Piezoelectric Nanogenerator Research Articles

Self-powered chitosan/graphene oxide hydrogel band-aids with bioadhesion for promoting infected wounds healing.

Typical anti-infection strategies, such as antibiotics and other antibacterial nanomaterials, are effective in preventing bacterial infections during the wound healing process. Additionally, electrical stimulation (ES) can also inhibit bacterial growth and facilitate skin wound repair. However, self-powered and therapeutic wearable devices combining antibacterial materials with ES are still lacking. In this research, a bio-adhesive band-aid with antibacterial activity and piezoelectric properties made up of a chitosan/graphene oxide (CSGO) hydrogel matrix and a piezoelectric nanogenerator (PENG) patch based on electrospun polyvinylidene difluoride (PVDF) nanofibers is developed for infected wound healing. Specifically, self-adhesive CSGO hydrogels help the band-aid closely adhere to the wound site, and PVDF nanofibers convert biokinetic energy into electricity to provide real-time ES. The in vitro antibacterial test demonstrates that >99 % of S. aureus and E. coli are killed by the treatment of CSGO hydrogel and ES. Remarkably, in the rat model of infected wounds, the assembled band-aid consisting of a PENG of 2.25 cm2 can promote angiogenesis, collagen deposition, and re-epithelialization, greatly accelerating infected wounds healing in 21 days. This study offers a simple and practicable method for the design of wearable bioelectronics, indicating a promising future in personalized healthcare and clinical treatment.

Advances of triboelectric and piezoelectric nanogenerators toward continuous monitoring and multimodal applications in the new era

Abstract Benefiting from the widespread potential applications in the era of the Internet of Thing and metaverse, triboelectric and piezoelectric nanogenerators (TENG & PENG) have attracted considerably increasing attention. Their outstanding characteristics, such as self-powered ability, high output performance, integration compatibility, cost-effectiveness, simple configurations, and versatile operation modes, could effectively expand the lifetime of vastly distributed wearable, implantable, and environmental devices, eventually achieving self-sustainable, maintenance-free, and reliable systems. However, current triboelectric/piezoelectric based active (i.e. self-powered) sensors still encounter serious bottlenecks in continuous monitoring and multimodal applications due to their intrinsic limitations of monomodal kinetic response and discontinuous transient output. This work systematically summarizes and evaluates the recent research endeavors to address the above challenges, with detailed discussions on the challenge origins, designing strategies, device performance, and corresponding diverse applications. Finally, conclusions and outlook regarding the research gap in self-powered continuous multimodal monitoring systems are provided, proposing the necessity of future research development in this field.

A comprehensive investigation on metal–organic framework based poly(vinylidene fluoride) composites as piezoelectric nanogenerators

A comprehensive investigation on metal–organic framework based poly(vinylidene fluoride) composites as piezoelectric nanogenerators

A Double‐Arch‐Structured Hybrid Triboelectric and Piezoelectric Nanogenerator Based on Polyvinylidene Fluoride/Graphene Oxide Composite Films

In this study, a methodology for fabricating double‐arch triboelectric and piezoelectric composite nanogenerators using polyvinylidene fluoride (PVDF) and graphene oxide (GO) is presented. Initially, nanofiber films comprising PVDF/GO are synthesized through electrostatic spinning. Subsequently, the PVDF/GO film is integrated with cotton fibers and a copper electrode to construct the triboelectric layer. In contrast, another portion of the PVDF/GO film, alongside a copper electrode, comprises the piezoelectric layer, with the central copper electrode acting as a common electrode. Finally, a double‐arch structure is established by employing polyethylene terephthalate film to facilitate synergistic operation between the triboelectric and piezoelectric layers. In the experimental results, it is indicated that the maximum open‐circuit voltage and short‐circuit current of the triboelectric layer of the double‐arch structure are 330 V and 36 μA, respectively, representing increases of 44% and 50% compared to those of the sandwich triboelectric structure. Additionally, the maximum open‐circuit voltage and short‐circuit current of the piezoelectric layer are 22 V and 4 μA, respectively, reflecting enhancements of 57% and 100% over those of conventional sandwich piezoelectric structures. The output power of the double‐arch composite nanogenerator is capable of lighting up 120 light‐emitting diodes. Thus, this composite nanogenerator shows great potential as an environmentally friendly energy source.

