles and everyday life. This paper reports the development of a cylindrical inductive energy harvesting device which exploits the accelerations available in the plane of the foot during walking. The modeling and characterization of the system is based upon real-world acceleration data recorded during treadmill runs. Although a wider range of test subjects would be required to increase the statistical relevance of the measured data, it is concluded that the energy provided by this system is sufficient to power low energy circuits at comparatively slow walking velocities. Additionally, the obtained knowledge can be used to develop a smaller, parallelized system.

Multi-modal vibration based MEMS energy harvesters for ultra-low power wireless functional nodes

In this work we discuss a novel design concept of energy harvester (EH), based on Microsystem (MEMS) technology, meant to convert mechanical energy, available in the form of vibrations scattered in the surrounding environment, into electrical energy by means of the piezoelectric conversion principle. The resonant structure, named four-leaf clover (FLC), is circular and based on four petal-like double mass-spring systems, kept suspended through four straight beams anchored to the surrounding Silicon frame. Differently from standard cantilever-type EHs that typically convert energy uniquely in correspondence with the fundamental vibration frequency, this particular shape is aimed to exploit multiple resonant modes and, thereby, to increase the performance and the operation bandwidth of the MEMS device. A preliminary non-optimized design of the FLC is discussed and physical samples of the sole mechanical resonator, fabricated at the DIMES Technology Center (Delft University of Technology, the Netherlands), are experimentally characterized. Their behaviour is compared against simulations performed in ANSYS Workbench™, confirming good accuracy of the predictive method. Furthermore, the electromechanical multiphysical behaviour of the FLC EH is also analysed in Workbench, by adding a layer with piezoelectric conversion properties in the simulation. The measured and simulated data reported in this paper confirm that the MEMS converter exhibits multiple resonant modes in the frequency range below 1 kHz, where most of the environmental vibration energy is scattered, and extracted power levels of 0.2 μW can be achieved as well, in closed-loop conditions. Further developments of this work are expected to fully prove the high-performance of the FLC concept, and are going to be addressed by the authors of this work in the on-going activities.

A Low-Power Photovoltaic Maximum Power Point Tracking Circuit for WSNs

Currently, most wireless sensor networks (WSNs) are powered by batteries. When energy stored in batteries is exhausted, the life of the WSNs goes to the end. The concept of energy harvesting provides a practical solution to the problem of the energy limitation. In this article, the feasibility and performance of a simple and low-cost analog solar energy harvesting circuit with the function of maximum power point tracking (MPPT) are investigated. The technique provided is based on the approximately linear relationship between the maximum power point (MPP) voltage and the open-circuit voltage of a solar panel under different irradiation levels. Several experiments have been carried out regarding the accuracy and efficiency of MPPT as well as the working process of the circuit. Results show that the maximum power point with different loads can be effectively tracked by the self-powered MPPT circuit, and in the meantime, a stable output voltage can be generated. The efficiency of energy conversion is guaranteed by a commercial off-the-shelf DC-DC chip. The detailed description of the circuit design and the comprehensive analysis of the circuit performance will provide a useful guide for the future applications.

Performance analysis of galloping-based piezoaeroelastic energy harvesters with different cross-section geometries

The concept of harvesting energy from galloping oscillations of a bluff body with different cross-section geometries attached to a cantilever beam is investigated. To convert these oscillations into electrical power, a piezoelectric transducer is attached to the transverse degree of freedom of the prismatic structure. Modal analysis is performed to determine the exact mode shapes of the structure. A coupled nonlinear distributed-parameter model is developed to determine the effects of the cross-section geometry, load resistance, and wind speed on the level of the harvester power. The quasi-steady approximation is used to model the aerodynamic loads. Linear analysis is performed to investigate the effects of the electrical load resistance and the cross-section geometry on the onset speed of galloping. The results show that the electrical load resistance and the cross-section geometry affect significantly the onset speed of galloping. Nonlinear analysis is performed to determine the effects of the electrical load resistance, cross-section geometry, and wind speed on the system’s outputs and particularly the level of the harvested power. A comparison of the performance of the different cross sections in terms of displacement and harvested power is presented. The results show that different sections are better for harvesting energy over different regions of the flow speed. The results also show that maximum levels of harvested power are accompanied with minimum transverse displacement amplitudes for all considered (square, D, and triangular) cross-section geometries.

Piezoelectric energy harvesting from vortex-induced vibrations of circular cylinder

The concept of harvesting energy from a circular cylinder undergoing vortex-induced vibrations is investigated. The energy is harvested by attaching a piezoelectric transducer to the transverse degree of freedom. Numerical simulations are performed for Reynolds numbers (Re) in the range 96≤Re≤118, which covers the pre-synchronization, synchronization, and post-synchronization regimes. Load resistances (R) in the range 500Ω≤R≤5MΩ are considered. The results show that the load resistance has a significant effect on the oscillation amplitude, lift coefficient, voltage output, and harvested power. The results also show that the synchronization region widens when the load resistance increases. It is also found that there is an optimum value of the load resistance for which the harvested power is maximum. This optimum value does not correspond to the case of largest oscillations, which points to the need for a coupled analysis as performed here.