Review Article Recent Advances in Energy …downloads.hindawi.com/archive/2014/410316.pdfReview...

Review ArticleRecent Advances in Energy Harvesting Technologies forStructural Health Monitoring Applications

Joseph Davidson and Changki Mo

School of Mechanical and Materials Engineering, Washington State University Tri-Cities, 2710 Crimson Way, Richland,WA 99354, USA

Correspondence should be addressed to Changki Mo; [email protected]

Received 23 September 2013; Revised 31 January 2014; Accepted 1 February 2014; Published 13 April 2014

Academic Editor: Hideki Hosoda

Copyright © 2014 J. Davidson and C. Mo. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

This paper reviews recent developments in energy harvesting technologies for structural health monitoring applications. Manyindustries have a great deal of interest in obtaining technology that can be used tomonitor the health ofmachinery and structures. Inparticular, the need for autonomous monitoring of structures has been ever-increasing in recent years. Autonomous SHM systemstypically include embedded sensors, data acquisition, wireless communication, and energy harvesting systems. Among all of thesecomponents, this paper focuses on the energy harvesting technologies. Since low-power sensors and wireless communicationsare used in newer SHM systems, a number of researchers have recently investigated techniques to extract energy from the localenvironment to power these stand-alone systems. Ambient energy sources include vibration, thermal gradients, solar, wind,pressure, etc. If the structure has a rich enough loading, then it may be possible to extract the needed power directly from thestructure itself. Harvesting energy using piezoelectric materials by converting applied stress to electricity is most common. Othermethods to harvest energy such as electromagnetic, magnetostrictive, or thermoelectric generator are also reviewed. Lastly, anenergy harvester with frequency tuning capability is demonstrated.

1. Introduction

Rapid advances in wireless technologies and low-powerelectronics have enabled the increased use of autonomoussystems for the monitoring of structural health. The useof wireless structural health monitoring (SHM) systemspresents several advantages, one of the most significant beingthat wireless systems can provide continuous monitoringwithout the associated installation costs of wiring, which,depending upon the size of the sensor network, can be pro-hibitive. Because many wireless sensor nodes are powered bytraditional batteries that must be replaced, recent researchhas focused on developing systems that can be powered byharvesting ambient energy, such as mechanical vibrations,solar, and wind, directly from their environments. Park etal. [1] reviewed developments in energy harvesting technolo-gies for SHM sensor systems prior to 2007. In addition todiscussing methods of energy harvesting, the system designconsiderations, sensor modalities, network strategies, and

dynamic power requirements of SHM sensor systems werealso considered.

This paper reviews developments from 2008 to 2013 in themethods of energy harvesting for the powering of wirelessSHM systems. This paper is not intended to provide anexhaustive literature survey, as the area of energy harvestingis very broad and most energy harvesting technologies havesome applicability for SHM. Rather, this paper serves asa concise introductory survey of recent energy harvest-ing research related to the SHM of machinery, civil, andaerospace applications. The focus of the paper is the methodof energy harvesting, thoughmany of the references reviewedalso discuss other design considerations like power man-agement, sensor network implementation, and so forth. Thespecific energy sources considered include ambient mechan-ical vibrations, wind and aeroelastic vibrations, rotationalkinetic energy, thermal energy, and solar energy. These aresome of the most frequently exploited energy sources, anda broad survey of their typical power densities has already

Hindawi Publishing CorporationSmart Materials ResearchVolume 2014, Article ID 410316, 14 pageshttp://dx.doi.org/10.1155/2014/410316

2 Smart Materials Research

Table 1: Comparison of energy harvesting methods [15].

Power density (𝜇W/cm3)1-year lifetime

Power density (𝜇W/cm3)10-year lifetime

Solar (outdoors) 15,000—direct sun150—cloudy day

15,000—direct sun150—cloudy day

Solar (indoors) 6—office desk 6—office deskVibrations 200 200Temperature gradient 15 @ 10∘C gradient 15 @ 10∘C gradientBatteries (nonrecharg. lithium) 45 3.5

been completed by Roundy [15].The results of this survey areshown in Table 1.

As much of the current research is focused on the fieldof nonlinear energy harvesting, recent advances in this areaare also reviewed. Lastly, to highlight some of the advantagesof tunable energy harvesters the authors present some of theirown experimental results for a piezoelectric cantilever energyharvester with frequency tuning capability designed for themonitoring of an industrial ventilation system.

2. Sources of Energy

2.1. Ambient Mechanical Vibrations. Mechanical vibration isa source of ambient energy commonly converted into usableelectrical energy. Typically, the electrical energy is generatedby using vibrations present in the environment or surround-ing system to apply strain energy to a piezoelectric material,which becomes electrically polarized when subjected tostrain, or to displace an electromagnetic coil. Piezoelectricmaterials form transducers that couple electrical energy andmechanical force. When a piezoelectric material is subjectedto a mechanical stress, an electrical charge is produced acrossthe material, and when a voltage is applied, a strain developsin the piezoelectric material.

The method and results of a study involving the develop-ment and demonstration of a wireless measurement systemfor use in the diagnosis of the state of a rotating machinerysystem were presented by Clark et al. [2]. Figure 1 shows thedriving motor with the energy harvesting devices attached.The energy harvesting devices are excited by the vibration ofthe motor itself. The complete system includes an integratedcircuit that acquires data from sensors, transmits that datawirelessly to a receiver, and manages the flow of energy intoand out of a battery which powers all of these operationsand is connected to the piezoelectric harvester. The resultsof a typical data acquisition and transmission test, whichmeasures the 3300𝜇F storage capacitor voltage versus time,show that initially the capacitor starts with almost no charge.In this particular test the capacitor voltage increases as energyis acquired from the harvester up to a steady-state level ofapproximately 6V. The sensor “sample and transmit” periodfor the test was approximately 10 minutes [2].

The powering of sensors for damage detection inmachin-ery is a common application of energy harvesting technology.Arms et al. [3] developed an energy harvesting wirelesssensor in order to track the load history of rotating helicopter

Figure 1: Photograph of motor test rig with the beam harvestersattached [2].

Figure 2: MicroStrain’s Energy Harvesting, wireless loads trackingpitch link installed on Bell M412 [3].

components thereby improving safety, reducing the cost offlight testing, and enhancing condition based maintenance.Piezoelectric materials bonded to the pitch link, which is acontrol rod responsible for controlling the rotors’ angle ofattack and sustains high dynamic loads, harvested sufficientstrain energy to successfully operate an integrated wirelesssensor node during flight. Figure 2 shows the energy harvest-ing wireless sensor node installed on the pitch link of a BellM412 helicopter.

Dumas et al. [16] also presented a smart wireless networkof piezoelectric patches for damage detection in airplane andhelicopter composite structures. Damage in the compositewas evaluated by using the strain energy harvested from thevibrating structure to generate guided ultrasonic waves thatare compared with stored reference signals. Finite element

Smart Materials Research 3

Pick-up coil

Base

Copper layer

MsM laminate

Copper layer

Figure 3: Prototype MsM energy harvesting Device [4].

simulations for wave propagation were completed and thencompared with experimental results. A vibrational energyharvesting system for a wireless sensor device designed toimprove the safety of operators using machinery to towtrailers was developed by Dondi et al. [17]. The harvester wasa PZT cantilever tuned to resonate at the 112Hz vibrationsof the agricultural baler used in the case study. For vibrationstrengths ranging from 0.5 to 1.0 g’s, the energy harvestercould generate 23𝜇W to 850 𝜇W of usable power.

