Piezoelectric Nanogenerator Device Research Articles

Enhancing piezoelectric effect of PVDF electrospun fiber through NiO nanoparticles for wearable applications

Flexible electrospun fiber-based piezoelectric nanogenerator (PENG) has attracted a lot of interest due to its ability of generating electrical energy from mechanical energy sources. The present work aims to improve the piezoelectric output of PENG devices based on electrospun polyvinylidene fluoride (PVDF) doped with nickel oxide nanoparticles (NiO NPs) in different concentrations (2, 4, 6, 8 and 10 wt.-%). Crystalline phase changes and β-crystalline content in electrospun fibers were evaluated using XRD and FTIR-ATR, respectively. Surface morphology and surface roughness of the electrospun fibers were observed using FE-SEM and AFM, respectively. The hydrophobic nature of the fibers was analyzed using a wettability test. PENG output voltage and short-circuit current performance of neat PVDF and PVDF doped with NiO (PN) composite electrospun fibers were calculated using a customized variable-pressure setup with an optimized force of 1.0 kgf and 1.0 Hz frequency. Neat PVDF-based PENG exhibited only 1.7 V and 0.7 μA, whereas, PVDF doped with 6 wt.-% NiO NP (PN-6) based PENG generated a high output voltage of 5.5 V and 1.83 μA current. The optimized PN-6 PENG device is demonstrated for use in wearable devices towards identifying certain body movements like tapping, wrist movement, walking and running.

Piezoelectric performance enhancement of electrospun functionally graded PVDF/BaTiO3 based flexible nanogenerators

Flexible piezoelectric electrospun films have gained widespread attention due to their ability to convert mechanical energy into electrical energy. Pure PVDF has a low output, while multi-layered film based nanogenerators with high concentrations of BaTiO3 give more output. This paper aims to fabricate a functionally graded nanogenerator with varying BaTiO3 concentrations from bottom to top. Multilayer films were synthesized using electrospinning and incorporated into a piezoelectric nanogenerator (PENG) device. The PENG devices were subjected to palm tapping, wrist tapping, and elbow hitting to extract energy. The PENG generated peak-to-peak voltage of 8.22 V, short circuit current of 3.36 µA, and an instantaneous power of 0.14 mW/cm2. Compared to monolayer films, functionally graded films exhibit greater piezoelectric performance as the number of nanofiber layers increases. The piezoelectric output of PENGs device is validated using Comsol Multiphysics software. This study demonstrated the first application of electrospun functionally graded nanostructures as piezoelectric nanogenerators.

Nature‐Driven Edible Black Soldier Fly (BSF) Insect Larvae Derived Chitin Biofilm for Sustainable Multifunctional Energy Harvesting

AbstractWith the increasing demand for portable electronic devices and the shortage of conventional energy resources, energy harvesting from natural resources has gained much attention. Herein, they proposed a black soldier fly (BSF) derived chitin biofilm to fabricate high‐performance triboelectric and piezoelectric nanogenerators. The physiochemical characterizations of the chitin biofilm are demonstrated by the presence of the hydroxyl group, alpha chitin, and beta chitin, which are responsible for the remarkable tribopositive, and piezoelectric function of the chitin derived from BSF. The electrical performance of the proposed work, such as voltage, current, and instantaneous power from BSF/PTFE‐based triboelectric nanogenerator (TENG) are exhibited at 121 V, 15 µA, and 217.8 µW, respectively. Ag/BSF/Ag piezoelectric nanogenerator (PENG) is generated 18 V voltage, 2.2 µA current, and 5 µW instantaneous power. Moreover, the proposed TENG and PENG devices demonstrate the ability to charge the dielectric capacitors and drive low‐power electronic devices like LEDs and a calculator. The proposed results suggested that chitin is a superior biomaterial for developing sustainable energy harvesting devices.

