Triboelectric Nanogenerator Device Research Articles

Enhancing the performance of NaNbO3 triboelectric nanogenerators by dielectric modulation and electronegative modification

Increasing the triboelectric charge density on the friction layer of polydimethylsiloxane (PDMS) is a basic approach towards improving the output performance of a triboelectric nanogenerator (TENG). Most previous work focuses on the surface structure or dielectric properties, nonetheless, a few studies have focused on electronegative modification. NaNbO3-PDMS TENG (N-TENG) devices are fabricated by dispersing cubic NaNbO3, which is a lead-free piezoelectric material with molecular oxygen dangling bonds on the surface of the crystal, into the PDMS at different mass ratios. When the mass ratio is 7 wt%, the maximum output performance of the N-TENG is obtained. The open-circuit voltage is 550 V, the short-circuit current is 16 µA, and the effective power densities reach up to 5.5 W m−2 at a load resistance of ~100 MΩ. The N-TENG has been used to assemble self-powered electronic watches and illuminate commercial light-emitting diodes, respectively. Its fundamental mechanism has also been discussed in detail from the perspective of dielectric modulation and electronegative modification. This N-TENG technology is revealed to be a splendid candidate for application in large-scale device fabrication, flexible sensors and biological devices thanks to its easy fabrication process, low consumption, high output power density and biocompatibility.

Fully stretchable and highly durable triboelectric nanogenerators based on gold-nanosheet electrodes for self-powered human-motion detection

A patchable triboelectric nanogenerator (TENG) is highly promising for self-powered human-motion detection, but it may undergo repeated stretching/releasing cycles during daily activities of a human, which may lead to mechanical fracture of each component and degradation in electrical output performance of the TENG device. Here, we report a fully stretchable and durable triboelectric nanogenerator (TENG) with gold (Au) nanosheets (NSs) embedded into both PDMS matrix and micropyramid-patterned PDMS. It was found that a new design of the Au NS electrodes dramatically improves the mechanical flexibility and stretchability, enabling to achieve the outstanding output stability of the Au NS electrode-based TENG (Au NS-TENG) during 10,000 cycles of repeated pushing and stretching tests. Our fully stretchable and durable Au NS-TENGs were successfully applied to the hand joints that can be used in the self-powered human-motion detection processes for wearable applications.

Nanopillar-array architectured PDMS-based triboelectric nanogenerator integrated with a windmill model for effective wind energy harvesting

Triboelectric nanogenerator (TENG) is an up-and-coming technology that functions based on the triboelectrification and electrostatic induction to generate the electricity from various mechanical energy sources. However, the practical applications still demand a significant improvement of the TENG output performance, so the optimization of key factors such as triboelectric material selectivity, nanostructure-like morphology, and surface contact area is very crucial. Here, we reported a TENG based on nanopillar-array architectured polydimethylsiloxane (NpA-PDMS) layers with simple and cost-effective fabrication process, high output performance, and long-term stability. We mainly focused on improving the output performance of TENG by optimizing the structural dimensions of nanopillar architectures (NpAs) distributed on the surface of PDMS. The effect of output performance of TENG by varying the period and diameter of NpAs on the surface of PDMS was theoretically and experimentally investigated. For theoretical study, we considered the NpA-PDMS as a viscoelastic material. From this simulation, we calculated the contact stress for NpA-PDMS layers and compared the behaviors by considering the contact area and stress together (i.e., the product of contact area and stress, called as a contact force). Surprisingly, the calculated results were well matched with the experimental data. And, an optimal NpA-PDMS with the period and diameter of 125nm and 60nm, respectively, was formed. Thus, the TENG with the optimal NpA-PDMS exhibited the open-circuit voltage (VOC) and short-circuit current (ISC) values of ~ 568V and ~ 25.6μA, respectively, under 10N of pushing force and 5Hz of pushing frequency. Additionally, the enduringness test of the TENG device was also conducted to confirm its mechanical stability and durability. Finally, for a real application, the optimized TENG device was incorporated with a windmill system to effectively harvest the wind energy available in indoor and outdoor environments. This windmill system effectively harvested the wind energy, exhibiting the VOC and ISC values of ~ 200V and ~ 24µA, respectively, at the wind speed of 14–15m/s.

