Waste Mechanical Energy Research Articles

Laminated Laser-Induced Graphene Composites.

Laser-induced graphene (LIG) is a porous graphene foam generated by lasing carbon-based precursors. Compositing LIG expands the spectrum of applications for which the material may be used. Techniques for scale-up of LIG composites will be essential as the technology approaches commercialization. Roll-to-roll processing is of special interest, as precisely controlled patterning can be performed in conjunction with continuous formation of composites. Here, we demonstrate a simple lamination compositing method that is compatible with roll-to-roll processing and yields functional, patterned, and multilayered LIG composites with various thermoplastic films. Multiple lamination steps are used to encapsulate LIG within composites. We also demonstrate several applications for LIG that have been enabled by the lamination compositing technique. These include robust flexible electrodes generated through laminating copper foil strips into the LIG composite, LIG-based triboelectric nanogenerators to harvest waste mechanical energy, antimicrobial LIG composite bandages with varying hydrophobicity, and LIG puncture detectors.

Aloe vera: A tropical desert plant to harness the mechanical energy by triboelectric and piezoelectric approaches

The tropical desert plant (aloe-vera, AV) derived natural bio-organic material used to convert the waste mechanical energy into electrical energy. The piezoelectric force microscopy measurement of AV film shows the amplitude resembles the butterfly-like shaped, and the phase loop depicts the 180° switching of domains confirming the ferroelectricity of AV. The obtained converse piezoelectric coefficient (d33) is 6.5 pm V−1, and remnant polarization is 1.02 μC/cm2 for poled AV film due to the development of long-range order of acemannan (A) chains and their interaction between them A-A or A-uronic acids through the newly formed hydrogen bonds. The piezoelectric AV film-energy harvester (AV film-EH) generates a peak-to-peak output response of (1.2 V, 200 nA), and the instantaneous peak power is ≈ 0.42 μW at 10 MΩ upon 4 N force. The non-contact surface potential measurement and KPFM results confirm the AV is a moderate positive triboelectric material having a surface potential of +1.14 V, respectively. The triboelectricity of AV explored in two approaches, such as dry film (F) and gel (G) type interacting with the different materials. The AV film-PDMS, AV gel-PDMS TENG, delivers an instantaneous power density of 0.19 μW/cm2 upon 2 m/s2 acceleration of shaft load and 0.22 μW/cm2 upon biomechanical hand force. Next, successfully demonstrated the AV film-EH could work as a self-powered finger monitoring sensor to monitor human finger bending angles. It also explored that the electrical output of AV film-PDMS TENG is used to power the smartwatch successfully. Here, the generated electric energy from the desert plant is clean, cost-effective, and plentiful to develop the self-powered biosensor/implantable devices.

PVDF–PZT nanohybrid based nanogenerator for energy harvesting applications

With the depletion of the conventional energy sources, measures are being taken to create an alternate energy sources for the future. Energy harvesting from different sources are one of the better steps taken in this direction. Mechanical energy harvesting from the waste mechanical source is gaining profound investigation. Here, a nanohybrid of poly(vinylidene fluoride) and lead zirconia titanate (PZT) is prepared through solution route for energy harvesting applications. PZT is synthesized using solid state route and its concentration was varied in the nanohybrid to get the best properties from the hybrid. Structural and morphological aspects of the nanohybrid have been explored for their suitable application. Device has been fabricated using the nanohybrid to convert the waste mechanical energy from various human motions to the useful electrical energy. The device is able to generate a maximum output voltage of 55 V and a power density of 36 μWcm−2. The device is able to produce voltage output from different human motions such as finger tapping, feet tapping and bending. The mechanism of charge conversion is also discussed which explains the generation of such a high electrical output from waste mechanical source.

Review on Nanomaterials and Their Utilization in the Recovery of Waste Mechanical Energy by Using Piezoelectric Nanogenerators

Nano scale materials are defined as a set of substances where at least one dimension is less than approximately 100 nanometers. A nanometer is one millionth of a millimeter- approximately 100,000 times smaller than the diameter of a human hair. Nanomaterials are of interest because at this scale unique optical, magnetic, electrical, and other properties emerge. These emergent properties have the potential for great impacts in electronics, medicine, and other fields. Energy harvesting from the environment is one of the core features of a functional, self-sufficient nanosystem. Self-powered nanosystems combine the nanogenerator with functional nanodevices in order to harvest mechanical energy from the environment into electricity to power nanodevices. It can work independently, without any other external power sources. Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress.Energy harvesting (or power scavenging) refers to capturing energy from environment, surrounding system or any other source and converting it into a usable form of energy to develop self-power system that doesn’t need external power supply e.g. piezoelectric process. In order to harvest the waste mechanical energy during various processes, piezoelectric properties of different materials such as ZnO can be utilised in order to convert the waste mechanical energy into electrical energy which could further be used.