Recognizing some of the limitations of piezoelectricmaterials, like aging, depolarization, charge leakage, andbrittleness, some researchers have developed vibration energyharvesters using magnetostrictive materials (MsM). MsMenergy harvesters rely on the Villari effect whereby vibration-induced strain of the material produces a change in itsmagnetization. As shown in Figure 3, Wang and Yuan [4]have developed a novel MsM energy harvester consisting ofMetglas 2605SC bonded to a copper substrate wound by apick-up coil. Under the dynamic loading of the vibration thechange in magnetization of the MsM laminate is convertedinto electrical energy by the pickup coil according to Faraday’sLaw. An electromechanicalmodel is derived usingHamilton’sprinciple and Euler-Bernoulli beam theory, and a completeenergy harvesting circuit consisting of a voltage quadrupler,ultracapacitor, and smart regulator is designed. Experimentalresults with a prototype showed that for a resonance fre-quency of 1.1 kHz the average power density during chargingof the ultracapacitor was 606𝜇W/cm3, which is comparableto the power density of piezoelectric energy harvesters. Uenoand Yamada [18] also propose an MsM energy harvestingdevice using iron-gallium alloy (Galfenol), which has ahigh robustness and low electrical impedance compared topiezoelectric materials, capable of producing 10mW/cm3.Their harvester is configured as a cantilever beam with twoparallel beams of Galfenol connected to iron yokes by epoxyresin. Zucca and Bottauscio [19] present a comprehensivehysteretic model of an MsM harvester and study the timebehavior of themagnetostrictive harvester with finite elementmodeling. The tested harvester consists of a 60mm tallTerfenol-D rod with a 6mm radius surrounded by a coil.

For input frequencies of 100–300Hz the power generatedacross a resistive load varied up to 10mW. Another possibleuse of MsM materials in addition to energy harvestingis for vibrational damping. Davino et al. [20] consider aTerfenol-D rod as a vibrational damper/energy harvester andexperimentally investigate the dependence of the mechanicaldamping on several parameters, including magnetic bias andresistive load. It was determined that an appliedmagnetic biasincreases the harvested power and mechanical damping.

A detailed analysis combining some of the fundamentalcivil engineering problems with the problem of energyharvesting with piezoelectric materials has recently beencompleted by Erturk [21]. The first problem considered isthe moving load problem, for which two methods of energyharvesting are presented—a piezoelectric cantilever and apiezoceramic patch. The second problem considered is theuse of a piezoceramic patch to harvest energy from two-dimensional surface strain fluctuations of large objects. Ana-lytical derivations are presented for different input forces, anda case study of using a patch to harvest energy from surfacestrain on a steelmultigirder bridge is discussed.Wischke et al.[22] demonstrated that piezoelectric energy harvesters couldbe used to harvest energy from the vibrations of railway ties intunnels to power wireless sensor nodes. Because the analyzedtraffic patterns revealed a broad spectrum of vibration fre-quencies and amplitudes, they designed an energy harvesterwith a broad frequency response by implementing an arrayof four PZT cantilevers with different resonance frequenciesranging from 437 to 498Hz. The cantilever harvesters weresupported on both sides by solid state hinges to increaseshock tolerance and limit the risk of device failure. Testresults showed that the average energy harvested per passingtrain was 395 𝜇J, which was enough energy to transmit anRF signal at each train passage. Future work would focuson the integration of an energy storage management systemand microcontroller with the RF interface to develop a self-powered wireless sensor node.

Like traffic tunnels, bridges are structures prone to dam-age from repeated dynamic loading. Most bridges in the USAare subject to infrequent visual inspections and are an agingand deteriorating infrastructure that make excellent candi-dates for SHM applications. Energy harvesting technologiesare particularly well suited for bridge applications because itis very difficult to maintain batteries on sensors that must belocated on, under, or within the structure. Therefore, manyrecent studies have examined the feasibility of using the lowfrequency vibrations of concrete and cable-stayed bridges topower SHM sensors. Jung et al. [23] conducted a field teston an in-service cable-stayed bridge using an electromagneticenergy harvester.The prototype device produced amaximumof 15.46mW of power when attached to the bridge’s staycable. Kim et al. [24] later improved the performance ofthe prototype by replacing the electromagnetic inductioncomponents of the systemwith amovablemass and rotationalgenerator. The system could be tuned to the frequency of thestay cable by changing the location of the proof mass. Resultsof a field test demonstrated that the normalized power ofthe improved device was 35.67mW, which was a significantimprovement upon the output of the original prototype and


Bottom of

bridge girderPFIG Accelerometer

Figure 4: Photograph of the harvester attached underneath thebridge girder alongside a crossbow accelerometer [5].

is sufficient for sustaining a wireless sensor node for once-a-day and twice-a-daymeasurements under gentle tomoderatewind conditions. Another field test using an electromagneticenergy harvester was completed by Sazonov et al. [25]. Acritical step in the design of the harvester was to set thenatural frequency of the electromagnetic generator equal toone of the natural frequencies of the bridge. A maximumof 12.5mW of power was harvested from bridge vibrationsinduced by passing traffic.

To improve the energy harvesting performance frombridges that have low acceleration, low frequency, and nonpe-riodic vibration, a parametric frequency-increased generator(PFIG) was developed by Galchev et al. [5] as shown inFigure 4. In the PFIG a centrally located mass that moves inresponse to the vibrations is used to induce high frequencymechanical oscillations in an electromechanical transducer.Advantages of the system are that it efficiently convertsthe low-frequency bridge vibrations and can be used in anunpredictable environment due to its nonresonant operation.After developing an analyticalmodel, Galchev et al. fabricatedand tested the energy harvester on a linear shaker where itsoperation over a large acceleration and frequency range (upto 30Hz) was demonstrated.The harvester was also tested onthe main span of the NC Bridge in Vallejo, California. Theharvester produced 0.5–0.75𝜇W of average power withoutany tuning or modification.

In [26] Wardlaw et al. propose a self-powered wirelesssensor system for the structural healthmonitoring of highwaybridges.Their energy harvester uses magnetic shape memoryalloy (MSMA), which can covert mechanical work intoa magnetic induction change, to first convert the bridgevibrations into a magnetization change and then, with theassistance of a pickup coil, into an alternating current.Circuits were also proposed for important elements of thesystem and some of the most key components, includingrectification circuitry, were designed and fabricated. Peigneyand Siegert [27] use the short time pulses of highway bridgevibrations to develop a model that predicts harvested powerbased on traffic statistics. A piezoelectric cantilever bimorphconsisting of a tip mass and two Milde QP20W piezoelectricpatches bonded to the clamped end of a steel plate wasfabricated and tested. The device produced up to 30 𝜇W ofpower during peak traffic intensity and could potentiallybe used to power wireless sensor nodes with low duty

cycles. Xiang et al. [28] consider harvesting energy fromthe deformation of pavement under moving vehicles forthe powering of wireless health monitoring sensor nodesmounted on civil infrastructure. They propose embeddinga piezoelectric transducer operating in the 𝑑

31mode under

the pavement to convert bending energy to electrical energy.The pavement is described as an infinite Euler-Bernoullibeam resting on a Winkler foundation and an analyticalmodel is developed with the Fast Fourier transform methodand Cauchy’s residue theorem. Numerical simulations arepresented that examine the effect of vehicle velocity, level ofdamping, and foundation condition. Depending on systemparameters, the harvested power for a vehicle moving with avelocity of 30m/s was approximately 0.5W.