Effect of electrode patterns on piezoelectric energy harvesting property of zinc oxide polyvinylidene fluoride based piezoelectric nanogenerator

Renewable energy generation is one of the key strategies to solve energy shortages and environmental problems. Among various techniques of renewable energy generation and harvesting, piezoelectric energy harvesting receives huge consideration due to the enormous demand in self-powered electronic devices. Therefore, the development of a piezoelectric nanogenerator (PENG) with effective piezoelectric energy harvesting performance is very important. Herein, we develop zinc oxide polyvinylidene fluoride based (ZnO@PVDF PENG) device and study on the effects of electrode patterns on the piezoelectric performances of the device. We also investigate real application of the device in our daily life. The findings show that interdigitated electrode patterned ZnO@PVDF PENG present the highest piezoelectric performance by harvesting output current, voltage, and power density of 1.15 μA, 50 V, and 20.10 mW/m2, respectively at 12 N. The device also scavenges energy that has capacity to light 20 green light emitting diodes (LEDs) and display a liquid crystal display (LCD) timer for 1 s. Moreover, the ZnO@PVDF PENG) device shows excellent cyclic charging and discharging property, which is very important for practical applications. Therefore, this PENG device is promising candidate to harvest green and renewable energy and use to power electronic devices.

Investigation of electrospun piezoelectric P(VDF-TrFE) nanofiber-based nanogenerators for energy harvesting

A piezoelectric nanogenerator (PENG) from thin poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) polymer fiber films synthesized by the electrospinning method demonstrated the enhanced output. The β-phase content in thin films that is essential for piezo responses in polymers was analyzed using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) imaging. The results showed an extremely high 92,8% of β-phase content in P(VDF-TrFE) thin films. The fabricated PENG device using P(VDF-TrFE) film demonstrated an outstanding peak-to-peak open-circuit voltage (Voc) of ∼25 V and short-circuit current (Isc) of 0.3 μA under 3 N applied force. The device could produce a maximum power density of ∼125 nW cm −2 under a 6 N load. The maximum voltage of ∼100 V was achieved with the compressive force of 20 N. Moreover, the ability to charge 0.1 μF capacity to ∼6.5 V within 180 sec was demonstrated under an external load of 6 N at 5 Hz. It can be concluded that the improved piezoelectric performance of PENG was achieved due to high β-phase content and the optimized synthesis route. The obtained electrical performance of PENG demonstrated its potential for powering low-power electronic devices by scavenging mechanical energy.

ZnO/f-MWCNT as a potential candidate for supercapacitive energy storage and piezoelectric energy generation

Zinc oxide/ functionalized multiwalled carbon nanotube (ZnO/f-MWCNT) composite was synthesized in two simple steps. In the first step, MWCNT was functionalized using acid refluxing method and in the second step, ZnO/f-MWCNT composite was synthesized in situ via hydrothermal route. Next, possibility of the ZnO/f-MWCNT composite as a hybrid energy storage device was explored through detailed electrochemical and other required investigations. Aiming to real-life applications, a symmetric supercapacitor device was also fabricated followed by detailed performance evaluation. In the last part, energy harvesting possibilities of the ZnO/f-MWCNT composite through the fabrication of a piezoelectric nanogenerator (PENG) was also explored. To do so, ZnO/f-MWCNT/ polyvinylidene fluoride (PVDF) composite films with varying wt% of the filler (i.e. ZnO/f-MWCNT) were prepared. The structural, morphological, compositional, electrochemical and electrical attributes of both the materials were thoroughly investigated. Highest specific capacitance obtained from this ZnO/f-MWCNT electrode was 794 F/g (at 1 A/g) with a power density of 4152 W/kg (at 50 A/g). The PENG device yielded an open circuit voltage of ∼80 V with a power density of 72 kW/m3.

