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Three major phases associated with piezoelectric energy harvesting: (i) mechanical- mechanical energy transfer, (ii) mechanical-electrical energy transduction, and (iii) electrical- electrical energy transfer.
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Energy recovery from wasted or unused power has been the topic of discussion for a long time. In recent years, industrial and academic research units have focused on harvesting energy from mechanical vibrations using piezoelectric transducers. These efforts have provided the initial research guidelines and have brought in light the problems and lim...
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... recovery from wasted or unused power has been the topic of discussion for a long time. Unused power exists in various mechanical forms such as ambient vibrations, water flow, wind, human motion and shock waves. In recent years, industrial and academic research units have focused their attention on harvesting energy from vibrations using piezoelectric transducers. These efforts have provided the initial research guidelines and have brought light to the problems and limitations of implementing the piezoelectric transducer [1]. Historically, our group started the research on passive vibration damping with using piezoelectric materials in 1980s. Figures 1(a) and 1(b) show the results for damping vibration generated in a bimorph transducer [2]. Resistor-shunt was used with the bimorph, and the vibration damping was measured by changing the external resistance. As shown in Fig. 1(b), the quickest damping was obtained with a 6.6 k resistor, which is almost the same value as the electrical impedance of the bimorph [i.e., R = 1/ ω C]. In these results, mechanical energy was dissipated through the resistor to Joule heat, effectively leading to the quickest damping. In addition to the resistive shunt, capacitive, inductive, and switch shunts have been successively studied, aiming at adaptive vibration control after our studies [1]. After getting into 2000s, we decided to save and store this generated electrical energy, instead of dissipating it through the resistance. This situation change is schematically illustrated in Fig. 2. Note that the maximum energy harvesting condition corresponds to the largest vibration damping; “If you run after two hares, you will catch BOTH”, rather than “you will catch NEITHER” (the original proverb), which seems to be the best development strategy! There are three major phases/steps associated with piezoelectric energy harvesting (see Fig. 3): (i) mechanical-mechanical energy transfer , including mechanical stability of the piezoelectric transducer under large stresses, and mechanical impedance matching, (ii) mechanical-electrical energy transduction , relating with the electromechanical coupling factor in the composite transducer structure, and (iii) electrical-electrical energy transfer , including electrical impedance matching. A suitable DC/DC converter is required to accumulate the electrical energy from a high impedance piezo-device into a rechargeable battery (low impedance). This paper deals with detailed energy flow analysis in piezoelectric energy harvesting systems with typical stiff “Cymbals” ( ∼ 100 mW) and flexible piezoelectric transducers ( ∼ 1 mW) under cyclic mechanical load, in order to provide comprehensive strategies on how to improve the efficiency of the harvesting system. Energy transfer rates are practically evaluated for all three steps above. We should also point out here that there is another research school of piezo-energy harvesting; that is, small energy harvesting (mW or lower) for signal transfer applications, where the efficiency is not a primary objective. This school usually treats a burst/pulse load to generate instantaneous electric energy for transmitting signals for a short period (100 ms—10 s), without accumulating the electricity in a rechargeable battery. Successful products (million sellers) in the commercial market belong mostly to this category at present, including “Lightning Switch [3]” [remote switch for room lights, with using a unimorph piezoelectric component] by PulseSwitch Systems, VA, and the 25 mm caliber “Programmable Ammunition [4]” [electricity generation with a multilayer piezo-actuator under shot impact] by ATK Integrated Weapon Systems, AZ. First of all, wasted or unused mechanical energy (vibration source) should be transferred properly to the energy converter such as piezoelectric devices. Mechanical impedance matching is one of the important factors we have to take into account. The mechanical impedance of the material is defined ...
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Citations
... Based on [13,14], it can be assumed that piezoelectric power harvesting involves three primary stages of energy flow. The first stage is a mechanical-to-mechanical energy transfer based on environmental excitation energy, ensuring the mechanical balance of the piezoelectric transducer under significant stresses and considering the damping factor. ...