In addition to considering the vibrations of civil struc-tures like tunnels, bridges and roads, researchers are continu-ing to investigate the harvesting of energy fromvibrating fluidsystems. Cunefare et al. [29] explore harvesting energy frompressure fluctuations in hydraulic systems to power SHMsensors. Hydraulic pressure energy harvesters (HPEH) thatconvert pressure ripple, which is the peak-to-peak amplitudeof the dynamic pressure, present in hydraulic systems intoelectricity by utilizing a piezoelectric stack arrangement areintroduced. The high energy density of the hydraulic systemassociated with its pressure and flow enabled generation ofusable power even when the system operated off-resonanceof the piezoelectric stack. The initial HPEH prototype wastested on a hydraulic pump system that included a nonpistonpump operating at 1500 rpm and provided power outputs ofup to 1.2mW from a dynamic pressure ripple of 400 kPa.Li and Tse [30] present a design for an energy-harvestinghydraulic damper that simultaneously damps vibrations andharvests energy. Vibration acting on a hydraulic damperis converted into amplified rotation of a hydraulic motor,and an electromagnetic generator connected to the out-put of the motor provides harvested power. An analyticalmodel for predicting mechanical and electrical responseswas developed and a prototype device was fabricated andtested. The maximum harvested power was 435.1W for a0.8Hz frequency. System performance deteriorated for high-frequency, high-amplitude vibrations. Li et al. [6] considera similar problem and propose an innovative regenerativeshock absorber design that uses an electromagnetic energyharvester based on amechanicalmotion rectifier (MMR) thatconverts oscillatory vibration into unidirectional rotation ofthe electrical generator. A dynamic model of the mechanical-electrical system is developed with a circuit-based methodand both simulations and laboratory experiments are con-ducted. During a road test a prototype of the device thatwas mounted on the suspension of a Chevrolet Suburbantraveling at 15mph on a smooth paved road produced 15.4Wof power. A 3D model and picture of the prototype energyharvesting shock absorber with MMR are shown in Figure 5.

Over the past decade, technology used to harvestmechanical vibrations has started to transition beyond therealm of the research laboratory to commercial application.For instance, established in 2004, Perpetuum is a leadingcompany in energy harvesting technology and provides anelectromagnetic energy harvester for use with wireless sensor


Figure 5: 3Dmodel and actual prototype of the shock absorber withmechanical motion rectifier [6].

systems in industrial and rail applications. The harvesterconverts vibration to electrical energy via an oscillatingmagnet that transverses across a fixed coil. It was recentlyannounced that Perpetuum would supply wireless sensorsystems for all 148 of the Electrostar train stock ownedby Southeastern Railways [31]. The self-powered sensorswill collect vibration data from moving trains that will betransmitted wirelessly to a database where software will lookfor bearing and wheel wear. This will enable maintenanceengineers to create condition-based maintenance programsthat will improve reliability and safety and also reduce costs.

2.2. Wind and Aeroelastic Vibrations. The use of wind as analternative energy source for large-scale power production isa well-developed technology that continues to receive muchattention due to climate change. However, harvesting energyfrom wind to sustain low-power electronics for use in SHMapplications is a relatively recent development. Given thatmany bridges are located in windy areas, the harvestingof kinetic energy from wind has received much attentionas a potential power source for wireless sensors designedto monitor the health of these structures. Park et al. [32]investigated the feasibility of using small scale wind gener-ators, referred to as microwind turbines, to power wirelesssensors on a cable-stayed bridge. Wind tunnel tests wereconducted with three different rotors in order to determinethe turbine that delivered the peak power performance. Fora 7m/s wind speed the 13.8 cm diameter, six-blade turbinegenerated a maximum output of 438.79mW and maximumpower density of 2.93mW/cm2. Another experiment withthe 6-blade turbine, wireless sensor node, and chargingcircuit intended to verify the system’s actual power-chargingcapability demonstrated that the microwind turbine couldgenerate sufficient electricity for wind speeds greater than4mph. Xu et al. [33] develop an equivalent circuit model ofthe microwind turbine to predict the output power and netefficiency of the system. Experiments were then conducted

with a system comprised of commercially available off-the-shelf components and a 6.2 cm plastic blade. The maximumoutput power of the turbine reached 18mW at a wind speedof 4.5m/s.

As reviewed in Section 2.1, to date most work on theharvesting of energy frommechanical vibrations has focusedon the use of ambient vibrations present in the system orenvironment. More recently, some researchers [7, 34] havebegun to consider the harvesting of energy from vibrationsdue to induced aerodynamic instability phenomena such asgalloping, flutter, and vortex induced vibration.These energyharvesters may provide advantages compared to microwindturbines that pull kinetic energy from the wind becauseconventional, geared rotating airfoils can be too expensiveor inefficient for some locations. Also, miniaturization ofwind turbines reduces their overall efficiency because ofmechanical losses at the bearings. Jung et al. [34] completedwind tunnel tests of an electromagnetic energy harvesterdesigned to harvest energy from vibrations due to wakegalloping, which is an aerodynamic instability phenomenoncaused by the wake interference between two cylinders.When the cylinders begin to vibrate, which during tests beganat a wind speed of 0.5m/s, permanent magnets are movedthrough solenoid coils. Wind tunnel tests were completed forcylinders 85 cm long with a 5 cm diameter, and the averagepower generated was 0.3–1.13W for wind speeds rangingfrom 1.8 to 5.6m/s. Sirohi and Mahadik [7] present an ana-lytical model for a piezoelectric wind energy harvester designthat harvests energy from a prismatic body oscillating dueto aerodynamic galloping (Figure 6). Transverse galloping ofan elastic bluff body occurs when the wind speed across thebody exceeds a certain critical value that depends onmultipleparameters. The analytical model consists of two parts, astructural model developed with the energy method and anaerodynamic model. During wind tunnel tests, the prototypedevice generated a maximum output power of more than50mW at a wind speed of 11.6mph (Figure 7), which issufficient power to supply most of the commercially availablewireless sensors currently in use.

Abdelkefi et al. [35] extend the analysis of energy har-vesting from transverse galloping of a bluff body by studyingthe performance of a piezoelectric transducer attached tothe transverse degree of freedom of three different crosssections: a square, isosceles triangle, and D shape. Theeffects of load resistance and cross section geometry ontransverse displacement, voltage output, and harvested powerwere considered. Modeling results demonstrated that for lowand high wind speeds the isosceles triangle and D crosssections, respectively, were the best for harvesting power. Foradditional research by Abdelkefi et al. on piezoaeroelasticenergy harvesters the reader is referred to [36–39]. Wu et al.[8] use a cantilever beam to harvest energy from vibrationsinduced by vortex shedding, which is an oscillating flowwhere vortices are created periodically and then detach fromthe leeward side of slender beams. As fluid flows acrossit, the beam tends to move toward the low pressure zonescreated by the low pressure vortices and, as a result, thepressure variations from the vortex shedding create a cross-wind induced vibration.The beamWu et al. designed consists


Piezoelectric sheetsClamped end

Gallopingmotion

Incident wind

Figure 6: Galloping energy harvester with tip body having equilat-eral triangle cross section [7].

50

40

30

20

10

00 50 100 150 200 250 300

Load resistance (kΩ)

Out

put p

ower

(mW

)

PredictedMeasured

Figure 7: Correlation between measured and predicted outputpower for an incident wind speed of 10mph [7].

of two piezoelectric PZT4 patches bonded to Polysulfone(PES) and is shown in Figure 8. A comprehensive numericalmodel is developed to calculate the response of the harvesterand the total electric power generated, and simulations focuson the effects of piezoelectric patch locations and dimensions.The RMS for the generated power of a harvester with thedimensions 1.2×0.15×0.012mhaving a 12 kg proofmass andexposed to a variable wind velocity of 9-10m/s was 1.02W.

Kwon [40] proposed a T-shaped piezoelectric energyharvester designed to harvest energy from aeroelastic flutter,which for the tested device occurred at a wind velocityof 4m/s. Six PZT-5A PZT ceramics were bonded to bothsides of the harvester’s fixed base in a bimorph cantilever

Proof mass

H

Piezoelectric patches

Wind

Host beam of the harvester

M

L aL1

h

Figure 8: Piezoelectric harvester subjected to wind load [8].

configuration.At the onset of aeroelastic flutter themaximumpower produced by the device was 0.35mW and for a windvelocity of 15m/s, which was the maximum tested windvelocity, the power produced was 4mW.