Sputter-deposited highly flexible noble metal multi-layer electrode viable for energy and luminescent devices

Transparent conducting Indium tin oxide (ITO) electrode is predominantly utilized currently in most of the display and energy harvesting devices. However, its sustained usage is an imminent imperil due to its low availability, dwindling supply and recycling issues. There is a dire need to supplement the usage of ITO with appropriate alternatives in desired resistance scale, depending on the device necessity. At this juncture, an analogous viable transparent conducting ultrathin Au/Cu/Ag/Pt/Au noble metallic multi-layer electrode sputtered onto PET substrate is investigated. The multi-layer presents highest transmittance of 44% (at 500 nm) with a nearly uniform trend over the complete visible region of the electromagnetic spectrum. Electrical transport measurements of the multi-layer yielded 60 Ω/□ sheet resistance and a carrier mobility of 2.02 cm2 V−1 s−1. The transition of bare PET from hydrophilic (73.85°) to hydrophobic (99.83°) upon depositing the metallic multi-layer is indicated from contact angle measurements. The surface features studied using atomic force microscope and optical profiler show a uniform topography, free from cracks. The metallic multi-layer exhibits high mechanical strength up to 50,000 bending - twisting sequences. The measured surface work function of Au/Cu/Ag/Pt/Au metallic multi-layer is 5.01 eV. The ultrathin pliable metallic multi-layer tested in a piezoelectric nanogenerator device and alternating current-operated electroluminescent device as top electrode and bottom electrode, displays significant performance.

P(VDF-TrFE)/BaTiO3 nanocomposite Langmuir-Schaefer thin film for piezoelectric nanogenerator

In this study, a piezoelectric nanogenerator (PENG) was fabricated based on nanocomposite thin films comprising piezoelectric poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) as a matrix and BaTiO3 (BTO) nanoparticles (NPs) as a nanofiller. The Langmuir-Schaefer (LS) technique was employed to prepare the films. A mixed solution of the polymer and ceramic NPs was spread on the surface of water subphase at a predetermined surface pressure, and thin films were then prepared by transferring the spread monolayer onto indium tin oxide-coated polyethylene terephthalate (ITO-PET) substrate multiple times at a constant surface pressure. Microstructure, crystallinity, β-phase content, dielectric constant, and piezoelectric coefficient (d33) of the thin films were measured with SEM, XRD, FT-IR, LCR meter, and Quasi-static meter, respectively. Six different PENG devices with different BTO contents were fabricated by arranging the thin film-coated substrates in sandwich structure, and they were subject to measurements of piezoelectric characteristics such as open-circuit output voltage (VOC) and short-circuit current (ISC). As results, it was found that the PENG with 4 wt% BTO with ten layers of monolayer deposited at the surface pressure of 15 mN/m yielded the highest VOC of 71.4 V, which was higher than pristine polymer LS film’s 66.2 V at the same conditions, and power density of 35.7 μW/cm2 at 2.5 Hz bending-releasing frequency. This optimum piezoelectric performance was explained in terms of the highest crystallinity, β-phase content, and dielectric properties at the specific BTO content. The optimum PENG coupled with a capacitor and several light emitting demonstrated that it is possibly used to supply power with large energy storage capability of 470 µJ with a 1 µF capacitor for 3 min. This PENG of improved performance is promising as a supply power for a self-powered microelectronics because it has additional advantages of facile fabrication and coating a large area.

Ferroelectric composite-based piezoelectric energy harvester for self-powered detection of obstructive sleep

Lead-free piezoelectric ceramic is a promising material for energy harvesters, as they have superior electromechanical, ferroelectric, and piezoelectric properties. In addition, piezoelectric ceramics can be blended with polymer to achieve high-flexibility polymer-ceramic composites, providing mechanical robustness and stability. In this context, a new lead-free ferroelectric material, having the chemical formula SrTi2O5 (STO), was synthesized using a high-temperature solid-state reaction. Detailed analyses of the structural, morphological, and electrical properties of the synthesized material were performed. STO crystallizes with orthorhombic symmetry and space group of Cmm2. The frequency and temperature-dependent dielectric parameters were evaluated, and impedance spectroscopy shed light on the charge dynamics. The PDMS-STO composites at different mass fraction of the STO were prepared using a solvent casting route, and a corresponding piezoelectric nanogenerator (PENG) was developed. The electrical output of the different PENG by varying massfractions of STO in PDMS and varying force were investigated. The 15% (in mass) PENG device delivered the highest peak-to-peak voltage, current, and power density of 25 V, 92 nA, and 0.64 μW @ 500 MΩ, respectively. The biomechanical energy harvesting using the PENG device by daily human motions, bending of the device, and attaching the device to laboratory equipment was demonstrated. Later the PENG device was attached to the human throat region, and snoring signals were recorded. A classification model was designed employing the convolutional neural network (CNN) model. Efforts have been laid to differentiate between normal and abnormal snores, which could help the patient with screening and early disease detection, contributing to self-powered healthcare applications.