... Energy harvesters have wide-angle energy sources ranging from the movement of humans and animals, industrial machinery, vehicles, large-scale infrastructure such as buildings and bridges, as well as natural elements such as water flow and wind. PE harvesters are recognized as promising autonomous energy sources for low-power electronic devices, including wireless sensors, portable gadgets, and medical implants [13,74]. The physical power (energy) derived from motion can be categorized into two forms: dynamic energy resulting from rigid body motion and spring energy stemming from elastic deformation [75]. ...
... Mechanical energy sources for harvesting include vibrations, body movements, acoustic fluctuations, and airflow [61]. The electromechanical device's reception component needs to be precisely built to match the vibration source's mechanical and/or acoustic impedance to be used effectively [13]. ...
In the current era, energy resources from the environment via piezoelectric materials are not only used for self-powered electronic devices, but also play a significant role in creating a pleasant living environment. Piezoelectric materials have the potential to produce energy from micro to milliwatts of power depending on the ambient conditions. The energy obtained from these materials is used for powering small electronic devices such as sensors, health monitoring devices, and various smart electronic gadgets like watches, personal computers, and cameras. These reviews explain the comprehensive concepts related to piezoelectric (classical and non-classical) materials, energy harvesting from the mechanical vibration of piezoelectric materials, structural modelling, and their optimization. Non-conventional smart materials, such as polyceramics, polymers, or composite piezoelectric materials, stand out due to their slender actuator and sensor profiles, offering superior performance, flexibility, and reliability at competitive costs despite their susceptibility to performance fluctuations caused by temperature variations. Accurate modeling and performance optimization, employing analytical, numerical, and experimental methodologies are imperative. This review also furthers research and development in optimizing piezoelectric energy utilization, suggesting the need for continued experimentation to select optimal materials and structures for various energy applications.
... Liang and Liao firstly introduced the energy flow chart for piezoelectric energy harvesters [99]. Uchino divided the energy flow of piezoelectric energy harvesters into three phases [100,101], and Xu provides a better explanation [42]: Phase I is the mechanical energy capture and transportation processing; Phase II is mechanical-to-electrical energy conversion processing; Phase III is the electrical energy transportation to the outside of the harvester. Shabara et al. modified the diagram of energy flow [102]. ...
... To enhance the comprehensibility of the energy flow associated with PEEHs, this paper divides the energy flow into four steps. [42,[99][100][101][102][103]. Reprinted with permission from [103]. ...
... Step III is mechanical-electrical energy conversion processing. Once the piezoelectric material is deformed, a surface charge with electrical potential (voltage) is generated in Figure 8. Energy flow chart of piezoelectric footwear energy harvesters [42,[99][100][101][102][103]. Reprinted with permission from [103]. ...
Over the last couple of decades, numerous piezoelectric footwear energy harvesters (PFEHs) have been reported in the literature. This paper reviews the principles, methods, and applications of PFEH technologies. First, the popular piezoelectric materials used and their properties for PEEHs are summarized. Then, the force interaction with the ground and dynamic energy distribution on the footprint as well as accelerations are analyzed and summarized to provide the baseline, constraints, potential, and limitations for PFEH design. Furthermore, the energy flow from human walking to the usable energy by the PFEHs and the methods to improve the energy conversion efficiency are presented. The energy flow is divided into four processing steps: (i) how to capture mechanical energy into a deformed footwear, (ii) how to transfer the elastic energy from a deformed shoes into piezoelectric material, (iii) how to convert elastic deformation energy of piezoelectric materials to electrical energy in the piezoelectric structure, and (iv) how to deliver the generated electric energy in piezoelectric structure to external resistive loads or electrical circuits. Moreover, the major PFEH structures and working mechanisms on how the PFEHs capture mechanical energy and convert to electrical energy from human walking are summarized. Those piezoelectric structures for capturing mechanical energy from human walking are also reviewed and classified into four categories: flat plate, curved, cantilever, and flextensional structures. The fundamentals of piezoelectric energy harvesters, the configurations and mechanisms of the PFEHs, as well as the generated power, etc., are discussed and compared. The advantages and disadvantages of typical PFEHs are addressed. The power outputs of PFEHs vary in ranging from nanowatts to tens of milliwatts. Finally, applications and future perspectives are summarized and discussed.