2.3. Kinetic Energy of Rotation. Systems designed to harvestkinetic energy from flowing fluids, like the winds presentaround bridges, were reviewed in Section 2.2. Researchershave also recently developed energy harvesters for wirelessSHM sensors that are designed to directly convert the kineticenergy of rotating system components into usable electricalpower. For example, Wang et al. [41] present a design fora rotating energy harvester that is based on magnetostaticcoupling between a stationary circular-arc hard magnetarray and rotating magnetic solenoids. When installed ona wheel rotating at 60mph, the prototype device produceda maximum output voltage of 9.2 V and power density of4.5W/cm3 and was demonstrated to be a viable methodfor powering a real-time tire pressure monitoring system(TPMS).

For all rotatingmachines and structures, like turbines, forexample, real-time condition monitoring is highly desirablein order to achieve improved safety and equipment perfor-mance. Khameneifar et al. [9] investigated a vibration-basedenergy harvester for rotary motion health applications (e.g.,strain gauges and accelerometers).Thenovel design consistedof a piezoelectric cantilever with tipmassmounted on a rotat-ing hub (Figure 9). During rotation of the cantilever beamthe alternating gravitational force on the tip mass generatescontinuous oscillations. An analytical model developed withthe energy method is presented for predicting the maximumoutput power and optimal resistive load. Experimental testswere then conducted with two different energy harvesters,


x

y

z

Rotating cross hub

Tip massCantilever beam

Piezoelectriclayer

Figure 9: Schematic view of the energy harvester mounted on arotating hub [9].

Figure 10: Device shown mounted across two ties of a section ofrailroad track [10].

one using PZT and another utilizing PVDF film. For proofof concept demonstration only one cantilever beam wasinstalled on the hub during the experiment. After tuningthe hub’s angular velocity to match the harvester’s naturalfrequency, the load resistance was varied until maximumpower was achieved. The amplitude of the generated powerfrom the PZT transducer was approximately 44 times higherthan that of the PVDF transducer. The 6.4mW of powerobtained from the PZT harvester beam with a tip mass of105 g is enough for supplying a typical wireless sensor. Powerlevels generated by the PVDF harvester were only suitable forsustaining wireless sensors in the sleeping state. The authorsnoted that a limitation of the PZT transducer was that thebrittle material could fail if the hub was exposed to largevariations in torque and that the more flexible PVDF filmmight be preferred.

Nelson et al. [10] and Phillips et al. [42] examine har-vesting energy from passing railroad cars to power warninglights and track health monitoring systems. The prototypeenergy harvester converts the vertical displacement of therailroad track and ties due to the passing cars into rota-tional motion with a rack and pinion gear. The rotationalmotion is then converted by a small generator into electrical

Figure 11: Energy harvesters placed inside the blades of a windturbine [11].

energy (Figure 10). A computer simulation was developedfor determining the maximum power potential for differentprototypes with various railcar loads and speeds. Field testsvalidated the simulation results for the power production of asingle device (0.317W) for a loaded train traveling at 11.5mph.

Joyce [11] developed an electromagnetic energy harvesterconsisting of a magnet inside a tube surrounded by coilsdesigned to monitor the structural health of large windturbines. When mounted on the rotating turbine bladesthe changing orientation of the blade causes the magnet toslide along the tube thereby generating the voltage requiredto power the SHM system. A schematic of the harvestersmounted on the turbine blades is shown in Figure 11.Experimental results showed that a sample harvester couldproduce up to 14.1mW when attached to a blade spinning at19 RPM.

2.4. Thermal Energy. Another method of obtaining energyfrom ambient sources is by taking advantage of thermalgradients with thermoelectric generators (TEGs) operatingon the Seebeck effect, which describes the generation of anelectric current at the junction of dissimilarmetals at differenttemperatures. In order to construct a TEG numerous 𝑝-typeand 𝑛-type junctions are arranged electrically in series andthermally in parallel [1]. The TEG is a mature technologythat has been extensively studied over the past three decades.An advantage of a TEG compared to a vibration-basedenergy harvester is that it has nomoving parts. Disadvantagesare that TEGs are relatively inefficient when low thermalgradients are present and that until recently the dimensionsand weight of the devices were too large to integrate themwith MEMS technologies [1].

Because aircrafts flying at high altitudes are subject tolarge thermal gradients, the use of TEGs to power wirelessSHM sensors for aerospace applications is a field of interest.Pearson et al. [12] investigated using piezoelectric materialsand TEGs to harvest ambient vibration and thermal gra-dients, respectively, present on aircraft. Simulation resultsutilizing temperature data taken from thermocouples placedat various positions on an aircraft (Figure 12) yield peak


Table 2: Simulated power levels for temperature gradients on an aircraft [12].

Peak temperature differential, ∘C Peak power, mW Average power, mWCargo skin 40 34.15 22.58Cargo primary InsulationHydraulic pipeline 1 20 7.97 3.07Hydraulic pipeline 2Waste water tank 15 5.46 2.99Waste water ambientE-bay fuselage skin 35 18.72 6.42E-bay primary insulationCabin wall fuselage skin 30 13.36 3.97Cabin wall primary insulationCabin wall fuselage skin 40 30.06 11.70Cabin wall secondary insulation

Ventilation 2

Waste water

Cargo/bilge

CrownHydraulics

Ventilation1Cabin wall

E-bay

Figure 12: Locations of thermocouples used for the TEG poweroutput simulation [12].

power levels ranging from 5.46 to 34.15mW depending onthe location of the thermocouple as shown in Table 2 [12].

Becker et al. [43] also propose an autonomous sensorsystem for monitoring strain in advanced aircraft materials.Solar cells, vibrations generators, and thermoelectric gen-erators are considered for the energy harvesting method.In a laboratory test, a TEG was connected to a sensorplatform and power management and storage system. For athermal gradient of 70∘C the power generated by the TEGwas approximately 20mW, which was stated to be enoughto sustain autonomous operation of the sensor node andits related data communication protocols. Samson et al.[44, 45] improve upon the performance of their aircraftspecific thermoelectric generator module by adopting a newTEG prototype for their module and modifying the powermanagement system. The prototype TEG used, which wasa TG1-2000 from Marlow Industries, Inc., was based on aspecially doped semiconductor alloy and was designed forthe temperature range experienced by an aircraft duringtakeoff and landing from a short-range flight. Use of theprototype TEG increased the heat to electricity conversion byapproximately 14%, andmodifications to the capacitors in thepowermanagement system added another 36% improvementin power management. The authors completed numericalsimulations and laboratory experiments in preparation forvalidation on a future test flight.

Using proprietary technology Micropelt has developeda MPG D655 thermogenerator chip that has more than 100pairs of 𝑝-type and 𝑛-type thermoelectric legs per squaremillimeter [46].This enables the chip to provide a high powerdensity from temperature gradients with a stated open circuitvoltage output of 80mV/K. The typical dimensions of thecompact chip are 3340 × 2465 × 1090 𝜇m. The prototypedevice, which is still being optimized and is only available fortesting and evaluation, is proposed as potential power supplyfor wireless sensor network applications where waste heat isavailable.

