Type Piezoelectric Energy Harvester Research Articles

Experimental study on the piezo-based energy harvester utilizing the ambient vibrations for smart applications

The proposed energy harvester has novel construction, its performance evaluated through frequency response, force response and power harvested under an optimum load, is presented. This harvester is more suitable for low power applications like IoT devices, Wireless sensor nodes and biomedical implants. The suggested harvester has two sections namely truncated cone and rectangular beam section (TCRB). The analytical model is formulated and natural frequencies are obtained using FEA tool. Simulations for natural frequencies and associated comprehensive parameters are done along with distribution of stress across the piezo patch. The tapered radius ratio of the truncated cone is analysed to obtain the optimal value. The simulated model is fabricated and verified experimentally. The result is compared with uniform cantilever beam harvester. The voltage produced by a TCRB harvester is 56.76 % higher than the harvester with a homogeneous rectangular cantilever beam. The rectangular harvester has a resonant frequency of 52.8 Hz, while the TCRB harvester has 39.4 Hz. Also, the TCRB type piezoelectric vibration energy harvester with optimum taper radius ratio provides greater power, than uniform and trapezoidal cantilever beams. The obtained experimental results match the simulation results, ascertains the validity of the proposed harvester.

An inclined pedal type piezoelectric energy harvester for pedestrian flow and vehicle safety monitoring

This paper proposed an inclined pedal-type piezoelectric energy harvester for pedestrian monitoring and vehicle safety monitoring (IPEH). The IPEH exterior adopts an inclined pedal design, the steel ball is placed inside its cylindrical channel to excite the piezoelectric patches to harvest and convert external mechanical energy. IPEH can be placed under the brake pedal of a car for the function of vehicle safety monitoring. IPEH can also be fixed on the road as an energy harvester and monitoring device, harvesting pedestrian trampling energy and monitoring the density of pedestrian traffic in realtime. The influence of the steel ball diameter and spring layout on the output performance of the prototype is studied in this paper. Under the best parameters of the prototype assembly, the maximum output voltage is 165.6 Vpp, and the maximum output power is 463.7 mW. In the application experiment, the practicability in energy harvesting applications of IPEH is verified through the experiment of lighting LEDs and charging capacity, and the monitoring ability of IPEH was verified by simulating the experiment of different human flow walking and vehicle braking. It provides a new idea for the subsequent application of piezoelectric equipment in traffic auxiliary facilities and intelligent sensing equipment.

Accurate finite element modeling of multilayered flexible piezoelectric energy harvesting devices with strong coupling of structure, piezoelectricity, and circuit

Multilayered flexible piezoelectric energy harvesting devices (FPEDs) are a new future harvesting technology which are highly flexible and lightweight than familiar cantilever piezoelectric energy harvesters. This mechanical vibration driven FPED is a strongly coupled multiphysics phenomena that involve complex natural three-way interaction among the composite piezoelectric structure, the electric charge accumulated in the piezoelectric material, and a controlling electrical circuit attached to it. Efficient and accurate computational solution approaches are essential for analyzing these mechanical vibration-driven FPEDs to capture the main physical aspect of the coupled phenomena and to accurately predict the output voltage. While there are some numerical models for simple familiar cantilever type piezoelectric energy harvester reported in the literature, a fully three-dimensional strongly coupled model for complex material distributed, complex geometry, and multilayered FPED involving strong coupling of structure, piezoelectricity, and circuit phenomena has not yet been developed. A partitioned iterative algorithm is developed using a hierarchical decomposition approach wherein the coupled three fields are solved separately and coupled through loop union integration techniques that provide an efficient and accurate simulation of FPEDs. The simulation results matched the experiment results very well. This study provides a basis for the natural extension of partitioned iterative finite element coupled algorithm to simulate the future piezoelectric energy harvesting technologies involving a strong coupling of structure, piezoelectricity, and circuit phenomenon.