... In Army, uninterruptedly powering up a soldier's wearable electronic gadgets such as communication devices used in military operations and also be used to tracking the soldier's location in remote areas. In Nature, to generate energy without damaging the environment and generate power as a renewable energy like solar energy, wind energy etc. Cho et al. (2016), Uchino & Ishii (2010) The functioning methodology of a Piezoelectric Transducer is based on the principle that when a pressure is applied on a piezoelectric crystal as a mechanical force, a voltage is produced across its faces due to the movement of electron atoms on the crystal disc is shown in the Figure 1. Thus, mechanical phenomena was converted into electrical energy as an AC output. ...
The aim of this paper is to built a smart shoe which is equipped with power generating capability while wearing this footwear during walking and running. Because, low power consumption electronic devices have been increased rapidly in our day to day life. So, We try to develop a Piezoelectric transducer based power generation through footwear. That can produce pressure during walking or running and it convert mechanical energy into electrical energy to charge the electronic devices. Bridge rectifier was used to convert the AC voltage output from the piezoelectric transducers into DC voltage. Then it will be boost up by the dc-dc Boost converter to charge the electronic devices through Li-ion battery by using a switch. Here, a round piezoelectric disc with diameter of 3.5cm was used. Finally, the produced mean output voltage of standard 12V to charge the electronic devices such as mobile, smartwatch etc., It was a renewable source of energy and it was also a green energy.
... For conversion of mechanical energy into electrical signal, of all the choices available like Electromagnetic, electrostatic, and piezoelectric, piezoelectricity is more attractive for applications that require higher values of energy density, voltage and capacitance with little mechanical damping [35,36]. PEH systems comprises of three phases (a) mechanicalmechanical energy conversion phase that involves high stresses and impedance, (b) mechanical to electrical energy conversion phase which includes piezoelectric coupling factor and piezoelectric coefficients, and (c) electrical-electrical energy conversion that is associated with electrical impedance matching (Fig. 4) [37]. Fig. 4 Phases of piezoelectric energy harvesting technologies [37]. ...
... PEH systems comprises of three phases (a) mechanicalmechanical energy conversion phase that involves high stresses and impedance, (b) mechanical to electrical energy conversion phase which includes piezoelectric coupling factor and piezoelectric coefficients, and (c) electrical-electrical energy conversion that is associated with electrical impedance matching (Fig. 4) [37]. Fig. 4 Phases of piezoelectric energy harvesting technologies [37]. ...
The book reviews our current knowledge of piezoelectric materials, including their history, developments, properties, process design, and technical applications in such areas as sensors, actuators, power sources, motors, environmental and biomedical domains. Piezoelectric materials will play a crucial role in the development of sustainable energy systems.
... As a result, the effectiveness of an energy harvester is dependent on both the piezoelectric transducers and its integration with the electrical circuit. In general, the piezoelectric energy harvesting system works towards the following three phases of energy conversion: [257,258] • Mechanical energy to mechanical energy: Linked with the compliance of mechanical impedance of piezoelectric energy harvester and its mechanical strength under high stresses. • Mechanical energy into electrical energy: Correlated with the electromechanical coupling factor and its coefficients of the piezoelectric energy harvester. ...