Breaking dielectric dilemma via polymer functionalized perovskite piezocomposite with large current density output

Organometal halide perovskite (OHP) composites are flexible and easy to synthesize, making them ideal for ambient mechanical energy harvesting. Yet, the output current density from the piezoelectric nanogenerators (PENGs) remains orders of magnitude lower than their ceramic counterparts. In prior composites, high permittivity nanoparticles enhance the dielectric constant (ϵr) but reduce the dielectric strength (Eb). This guides our design: increase the dielectric constant by the high ϵr nanoparticle while enhancing the Eb by optimizing the perovskite structure. Therefore, we chemically functionalize the nanoparticles to suppress their electrically triggered ion migration for an improved piezoelectric response. The polystyrene functionalizes with FAPbBr2I enlarges the grains, homogenizes the halide ions, and maintains their structural integrity inside a polymer. Consequently, the PENG produces a current density of 2.6 µAcm−2N−1. The intercalated electrodes boost the current density to 25 µAcm−2N−1, an order of magnitude enhancement for OHP composites, and higher than ceramic composites.

Harnessing the mechanical and magnetic energy with PMN-PT/Ni-Mn-In-based flexible piezoelectric nanogenerator

Multifunctional piezoelectric nanogenerators (PENG) hold significant potential in developing smart sensing technologies for the military, healthcare, and industrial sectors. Here, we present the efficient energy harvesting from mechanical and magnetic stimuli in 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) / Ni50Mn35In15 (Ni-Mn-In)-based PENG fabricated on a flexible nickel substrate using the DC/RF magnetron sputtering technique. The performance of the device has been assessed by imparting forces in the range of 0.12–0.61 N using various weights, finger tapping, bending, and magnetic fields. The device generates the maximum open circuit voltage (Voc) of 9.3 V and 6 V with 0.61 N of force and finger tapping, respectively. The corresponding short circuit current (Isc) has been obtained as 1.33 µA (0.61 N) and 0.9 µA (finger tapping). The device shows a maximum Voc of 10.6 V and Isc of 1.51 µA at the bending angle of 120°. Furthermore, the Voc and Isc have increased from 0 mV and 0 nA to 240 mV and 35 nA under the presence of 0 Oe to 500 Oe of DC magnetic field, respectively. The fabricated device exhibited a power density of 2.7 µW/cm2 with a high mechanical stability of 2500 cycles. Additionally, LEDs of green, red, yellow, and white color have been illuminated. The receptiveness of the fabricated PENG towards mechanical and magnetic stimuli highlights its potential in areas such as tactile sensing, wearable electronics, human-machine interfaces, and biomedical devices.

Dual fillers ZrO2/BaTiO3 incorporated PVDF-HFP nanofiber composite for enhanced piezoelectric energy harvesting and piezo catalytic reduction of hexavalent chromium

A novel Piezoelectric Nanogenerator (PENG) was designed and fabricated using electrospun nanocomposite fibers of Poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP) with Barium Titanate (BaTiO3) and Zirconium Oxide (ZrO2) as dual fillers. ZrO2 fillers were incorporated at varying loadings into the PVDF-HFP polymer matrix to produce the PBZ nanocomposite fibers. The synergistic effect of BaTiO3 and ZrO2 significantly enhanced the piezoelectric performance of the resulting PBZ composite. The dual fillers also induced the nucleation of the β-phase in the nanofiber composite, which further improved its piezoelectric properties. This enhancement rendered the composite highly effective for dual applications: energy harvesting and the piezocatalytic reduction of hexavalent chromium (Cr(VI)). The PENG exhibited an open-circuit voltage of 6.3 V, a current of 0.67 µA, and a power density of 30.91 mW/m². The device was also tested in real-world scenarios, such as finger tapping and shoe sole applications, additionally it successfully powered up to five LEDs and charged a 1–2.2 μF capacitor to approximately 1–3 V under an external load of 1 N at 2 Hz. In addition to energy harvesting, the PBZ nanofibers demonstrated remarkable piezocatalytic activity by converting highly toxic Cr(VI) to Cr(III), which is biologically essential in trace amounts. The PBZ nanofiber mats achieved an impressive Cr(VI) reduction rate of up to 90.1 % under acidic conditions within 20 minutes and were recyclable for up to five cycles without loss of efficiency. Furthermore, Density Functional Theory (DFT) calculations, focusing on the Density of States (DOS), were performed to elucidate the underlying mechanisms contributing to the observed improvements in piezoelectric and piezocatalytic performance.