Effect of simultaneous use of two different piezoelectric materials on the performance of cavity based segmented doubly clamped piezoelectric energy harvester

From the past several decades, energy harvesting using piezoelectric materials has emerged as a potential technique in scavenging electrical energy from environmental low frequency vibrations. In this direction, a cantilever type piezoelectric energy harvester is observed to be the most appropriate structure that constitutes a substrate layer over which one or two layers of same piezoelectric material and a proof mass are embedded. In this paper, the performance of cavity based segmented doubly clamped piezoelectric energy harvester (C-SDC-PEH) has been analyzed for simultaneous use of two piezoelectric materials (PMN-35 wt% PT and PZT-5H) using COMSOL Multiphysics software. Here, the C-SDC-PEH device encompasses the advantages of doubly clamped boundary conditions, cavity inclusion, electrodes and piezoelectric layers segmentation. Also, from observations PMN-35 wt% PT - PZT-5H - PMN-35 wt% PT placing format is found to be most appropriate combination of piezoelectric materials corresponding to which improved values of output voltage (251.2 V), mechanical power (235.7 mW) and electrical power (201.2 m W) have been attained at low (71 Hz) resonant frequency.

Research on nonlinear isometric L-shaped cantilever beam type piezoelectric wind energy harvester based on magnetic coupling.

Harvesting wind energy using piezoelectric materials is expected to be an alternative solution for powering wireless sensing networks. This paper proposed a nonlinear isometric L-shaped cantilever beam type piezoelectric wind energy harvester based on magnetic coupling (L-PWEH). The transducer consists of an array of equidistant L-shaped piezoelectric vibrators that are sealed inside the shell. It greatly improves the equivalent piezoelectric coefficient, robustness, and wind speed range for reliable operation. Theoretical and simulation analyses of the structural parameters related to the widening of the L-PWEH were performed. The prototype was built and the experimental system was constructed to verify the feasibility of the L-PWEH and the results of the analyses. Experiments have shown that increasing the magnetic force, additional springs, and the appropriate quantity of excitation magnets can effectively increase the output voltage and widen the wind speed range at high voltage output. When the wind speed is 16.35m/s and the load resistance is 2 MΩ, the best output power of the piezoelectric vibrator is 142.3 µW. At this time, the height of the middle excitation magnet of the prototype is 12mm, the number is 5, and the wire diameter of the additional spring is 1mm. The prototype can successfully make the electronics work properly.

Performance of a Lever‐Gear Type Piezoelectric Energy Harvester for Collecting Pedestrian Energy

As pedestrian‐induced energy exists widely in our daily life, the collection of pedestrian energy has attracted increasing attention. Herein, a novel energy harvester is developed to capture the kinetic energy of pedestrians. The mechanical part of the energy harvester mainly consists of a lever structure and a gear transmission component, which is used to convert the kinetic energy of pedestrians into that associated with the rotation of the device. Energy is collected by a polyvinylidene fluoride (PVDF) piezoelectric film. The performance of the harvester is tested under both indoor and outdoor conditions. Experimental results show that the maximum output voltage of the harvester with a single PVDF film is 1170 mV, and the harvester reaches the best output state when the load is 510 kΩ (acceleration 0.3 g (1 g = 9.8 m s−2), frequency 5 Hz) with the maximum output power equal to 1.41 μW. The harvester is then optimized by adding more PVDF films, and the improved device is found to possess a higher working efficiency, with the output voltage and power increased by 58.6% and 26%, respectively. Finally, outdoor tests are conducted, and the results further confirm the feasibility of using the device to harvest the ultralow frequency kinetic energy of pedestrians.