... Piezoelectric energy harvesting (PEH) devices have gained popularity due to their simple design, high conversion efficiency, and ability to be incorporated into more complicated systems (Beeby et al. 2006). The PEH system is primarily associated with three vital phases: (a) mechanical-mechanical energy conversion incorporating mechanical stability of the PEH under extreme stresses and mechanical impedance matching, (b) mechanical-electrical energy transformation encompassing electromechanical coupling factor of the PEH structure and piezoelectric coefficients, and (c) electrical-electrical energy transfer involving electrical impedance matching (Uchino and Ishii 2010). There are around 200 piezoelectric materials available for energy harvesting applications (Priya et al. 2017), with piezoceramics attracting the most interest owing to its high piezoelectric capabilities when comparing to certain other piezoelectric materials. ...
Polymeric piezoelectric composites for energy harvesting applications are an important study subject because they offer mechanical versatility, adequate voltage with adequate output power, cheaper cost of manufacturing, and faster processing than ceramic-based composites. Several kinds of piezoelectric polymers and its composites are intensively discussed and explored as a viable alternative to lead-based piezo-ceramics in energy harvesting applications. The chapter focuses on the core theory and concepts of piezoelectric energy harvesting (PEH) devices, following the materials employed in the various devices. The many structural configurations involved in the production of PEH devices are described. This chapter also includes existing circumstances for PEH devices, main issues related with them, and the future outlook for such devices.
... In general, the piezoelectric energy harvesting process can be accomplished in three phases, as shown in Figure 2. 8,9 First, the mechanical energy input phase contains the piezoelectric energy harvester's mechanical strength under extreme stress and mechanical impedance matching. Second, the mechanical and the electrical energy conversion phase includes the piezoelectric coefficients and the electromechanical coupling factor. ...
Over the years, energy harvesting technologies have been used in various self-powered systems. These technologies have several methods of application depending on their usage. Renewable energy is one of the types of energy harvesting technologies where energy is generated from naturally replenished sources. One of the energy harvesting methods that is commonly used is piezoelectric transducers. Piezoelectric materials are groups of elements that can be used to generate electricity when mechanical energy is applied. When external mechanical stress is applied, the inner lattice is deformed, resulting in the separation of the positive and negative centers of the molecule and thus the generation of a small dipole. Therefore, this paper aims to discuss the output of the piezoelectric transducer by reviewing it depending on two different material types and in other energy harvesting structures. Furthermore, a comparison was made in order to compare the power output of the two materials. Similarly, the most used piezoelectric transducer structures for power harvesting applications were revised. In addition, the parameters that affect the value of the generated power output were discussed using the figures of merit (FOM) concept. Moreover, the according to the FOM concepts, when stress is applied, the electrical energy extracted from a piezoelectric energy harvesting material is determined by the change in stored electrical energy within a piezoelectric material. The figures of merit (FOM) depend on the piezoelectric strain and its permittivity. The piezoelectric strain directly relates to FOM, while the permittivity has an inverse relationship with FOM. Thus, the highest strain constant and low permittivity material will provide the highest energy output. Additionally, lead-based (PZT) material has a strain coefficient d33 equal to 390 Coul/Nx10-12, and permittivity value ranging from 1000 to 3500 and can generate power output that is equal to 52mW at 100Hz, which is higher than the output of the lead-free-based material Barium Titanate (BaTiO3). The output of piezoelectric also depends on the piezoelectric transducer’s structure. The circular diaphragm’s power output is greater than the bimorph cantilever’s power output due to the presence of a proof mass in the center of the diaphragm that provides prestress to the piezoelectric which improves the low-frequency performance of the energy harvester.
... Hence, a PEH's performance depends on both the transducer as well as the circuit. The PEH's, in general, consist of three phases, mechanical to mechanical energy conversion, mechanical to electrical conversion, and electrical to electrical energy conversion [30,71]. Various piezoelectric materials can be used in PEH's. ...