3D-printed polymer composite devices based on a ferroelectric chiral ammonium salt for high-performance piezoelectric energy harvesting.

Three-dimensional printing (3DP) is an emerging technology to fabricate complex architectures, necessary to realize state-of-the-art flexible and wearable electronic devices. In this regard, top-performing devices containing organic ferro- and piezoelectric compounds are desired to circumvent significant shortcomings of conventional piezoceramics, e.g. toxicity and high-temperature device processibility. Herein, we report on a 3D-printed composite of a chiral ferroelectric organic salt {[Me3CCH(Me)NH3][BF4]} (1) with a biodegradable polycaprolactone (PCL) polymer that serves as a highly efficient piezoelectric nanogenerator (PENG). The ferroelectric property of 1 originates from its polar tetragonal space group P42, verified by P-E loop measurements. The ferroelectric domain characteristics of 1 were further probed by piezoresponse force microscopy (PFM), which gave characteristic 'butterfly' and hysteresis loops. The PFM amplitude vs. drive voltage measurements gave a relatively high magnitude of the converse piezoelectric coefficient for 1. PCL polymer composites with various weight percentages (wt%) of 1 were prepared and subjected to piezoelectric energy harvesting tests, which gave a maximum open-circuit voltage of 36.2 V and a power density of 48.1 μW cm-2 for the 10 wt% 1-PCL champion device. Furthermore, a gyroid-shaped 3D-printed 10 wt% 1-PCL composite was fabricated to test its practical utility, which gave an excellent output voltage of 41 V and a power density of 56.8 μW cm-2. These studies promise the potential of simple organic compounds for building PENG devices using advanced manufacturing technologies.

High-Performance Flexible Piezoelectric Nanogenerator Based on Electrospun PVDF-BaTiO3 Nanofibers for Self-Powered Vibration Sensing Applications

In the present era of intelligent electronics and Internet of Things (IoT), the demand for flexible and wearable devices is very high. Here, we have developed a high-output flexible piezoelectric nanogenerator (PENG) based on electrospun poly(vinylidene fluoride) (PVDF)-barium titanate (BaTiO3) (ES PVDF-BT) composite nanofibers with an enhanced electroactive phase. On addition of 10 wt % BaTiO3 nanoparticles, the electroactive β-phase of the PVDF is found to be escalated to ∼91% as a result of the synergistic interfacial interaction between the tetragonal BaTiO3 nanoparticles and the ferroelectric host polymer matrix on electrospinning. The fabricated PENG device delivered an open-circuit voltage of ∼50 V and short-circuit current density of ∼0.312 mA m-2. Also, the PVDF-BT nanofiber-based PENG device showed an output power density of ∼4.07 mW m-2, which is 10 times higher than that of a pristine PVDF nanofiber-based PENG device. Furthermore, the developed PENG has been newly demonstrated for self-powered real-time vibration sensing applications such as for mapping of mechanical vibrations from faulty CPU fans, hard disk drives, and electric sewing machines.

Magnetically tunable enhanced performance of CoFe2O4–PVDF nanocomposite film-based piezoelectric nanogenerator

Flexible piezoelectric nanogenerator (PENG) using a poly(vinylidene fluoride)–cobalt ferrite (PVDF–CFO) nanocomposite film is prepared in which the output power of the PENG device can be tuned by the application of an external magnetic field. Ferromagnetic CFO nanoparticles were prepared by the hydrothermal method and are incorporated in the PVDF matrix using the drop casting technique. The presence of CFO in the PVDF matrix enhances the ferroelectric β phase fraction of PVDF from 59% to 75% and also provides magnetic tunability to the PENG device. With the application of a 2.1 kG field, there is 2.33 times increment in instantaneous output power of the PENG, which is attributed to a decrease in the resistance of the nanocomposite film due to the alignment of the magnetic moment of CFO nanoparticles leading to a reduction in the scattering of mobile charges. These outcomes open up a possibility in piezomagnetotronic materials through the realization of magneto-sensitive multifunctional PENGs, which can be scaled up for fabricating compact, high-performance, portable devices for smart sensor applications.

