Mechanical Energy Harvesting Applications Research Articles

Nanogenerator for dynamic stimuli detection and mechanical energy harvesting based on compressed SbSeI nanowires

In this paper, a novel fabrication technology for generating antimony selenoiodide (SbSeI) nanowire pellets is presented, and their application as piezoelectric nanogenerators is discussed. The prepared samples can be used to convert mechanical energy into electrical energy via the piezoelectric effect. The SbSeI nanowires are fabricated sonochemically and then compressed under high pressure (120 MPa). The morphological and electrical properties of the samples have been investigated using various techniques, including scanning electron microscopy, high-resolution transmission electron microscopy, and other electrical and piezoelectric measurements. The relationship between frequency of impact and the piezoelectric signal has been measured to calculate the output voltage and power produced by the nanogenerator. The maximum open circuit voltage of 384.7 (11) mV, corresponding to a maximum surface power density of 14.1 (21) nW⋅cm-2 and volume power density of 0.380 (83) μW⋅cm-3 has been achieved for periodic striking excitation with force of 17.8 N and resonant frequency of 70 Hz. The presented SbSeI nanogenerator has been found as promising for mechanical energy harvesting applications. Furthermore, it can also be employed as a self-powered sensor for the detection of dynamic pressure changes and vibrations with frequencies up to 200 Hz.

Effect of annealing treatment on PVDF nanofibers for mechanical energy harvesting applications

Piezoelectric nanofibrous films with superior flexibility have attracted the emerging applications including sensors and actuators, piezoelectric nanogenerators (PNG) and energy storage devices. Herein, polyvinylidene fluoride (PVDF) piezoelectric nanofibrous film have been made by the electrospinning technique and been exposed to annealing as a post processing treatment at 40, 70, 100 and 130 °C for 4 h in air-flow oven. Four kinds of samples annealed at various temperatures have been pointed out as PVDF40, PVDF70, PVDF100 and PVDF130, respectively. The crystalline phases and thermal responses of the annealed film have been examined with XRD, FTIR and DSC. Also, mechanical and electroactive investigations exhibited that annealing treatment has effectively enhanced the dielectric constant, piezoelectric coefficient and the polar β-phase. Moreover, the annealed PVDF film acts as an effective layer of the PNG with enhanced crystalline structure and polar β-phase fraction. When the film is annealed at 100 °C, the voltage output of the PNG can attain maximum microstrain of 1000 με. The developed PVDF100 nanofibrous film-based PNG can generate output voltage of 0.516 V and 0.505 V with a tensile and compressive microstrain measured using the microstrain indicator of 1000 με. It shows better results compared to PVDF40 of 0.221 V. The enhanced voltage output of the PNG is recognised to be the collaborative involvement of the electrospinning and annealing treatment which could improve the piezoelectric response of the annealed film. This work presents that the annealed PVDF nanofibrous film based highly compliant PNG could be a promising candidate for flexible self-powered electronic applications.

Mechanical energy harvesting properties of free-standing carbyne enriched carbon film derived from dehydrohalogenation of polyvinylidene fluoride

The development of functional materials towards mechanical energy harvesting applications is rapidly increasing during this decade. In this study, we are reporting the mechanical energy harvesting properties of free-standing carbyne-enriched carbon film (prepared via dehydrohalogenation of PVDF). Physico-chemical characterizations such as X-ray diffraction, Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, 13C NMR spectroscopy, and laser Raman spectral analyses confirmed the formation of the carbyne-enriched carbon film. The Raman mapping analysis revealed the homogeneous distribution of cumulenic (β-carbyne) networks in carbonoid matrix of the prepared film. The mechanical energy harvesting properties of carbyne-enriched carbon film have been examined under various applied compressive forces. The carbyne-enriched carbon film based energy harvester generates a peak to peak voltage of 6.48 V using a periodic force of 0.2 N, and the output voltage is directly proportional to the levels of applied compressive force. The carbyne-enriched carbon film based energy harvester possesses an instantaneous power density of about 72 nW cm−2 with excellent electromechanical stability. These experimental findings ensure the use of carbyne-enriched carbon film as a mechanical energy harvester for the first time, which can create new insights towards the development of carbon-based mechanical energy harvesters.