Exact solutions for bimorph cross-ply and antisymmetric angle-ply plate piezoelectric energy harvesters

This paper presents the exact solutions for the plate type piezoelectric bimorph energy harvesters composed of laminated cross-ply or angle-ply substrate plate. Both series and parallel connections of the piezoelectric layers of the bimorphs are considered for deriving the exact solutions. Since the exact solutions for the layers of the laminated substrate plate are available in the open literature exact solutions for the piezoelectric layers are only derived here for finding the exact solutions of the harvesters. The piezoelectric layers should be orthotropic or generally orthotropic for deriving the exact solutions. Three sets of exact solutions for the piezoelectric layers are required to be derived. The electric potential induced by the bimorph in which the piezoelectric layers are connected in series is significantly larger than that in case of the bimorph with piezoelectric layers connected in parallel. The effects of the variations of the off-axis angle in the generally orthotropic piezoelectric layer, the length over width ratio of the harvester and the thickness of the piezoelectric layers on the induced electric potential have been studied. The expressions for the exact solutions can be used in a straight forward manner for verifying the experimental and the numerical results.

Design, Simulation & Optimization of a MEMS Based Piezoelectric Energy Harvester

Energy harvesting is defined as a process of acquiring energy surrounding a system and converting it into electrical energy for usage. Piezoelectric energy harvesting is a very important concept in energy harvesting in microelectronics. In this report, an analysis of the cantilever type piezoelectric energy harvester is conducted using the finite element method (FEM) based software COMSOL Multiphysics. A unimorph type cantilever beam of the silicon substrate, structural steel as proof mass and support, and PZT-5A material as piezoelectric constitute the physical system.

Piezoelectric vibration energy harvester with tapered substrate thickness for uniform stress

This paper presents modification in the thickness profile of bimorph cantilever type piezoelectric vibration energy harvester (PVEH) to achieve uniform stress along the beam length. The thickness profile is obtained by varying the thickness of substrate layer and keeping the thickness of piezoelectric layers constant. Analytical expressions for the cantilever beam displacement, stress on the beam and generated voltage are derived and solved for sinusoidal input excitations. The results from the analytical expressions are validated with that of the finite element (FE) analysis of an identical PVEH. The generated power and stress distribution in the proposed PVEH are compared with that of an equivalent conventional PVEH of uniform thickness. Compared to the conventional PVEH, in the proposed PVEH the generated power is 20% higher for an input acceleration of 0.2g, and the stress on the proposed device is found to be uniformly distributed with the peak stress value reduced significantly by 46%.

Fabrication process for very-low frequency operation of guided two-beam piezoelectric energy harvester

MEMS-based piezoelectric vibration energy harvesters found suitable to power wireless sensor nodes, typically in a remote area of operation. In MEMS technology, piezoelectric type vibration energy harvesters are realized using fixed-fixed or fixed-free cantilever structures. These structures are spring mass damper systems that have a fixed resonance frequency which is to be matched with ambient vibration frequency. The low resonance frequency of the cantilever gives better output with the low-frequency mechanical vibrations. Parameters such as width, length and thickness must be critically controlled to achieve low-frequency response during device fabrication. This paper presents the optimized fabrication process for guided two-beam type piezoelectric vibration energy harvester device. The device thickness is critically controlled using tetramethylammonium hydroxide zig during wet bulk micromachining followed by beam thinning process using deep reactive ion etching on the back side of the silicon wafer. A highly c-axis oriented zinc oxide layer of 2.5 µm thickness is sandwiched between aluminum electrodes on the front side of the silicon wafer for harvesting electric potential. The laser Doppler vibrometer test gives the resonance frequency of the fabricated device around 466 Hz which is lowest reported so far for the guided two-beam device. The resonance frequency of the device reported has been reduced by 32.85% than the earlier reported guided two-beam device. The device when vibration shaker tested was found to be operational in the very low-frequency range up to 10 Hz giving a sensitivity of 1.648 mV/m/s2 near resonance frequency.