Toward large-scale fabrication of triboelectric nanogenerator (TENG) with silk-fibroin patches film via spray-coating process

Over the past several years, the development of triboelectric nanogenerator (TENG) has blossomed owing to many advantages such as the simple structure, high conversion efficiency and wide material selectivity. Currently, most of TENG devices are constructed with micro-structured surfaces using complicated manufacturing processes. Owing to the lack of high-volume manufacturing scalability, it still remains a bottleneck to apply TENG into the commercial products. In this work, we report the development of a novel TENG, which leverages on the regenerated, flexible, biocompatible, and highly transparent silk-fibroin as a triboelectric layer and can be deposited on a PET/ITO substrate (SF/PET/ITO) using a simple spray-coating process. The as-fabricated TENG exhibits a maximum voltage of 213.9V and a high power density of 68.0mW/m2 as a result of the ability of losing electrons and rough surface rendered by the silk-fibroin. We further demonstrate that this generator can charge a capacitor (10μF) to 4.5V in 6mins, and instantaneously light up as many as 100 commercial LED bulbs. We anticipate that the large-scale fabrication of silk-fibroin-based TENGs will serve as a promising system for electricity generation with an extremely low cost to commercial applications.

Improving Triboelectric Nanogenerator Performance Using AAO and Nanopatterned PDMS

The huge environmental crises nowadays from energy consumption pushes the use of green energy grow rapidly, such as the harvest of solar, waves, wind, geothermal, or mechanical energy sources. Among these techniques, triboelectric nanogenerators (TENG) have a promising potential based on the triboelectrification and electrostatic induction. Even though, TENG have high power conversion efficiency in many previous study but low output power. Here, we focus on the improvement of the output of TENG based on anodic aluminum oxide (AAO) and nanopatterned polydimethylsiloxane (NP-PDMS) soft-lithography. The TENGs were fabricated by using PDMS with a nanoporous AAO template as a replica mold. The AAO nanopore arrays can be formed by a low cost, light weight, and simple manufacturing process. For bottom electrode, after PDMS was laminated on the nanoporous AAO arrays (PDMS/AAO), it was stuck to Aluminum foil. In order to peel off the nanostructure PDMS from AAO arrays easily, the AAO was treated by HDFS (heptadecafluoro-1,1,2,2-tetrahydrodecyl trichlorosilane) before laminating. By changing the period and diameter of NP-PDMS, we find the optimum TENG output. For the top electrode, we test with AAO and Al foil. With external input frequency of 5 Hz and force of 5N to the TENG device, we can obtain maximum output of 520V open-circuit voltage and 24uA short-circuit current for Al foil as top electrode and 125nm period, 60nm diameter NP-PDMS as bottom electrode. This TENG device after rectification was able to drive 180 LEDs connected in series.

Significant triboelectric enhancement using interfacial piezoelectric ZnO nanosheet layer