Biocompatible CaTiO3-PVDF composite-based piezoelectric nanogenerator for exercise evaluation and energy harvesting

Biocompatible energy-harvesting platforms can significantly promote the development of self-powered devices to improve the human lifestyle. However, the low power of these devices is a bottleneck and requires an alternative power source. Herein, we have developed calcium titanate (CTO) perovskite-based polymeric composite (polyvinylidene fluoride (PVDF)) as a piezoelectric nanogenerator (PENG) to be used as a power source. X-ray tomography images confirm that CTO particles are well dispersed inside the PVDF matrix. It is realized that the electrical output of the device increases with the addition of CTO in PVDF. The maximum device performance was observed for 8 wt. % CTO-PVDF composite film with an output voltage of 20 V, current of 250 nA, and power density of 0.19 μW/cm2 at 108 Ω. The PENG delivered a consistent output and could charge commercial capacitors demonstrating its potential as a sustainable power source. Moreover, the biocompatibility of CTO-PVDF film was validated by NIH3T3 cells. The CTO-PVDF composite-based PENG device was installed in the heel area to collect the signal generated from the skipping practice of individuals. The digital signal processing techniques and the artificial neural network (ANN) were utilized to detect the skipping patterns. Such a self-powered activity tracker unit will correctly monitor human health, preventing severe chronic conditions such as knee pain, calf strain, and plantar fasciitis.

Enhanced Output Performance of a Flexible Piezoelectric Nanogenerator Realized by Lithium-Doped Zinc Oxide Nanowires Decorated on MXene.

A flexible piezoelectric composite is composed of a polymer matrix and piezoelectric ceramic fillers to achieve good mechanical flexibility and processability. The overall piezoelectric performance of a composite is largely determined by the piezoelectric filler inside. Thus, different dispersion methods and additives that can promote the dispersion of piezoelectric ceramics and optimal composite structures have been actively investigated. However, relatively few attempts have been made to develop a filler that can effectively contribute to the performance enhancement of piezoelectric devices. In the present work, we introduce the fabrication and performance of the composite piezoelectric devices composed of Li-doped ZnO nanowires (Li: ZnO NWs) grown on the surface of MXene (Ti3C2) via the hydrothermal process. Through this approach, a semiconductor-metal hybrid structure is formed, increasing the overall permittivity. Moreover, the Ti3C2 layer can serve as a local ground in the composite so that the ferroelectric phase-transformed Li: ZnO NWs grown on its surface can be more effectively polarized during the poling process. In addition, the NW-covered surface of Ti3C2 prevents the aggregation of metallic Ti3C2 particles, promoting a more uniform electric field distribution during the poling process. As a result, the output performance of the piezoelectric nanogenerator (PENG) fabricated with a Li: ZnO NW/Ti3C2 composite was greatly improved compared to that of the devices fabricated with Li: ZnO NWs without the Ti3C2 platform. Specifically, the Li: ZnO NW/Ti3C2 composite piezoelectric nanogenerator (PENG) demonstrated a twofold higher output power density (∼9 μW/cm2) compared with the values obtained from the PENG devices based on Li: ZnO NWs. The approach introduced in this work can be easily adopted for an effective ferroelectric filler design to improve the output performance of the piezoelectric composite.