2.5. Solar Energy. Wireless SHM sensor networks that har-vest solar energy use photovoltaic (PV) cells, or solar cells,that convert the sun’s energy into usable electricity. In brief,when sunlight strikes a PV cell photons are absorbed bysemiconducting materials like silicon. The energy from thephotons loosens free electrons that then flow as current dueto the presence of an electric field that has been created bythe separation of charge carriers in the cell. Placing contactson the top and bottom of the cell allows DC current tobe extracted. As shown in Table 1, solar energy harvestersexposed to direct sunlight provide the highest relative powerdensity of the energy harvesting methods considered. How-ever, a limitation of solar energy harvesting is that the sunwill not shine 24 hours a day. Also, PV cells are currentsources and do not supply a constant voltage. So, despite thehigh power density provided, systems using PV cells needan integrated energy storage device such as a rechargeablebattery.

Because of their high power density, solar energy har-vesting methods have received much consideration for out-door SHM applications, like roads and bridges. As solarpanels/energy harvesters are a relatively well-developed tech-nology, the research reviewed in this paper focuses on imple-mentation and validation of the complete network rather thanfurther recent enhancements of the harvesting method ordevelopments in photovoltaic technology. Hassan et al. [47]have developed and tested a novel solar energy harvestingevaluation kit for monitoring the propagation of cracks in


Figure 13: Solar poweredwirelessG-link seismic sensors onCorinthBridge, Greece [3].

concrete structures. The complete system included a solarpanel connected to two batteries and a power managementblock. Inamdar [48] also proposed several designs of a solarenergy harvester system developed to monitor the strainsof bridges. A PV array performance model was used todetermine the proper PV size, battery bank size, and panelorientation. A prototype solar energy harvester optimizedaccording to results from physical experiments and theanalytical model was then designed and fabricated.

Some complete solar-powered SHM systems are alreadycommercially available. For example, Arms et al. [3] havereviewed the installation of a commercially available solarpowered wireless G-Link seismic sensor developed byMicrostrain, Inc. The particular unit discussed is shown inFigure 13 and was installed on the Corinth Bridge in Greece.This particular system uses an array of wireless accelerometernodes attached to solar panels to continuously monitor thebridge span’s vibration levels. Should any node detect seismicactivity, the entire network is alerted and data is collectedsimultaneously from all of the nodes.

Miller and Spencer Jr. [49] propose a smart sensornetwork for civil structures developed by the NewmarkStructural Engineering Laboratory (NSEL) at the Univer-sity of Illinois at Urbana-Champaign. The complete systemuses the Imote2 smart sensor, custom-designed multimetricsensor boards, base stations, and software provided by theIllinois Structural Health Monitoring Project (ISHMP) Ser-vices Toolsuite.The smart sensor networkwas experimentallyvalidated during a test on the Jindo Bridge in South Korea.The test involved 70 total sensor nodes, eight of which wereequipped with solar energy harvesters. Five of the solarharvesting nodes were installed on cables, two were installedon top of pylons, and one was placed on the bridge deck.The objective of the test was to track the voltage of therechargeable batteries connected to the solar energy harvesterand the current and voltage from the solar panels. Evaluationof the test data is provided by Jang et al. [50]. Over thecourse of 40 days, seven of the eight solar energy sensor nodesmaintained battery voltage levels above 4.1 volts, which wasan indication that these energy harvesters provided sufficientlong-term power for sensor operation.The harvester that didnot provide sufficient power was mounted at the deck levelunder the box girder and relied on reflected sunlight for most

of its energy. Therefore, other energy harvesting methodsalready reviewed, like scavenging ambient bridge vibrations,may be more viable for sustaining sensor nodes in areas oflow direct sunlight.

2.6. Combination of Energy Harvesting Methods. In manyenvironments where multiple sources of ambient energy arepresent it may be possible to develop an energy harvestingstrategy that utilizes multiple transduction mechanisms. Forexample, a wireless SHM network on a vibrating highwaybridge in a windy location could rely on a combinationof piezoelectric cantilevers, microwind turbines, and solarpanel. Such an approach could provide redundancy in theevent that the operating conditions deteriorate for a certaintransduction method. For example, the resonant cantileverscould possibly sustain the system and compensate for theturbines on cloudy days when winds are nonexistent. Forthis reason, researchers have completed or are completingprojects where the combination of multiple methods ofenergy harvesting is explored. A four-year cross-disciplinaryproject supported by Mistras Group Inc., Virginia Tech, theUniversity of South Carolina, and the University of Miamito develop a self-powered wireless sensor node for steel andconcrete bridges has been reviewed by Godınez-Azcuagaet al. [51]. For the energy harvesting component of the projectthe research team is considering the integration of miniaturewind turbines and nonlinear vertical piezoelectric windmills.Theminiature wind turbines produced electrical power in therange of 100 to 700mW when the wind speed was between6 and 11mph, and the nonlinear piezoelectric windmill wasa possible alternative for lower wind speeds. A mat typeharvester containing piezoelectric patches and designed to beembedded in the pavement in order to harvest energy fromstrain fluctuations induced by pressure loading from passingtraffic was also under consideration.

Farinholt et al. [52] have reported on the use of a wirelesssensor system that relies on a hybrid approach combiningseveral transducer types to harvest energy from multiplesources. Piezoelectric bimorph cantilevers and TEGs wereconsidered for harvesting ambient vibrations and thermalgradients, respectively, from the Omega Bridge in LosAlamos, New Mexico. Vibration data was collected in orderto identify the fundamental frequencies of the bridge, anda PZT bimorph cantilever was fabricated and tuned so thatits fundamental frequency matched one of the fundamentalfrequencies observed in the vibration response of the bridge.Temperature differences between the concrete deck of thebridge and the ambient air were also recorded. During alaboratory experiment using an electromagnetic shaker andhot plate, the PZT harvester and TEG were coupled in orderto determine the time required to charge a capacitor to the3.5 V required to operate the selected sensor node. After 912 sof charging the node powered on and performed 100-pointmeasurements on three sensors used tomonitor bolt preload.This charging rate would provide an operating cycle sufficientfor applications where data would only need to be recordedseveral times a day. The use of wireless energy transmissionfrom an RF energy source to supplement energy harvestingapproaches was also considered.


3. Nonlinear Energy Harvesting

It is well documented that a limitation of vibration-basedenergy harvesters is their narrow operating bandwidth [53].Optimal performance is obtained when the harvester oper-ates at its fundamental resonance frequency, which typicallypeaks over a very narrow range. However, frequency match-ing between the harvester and ambient vibrations can bedifficult because of manufacturing tolerances, electric loadchanges, and excitation frequency changes as most sourcesdo not have constant frequency spectrums [54]. For thisreason, the energy harvesting community has transitionedits focus to the concepts of broadband energy harvesters,which will be discussed first, and tunable harvesters, both ofwhich can provide optimal performance over a larger range ofinput frequencies as compared to linear, resonant harvesters.Note that there have been numerous studies published inthe area of nonlinear energy harvesting over the past fiveyears, so the literature reviewed here is only meant to providean introduction to ongoing developments in the field. For arecent comparison of linear and nonlinear energy harvestersrefer to the recent work by Beeby et al. [55]. Their researchpresents analytical models of linear, bistable, and nonlinearenergy harvesters for the electromagnetic and piezoelectrictransduction mechanisms. Computer simulations of poweroutput are completed for the three types of energy harvestersusing vibration data taken from measurements of a dieselferry engine, heat and power pump, car engine, and whitenoise vibration. Results show the importance of simulationsand the use of real vibration data for selecting and optimizingenergy harvesters for a particular application.

A broadband energy harvester using a piezomagnetoe-lastic generator has recently been proposed by Erturk et al.[56]. The device consists of a ferromagnetic cantileveredbeam with two permanent magnets located symmetricallynear the free end. Depending on the spacing of the magnetsthe magnetoelastic structure can have multiple equilibriumpositions. Two layers of PZT-5A are attached to both facesat the beam’s root in order to create an energy harvester.Laboratory experiments are conducted to determine theresponse of the nonlinear, piezomagnetoelastic structure toharmonic base excitation. The magnets are then removed soas to compare the performance of the nonlinear harvesterwith a standard resonant harvester. Whereas the resonantharvester without magnetic buckling only provided a largervoltage output near its resonance frequency (7.4Hz), and theoutput of the nonlinear harvester was up to three times thatof the resonant harvester at frequencies below its resonancefrequency (10.6Hz). It was noted that the piezomagnetoelas-tic harvester provided a 200% increase in the open-circuitvoltage amplitude.