Utilising an interfacial piezoelectric ZnO nanosheet layer, a significant enhancement in the power density is reported for the triboelectric nanogenerators (TENG) based on phase inversion membranes of polyvinylidene fluoride (PVDF) and polyamide-6 (PA6). At an applied force of 80N, the TENG device incorporating electrochemically deposited ZnO nanosheets produces an output voltage of ~ 625V and a current density of ~ 40mAm−2 (corresponding a charge density of 100.6μCm−2), respectively; significantly higher than ~ 310V and ~ 10mAm−2 (corresponding a charge density of 77.45μCm−2) for the pristine TENG device. The enhancement in the surface charge density provided by the interfacial piezoelectric ZnO layer is also reflected in the high piezoelectric coefficient d33 (−74pmV−1) as compared to the pristine fluoropolymer membranes (−50pmV−1). For tribo-negative membranes incorporating the interfacial ZnO layer, piezoelectric force microscopy measurements further show enhanced domain size which can be attributed to the interfacial dipole-dipole interaction with the ferroelectric polarisation of PVDF, which promotes the alignment with the polar axis of ZnO. Under compressive stress, the piezoelectric potential thus produced in the ZnO nanosheets provides charge injection on to the surface of ZnSnO3-PVDF membrane, improving the charge density, which in-turn significantly enhances the power density from 0.11 to ~ 1.8W/m2. The TENG devices thus fabricated using a facile electrochemical deposition and phase inversion technique show enhanced output power without the need for high electric field poling or external charge injection process by relying on the coupling of triboelectric and piezoelectric effects.

Self-powered modulation of elastomeric optical grating by using triboelectric nanogenerator

Tunable optical gratings (TOGs) based on dielectric elastomer actuator (DEA) are combined with triboelectric nanogenerator (TENG), where the actuated strain of DEA under the drive of TENG can regulate the grating period. Hence, a self-powered TOG system can be achieved and TENG can serve as both power supplier and control module for this system. Three different TOG structures have been delicately designed to cooperate with the unique output performance of TENG and the actuated strain of DEA can be utilized to either compress or expand the spacing between grating array. The separation motion of the TENG with a contact surface of 120cm2 can induce a decrease of 16.5% or an increase of 9.4% for the grating period. Both one-dimensional and two-dimensional grating matrixes are designed for the TOG system, while TENG can control two kinds of grating systems to realize several functionalized modulations. The TOG systems based on TENG-DEA conjunction can achieve a fast-speed, highly efficient and multifunctional modulation of the grating period, while the breakdown problem of these TOG devices is largely suppressed since the maximum transferred charges from TENG device is under a limited value. Therefore, the demonstrated self-powered TOG may have tremendous application prospects for various display system, optical sensors, optical communications and so on.

Interdigital electrode based triboelectric nanogenerator for effective energy harvesting from water

Despite high voltage output, the low current output of triboelectric nanogenerators (TENGs) limits their expansion into practical applications. The incorporation of additional machinery, such as transformers and gear trains, has been proposed to remove this bottleneck. Here, we report a simple and cost-effective strategy that employs a compact interdigital electrode (IDE) to increase the current output in TENG devices. A foldable, twistable, and rollable IDE-based TENG, comprised of finger-like aluminum electrodes sandwiched between polytetrafluoroethylene and polyester films, was fabricated to harvest triboelectric energy from water. This IDE-based TENG exhibited a triboelectric charge threefold higher than that of a single electrode-based TENG. Triboelectric charge is greatly enhanced when the width of the IDE is comparable to the size of the water droplet being harvested. Using a cone-shaped IDE-based TENG, we showed that the folding angle of the device and the water droplet volume rate are important for enhancing triboelectric currents. Using a cylinder-shaped IDE-based TENG, we demonstrated the powering of 10 light emitting diodes and the charging of a 0.1-μF capacitor to 15V within 20s.

Crumpled Graphene Triboelectric Nanogenerators: Smaller Devices with Higher Output Performance

The rapid growth of flexible and stretchable electronics paves the way toward compact and wearable power source devices. A shape‐adaptive and stretchable energy harvester is particularly attractive due to its mobility, sustainability, and availability. In this work, a crumpled‐graphene‐based stretchable triboelectric nanogenerator (TENG) to harvest mechanical energy under various deformations is reported. Due to the unique stretchability of crumpled graphene structures, the crumpled‐graphene‐based TENGs could operate under compressive mode, stretching mode, and, more uniquely, their hybridized mode. Importantly, by shrinking a given planar graphene layer into a smaller region, a more crumpled TENG device delivered a higher output voltage, revealing the superior potential to develop smaller and better performance power generators for emerging wearable electronics. Its application as the energy harvester and motion sensor was demonstrated using finger and wrist motions.