MXene-reinforced water insensitive self-healing piezoelectric nanogenerator for ambient and aquatic mechano-pressure sensing

The development of soft electronic devices capable of autonomous self-healing (SH) holds immense potential across various endeavours, promising to revolutionize product durability, reliability, and maintenance practices. Despite some progress has been made, underwater stable SH continues to be an active area of research. Herein, SH polymer PDMS-MDI0.4-TFB0.6 (SHP) with excellent mechanical property was composited with MXene to investigate the piezoelectric nature under various circumstance. By leveraging MXene into SHP not only improves the material properties of mechanical stress but also permittivity of the elastomer. Thus, MXene incorporated SHP (mSHP) induce high polarized charges under mechanical pressure. The fabrication of mSHP piezoelectric nanogenerator (mSHP-PENG) device via spray coating AgNWs on the surface forms ohmic contact, which facilitate high sensitivity and flexibility. Nevertheless, the generated piezoelectricity (30 V, 4.2 μA: 3 Hz) upon mechanical pressure gives maximum power density of 128 μW/m2 indicating that our device can act as a reliable power source for portable electronic gadgets. In addition, SHP with amphiphilic functional groups sustain the original shape even after immerse into water for so long. Taking this into account, our device undergoes effective deformation even at low pressures, thus render to fabricate touch sensitive piezo-switches for both atmospheric and aquatics environments.

“One-stone-two-birds”: engineering a 2D layered heterojunction of terbium tungstate incorporated on molybdenum disulfide nanosheets for a battery-free self-charging power system via the integration of a wearable piezoelectric nanogenerator and an asymmetric supercapacitor

“One-stone-two-birds”: engineering a 2D layered heterojunction of terbium tungstate incorporated on molybdenum disulfide nanosheets for a battery-free self-charging power system via the integration of a wearable piezoelectric nanogenerator and an asymmetric supercapacitor

Flexible Composites with Rare-Earth Element Doped Polycrystalline Particles for Piezoelectric Nanogenerators

Energy harvesting plays an important role in advancing personalized wearables by enabling continuous monitoring, enhancing wearable functionality and facilitating sustainable solutions. We aimed to develop a flexible piezoelectric energy harvesting system based on inorganic piezoelectric materials that convert mechanical energy into electricity to power a wide range of mobile and portable electronic devices. There is significant interest in flexible piezoelectric energy harvesting systems that use inorganic piezoelectric materials due to their exceptional physical features and prospective applications. Herein, we successfully demonstrated a flexible piezoelectric nanogenerator (PENG) designed by the co-doped rare-earth element ceramics (RE-PMN-PT) embedded in PVDF and PDMS composite film and attained a significant output performance while avoiding electrical poling process. The impact of dielectric characteristics on the electrical output of nanogenerators was investigated, together with the structure of the composites. The Sm/La-PMN-PT particles effectively amplify both the voltage and current output, showcasing their potential to power portable and wearable devices, as demonstrated by their capacity to illuminate LEDs. The maximal output power of 2 mW was correlated with the high voltage (220 V) and current (90 µA) of Sm/La-PMN-PT/PVDF, which demonstrated that the device has the potential for energy harvesting in biomedical applications.

Glucose-Templated Porous PVDF-HFP Films as High-Performance Piezoelectric Nanogenerators for Charging Lithium Batteries

Glucose-Templated Porous PVDF-HFP Films as High-Performance Piezoelectric Nanogenerators for Charging Lithium Batteries

Manufacturing strategies for highly sensitive and self-powered piezoelectric and triboelectric tactile sensors