The use of magnets in the development of nonlinear har-vesters is a common theme. Lin et al. [57] have demonstratedhow the power output of piezoelectric cantilever beam can beenhanced by applying a simple repulsive force. Experimentalresults showed that the magnetically coupled cantileverresponded to vibration over a much broader frequencyrange than the standard beam and provided no reduction inperformance at the resonant frequency during application of

a symmetric magnetic force. A harvester configuration uti-lizing a cantilevered beam with a permanent tip magnet hasbeen modeled and studied by Wickenheiser and Garcia [58].Ferromagnetic structures, which remain stationary while thebase moves, are placed near the tip of the vibrating beamto create a sequence of wells of attraction. This rectificationapproach induces vibrations at the resonant frequency of thebeam regardless of the input frequency thereby increasingthe broadband behavior of the beam compared to the stan-dard cantilever harvester. During simulations the proposedmagnetic rectification approach is shown to harvest 400%of the power of the linear design. The theoretical analysisand analytical solutions for a nonlinear vibration energyharvester based on statically stable diamagnetic levitationhave been completed by Liu and Yuan [59]. The proposeddesign uses spiral coils made of diamagnetic materials toprovide nonlinear restoring forces. Potential advantage of theuntested device is that it has no mechanical energy loss dueto material friction and/or damping and that it can providea wide bandwidth response. Barton et al. [60] have pre-sented a broadband electromagnetic energy harvester wherethe nonlinearity is created by the arrangement of magnetsin conjunction with an iron-cored stator. An importantexperimental finding was that the advantages of the widebandwidth provided by their design were only present whenthere was an uninterrupted/nonrandom vibration source.This observation prompted Barton et al. to further investigateincorporating a restarting mechanism to overcome the sud-den drops associated with random source vibrations therebymaintaining the harvester in an optimal energy state.

Whereas broadband energy harvesting is a field receivingmuch attention, other researchers [54, 61] have focused ontuning the frequency of resonant harvesters to accommodatechanges to the excitation frequency. Two of the tuning meth-ods investigated are the application of axial loads and the useof magnets, both of which change the harvester’s transversestiffness. Al-Ashtari et al. [54] used magnets to design andtest an energy harvester with a tunable resonance frequency.Cottone et al. [61] modeled and tested a buckled beam underaxial compression that exhibited superior power generationcompared to the unbuckled beam. Rhimi and Lajnef [13] usethe Hamiltonian Principle to analytically estimate the poweroutput of a bimorph piezoelectric cantilever beam that ispreloaded with a variable axial stress applied by adjusting twometallic springs connecting the tip of the beam to the baseas shown in Figure 14. The derived model encompasses all ofthe theoretical vibration modes of the beam. Experimentalresults of the response of the bimorph energy harvester tovarying preload conditions validated the theoretical model(Figure 15). Using recorded vibration data of a bridge underambient loading, it was demonstrated that an application of8Nof compressive axial force increased the energy harvester’spower output 2.5 times compared to the unloaded condition[13].

Themodeling and testing of an energy harvester designedto convert ambient vibrations generated by a nuclear facility’sventilation fans into the electrical power required to sustaina wireless industrial health system providing feedback aboutthe ventilation system’s performance were also presented by


Figure 14: Experimental setup: loaded piezoelectric bimorph beamwith attached tip mass [13].

the authors [14]. Because the vibration frequencies of thefans change due to varying plant ventilation requirements,harvesters that can provide useful power across a range offrequencies are required. Therefore, energy harvesters thatcan be tuned by using magnets to adjust the harvester’sstiffness were considered. Figure 16 shows a picture of theexperimental setup with the adjustable slide and magnets.Figure 17 compares the tuned and untuned power outputsof the energy harvester with respect to frequency. For allmeasurements the load resistance remained constant at 180kohm.The untuned data points represent the power output ofthe harvester as the input frequency of the excitation force isadjusted away from the harvester’s fundamental frequency of39Hz and the tuned data points represent power output afterthe magnets have been used to tune the harvester to the newinput frequency. The data show that, as expected, variationsin the excitation frequency causemarked deterioration in sys-tem performance of the linear harvester and that the poweroutput of the tuned beam was significantly better than theoutput of the untuned beam. The deteriorating performanceof the tuned beam for increasing input frequencies is assumedto be due to the loss of the impedance match between thesource and load as the harvester’s stiffness and resonancefrequency are adjusted with the magnets.

Some researchers [58] have noted that frequency tuningcan be considered “quasistatic” because the rate at whichthe fundamental frequency is tuned is usually much slowerthan the excitation frequency. Likewise, compared to theresponse of nonlinear, broadband harvesters the response oftunable harvesters is still linear and, rather than increasingthe harvester’s band of efficient operation, tuning shifts thecenter point. In addition to a potential lag between excitationfrequency changes and harvester tuning, another potentialdrawback of tunable harvesters is that active tuning mayrequire using some of the harvested power thus reducing theamount available for the load. For this reason passive tuningis typically preferred.

4. Conclusion

This paper reviews some of the advances from 2008 to 2013in the field of energy harvesting technologies for the SHM

Out

put v

olta

ge (V

/g)

Time (s)

10

5

0

−5

−100.5 0.55 0.6 0.65 0.7

TheoreticalExperimental

Figure 15: Predicted and measured output voltage across a10MΩ resistance: frequency = 40Hz, axial preload =−2N, and tipmass = 3.75 g [13].

Magnets

Adjustable slide

Tektronix digital storage oscilloscope

Energy harvester

Accelerometer

Figure 16: Photograph of the experimental setup for tuning theharvester with magnets [14].

of machinery, civil, and aerospace applications. The methodof energy harvesting is one of the major considerationsin the design of any self-powered, wireless SHM system.The most common ambient energy sources, which includemechanical vibrations, wind, rotational kinetic energy, andsolar and thermal energy, used for SHM systems are brieflyoverviewed. An introductory survey of nonlinear energy har-vesters and some of the frequency tuningmethods developedfor linear, resonant piezoelectric harvesters is also presented.Current trends are towards further development of nonlin-ear, vibration-based energy harvesters and the integrationof multiple harvesting methods for the sustained, efficientoperation of wireless sensor networks. The development ofautonomous, self-powered SHM systems powered by theharvesting of ambient energy from the local environmentis an area of research that offers much potential and willcontinue to expand in combination with new developmentsin the field of low-power electronics.


Pow

er (𝜇

w)

70

60

50

40

30

20

10

0

−1038 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Frequency (Hz)

TunedUntuned

Comparison of tuned and untuned measured power outputwith respect to frequency

Figure 17: Tuned versus untuned power output with respect to frequency [14].

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper.

References

[1] G. Park, T. Rosing, M. Todd, C. Farrar, and W. Hodgkiss,“Energy harvesting for structural health monitoring sensornetworks,” Journal of Infrastructure Systems, vol. 14, no. 1, pp.64–79, 2008.

[2] W. Clark, J. Romeiko, D. Charnegie, G. Kusic, and C. Mo, “Acase study in energy harvesting for powering a wireless mea-surement systems,” in Proceedings of the InternationalWorkshopon Structural Health Monitoring (IWSHM ’07), pp. 1765–1772,Stanford University, Stanford, Calif, USA, September 2007.