Effect of seismic mass thickness on the resonance frequency of cantilever type piezoelectric energy harvester

Piezoelectric energy harvesters find applicability in remote area of application because of simple design and operation. Micro-electromechanical system (MEMS) process technology is utilized to fabricate these cantilever based structures. Piezoelectric layer length and thickness are the key parameters for controlling the resonance frequency. However, for further lowering the resonance frequency and having optimal output a seismic mass is introduced at the tip of the cantilever structure. In this paper, the effect of increasing the thickness of the seismic mass on the resonance frequency of the cantilever structure has been investigated. Finite Element Method (FEM) results have been obtained using Coventorware software by varying the thickness of the seismic mass 10–20 µm. It has been observed the variation of the thickness of the seismic mass has an effect on the resonance frequency of the cantilever. As the thickness increases, the volume of the seismic mass increases and the resonance frequency of the cantilever decreases. The base of the cantilever is Silicon; Aluminum Nitride (AlN) piezoelectric material has been selected of 3 µm thickness. The length of the silicon cantilever is varied from 1600 to 2500 µm and the resonance frequency is obtained. At a length of 1600 µm, variation of seismic mass thickness from 10 to 15 µm results in reduction in resonance frequency by 17.27% whereas when seismic mass is varied from 15 to 20 µm the resonance frequency is reduced by 12.63%.

Piezoelectric layer length and thickness variation effects on displacement, von-Mises stress and electric potential generated by cantilever type piezoelectric energy harvester

Piezoelectric energy harvesters find applicability in remote area of application because of simple design and operation. Piezoelectric layer length and thickness are the key parameters for controlling the resonance frequency and optimal output. In this paper the effect of length and thickness of the piezoelectric layer on the von-Mises stress has been investigated. FEM results have been obtained for varying the length of piezoelectric layer from 50 to 200 µm for two different thicknesses of 2 and 5 µm. It has been observed the variation of the length of the piezoelectric layer has an effect on the von-Mises stress of the cantilever which affects the net potential generated. The base of the cantilever is Silicon; PZT piezoelectric material has been selected for the analysis. The length of the silicon cantilever has been fixed to 200 µm. The parameters for simulation are set as: Variation of Length of piezoelectric layer lpiezo as; 50, 75, 100, 125, 150, 175, and 200 µm. Variation of Thickness of the piezoelectric layer tpiezo as 2 and 5 µm. Thickness of beam Tcanti = 10 µm. Length of beam Lcanti = 200 µm. Displacement, von-Mises stress and electric potential has been obtained from FEM results for the piezoelectric layer length variation from 50 to 200 µm. The displacement of the cantilever increases from 0.0207 to 1.0462 µm, von-Mises stress of the cantilever increases from 6.6899 × 105 to 1.0728 × 108 N/m2 and the electric potential increases from 0.01 to 0.26 Volts when the length is increased from 50 to 200 µm. The results depicts that there is an effect of length and thickness of piezoelectric layer on the total displacement, net stress and electric potential generated by the cantilever.

Energy Harvesting from Piezoelectric Cantilever Beam with Different Shapes

This paper reviews the piezoelectric energy harvesting from mechanical vibration. The recent development in the microelectronic devices and wireless sensor networks (WSNs) requires continuous power source for better performance. Many researchers have been done to develop a permanent portable power source for microelectronic devices. Micro energy harvesting (MEH) consists of two basic elements; freely available energy and transducer. Energy is everywhere around us in different forms. The energy conversion ability of piezoelectric energy harvester is high among different MEH techniques. A cantilever type piezoelectric energy harvester under different shapes is mostly studied in the last few years. The output of piezoelectric harvester depends upon the deflection produced, more deflection led to more electrical output. The deflection in cantilever beam under different shapes is different. This review paper presents a comparison of different piezoelectric cantilever beam shapes and output generated analyzed in the last decade.