A Flexible Composite Mechanical Energy Harvester from a Ferroelectric Organoamino Phosphonium Salt.

A new binary organic salt diphenyl diisopropylamino phosphonium hexaflurophosphate (DPDP⋅PF6 ) was shown to exhibit a good ferroelectric response and employed for mechanical energy harvesting application. The phosphonium salt crystallizes in the monoclinic noncentrosymmetric space group Cc and exhibits an H-bonded 1D chain structure due to N-H⋅⋅⋅F interactions. Ferroelectric measurements on the single crystals of DPDP⋅PF6 gave a well-saturated rectangular hysteresis loop with a remnant (Pr ) polarization value of 6 μC cm-2 . Further, composite devices based on polydimethylsiloxane (PDMS) films for various weight percentages (3, 5, 7, 10 and 20 wt %) of DPDP⋅PF6 were prepared and examined for power generation by using an impact test setup. A maximum output peak-to-peak voltage (VPP ) of 8.5 V and an output peak-to-peak current (IPP ) of 0.5 μA was obtained for the non-poled composite film with 10 wt % of DPDP⋅PF6 . These results show the efficacy of organic ferroelectric substances as potential micropower generators.

Organo-lead halide perovskite regulated green light emitting poly(vinylidene fluoride) electrospun nanofiber mat and its potential utility for ambient mechanical energy harvesting application

Methylammonium lead bromide (CH3NH3PbBr3) (MAPbBr) has been synthesized and then introduced in the poly(vinylidene fluoride) (PVDF) nanofiber made by the process of electrospinning. The β-phase composition, degree of crystallinity as well as mechanical, optical and energy harvesting properties of this composition has been investigated. Increased electroactive phase composition (91%) and dramatic improvement in tensile strength of the PVDF nanofiber mats is found by the addition of MAPbBr. This increase in electroactive phase composition can play a significant role in the enhancement of output power which is a premiere observation. The acoustic nanogenerator (ANG) made from MAPbBr doped PVDF nanofibers (NFs) can also be utilized in energy scavenging from acoustic vibration with a higher degree of acoustic sensitivity (~ 13.8 V Pa−1) and efficiency (58.5%). This suggests that ANG could be a potential tool for power generation in portable electronics. This fact may open up the prospect of using the MAPbBr doped PVDF electrospun nanofibers, with their multifunctional properties such as vibration sensitivity, piezoelectric energy harvesting, green light emission capability (quantum yield ~ 32.6%), for various promising applications in portable electronics, noise detection and security monitoring.

Influence of in situ synthesized bismuth oxide nanostructures in self‐poled PVDF‐based nanogenerator for mechanical energy harvesting application

A self‐poled piezoelectric nanogenerator (NG) based on bismuth oxide (Bi2O3) nanostructures (BNS)‐doped poly(vinylidene fluoride) (PVDF) is demonstrated. The in‐situ formation of BNS incorporated in the PVDF matrix is realized through a simple solution casting technique that favors the nucleation and stabilization of 99.6% of the electroactive phase in PVDF (i.e., β/γ‐phases). The enhancement of the output voltage (3.6 V) and current (2.4 µA) of the NG based on a nonelectrically poled BNS containing PVDF composite film is achieved and demonstrated by simple repeated human finger imparting. The improvement of the output performance is influenced by the generation of the electroactive polar β‐phase in PVDF, due to the electrostatic interactions between the –CH2–/–CF2– dipoles of PVDF and the surface charge of the BNS. The NGs are able to charge up capacitors demonstrating that the power generation from such a hybrid device structure can be utilized for powering various portable devices. POLYM. COMPOS., 40:E265–E274, 2019. © 2017 Society of Plastics Engineers