Abstract Piezoelectric and triboelectric effects are of growing interest for facilitating high-sensitivity and self-powered tactile sensor applications. The working principles of piezoelectric and triboelectric nanogenerators provide strategies for enhancing output voltage signals to achieve high sensitivity. Increasing the piezoelectric constant and surface triboelectric charge density are key factors in this enhancement. Methods such as annealing processes, doping techniques, grain orientation controls, crystallinity controls, and composite structures can effectively enhance the piezoelectric constant. For increasing triboelectric output, surface plasma treatment, charge injection, microstructuring, control of dielectric constant, and structural modification are effective methods. The fabrication methods present significant opportunities in tactile sensor applications. This review article summarizes the overall piezoelectric and triboelectric fabrication processes from materials to device aspects. It highlights applications in pressure, touch, bending, texture, distance, and material recognition sensors. The conclusion section addresses challenges and research opportunities, such as limited flexibility, stretchability, decoupling from multi-stimuli, multifunctional sensors, and data processing.

The MnAl-alloy nanoparticles incorporated PVDF-based piezoelectric nanogenerator as a self-powered real-time pedometer sensor

This study introduces a flexible, sensitive, and cost-effective hybrid piezoelectric nanogenerator (PENG) by integrating MnAl-alloy nanoparticles into a poly (vinylidene fluoride) (PVDF) nanocomposite film. The MnAl-alloy nanoparticles serve as a nucleating agent for promoting the formation of the electroactive β-phase. It is observed that the electroactive β-phase, dielectric permittivity, saturation polarization, and output performance of the device improve with the incorporation of the MnAl-alloy nanoparticles up to 7.5 wt. % in the PVDF matrix. Hence, in this work, we report a MnAl-alloy-based optimized piezoelectric nanogenerator device using a free-standing nanofiber mat (7.5 wt. % MnAl-alloy) prepared by the electrospinning technique. The as-fabricated piezoelectric nanogenerator effectively channels charges generated by mechanical stress to the electrodes, resulting in an impressive output voltage of approximately 16 V and an output current of around 7.1 μA, yielding a power of 47 μW across 4.5 MΩ resistor. Furthermore, energy harvesting from human movements such as jogging, knee bending, and walking is demonstrated for practical application. A piezo potential of approximately 8 V generated during walking showcases the development of a self-powered pedometer. Furthermore, tapping the PENG charges a capacitor of 0.1 μF up to approximately 1 V, demonstrating the potential application for the power up of small portable electronic devices.

Advancing High-Performance Piezoelectric Nanogenerators: Simple Electric Field Switching for Orientated and Aligned BaTiO3/PDMS Composite.

Barium titanate (BaTiO3) is renowned for its high dielectric constant and remarkable piezoelectric attributes, positioning it as a key element in the advancement of environmentally sustainable devices. Nevertheless, the effectiveness of piezoelectric nanogenerators (PENGs) that integrate BaTiO3 nanoparticles (NPs) and poly(dimethylsiloxane) (PDMS) poses a challenge, thereby restricting their utility in energy harvesting applications. This study presents a direct approach involving the cyclic manipulation of direct current (DC) power supply terminals to achieve unidirectional alignment of BaTiO3 NPs within a PDMS matrix, aiming to enhance the performance of the PENGs. Examination of the morphology and evaluation of diffraction planes, notably (111) and (200), in the aligned BaTiO3 PENGs exhibited well-oriented structures resulting from the repetitive switching between two electrodes, leading to improved piezoelectric properties. The BaTiO3 PENGs manifested notably higher output power (∼15 V and 1.91 μA) in contrast to devices containing randomly distributed polarized BaTiO3-PDMS composite films. The generated power was sufficient to directly operate six light-emitting diodes (LEDs) connected in series, with a collective nominal voltage of around 14 V, encompassing red, green, and blue LEDs. Nanoindentation verified the enhanced piezoelectric characteristics attributed to the alignment, sensitivity to bending, and energy-cohesive effects of clustered BaTiO3 one-dimensional (1D) pillars. These findings suggest a widely applicable technique for aligning and situating nanoparticles vertically within a polymer matrix, exploiting the intrinsic dielectric properties of the nanoparticles through a straightforward electric field switching mechanism.