Self‐Powered Electrostatic Actuation Systems for Manipulating the Movement of both Microfluid and Solid Objects by Using Triboelectric Nanogenerator

By integrating a triboelectric nanogenerator (TENG) and an electrostatic actuation system (EAS), two kinds of self‐powered EAS are designed for manipulating the movement of both microfluid and tiny solid objects. The mechanical triggering of the TENG can generate an extremely high electrostatic field inside EAS and thus the tiny object (liquid or solid) in the EAS can be actuated by the Coulomb force. Accordingly, the tribomotion of TENG can be used as both the driving power and control signal for the EAS. The TENG device with a contact surface of 70 cm2 can drive a water droplet to move across a gap of 2 cm. Meanwhile, the confluence of two droplets with the same charge polarity and different components can also be induced and controlled by this self‐powered EAS. In addition, based on the same working principle, this EAS also demonstrates its capability for manipulating solid object (e.g., a tiny steel pellet). By sliding the Kapton film along a segmented annular electrode, the tiny pellet can well follow the rotated motion of the Kapton film. The demonstrated concept of this self‐powered EAS has excellent applicability for various micro/miniature actuation devices, electromechanical systems, human–machine interaction, etc.

Modeling a dielectric elastomer as driven by triboelectric nanogenerator

By integrating a triboelectric nanogenerator (TENG) and a thin film dielectric elastomer actuator (DEA), the DEA can be directly powered and controlled by the output of the TENG, which demonstrates a self-powered actuation system toward various practical applications in the fields of electronic skin and soft robotics. This paper describes a method to construct a physical model for this integrated TENG-DEA system on the basis of nonequilibrium thermodynamics and electrostatics induction theory. The model can precisely simulate the influences from both the viscoelasticity and current leakage to the output performance of the TENG, which can help us to better understand the interaction between TENG and DEA devices. Accordingly, the established electric field, the deformation strain of the DEA, and the output current from the TENG are systemically analyzed by using this model. A comparison between real measurements and simulation results confirms that the proposed model can predict the dynamic response of the DEA driven by contact-electrification and can also quantitatively analyze the relaxation of the tribo-induced strain due to the leakage behavior. Hence, the proposed model in this work could serve as a guidance for optimizing the devices in the future studies.

Enhancement of output performance through post-poling technique on BaTiO3/PDMS-based triboelectric nanogenerator

In the modern era, the invention of new energy sources is important in order to make advances possible in electronic media. A triboelectric nanogenerator (TENG) is considered to be strong design that converts mechanical power into electrical power, using organic (polymer) or inorganic (lead, ceramic etc) materials to initiate the triboelectrification process, followed by charge separation. In this study, a lead-free BaTiO3/PDMS-Al-based TENG was fabricated by mixing tetragonal ferroelectric BaTiO3 nanocrystals in a PDMS matrix to make a composite for a working electrode film. It is worth noting that a new post- poling process has been introduced to align the dipole structures in the BaTiO3 nanocrystals, and to attain a high electron density on the surface of the working electrode film. The output was recorded up to 375 V and 6 μA of close circuit voltage and short circuit current, respectively, at a current density of 0.3 μA cm−2 and an effective power equal to 2.25 mW at a load resistance of 100 MΩ, and is four times higher than a PDMS-Al-based TENG. This study also reveals the hidden locks that will enable other inorganic materials with a dipole structure to enhance their output using the post-poling technique. The TENG has a vast field of applications due to its stability, the flexibility of its thin films and its biocompatibility. It is also an aid for exploring new TENG devices with enhanced output performance.

A Self-Powered Implantable Drug-Delivery System Using Biokinetic Energy.