Electroactive β-crystalline phase inclusion and photoluminescence response of a heat-controlled spin-coated PVDF/TiO2 free-standing nanocomposite film for a nanogenerator and an active nanosensor

The electroactive β-phase is most desirable due to its highest piezo-, pyro- and ferroelectric properties in poly(vinylidene fluoride) (PVDF). Induction of the β-phase is successfully accomplished in titanium dioxide (TiO2) nanoparticles (NPs) doped spin-coated PVDF nanocomposite (PNC) films. The optimized yields of β-phase and homogeneous ultra-smooth free-standing PNC film is utilized in a mechanical-energy harvesting application by fabricating a nanogenerator (NG) where the typical electrical poling step is not undertaken. Under a repeated human finger touch and release process, it delivers an open-circuit voltage of 5 V. Moreover, the physical sensing capabilities of the NG are examined through harvesting mechanical energy from mouse clicking of a laptop and wrist pulse detection, which indicates that it can also be used as a nanosensor. The blue photoluminescence centred at 444 nm, which was also observed in PNC films, makes us anticipate a new type of photonic application where the design feasibility of hybrid sensors, i.e. electromechanical and photonic combination, is also possible.

Organic microcantilevers based on reduced graphene oxide composite for electrostrictive energy harvesting

Electrostrictive materials are promising for mechanical energy harvesting applications because of their high power density, low cost and scalability. In this paper, strain sensitive nanocomposite materials based on reduced graphene (rGO) and PDMS are used for energy harvesting; they are characterized by a high electrostrictive coefficient (2.4x10-15 m2/V2) and a giant dielectric constant (ranging from 100 to 1000 at 100 Hz, depending of rGO concentration). Using these nanocomposite materials, electrostrictive MEMS microgenerators are fabricated with an innovative low-cost and environment friendly process in an all-organic approach. The fabricated microcantilevers exhibit excellent mechanoelectrical performances in dynamic mode. With an acceleration of 1 g of the microcantilever base using a shaker, experiment at the first resonant mode (≈ 16 Hz) generates an electrical power density of 8.15 μW/cm3.

Hybrid energy harvesting systems, using piezoelectric elements and dielectric polymers

Interest in energy harvesting applications has increased a lot during recent years. This is especially true for systems using electroactive materials like dielectric polymers or piezoelectric materials. Unfortunately, these materials despite multiple advantages, present some important drawbacks. For example, many dielectric polymers demonstrated high energy densities; they are cheap, easy to process and can be easily integrated in many different structures. But at the same time, dielectric polymer generators require an external energy supply which could greatly compromise their autonomy. Piezoelectric systems, on the other hand, are completely autonomous and can be easily miniaturized. However, most common piezoelectric materials present a high rigidity and are brittle by nature and therefore their integration could be difficult. This paper investigates the possibility of using hybrid systems combining piezoelectric elements and dielectric polymers for mechanical energy harvesting applications and it is focused mainly on the problem of electrical energy transfer. Our objective is to show that such systems can be interesting and that it is possible to benefit from the advantages of both materials. For this, different configurations were considered and the problem of their optimization was addressed. The experimental work enabled us to prove the concept and identify the main practical limitations.

Modeling of semiconducting piezoelectric nanowires for mechanical energy harvesting and mechanical sensing

ZnO and GaN semiconducting piezoelectric nanowires (NWs) have attracted much attention because of their improved mechanical and piezoelectric properties compared to bulk materials. They have been integrated into different devices ranging from sensors to energy harvesting devices. In this review article we focalize on the modeling of these nanostructures and devices: First, we synthesize the modeling studies at an individual level including the different approaches developed. Then we consider NW arrays integrated into devices for mechanical energy harvesting applications and the different modeling techniques, including finite element methods, analytical methods and equivalent circuit models, to estimate the performance and the optimization guidelines of such devices. Finally, composite materials integrating piezoelectric NWs and a dielectric matrix are also considered as a route for improved performance compared to piezoelectric thin films.