Lead-free Polymer Composite Film for Photon Energy Influenced Piezoelectric Nanogenerator based on Photoactive SnS2

Piezoelectric nanogenerators (PENGs) can power microelectronics, which convert weak mechanical vibrations to electrical impulses; however, low output voltage and poor mechanical durability limit PENG use. Thus, we provide photoactive SnS2 nanofillers in a PVDF matrix for piezoelectric nanogenerators (PPENGs). Raman spectroscopy demonstrates improvement of the electroactive β-phase of PVDF due to adding photoactive hexagonal SnS2 nanoparticles with a band gap of 2.4 eV. Sandwiching the PVDF-SnS2 composite between ITO-coated substrates with silver paste contacts fabricated the PPENG. The open-circuit voltage of PPENG is 24.4 V in the dark and 72.9 V under illumination with a short-circuit current of 0.75 μA, showing its outstanding photo responsiveness. The high light absorption of SnS2 and PVDF-SnS2 interfacial polarization caused the improved response. High-performance optoelectronic and energy harvesting applications may employ this photoactive piezoelectric nanogenerator development technique.

Balancing PEDOT:PSS conductivity for optimal power output of p-n junction based ZnO piezoelectric nanogenerator

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS), has been employed in a wide range of applications owing to its good film-forming properties, high transparency, tunable conductivity, and good thermal and environmental stability. In piezoelectric nanogenerators (PENGs), p-type PEDOT:PSS has been used to form a p-n junction with n-type ZnO nanorods, which slows down the screening of the piezoelectric polarisation to increase the generated output voltage. Optimizing the conductive property of PEDOT:PSS is therefore a potential way to improve the performance of a PENG by controlling the screening effect and internal resistance of the device. In this work, ethylene glycol (EG) is added to the PEDOT:PSS layer in a ZnO PENG to modify its conductivity. Doping with EG, induces a change in conformation of the PEDOT which transform from a coil shape to expanded-coil or linear shapes as confirmed by Raman spectroscopy. The conductivity of the PEDOT:PSS layer is enhanced and the internal resistance of the PENG device is reduced, producing a higher current output. However, at the same time, devices using higher EG doping levels produce reduced voltage output, which is related to the rapid screening of the developed polarisation. Specifically, the optimal EG content was identified at 2.5%; although this resulted in a slight 4.0% reduction in voltage output compared to undoped devices, the current output increased by 41.6%, ultimately leading to a 33.1% improvement in peak power output. Therefore, we find that a balance between reducing the device resistance, which increases current output, and supressing the screening effect, which increases voltage output, is required to produce an optimum power output from the devices.

Flexible and ferroelectric electrospun PVDF- non-stoichiometric PZT nanogenerators (PENGs) membranes for low-frequency acoustic energy harvesting

Acoustic energy harvesting (AEH) at low-frequency has been exposed to serious problems such as low energy of input sound and lack of efficient materials to absorb the sound and convert it to electrical power. This study focused on the enhancement of the AEH performance of polyvinylidene fluoride (PVDF) membrane via the incorporation of non-stoichiometric PZT (nsPZT) nanoneedles as piezoelectric nanogenerators (PENG). The nanofibrous membranes with different amounts of PENG (x = 0, 2.5, 5, and 10 wt %) were synthesized by the electrospinning method. The nsPZT was provided via Nd3+ and Nb5+ co-doping as a novel approach. The microstructures revealed that the PENG was embedded well inside the fibers (x = 2.5), while the agglomerates were formed at higher amounts (x = 10). Also, the fiber diameters and porosity of membranes were changed. It was found that the maximum crystallization of the β-phase of PVDF has occurred at x = 2.5 (71 %). The dielectric of the PVDF membrane decreased with increasing the x factor due to the formation of further pores. In contrast, the ferromagnetic properties, piezoelectric sensitivity, and electrical conductivity were improved by adding the PENG. The maximum coercivity of 750 Oe, piezoelectric sensitivity of 1.959 V N−1, and minimum sheet resistance of 1.2 kΩ.sq−1 were achieved by x = 2.5. The noise reduction coefficient (NRC) of the PVDF membrane was enhanced drastically (53–163 %) by adding the PENG. The AEH performance was also enhanced by adding the PENG. The highest power density was achieved 0.0822 W g−1 (56.23 W m−2) by the PVDF-PENG membrane (x = 2.5) under 90 dB sound pressure at 2000 Hz frequency. These findings suggest the high potential of nanofibrous PVDF-PENG membrane for use in low-frequency AEH systems.