[3] S. Arms, C. Townsend, D. Churchill et al., “Energy harvesting,wireless, structural health monitoring and reporting system,”in Proceedings of the 2nd Asia Pacific Workshop on SHM,Melboune, Australia, December 2008.

[4] L. Wang and F. G. Yuan, “Vibration energy harvesting by mag-netostrictive material,” Smart Materials and Structures, vol. 17,no. 4, Article ID 045009, 14 pages, 2008.

[5] T. V. Galchev, J. McCullagh, R. L. Peterson, and K. Najafi, “Har-vesting traffic-induced vibrations for structural healthmonitor-ing of bridges,” Journal of Micromechanics and Microengineer-ing, vol. 21, no. 10, Article ID 104005, 13 pages, 2011.

[6] Z. Li, L. Zuo, J. Kuang, and G. Luhrs, “Energy-harvesting shockabsorber with a mechanical motion rectifier,” Smart Materialsand Structures, vol. 22, no. 2, Article ID 025008, 10 pages, 2013.

[7] J. Sirohi and R. Mahadik, “Piezoelectric wind energy harvesterfor low-power sensors,” Journal of Intelligent Material Systemsand Structures, vol. 22, no. 18, pp. 2215–2228, 2011.

[8] N. Wu, Q. Wang, and X. Xie, “Wind energy harvesting with apiezoelectric harvester,” Smart Materials and Structures, vol. 22,no. 9, Article ID 095023, 9 pages, 2013.

[9] F. Khameneifar, S. Arzanpour, andM.Moallem, “A piezoelectricenergy harvester for rotary motion applications: design and

experiments,” IEEE/ASME Transactions on Mechatronics, vol.18, no. 5, pp. 1527–1534, 2013.

[10] C. A. Nelson, S. R. Platt, S. E. Hansena, and M. Fateh, “Powerharvesting for railroad track safety enhancement using verticaltrack displacement,” in Active and Passive Smart Structures andIntegrated Systems, vol. 7288 of Proceedings of the SPIE, p. 11, SanDiego, Calif, USA, April 2009.

[11] B. Joyce, Development of an electromagnetic energy harvester formonitoring wind turbine blades [M.S. thesis], Virginia Polytech-nic Institute and State University, 2011.

[12] M. R. Pearson, M. J. Eaton, R. Pullin, C. A. Featherston, and K.M. Holford, “Energy harvesting for aerospace structural healthmonitoring systems,” Journal of Physics: Conference Series, vol.382, no. 1, Article ID 012025, 2012.

[13] M. Rhimi and N. Lajnef, “Tunable energy harvesting fromambient vibrations in civil structures,” Journal of Energy Engi-neering, vol. 138, no. 4, pp. 185–193, 2012.

[14] J. Davidson and C. Mo, “Piezoelectric energy harvesting withfrequency tuning for ventilation system monitoring,” Interna-tional Journal of Engineering Science and Innovative Technology,vol. 2, no. 5, pp. 114–124, 2013.

[15] S. J. Roundy, Energy scavenging for wireless sensor nodes with afocus on vibration to electricity conversion [Ph.D. dissertation],Department of Mechanical Engineering, University of Califor-nia, Berkeley, calif, USA, 2003.

[16] D. Dumas, F. Lani, T. Monnier, R. Smaili, and J. Loyer, “Damagedetection in composite structures using autonomous wirelesssystems: simulation& validation,” Journal of Physics: ConferenceSeries, vol. 305, no. 1, Article ID 012084, 2011.

[17] D. Dondi, G. Napoletano, A. Bertacchini, L. Larcher, and P.Pavan, “AWSN system powered by vibrations to improve safetyofmachinery with trailer,” in Proceedings of the IEEE Conferenceon Sensors, pp. 28–31, Taipei, Taiwan, October 2012.

[18] T. Ueno and S. Yamada, “Performance of energy harvesterusing iron-gallium alloy in free vibration,” IEEE Transactions onMagnetics, vol. 47, no. 10, pp. 2407–2409, 2011.

[19] M. Zucca and O. Bottauscio, “Hysteretic modeling of electricalmicro-power generators based on Villari effect,” IEEE Transac-tions on Magnetics, vol. 48, no. 11, pp. 3092–3095, 2012.


[20] D. Davino, A. Giustiniani, C. Visone, and A. Adly, “Experimen-tal analysis of vibrations damping due tomagnetostrictive basedenergy harvesting,” Journal of Applied Physics, vol. 109, no. 7,Article ID 07E509, 2011.

[21] A. Erturk, “Piezoelectric energy harvesting for civil infrastruc-ture system applications: moving loads and surface strain fluc-tuations,” Journal of Intelligent Material Systems and Structures,vol. 22, no. 17, pp. 1959–1973, 2011.

[22] M. Wischke, M. Masur, M. Kroner, and P. Woias, “Vibrationharvesting in traffic tunnels to power wireless sensor nodes,”SmartMaterials and Structures, vol. 20, no. 8, Article ID 085014,8 pages, 2011.

[23] H.-J. Jung, I.-H. Kim, and J. Park, “Experimental validation ofenergy harvesting device for civil engineering applications,” inSensors and Smart Structures Technologies for Civil, Mechanical,and Aerospace Systems, vol. 8345 of Proceedings of the SPIE, p. 4,San Diego, Calif, USA, April 2012.

[24] I.-H. Kim, S.-J. Jang, and H.-J. Jung, “Performance enhance-ment of a rotational energy harvester utilizing wind-inducedvibration of an inclined stay cable,” Smart Materials andStructures, vol. 22, Article ID 075004, 7 pages, 2013.

[25] E. Sazonov, H. Li, D. Curry, and P. Pillay, “Self-powered sensorsfor monitoring of highway bridges,” IEEE Sensors Journal, vol.9, no. 11, pp. 1422–1429, 2009.

[26] J. Wardlaw, I. Karaman, and A. Karsılayan, “Low power circuitsand energy harvesting for structural health monitoring ofbridges,” IEEE Sensors Journal, vol. 13, no. 2, pp. 709–722, 2013.

[27] M. Peigney and D. Siegert, “Piezoelectric energy harvestingfrom traffic-induced bridge vibrations,” Smart Materials andStructures, vol. 22, no. 9, Article ID 095019, 11 pages, 2013.

[28] H. J. Xiang, J. J. Wang, Z. F. Shi, and Z. W. Zhang, “Theoreticalanalysis of piezoelectric energy harvesting from traffic induceddeformation of pavements,” SmartMaterials and Structures, vol.22, no. 9, Article ID 095024, 9 pages, 2013.

[29] K. Cunefare, E. Skow, A. Erturk, J. Savor, N. Verma, and M.Cacan, “Energy harvesting from hydraulic pressure fluctua-tions,” Smart Materials and Structures, vol. 22, no. 2, Article ID025036, 2013.

[30] C. Li and P. Tse, “Fabrication and testing of an energy-harvesting hydraulic damper,” Smart Materials and Structures,vol. 22, no. 6, Article ID 065024, 11 pages, 2013.

[31] Media Release, “Perpetuum wins contract to supply South-eastern Railways with energy harvester powred wireless sensorsystems for 148 trains,” June 2013, http://www.perpetuum.com/news.asp.

[32] J.-W. Park, H.-J. Jung, H. Jo, and B. F. Spencer Jr., “Feasibilitystudy ofmicro-wind turbines for poweringwireless sensors on acable-stayed bridge,” Energies, vol. 5, no. 9, pp. 3450–3464, 2012.

[33] F. J. Xu, F. G. Yuan, J. Z. Hu, and Y. P. Qiu, “Design of a minia-ture wind turbine for powering wireless sensors,” in Sensorsand Smart Structures Technologies for Civil, Mechanical, andAerospace Systems, vol. 7647 of Proceedings of the SPIE, SanDiego, Calif, USA, April 2010.