The first triboelectric-nanogenerator (TENG)-based self-powered implantable drug-delivery system is presented. Pumping flow rates from 5.3 to 40 µL min-1 under different rotating speeds of the TENG are realized. The implantable drug-delivery system can be powered with a TENG device rotated by human hand motion. Ex vivo trans-sclera drug delivery in porcine eyes is demonstrated by utilizing the biokinetic energies of human hands.

Self‐Powered Wireless Sensor Node Enabled by a Duck‐Shaped Triboelectric Nanogenerator for Harvesting Water Wave Energy

This paper presents a fully enclosed duck‐shaped triboelectric nanogenerator (TENG) for effectively scavenging energy from random and low‐frequency water waves. The design of the TENG incorporates the freestanding rolling mode and the pitch motion of a duck‐shaped structure generated by incident waves. By investigating the material and structural features, a unit of the TENG device is successfully designed. Furthermore, a hybrid system is constructed using three units of the TENG device. The hybrid system achieves an instantaneous peak current of 65.5 µA with an instantaneous output power density of up to 1.366 W m−2. Following the design, a fluid–solid interaction analysis is carried out on one duck‐shaped TENG to understand the dynamic behavior, mechanical efficiency, and stability of the device under various water wave conditions. In addition, the hybrid system is experimentally tested to enable a commercial wireless temperature sensor node. In summary, the unique duck‐shaped TENG shows a simple, cost‐effective, environmentally friendly, light‐weight, and highly stable system. The newly designed TENG is promising for building a network of generators to harvest existing blue energy in oceans, lakes, and rivers.

Hydrophobic SiO2 Electret Enhances the Performance of Poly(vinylidene fluoride) Nanofiber-Based Triboelectric Nanogenerator

Mechanical energy harvesting is a green technology with great potential for applications in self-powered portable electronics, wireless sensing, implanted devices, and security systems. We have previously reported a triboelectric nanogenerator (TENG) fabricated from poly(vinylidene fluoride) (PVDF) electrospun nanofibers. This device enabled harvesting of mechanical energy and exhibited an output voltage of 210 V. Here we report doping of the PVDF nanofibers with silica (SiO2) nanoparticles, which increased the output performance of the resultant TENG devices. The output peak to peak voltage was increased to 370 V as the SiO2 nanoparticles content was increased to 0.6 wt % and then declined with further increases in SiO2 content. Hydrophobic SiO2 nanoparticles (mSiO2) were prepared by an octanol treatment and markedly increased the performances of the resulting TENG devices. An output peak to peak voltage of up to 430 V was achieved with 0.8 wt % mSiO2 representing a 48% increase over the value obtained f...

Hybrid Energy Cell with Hierarchical Nano/Micro-Architectured Polymer Film to Harvest Mechanical, Solar, and Wind Energies Individually/Simultaneously.

We report the creation of hybrid energy cells based on hierarchical nano/micro-architectured polydimethylsiloxane (HNMA-PDMS) films with multifunctionality to simultaneously harvest mechanical, solar, and wind energies. These films consist of nano/micro dual-scale architectures (i.e., nanonipples on inverted micropyramidal arrays) on the PDMS surface. The HNMA-PDMS is replicable by facile and cost-effective soft imprint lithography using a nanoporous anodic alumina oxide film formed on the micropyramidal-structured silicon substrate. The HNMA-PDMS film plays multifunctional roles as a triboelectric layer in nanogenerators and an antireflection layer for dye-sensitized solar cells (DSSCs), as well as a self-cleaning surface. This film is employed in triboelectric nanogenerator (TENG) devices, fabricated by laminating it on indium-tin oxide-coated polyethylene terephthalate (ITO/PET) as a bottom electrode. The large effective contact area that emerged from the densely packed hierarchical nano/micro-architectures of the PDMS film leads to the enhancement of TENG device performance. Moreover, the HNMA-PDMS/ITO/PET, with a high transmittance of >90%, also results in highly transparent TENG devices. By placing the HNMA-PDMS/ITO/PET, where the ITO/PET is coated with zinc oxide nanowires, as the top glass substrate of DSSCs, the device is able to add the functionality of TENG devices, thus creating a hybrid energy cell. The hybrid energy cell can successfully convert mechanical, solar, and wind energies into electricity, simultaneously or independently. To specify the device performance, the effects of external pushing frequency and load resistance on the output of TENG devices are also analyzed, including the photovoltaic performance of the hybrid energy cells.