In the last three decades, smart materials have become popular. The piezoelectric materials have shown key characteristics for engineering applications, such as in sensors and actuators for industrial use. Because of their excellent mechanical-to-electrical and vice versa energy conversion properties, piezoelectric materials with high piezoelectric charge and voltage coefficient have been tested in renewable energy applications. The fundamental component of the energy harvester is the piezoelectric material, which, when subjected to mechanical vibrations or applied stress, induces the displaced ions in the material and results in a net electric charge due to the dipole moment of the unit cell. This phenomenon builds an electric potential across the material. In this review article, a detailed study focused on the piezoelectric energy harvesters (PEH's) is reported. In addition, the fundamental idea about piezoelectric materials, along with their modeling for various applications, are detailed systematically. Then a summary of previous studies based on PEH's other applications is listed, considering the technical aspects and methodologies. A discussion has been provided as a critical review of current challenges in this field. As a result, this review can provide a guideline for the scholars who want to use PEH's for their research.
... According to the literature, [64] there are three major steps associated with piezoelectric energy harvesting in an electromechanical system: ...
Wearable devices can be used for monitoring vital physical and physiological signs remotely, as well as for interacting with computers. Widespread adoption of wearables is somewhat hindered by the duration time they can be used without re‐recharging. To ensure uninterrupted operation, these devices need a constant and battery‐less energy supply. Scavenging energy from the wearable's surroundings is, therefore, an essential step towards achieving genuinely autonomous and self‐powered devices. While energy harvesting technologies may not completely eliminate the battery storage unit, they can ensure a maximum duration of use. Piezoelectric energy harvesting is a promising and efficient technique to generate electricity for powering wearable devices in response to body movements. Consequently, we systematically survey the range of technologies used for scavenging energy from the human body, with a particular focus on the upper‐limb area. According to our review and in comparison to other upper limb locations, highest power densities can be achieved from piezoelectric transducers located on the wrist. For short and fast battery charging needs, we therefore review the range of materials, architectures and devices used to scavenge energy from these upper‐limb areas. We provide comparisons as well as recommendations and possible future directions for harvesting energy using this promising technique.
... Moreover, the high-anisotropy piezoelectric elements are highly suited for medical diagnostic devices with ultrasonic antennae based on pulse-echo principles and controlling the preferred direction [49]. As is known from work [50] on harvesting energy from mechanical vibrations using the piezoelectric transducers, the key to dramatic enhancement of the effectiveness of this conversion of energy is to use a high k mode, e.g. k 33 and k t . ...
A novel lead-free 1-3-type composite based on a ferroelectric domain-engineered single crystal is put forward. In the porous polymer matrix of this composite, two different porous structures are observed, and the effect of these structures on the piezoelectric performance, electromechanical coupling and related anisotropy parameters of 1-3-type composites is first studied. New diagrams that link the volume fractions of the single-crystal component and the porous regions in the polymer medium are built to show validity of conditions for a large anisotropy of piezoelectric coefficients d3j∗ and electromechanical coupling factors k3j∗, kt∗ and kp∗. In the composites based on the complex alkali niobate alkali tantalate single crystal with small piezoelectric anisotropy (d331)/|d311)| = 2.1), the three anisotropy factors d33∗/|d31∗| ≥ 5, k33∗/|k31∗| ≥ 5 and kt∗/|kp∗| ≥ 5 hold simultaneously due to the presence of layers with heavily prolate and heavily oblate air pores in the porous polymer matrix. The two porosity levels influence the elastic anisotropy of the porous matrix, and this leads to an increase in the three anisotropy factors across wide volume-fraction ranges. Of independent interest is the high piezoelectric sensitivity of the composites for which the condition g33∗ ≥1 V m N-1 holds at their piezoelectric coefficient d33∗ ≈ (200-500) pC N-1 and electromechanical coupling factors k33∗ ≈ kt∗ ≈ 0.8-0.9. The studied parameters of the novel piezo-active 1-3-type composites are of value for various applications such as active elements of piezoelectric transducers, energy-harvesting devices and sensors.
