Triboelectric Energy Harvesting Research Articles

Enhance vortices vibration with Y-type bluff body to decrease arousing wind speed and extend range for flag triboelectric energy harvester

The Internet of Things (IoT) has approached network construction by billions of intelligent wireless sensor nodes (WSNs). The major challenge is the desirable self-power generator by environment local energy. This paper presents a novel flag-type triboelectric nanogenerator with a Y-type bluff body that is YF-TENG to harvest wind energy. It exhibits a wider range and lower wind velocities for energy harvesting. The Y-type bluff body enhances YF-TENG vibration of the vortices shedding which is recorded by high-speed camera. The mounting position, designing dimension, and windward angle of the Y-type bluff body are investigated to enhance the flag vibration and the output triboelectric power. The test results show that the power is twice as much as the traditional flag-type triboelectric nanogenerator with a wind velocity of 6 m/s. Furthermore, a proof-of-concept application of the arrayed YF-TENG units supplies sufficient electric power for the wireless temperature and humidity sensor in a wind tunnel. It is envisioned that the enhancement of YF-TENG sensitivity and stability via a Y-type bluff body affords significant potential power for a large number of sensor nodes in a wide wind region.

A coupled piezo-triboelectric nanogenerator based on the electrification of biaxially oriented polyethylene terephthalate food packaging films

This study reports that biaxially oriented silica-filled polyethylene terephthalate (BOPET) films used worldwide as food packaging materials combine unique dual electrification properties that enable the effective conversion of mechanical energy into electricity. The electricity output depends on the physical contact and separation of the polymeric matrix and triboelectric pair material with different affinities for electrons on its surface. To exploit the dual piezoelectric and triboelectric electrification of the films materials, a hybrid piezoelectric triboelectric nanogenerator energy harvester using this film as an electron source was assembled and tested. When BOPET film is paired with polyvinylidene fluoride (PVDF) nanofibre network, which due to the electronegativity difference gained electrons, the performance of the nanogenerator to the output open-circuit increases voltage values above 305 V, and the short-circuit current density and charge density to 12 ± 1μAcm−2 and 37 ± 2μCm−2, respectively. Further, underlaying the PVDF tribo-contact layer by a dielectric low permittivity spunbond non-woven polypropylene raises the performance of the nanogenerator more than doubled (624 V) with corresponding densities of 61 ± 7μAcm−2 and 101 ± 4μCm−2.

Advances in Bioresorbable Triboelectric Nanogenerators.

With the growing demand for next-generation health care, the integration of electronic components into implantable medical devices (IMDs) has become a vital factor in achieving sophisticated healthcare functionalities such as electrophysiological monitoring and electroceuticals worldwide. However, these devices confront technological challenges concerning a noninvasive power supply and biosafe device removal. Addressing these challenges is crucial to ensure continuous operation and patient comfort and minimize the physical and economic burden on the patient and the healthcare system. This Review highlights the promising capabilities of bioresorbable triboelectric nanogenerators (B-TENGs) as temporary self-clearing power sources and self-powered IMDs. First, we present an overview of and progress in bioresorbable triboelectric energy harvesting devices, focusing on their working principles, materials development, and biodegradation mechanisms. Next, we examine the current state of on-demand transient implants and their biomedical applications. Finally, we address the current challenges and future perspectives of B-TENGs, aimed at expanding their technological scope and developing innovative solutions. This Review discusses advancements in materials science, chemistry, and microfabrication that can advance the scope of energy solutions available for IMDs. These innovations can potentially change the current health paradigm, contribute to enhanced longevity, and reshape the healthcare landscape soon.

Enhanced Triboelectric Charge Stability by Air-Stable Radicals.

This paper demonstrates that air-stable radicals enhance the stability of triboelectric charge on surfaces. While charge on surfaces is often undesirable (e.g., static discharge), improved charge retention can benefit specific applications such as air filtration. Here, it is shown that self-assembled monolayers (SAMs) containing air-stable radicals, 2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO), hold the charge longer than those without TEMPO. Charging and retention are monitored by Kelvin Probe Force Microscopy (KPFM) as a function of time. Without the radicals on the surface, charge retention increases with the water contact angle (hydrophobicity), consistent with the understanding that surface water molecules can accelerate charge dissipation. Yet, the most prolonged charge retention is observed in surfaces treated with TEMPO, which are more hydrophilic than untreated control surfaces. The charge retention decreases with reducing radical density by etching the TEMPO-silane with tetrabutylammonium fluoride (TBAF) or scavenging the radicals with ascorbic acid. These results suggest a pathway toward increasing the lifetime of triboelectric charges, which may enhance air filtration, improvetribocharging for patterning charges on surfaces, or boost triboelectric energy harvesting.