Triboelectric nanogenerators and power-boards from cellulose nanofibrils and recycled materials

This paper reports the implementation of renewable, biodegradable, and abundant cellulose nanofibrils (CNFs) in triboelectric nanogenerator (TENG) development. Flexible and transparent CNF thin films are triboelectric positive material with nanoscale surface roughness. They are paired with FEP (fluorinated ethylene propylene) to assemble TENG devices, which exhibit comparable performance to the reported TENG devices built on synthetic polymers. CNF-based TENG is further integrated within a fiberboard made from recycled cardboard fibers using a chemical-free cold pressing method. The fiberboard produces up to ~30V and ~90μA electric outputs when subjected to a normal human step. This development shows great promises in creating large-scale and environmentally sustainable triboelectric board for flooring, packaging and supporting infrastructures from CNF and other natural wood-extracted materials.

Wind energy and blue energy harvesting based on magnetic-assisted noncontact triboelectric nanogenerator

Triboelectric nanogenerator (TENG) as a promising approach has attracted extensive attentions from academic and industry. Herein, a novel strategy of wind and blue energy harvesting based on magnetic-assisted noncontact TENG has been demonstrated. Through the combination of magnetic responsive composite with TENG device, the wind and water forces could be converted into the contact-separation action between Al/Ni electrode and PDMS film. The influence of the relevant parameters (contact-separation frequency, wind speed and humidity, etc.) on the performances of the fabricated TENG has been systematically investigated. The results show the robust potential of magnetic-assisted noncontact TENG for wind and blue energy harvesting applications.

Mechanically Robust Silver Nanowires Network for Triboelectric Nanogenerators

The authors develop a mechanically robust silver nanowires (AgNWs) electrode platform for use in flexible and stretchable triboelectric nanogenerators (TENGs). The embedding of an AgNWs network into a photocurable or thermocurable polymeric matrix dramatically enhances the mechanical robustness of the flexible and stretchable TENG electrodes while maintaining a highly efficient triboelectric performance. The AgNWs/polymeric matrix electrode is fabricated in four steps: (i) the AgNWs networks are formed on a hydrophobic glass substrate; (ii) a laminating photocurable or thermocurable prepolymer film is applied to the developed AgNWs network; (iii) the polymeric matrix is crosslinked by UV exposure or thermal treatment; and (iv) the AgNWs‐embedded polymeric matrix is delaminated from the glass substrate. The AgNWs‐embedded polymeric matrix electrodes with four different sheet resistances, controlled by varying the AgNWs network deposition density, are deployed in TENG devices. The authors find that the potential difference between the two contact surfaces of the AgNWs network‐embedded polymer matrix electrodes and the nylon (or perfluoroalkoxy alkane) governs the output triboelectric performances of the devices, rather than the sheet resistance. Both Kelvin probe force microscopy and numerical simulations strongly support these observations.

Triboelectric Nanogenerator Accelerates Highly Efficient Nonviral Direct Conversion and In Vivo Reprogramming of Fibroblasts to Functional Neuronal Cells.

Triboelectric nanogenerators (TENGs) can be an effective cell reprogramming platform for producing functional neuronal cells for therapeutic applications. Triboelectric stimulation accelerates nonviral direct conversion of functional induced neuronal cells from fibroblasts, increases the conversion efficiency, and induces highly matured neuronal phenotypes with improved electrophysiological functionalities. TENG devices may also be used for biomedical in vivo reprogramming.