Sustainable Human-Machine Interactive Triboelectric Nanogenerator toward a Smart Computer Mouse

A rapid increase in day-to-day consumer electronics and maximum usage of it builds multiple possibilities in human–machine interaction (HMI). By considering the use of electronic components, such as smartphones, tablet computers, keyboards, etc., a large amount of biomechanical energy would be generated. To harvest the waste mechanical energy, the authors have fabricated a smart computer mouse-triboelectric nanogenerator (SCM-TENG) with an interdigitated array (IDA) electrode made of aluminum (Al) and nylon, paper, cotton, polyethylene, and fluorinated ethylene propylene (FEP) as sliding layers. The SCM-TENG has a high energy output with FEP/Al as a triboelectric material and shows a maximum output of VOC ≈ 210 V and JSC (peak–peak) ≈ 3 μA/m2. We have also carried out stability tests, load resistance analysis, charging commercial capacitors, and a lithium ion (Li-ion) battery. These types of TENG-based electronic devices pave the way for battery-free electronics and commercialization.

Enhanced piezoelectric response in nanoclay induced electrospun PVDF nanofibers for energy harvesting

Templated nanofibers of poly(vinylidene fluoride) have been designed on top of two dimensional nanoclay platelets for energy harvesting application. Dimension of nanofiber has been varied using different nanoclay content prepared through optimized electrospinning. The alteration in structure (electroactive phase) and morphology has been worked out as a function of nanoclay concentration. Nearly 90% piezoelectric active phase has been stabilized in presence of minimum quantity of nanoclay. Hybrid nanofiber is found to be tougher (300%) and stiffer by design, which in turn suitable for device application. Unimorph using hybrid nanofiber exhibits power generation up to 100 ms against less than 50 ms tenure using pristine fiber. Device has been fabricated using various nanofibers and demonstrates very high output voltage (70 V) and power density (68 μW cm−2) from the device made of hybrid nanofiber. Various modes of body movements e.g. bending, twisting, walking, foot and finger tapping can generate considerable power using the hybrid device and are able to transform waste mechanical energy to useful electric power. Underlying mechanism of charge separation in template system has been revealed which explain the high conversion of energy using the hybrid device.

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.

Efficient Energy Harvesting Using Processed Poly(vinylidene fluoride) Nanogenerator

Poly(vinylidene fluoride) (PVDF) is processed at high temperature to generate energy from waste mechanical energy. The piezoelectric β-phase has been induced through uniaxial elongation of polymer films at high temperature. The extent of β-phase has been confirmed from a deconvoluted XRD pattern, found to be ∼75% of the electroactive phase, and able to demonstrate high piezoelectric effect as evident from the measured piezoelectric coefficient of −30 pC/N after a suitably processed and poled specimen. Bulk morphology and spectroscopic studies support the structural alteration. Following the direct piezoelectric effect, energy harvesting devices have been fabricated which show very high power output of 55.2 μW/cm2 using the processed and poled specimen. Thus, robust and easily processable polymeric material having very high energy conversion efficiency is demonstrated which is sufficient to power miniaturized devices.

Direct degradation of dyes by piezoelectric fibers through scavenging low frequency vibration

A newly discovered nanometer material-mediated piezoelectrochemical (PZEC) for the direct conversion of mechanical energy to chemical energy has attracted increasing attention, for its great potential to be a green dye water decomposition technique. However, it is far from being a cost-effective and practical technique because only ultrasonic can be scavenged to decomposed organic pollutant in previous studies. Here, we prepared 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) piezoelectric fibers for the degradation of dye solution via slow stirring and studied the degradation mechanism. It provides a practical, green and low-cost method for decomposing organic dye by scavenging waste mechanical energy from the surrounding environment.