Ultra-robust tribo- and piezo-electric nanogenerator based on metal organic frameworks (MOF-5) with high environmental stability

Isoreticular metal–organic frameworks (IRMOFs) as a subseries of metal-organic frameworks (MOF) have excellent thermal and chemical stability, tuneable porosity, and high surface area as compared to other MOFs. IRMOFs' appealing properties can lead to their usefulness in the fabrication of tribo- and piezo-electric nanogenerators. For the first time, this paper applies metal-organic frameworks (MOF-5 or IRMOF-1) for fabricating tribo- and piezo-electric nanogenerator for energy harvesting. The MOF-5 based tribo-electric nanogenerator (TENG) produces an excellent output performance with the open-circuit voltage of 484 V, short-circuit current of 40 µA, and maximum instantaneous power of 3174 µW. Here, the proposed TENG presents a stable performance under adverse environmental conditions such as temperature and humidity, showing its robustness under harsh environmental conditions. The fabricated TENG device is utilized to charge the various commercial capacitors, power up the light-emitting diodes (LEDs) and drive low-power electronic devices such as a calculator and stopwatch. In addition, the MOF-5 is further studied for fabricating piezo-electric nanogenerator (PENG). The fabricated PENG device with 5 wt% MOF-5 blended in PDMS yields an open-circuit voltage of 27 V, short-circuit current of 2.9 µA, and maximum instantaneous power of 5.76 µW, respectively. Furthermore, the PENG device is utilized to charge the various commercial capacitors and power up the LEDs. These results demonstrate that MOF-5 can be applied for fabricating ultra-robust TENG for a harsh environmental condition, and also an effective way towards piezo-electric nanogenerators.

Anisotropic Piezoelectric Response from InGaN Nanowires with Spatially Modulated Composition and Topography over a Textured Si(100) Substrate.

An anisotropic piezoelectric response is demonstrated from InGaN nanowires (NWs) over a pyramid-textured Si(100) substrate with an interfacet composition and topography modulation induced by stationary molecular beam epitaxy growth conditions, taking advantage of the unidirectional source beam flux. The variations of InGaN NWs between the pyramid facets are verified in terms of morphology, element distribution, and crystalline properties. The piezoelectric response is investigated by electrical atomic force microscopy (AFM) with a statistic analyzing method. Representative pyramids from the ensemble, on top of which InGaN NWs grown with a substrate held at an oblique angle, were characterized for understanding and confirming the degree of anisotropy. The positive deviated oscillation of the peak force error is identified as a measure of the effective AFM tip/NW interaction with respect to the electrical contact and mechanical deformation. The Schottky contact between the metal-coated AFM tip and the NWs on the different facets reveals distinctions consistent with the interfacet composition variation. The interfacet variation of the piezoelectric response of the InGaN NWs is first evaluated by electrical AFM under zero bias. The average current monotonically depends on the scan frequency, which determines the average peak force error, that is, mechanical deformation, with a facet characteristic slope. A piezoelectric nanogenerator device is fabricated out of a sample with an ensemble of pyramids, which exhibits anisotropic output under periodic directional pressing. This work provides a universal strategy for the synthesis of composite semiconductor materials with an anisotropic piezoelectric response.

Piezoelectric Nanogenerator Based on Lead-Free Flexible PVDF-Barium Titanate Composite Films for Driving Low Power Electronics

Self-powered sensor development is moving towards miniaturization and requires a suitable power source for its operation. The piezoelectric nanogenerator (PENG) is a potential candidate to act as a partial solution to suppress the burgeoning energy demand. The present work is focused on the development of the PENG based on flexible polymer-ceramic composite films. The X-ray spectra suggest that the BTO particles have tetragonal symmetry and the PVDF-BTO composite films (CF) have a mixed phase. The dielectric constant increases with the introduction of the particles in the PVDF polymer and the loss of the CF is much less for all compositions. The BTO particles have a wide structural diversity and are lead-free, which can be further employed to make a CF. An attempt was made to design a robust, scalable, and cost-effective piezoelectric nanogenerator based on the PVDF-BTO CFs. The solvent casting route was a facile approach, with respect to spin coating, electrospinning, or sonication routes. The introduction of the BTO particles into PVDF enhanced the dielectric constant and polarization of the composite film. Furthermore, the single-layered device output could be increased by strategies such as internal polarization amplification, which was confirmed with the help of the polarization-electric field loop of the PVDF-BTO composite film. The piezoelectric nanogenerator with 10 wt% BTO-PVDF CF gives a high electrical output of voltage 7.2 V, current 38 nA, and power density of 0.8 μW/cm2 at 100 MΩ. Finally, the energy harvesting using the fabricated PENG is done by various actives like coin dropping, under air blowing, and finger tapping. Finally, low-power electronics such as calculator is successfully powered by charging a 10 μF capacitor using the PENG device.