[34] H.-J. Jung, S.-W. Lee, andD.-D. Jang, “Feasibility Study on a newenergy harvesting electromagnetic device using aerodynamicinstability,” IEEE Transactions on Magnetics, vol. 45, no. 10, pp.4376–4379, 2009.

[35] A. Abdelkefi, M. R. Hajj, and A. H. Nayfeh, “Piezoelectricenergy harvesting from transverse galloping of bluff bodies,”Smart Materials and Structures, vol. 22, no. 1, Article ID 015014,11 pages, 2013.

[36] A. Abdelkefi,M. R. Hajj, andA.H. Nayfeh, “Modeling and anal-ysis of piezoaeroelastic energy harvesters,”Nonlinear Dynamics,vol. 67, no. 2, pp. 925–939, 2012.

[37] A. Abdelkefi,M. R. Hajj, and A. H. Nayfeh, “Design of piezoaer-oelastic energy harvesters,” Nonlinear Dynamics, vol. 68, no. 4,pp. 519–530, 2012.

[38] A. Abdelkefi, M. R. Hajj, and A. H. Nayfeh, “Enhancementof power harvesting from piezoaeroelastic systems,” NonlinearDynamics, vol. 68, no. 4, pp. 531–541, 2012.

[39] A. Abdelkefi, M. R. Hajj, and A. H. Nayfeh, “Sensitivity analysisof piezoaeroelastic energy harvesters,” Journal of IntelligentMaterial Systems and Structures, vol. 23, no. 13, pp. 1523–1531,2012.

[40] S.-D. Kwon, “A T-shaped piezoelectric cantilever for fluidenergy harvesting,”Applied Physics Letters, vol. 97, no. 16, ArticleID 164102, 2010.

[41] Q. Wang, Y. Zhang, N. X. Sun, J. G. McDaniel, and M. L. Wang,“High power density energy harvester with high permeabilitymagnetic material embedded in a rotating wheel,” in Nonde-structive Characterization for Composite Materials, AerospaceEngineering, Civil Infrastructure, and Homeland Security, vol.8347 of Proceedings of the SPIE, p. 6, April 2012.

[42] K. J. Phillips, C. A. Nelson, and M. Fateh, “Simulation and con-trol systemof a power harvesting device for railroad track healthmonitoring,” in Health Monitoring of Structural and BiologicalSystems, Proceedings of the SPIE, p. 10, San Diego, Calif, USA,March 2011.

[43] T. Becker, M. Kluge, J. Schalk et al., “Autonomous sensor nodesfor aircraft structural health monitoring,” IEEE Sensors Journal,vol. 9, no. 11, pp. 1589–1595, 2009.

[44] D. Samson, T. Otterpohl, M. Kluge, U. Schmid, and T. Becker,“Aircraft-specific thermoelectric generator module,” Journal ofElectronic Materials, vol. 39, no. 9, pp. 2092–2095, 2010.

[45] D. Samson, M. Kluge, T. Becker, and U. Schmid, “Wirelesssensor node powered by aircraft specific thermoelectric energyharvesting,” Sensors and Actuators A: Physical, vol. 172, no. 1, pp.240–244, 2011.

[46] “MPG-D655 Thin Film Thermogenerator PreliminaryDatasheet,” Accessed January 2014, http://micropelt.com/downloads/datasheet mpg d655.pdf.

[47] M. Hassan, S.-H. Man, C. Z. Ng, A. Bermak, and C.-C. Chang,“Development of energy harvested wireless sensing node forstructural health monitoring,” in Proceedings of the 18th IEEEInternational Mixed-Signals, Sensors and Systems TestWorkshop(IMS3TW ’12), pp. 22–27, May 2012.

[48] S. Inamdar, Design of a solar energy harvesting system for struc-tural health monitoring systems [M.S. thesis], The University ofTexas, Austin, Tex, USA, 2012.

[49] T. Miller and B. F. Spencer Jr., “Solar energy harvesting andsoftware enhancements for autonomous wireless smrt net-works,” NSEL Report Series UILU-ENG-2010-1802, Universityof Illinois, Champaign, Ill, USA, 2009.

[50] S. Jang, H. Jo, S. Cho et al., “Structural health monitoring of acable-stayed bridge using smart sensor technology: deploymentand evaluation,” Smart Structures and Systems, vol. 6, no. 5-6, pp.439–459, 2010.

[51] V. F. Godınez-Azcuaga, J. Farmer, P. H. Ziehl, V. Giurgiutiu,A. Nanni, and D. J. Inman, “Status in the development of self-powered wireless sensor node for structural health monitoringand prognosis,” inNondestructive Characterization for Compos-ite Materials, Aerospace Engineering, Civil Infrastructure, and


Homeland Security, vol. 8347 of Proceedings of the SPIE, p. 6,San Diego, Calif, USA, April 2012.

[52] K. M. Farinholt, N. Miller, W. Sifuentes, J. MacDonald, G.Park, and C. R. Farrar, “Energy harvesting and wireless energytransmission for embedded SHM sensor nodes,” StructuralHealth Monitoring, vol. 9, no. 3, pp. 269–280, 2010.

[53] B. Koser and H. Marinkovic, “Demonstration of wide band-width energy harvesting from vibrations,” Smart Materials andStructures, vol. 21, no. 6, Article ID 065006, 2012.

[54] W. Al-Ashtari, M. Hunstig, T. Hemsel, and W. Sextro, “Fre-quency tuning of piezoelectric energy harvesters by magneticforce,” Smart Materials and Structures, vol. 21, no. 3, Article ID035019, 2012.

[55] S. P. Beeby, L. Wang, D. Zhu et al., “A comparison of power out-put from linear and nonlinear kinetic energy harvesters usingreal vibration data,” Smart Materials and Strctures, vol. 22, no. 7,Article ID 075022, 15 pages, 2013.

[56] A. Erturk, J. Hoffmann, andD. J. Inman, “Apiezomagnetoelasticstructure for broadband vibration energy harvesting,” AppliedPhysics Letters, vol. 94, no. 25, Article ID 254102, 2009.

[57] J.-T. Lin, B. Lee, and B. Alphenaar, “The magnetic couplingof a piezoelectric cantilever for enhanced energy harvestingefficiency,” Smart Materials and Structures, vol. 19, no. 4, ArticleID 045012, 7 pages, 2010.

[58] A. M. Wickenheiser and E. Garcia, “Broadband vibration-based energy harvesting improvement through frequency up-conversion by magnetic excitation,” Smart Materials and Struc-tures, vol. 19, no. 6, Article ID 065020, 11 pages, 2010.

[59] L. Liu and F. G. Yuan, “Nonlinear vibration energy harvesterusing diamagnetic levitation,” Applied Physics Letters, vol. 98,no. 20, Article ID 203507, 2011.

[60] D. A. W. Barton, S. G. Burrow, and L. R. Clare, “Energy har-vesting from vibrations with a nonlinear oscillator,” Journal ofVibration and Acoustics, vol. 132, no. 2, Article ID 021009, 7pages, 2010.

[61] F. Cottone, L. Gammaitoni, H. Vocca, M. Ferrari, and V.Ferrari, “Piezoelectric buckled beams for random vibrationenergy harvesting,” Smart Materials and Structures, vol. 21, no.3, Article ID 035021, 2012.

Submit your manuscripts athttp://www.hindawi.com

ScientificaHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation http://www.hindawi.com Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation http://www.hindawi.com Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials

Review Article Recent Advances in Energy …downloads.hindawi.com/archive/2014/410316.pdfReview...

Documents

Transcript of Review Article Recent Advances in Energy …downloads.hindawi.com/archive/2014/410316.pdfReview...