Metallic MXenes: A new family of materials for flexible triboelectric nanogenerators

Wearable and flexible electronics warrant the development of self-powered devices to circumvent the limitations imposed by traditional energy storage devices. Triboelectric nanogenerators (TENGs) that convert waste mechanical energy from human motion into electric power offer a solution. Highly electronegative and conducting TENG materials that support the generation of both large potential differences and high currents are imperative for effectively harvesting electric power from human muscle movements. Here, we demonstrate that two-dimensional MXenes (e.g., titanium carbide Ti3C2Tx, where Tx stands for surface functional groups such as -O, -OH, and -F) are a family of electrically conducting materials that are triboelectrically more negative than polytetrafluorethylene, or Teflon. Specifically, flexible MXene TENGs support both high open circuit voltages ranging from ~500 to ~650V and an instantaneous peak power ~ 0.5–0.65mW that could power > 60 light-emitting diodes or quickly charge a 1μF capacitor up to 50V. Lastly, we demonstrate that flexible MXene TENGs are capable of harvesting electrical power from simple muscle movements (e.g., texting) even when the device is flexed by ~ 30° suggesting facile integration with wearable electronics.

Breath Figure Micromolding Approach for Regulating the Microstructures of Polymeric Films for Triboelectric Nanogenerators

A triboelectric nanogenerator (TENG) is an innovative kind of energy harvester recently developed on the basis of organic materials for converting mechanical energy into electricity through the combined use of the triboelectric effect and electrostatic induction. Polymeric materials and their microstructures play key roles in the generation, accumulation, and retainment of triboelectric charges, which decisively determines the final electric performance of TENGs. Herein we report a simple and efficient breath figure (BF) micromolding approach to rapidly regulate the surface microstructures of polymeric films for the assembly of TENGs. Honeycomb porous films with adjustable pore size and dimensional architectures were first prepared by the BF technique through simply adjusting the concentration of the polymer solution. They were then used as negative molds for straightforward synthesis of polydimethylsiloxane (PDMS) films with different microlens arrays (MLAs) and lens sizes, which were further assembled for TENGs to investigate the influence of film microstructures. All MLA-based TENGs were found to have an obviously enhanced electric performance in comparison with a flat-PDMS-film-based TENG. Specifically, up to 3 times improvement in the electric performance can be achieved by the MLA-based TENG with optimal surface microstructures over flat-PDMS-film-based TENG under the same triggering conditions. A MLA-based TENG was further successfully used to harvest the waste mechanical energy generated by different human body motions, including finger tapping, hand clapping, and walking with a frequency ranging from 0.5 to 5.5 Hz.

A flexible, planar energy harvesting device for scavenging road side waste mechanical energy via the synergistic piezoelectric response of K0.5Na0.5NbO3-BaTiO3/PVDF composite films.

Flexible, planar composite piezoelectric nanogenerators (C-PNGs) were developed to harness waste mechanical energy using cost-effective composite films (CFs) prepared via a probe-sonication technique. CFs, made up of highly crystalline, randomly oriented lead free piezoelectric nanoparticles (1 - x)K0.5Na0.5NbO3-xBaTiO3, where x = 0.02, 0.04, 0.06, or 0.08 [designated as KNN-xBTO], were impregnated in a polyvinylidene fluoride (PVDF) matrix. The KNN piezoelectric properties were tuned via the substitution of BTO nanoparticles, without altering the orthorhombic phase. A C-PNG device (x ≈ 0.02) generates a maximum open circuit voltage ≈160 V, and the instantaneous area power density is ≈14 mW m-2 upon a low mechanical force ≈0.4 N. The effects of BTO concentration in the KNN lattice, electrical poling effects, the fixed weight ratio of nanoparticles in the PVDF matrix, switching polarity tests, and load resistance analysis of C-PNG devices were investigated with constant mechanical force. Furthermore, the experimentally demonstrated C-PNG device output is sufficient to drive commercial blue light emitting diodes. The C-PNG device was placed on a road side, and the maximum energy generation and stability under real time harsh conditions, such as vehicle motion (motorcycle and bicycle) and human walking, were tested. C-PNG generates a peak-to-peak output voltage ≈16 V, when motorcycle forward/backward motion acts on it. This result indicates that the C-PNG device is a potential candidate to power road side sensors, speed tachometers, light indicators, etc. on highways.

Energy harvesting using martensite variant reorientation mechanism in a NiMnGa magnetic shape memory alloy

Magnetic shape memory alloys demonstrate significant potential for harvesting waste mechanical energy utilizing the Villari effect. In this study, a few milliwatts of power output are achieved taking advantage of martensite variant reorientation mechanism in Ni51.1Mn24Ga24.9 single crystals under slowly fluctuating loads (10Hz) without optimization in the power conversion unit. Effects of applied strain range, bias magnetic field, and loading frequency on the voltage output are revealed. Anticipated power outputs under moderate frequencies are predicted showing that the power outputs higher than 1W are feasible.