Piezoelectric Energy Harvesting in Poly(vinylidene Fluoride‐co‐hexafluoropropylene)/Barium Titanate Nanofibers and Ultrasonic Assisted Piezocatalytic Degradation of Ciprofloxacin

AbstractAn innovative approach has been adopted through the synthesis of a cost‐effective ferroelectric host polymer, which was integrated with Barium Titanate (BaTiO3) to develop an efficient electrospun Polyvinylidene Fluoride‐Hexafluoropropylene/BaTiO3 (PVdF‐HFP/BaTiO3) nanocomposite (PBT), designated for energy harvesting and piezocatalytic applications. FT‐IR affirmed the existence of the crystalline β‐phase within the nanofibers. SEM images showed that nanofiber diameter decreases as applied voltage is increased in electrospinning. The BaTiO3 nanoparticles were scattered evenly in PBT, but at lower voltages, they aggregate. PBT showed enhanced piezoelectric performance under higher voltage conditions, registering a maximum piezoelectric output of ~7.7 V and an output current of 0.77 μA. Moreover, the composite exhibited a power density of 14.15 mW/m2 at a load resistance of 20 MΩ. Fabricated piezoelectric nanogenerator (PENG) demonstrated practical utility in flexible electronics, notably in charging capacitors of 0.47 μF and 1 μF. Additionally, the piezocatalytic degradation of the antibiotic ciprofloxacin (CIP) was effectively achieved using the electrospun nanofibers, with an impressive degradation rate of up to 99.6 % within 30 minutes under acidic conditions, and the material displayed notable reusability, maintaining up to 95.5 % efficiency after five cycles. DFT calculations and COMSOL simulations alongside a comparative examination of the electronic properties of PBT.

Spontaneous Alignment of Boron Nitride Nanotubes into Polycrystalline Film Arrays for Enhanced Piezoelectric Nanogeneration

1D nanomaterials feature distinct physical properties owing to their characteristic anisotropy and size‐induced quantization; yet, creating an ordered ensemble of the nanomaterials is nontrivial, marking it as a grand challenge in materials science. Herein, the spontaneous alignment of a model 1D nanomaterial, boron nitride nanotube (BNNT), into a highly ordered multidomain film is presented. A conventional, benchtop gravity filtration is employed, during which thickening of the BNNT dispersion leads to a formation of the liquid crystal (LC) phase that is readily isolatable. The spontaneity of the phase separation excludes notoriously persisting synthetic impurities to a degree >99%, from ≈50% of the initial material purity. The LC‐based thin film features an aligned multidomain with an exceptionally low angular deviation of <2.5° and a domain size of >50 μm. A piezoelectric nanogenerator based on the thin film records a 1000‐fold increase in the piezocurrent compared to its random analog. This work demonstrates the first example of the spontaneous alignment of an unconventional nanotube system and the realization of the macroscopic properties therefrom, which can be readily expanded to 1D materials in general.

Enhanced Flexible Piezoelectric Nanogenerators Using Ethanol-Exfoliated g-C3N4/PVDF Composites via 3D Printing for Self-Powered Applications.

This study presents the development of flexible piezoelectric nanogenerators (PENGs) utilizing graphitic carbon nitride (g-C3N4) nanoflakes (CNNFs) and polyvinylidene fluoride (PVDF) composites fabricated via the direct ink writing (DIW) 3D printing method. A novel approach of synthesizing CNNFs using the ethanol exfoliation method was demonstrated, which significantly reduces preparation time and cost compared to traditional acid exfoliation. The CNNFs are incorporated into PVDFs at varying weight percentages (5, 7.5, 10, and 15 wt.%) to optimize the β-phase content and piezoelectric properties. Characterization techniques including XRD, FTIR, and FESEM confirm the successful synthesis and alignment of nanoflakes inside the PVDF matrix. The film with 7.5% CNNF achieves the highest performance, exhibiting a peak output voltage of approximately 6.5 V under a 45 N force. This study also explores the effects of UV light exposure. Under a UV light, the film exhibits an output voltage of 8 V, indicating the device's durability and potential for practical applications. The fabricated device showed significant voltage outputs during various human motions, confirming its suitability for wearable self-powered IoT applications. This work highlights the efficacy of the ethanol exfoliation method and the DIW printing technique in enhancing the performance of flexible PENGs.