Tin disulfide piezoelectric nanogenerators for biomechanical energy harvesting and intelligent human-robot interface applications

Abstract Tin disulfide nanosheets (SnS2 NSs), belonging to a new family of layered metal dichalcogenides, have evoked considerable attention in multidisplinary scientific applications because of their high electron mobility, excellent chemical stability, and wide accessibility to optoelectronic devices. However, despite the prediction of SnS2 to possess excellent piezoelectricity, only very few attempts have been made to investigate the electromechanical characterisitcs of SnS2. Herein, we report the experimental investigation of the intrinsic piezoelectricity of SnS2 NSs, which were synthesized with a facile chemical vapor deposition (CVD) method. The prominent inverse piezoelectricity of SnS2 NSs was measured via piezoresponse force microscpoy (PFM). To further evaluate the piezoelectric performance, SnS2 NSs were integrated into a piezoelectric nanogenerator (PENG) device to display the energy harvesting and active sensing capabilities. Most importantly, the SnS2 PENG device was utilized to explore the synchronous human-robot control of a smart sign language system, which demonstrates great potential for the future applications in human-machine interface and enabling sensing technology.

Development of Sn-doped ZnO based ecofriendly piezoelectric nanogenerator for energy harvesting application

In this work, we have a demonstrated zinc oxide (ZnO) polymer-based ecofriendly piezoelectric nanogenerator (PENG) on a paper substrate for an energy harvesting application. The ZnO thin film is developed on the paper substrate, where different doping concentrations of Sn have been investigated systematically to validate the effect of doping towards enhancing the device performance. The piezoelectric potential of the fabricated device is evaluated by applying three different loads (4 N, 8 N, 22 N), where the source of the corresponding mechanical loads is based on the object of a musical drum stick. The results suggest that the pristine ZnO PENG device can generate a maximum output voltage and current of 2.15 V and 17 nA respectively. Moreover, the ZnO PENG device doped with 2.5% Sn achieved an even higher voltage (4.15 V) and current (36 nA) compared to pristine ZnO devices. In addition, the hydrothermal growth technique used to develop Sn-doped ZnO has the benefits of high scalability and low cost. Hence, the Sn-doped PENG device is a suitable candidate for energy harvesting applications operating in both uniform and non-uniform loading conditions.

Performance of all-solution-processed, durable 2D MoS2 flakes−BaTiO3 nanoparticles in polyvinylidene fluoride matrix nanogenerator devices using N-methyl-2-pyrrolidone polar solvent

Piezoelectric nanogenerator (PENG) is an alternative sustainable solution by transforming surrounding mechanical energy into electrical power. In this work, the optically transparent and mechanically flexible PENG devices were fabricated using simple all-solution-processed techniques. The device was constructed using spin- and spray coating methods to form the structure of silver nanowires/nanocomposite/poly (3,4-ethylenedioxythiophene) polystyrene sulfonate. The nanocomposite is a blending of barium titanite nanoparticles and molybdenum disulfide flakes in the polyvinylidene fluoride matrix. PENG devices were prepared with dimethylformamide (DMF) and N-Methyl-2-pyrrolidone (NMP) solvents, respectively to examine the influence of the solvents towards the output voltage. It is found that the PENG device prepared with the NMP solvent generated a voltage of 750 mV, significantly higher output voltage than the PENG device prepared by DMF, which is about 100 mV. The probable reasons could be the higher dipole moment of NMP solvent, interaction, and intercalation of MoS2 flakes in the PVDF polymer chain matrix. An automated self-tapping machine was designed to perform the endurance study. The device was able to generate stable 1.5 V of peak-to-peak voltage up to 5000 cycles in a total 5-day intermittent test without significant degradation. The PENG device prepared in the NMP solvent maintained at least 95% of its 1.5 V throughout the whole testing cycle.