Effect of elastic modulus of cantilever beam on the performance of unimorph type piezoelectric energy harvester

Piezoelectric energy harvesting is a technique that can utilize ambient vibration energy to generate useful electrical energy, which is promising for powering small-scale autonomous devices such as sensors for wearable, biomedical, and industrial applications. Typically, cantilever-type piezoelectric energy harvesters (PEHs) are operated under resonance condition to achieve the maximum output power at low frequency stimuli. Along with resonance matching, it is also necessary to optimize the PEH configuration with high electromechanical properties for the efficient energy conversion. The purpose of this study is to investigate the effect of the elastic modulus of the passive layer in the cantilever structured PEH on the electromechanical properties and thus harvesting performance. In this regard, two unimorph type PEHs having the identical geometry, piezoelectric properties, and proof mass but with different elastic modulus (55 GPa and 97 GPa) of Ti alloy-based passive layers were fabricated and their output performance was compared under the same acceleration amplitude excitation stimuli. The PEH with the smaller elastic modulus passive layer exhibited almost 53% improvement in the maximum power than that with the higher elastic modulus passive layer, which is attributed to a smaller mechanical damping ratio, higher quality factor, and larger vibration amplitude.

Design of optimized cantilever form of a piezoelectric energy harvesting system for a wireless remote switch

A smart lighting system can be controlled using a smartphone and/or human activated wireless remote switches. We designed a wireless remote switch using a cantilever type piezoelectric energy harvester to make a battery-less IoT node device that has high output power but a small tip displacement through frequency up-conversion. The purpose of this design is to overcome the conventional volume problem of the piezoelectric cantilever beam. In order to apply the high resonance frequency to the model at constant displacement, we set the limiting conditions of maximum vertical displacement of the cantilever beam to be 1 mm and a human input pressing force of 5–8 N, the force generally required when a human presses a switch button. In these limiting conditions, different shapes of steel substrate were used to find the optimal harvester that meets the limiting conditions and generates about 65 μJ of energy at 5 kΩ resistive loads under free vibration. Using this harvester, we designed a wireless remote switch with an impact type mechanical mechanism with two cantilever type energy harvesters to generate 140 μJ of energy, requiring no impedance matching circuit. This energy was then used to power a microcontroller to transmit data packets using ZigBee Green Power communication. Three identical data packets were transmitted by the wireless remote control switch to ensure data reception by the smart LED bulb and to toggle the bulb on or off state. Finally, this study successfully contributed to elevating the possibility of commercialization of the piezoelectric harvester based wireless remote switch for IoT.

Sustainable yarn type-piezoelectric energy harvester as an eco-friendly, cost-effective battery-free breath sensor

A cost-effective layer-by-layer brush-coating technique was developed to fabricate a flexible yarn-based piezoelectric nanogenerator (FY-PNG) to harness abundant waste mechanical energy. A simple sol-gel method was used to synthesize the orthorhombic crystalline phase of bismuth titanate perovskite, i.e., Bi4Ti3O12 (BiTO). A single FY-PNG device generated a maximum peak-to-peak open-circuit voltage (VOC(P–P)), short-circuit current (ISC(P–P)), and instantaneous area power density of 60 V, 400 nA, and 18.5 mW/m2, respectively, upon application of a 1 N periodic mechanical load. The switching polarity of the FY-PNG demonstrated good phase shifting between the output signals and confirmed that the output derived from the device and not from any external sources. The working mechanism, electrical poling effect, force analysis, repeatability, stability, charging, energy storage analysis, and sensitivity to biomechanical force of the FY-PNG was thoroughly investigated. The FY-PNG device output was used to power five commercial green light-emitting diodes (LEDs) and a display system. Additionally, a non-invasive self-powered breathing sensor (SPBS) was developed to monitor human inhalation/exhalation. The repeatability and reproducibility of SPBS evaluated using different devices and test subjects demonstrated a good variation in output (i.e., 0.2–0.4 V) for inhalation/exhalation; the SPBS was also evaluated under slow/fast and constant breathing conditions. The proposed brush-coating technique for FY-PNGs is an efficient, cost-effective, eco-friendly, and easily scalable technique that can pave the way to the design of novel-shaped PNG devices for applications such as implantable self-powered biosensors and automotive electronic systems.

Micron scale energy harvesters using multiple piezoelectric polymer layers

This paper presents the design, fabrication, and experimental results of micron scale energy harvesters that utilize piezoelectric polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE). Proposed devices are free-standing thin film cantilevers with multiple PVDF-TrFE and electrode layers. During the design phase, optimal piezoelectric layer thickness for the chosen substrate was calculated as 7.4μm. In order to alleviate the potential fabrication problems, a multilayer approach was adopted instead of coating a single layer. Device dimensions were selected to yield resonance frequencies below 1kHz. Cantilever type piezoelectric energy harvesters with 3 parallel-connected PVDF-TrFE layers were created using standard microfabrication techniques. Energy harvesting performances of the fabricated devices were evaluated using an electrodynamic shaker and an accelerometer to create and observe input vibrations at different amplitudes and frequencies. Measurement results were compared with theoretical calculations and the effect of substrate clamping was discussed. The power output of a (1800μm×2000μm) prototype was measured as 0.1μW when driven with a peak input acceleration of 1.0g at its resonance frequency of 192.5Hz. Half power bandwidth of the same prototype was measured as 2.9Hz. Proposed energy harvesters have relatively low resonance frequencies for their sizes and have the potential to be easily integrated with other microfabricated devices.

A Comparative Research on Maximized Output Power Between Disc Type and Multilayered Type Piezoelectric Energy Harvesters

A Comparative Research on Maximized Output Power Between Disc Type and Multilayered Type Piezoelectric Energy Harvesters

Dynamic characterization of fabricated guided two beam and four beam cantilever type MEMS based piezoelectric energy harvester having pyramidal shape seismic mass

Piezoelectric energy harvesters are gaining importance due to simplicity in design, operation and ability to power microelectronic sensor nodes in remote areas. A cantilever based piezoelectric energy harvester acts as a spring mass damper system having a resonance frequency tuned with ambient vibrations of low frequency. Maximum potential is generated when the resonance frequency of the energy harvester matches with frequency of ambient vibration. The highlight of this paper is a pyramidal shape seismic mass which results in a higher generated potential as compared to the square shaped seismic mass. This pyramidal shape is realized using tetra methyl ammonium hydroxide CMOS compatible 25 wt% wet etching. Two beam and four beam structures are front released using deep reactive ion etching which are fixed from both ends and having pyramidal shape seismic mass at the center. This paper presents a comparison of guided four beam and two beam cantilever type piezoelectric energy harvester fabricated using MEMS technology using a laser doppler vibrometer (LDV). Experimentally using LDV the resonance frequency for the fabricated guided two beam cantilever structure resonance frequency is 1971.9 Hz and for the guided four beam cantilever structure is 2540.6 Hz. Bandwidth for two beam cantilever structure is 40.6 Hz whereas for four beam cantilever structure bandwidth comes as 101.9 Hz. The maximum displacement measured for two beam cantilever structure at resonance frequency is 49.67 nm and for four beam cantilever structure maximum displacement is 32.17 nm. FEM (Finite Element Method) analysis for the guided two beam and guided four beam device is also performed and parameters such as resonance frequency, displacement, electric potential and von Mises stress are also reported and compared in this paper. Further the resonance frequency calculated analytically and the results obtained from FEM simulator and experimental results are also compared and it is found that they are in close agreement with each other.

Optimization of energy harvesting based on the uniform deformation of piezoelectric ceramic

Since the piezoelectric properties were used for energy harvesting, almost all forms of energy harvester needs to be bonded with a mass block to achieve pre-stress. In this article, disc type piezoelectric energy harvester is chosen as the research object and the relationship between mass bonding area and power output is studied. It is found that if the bonding area is changed as curved, which is usually complanate in previous studies, the deformation of the circular piezoelectric ceramic is more uniform and the power output is enhanced. In order to test the change of the deformation, we spray several homocentric annular electrodes on the surface of a piece of bare piezoelectric ceramic and the output of each electrode is tested. Through this optimization method, the power output is enhanced to more than 11[Formula: see text]mW for a matching load about 24[Formula: see text]k[Formula: see text] and a tip mass of 30[Formula: see text]g at its resonant frequency of 139[Formula: see text]Hz.