Upcycling of plastic wastes and biomass to mechanically robust yet recyclable energy-harvesting materials

Plastic pollution is a growing global concern. From the perspective of decarbonization throughout entire lifecycle, the development of mechanically robust yet recyclable materials from sustainable building blocks is highly desirable but remains challenging. Here, we propose a supramolecular in situ assembly strategy to fabricate sustainable materials by integrating reclaimed glass fiber fabric (RGFF, from wind turbine blades wastes) and bio-based epoxidized soybean oil (ESO) vitrimer. The key principle of the design is the construction of supramolecular interface with densely aggregated hydrogen bonds between the resin residual on RGFF and ESO vitrimer, which facilitates the in situ assembly process to form a homogeneous and dense cartilage-like interwoven structure. The resulted materials show not only excellent mechanical properties during service (tensile strength of 152.9 MPa and toughness of 33.9 MJ m−3), but also desirable recyclability in terms of end-of-life options. Furthermore, the favorable dielectric modulation (promote 11.6 times in surface potential) allows the materials to be used in efficient and durable triboelectric energy harvesting. This upcycling strategy to integrate plastic wastes with biomass exhibits 44 %－49 % reduction in carbon footprint, opening up an avenue for sustainable materials as promising alternatives to petrochemical plastics.

Triboelectric energy harvesting using inductor towards self-powered real-time wireless communication system

A wireless communication has attracted significant research interest in response to recent rapid advancement of the Internet of Things. Typical wireless communication systems utilize a battery to power the transmission of communication via transmitter, which can lead to problems of high design complexity and limited service life. There have been reports of self-powered wireless systems using a triboelectric nanogenerator (TENG) to resolve the challenges of battery issues. However, these systems require a significant time interval to operate the transmitter and these systems are not suitable to handle the signal with low frequency. Hence, the self-powered, real-time wireless communication system, which can handle signals with low frequency, is required. Herein, we demonstrate a self-powered, real-time wireless communication system (SRWS) using a TENG, transmitting inductor, and receiving inductor. At the receiving inductor, a change in the intensity of the magnetic field is observed from 3.79 mA/m to 4.91 mA/m, while the TENG is generating electricity. A variation in the magnetic field induces electricity at the receiving inductor, and the SRWS utilizes the generated electricity to conduct self-powered, real-time wireless communication. Simultaneously, wasted electrical energy in forms of electromagnetic field is harvested in the receiving inductor and utilized as the electrical signal. When the 0.47 μF capacitor is charged using both triboelectricity and induced electricity, the stored energy in the capacitor is 325% higher than the sum of the energies obtained from charging with triboelectricity and induced electricity separately. Also, despite its simple structure, the proposed system achieves wireless communication up to a distance of 60 cm. As a potential application, a rotation speed detection system is implemented using the proposed SRWS and evaluated. The proposed rotation speed detection system successfully detects rotation speeds of 120, 180, and 240 rpm, as well as changes in the rotation speed in each region. The security system is implemented with the aid of machine learning and this system can recognize the security key based on the electrical output. Considering these results, the proposed system shows great potential to overcome issues related to power and charging time and is expected to be utilized in next-generation self-powered, real-time wireless communication system.

Nature-inspired surface for simultaneously harvesting water and triboelectric energy from ambient humidity using polymer brush coatings

Atmospheric water harvesting provides a promising, sustainable solution for alleviating the ever-growing water and energy crisis. Here, inspired by the Namib desert beetle, a wettability patterned surface was designed to simultaneously harvest water and triboelectric energy from ambient moisture. Indium tin oxide (ITO) conductive glass was coated by environmentally friendly perfluoropolyether (PFPE) polymer brushes to obtain a hydrophobic surface, decorated by hydrophilic patterns. The PFPE brushes enabled the droplet to slide down and served as the tribonegative material. The water and triboelectric energy harvesting performance of the hydrophilic-hydrophobic “patterned water and energy harvesting” (P-WEH) system was then investigated. In this regard, a water collection rate of 703 mg cm-2 h-1 was achieved when the P-WEH was placed within an artificial fog. The influence of pattern size and tilt angle, and their relationship with water droplet volume and speed on the triboelectric output, were measured. The effect of the water harvesting area on the output performance of the P-WEH was investigated. The P-WEH with an area of 100 cm2 and a tilt angle of 60° exhibited a high output current of 8.15 µA and a maximum output power of 3.35 µW. Finally, the P-WEH was integrated into a four-season greenhouse to demonstrate its application in reducing external water-energy consumption. This study presents insights into the design of simultaneous water and energy harvesting systems and may contribute to building a sustainable society.

Experimental Study of Triboelectric Energy Harvesting for Different Pairs of Materials and under Various Contact Frequencies

Background: In order to harvest triboelectric energy for self-powered devices, triboelectric nanogenerator technology (TENG) is used. It converts mechanical energy into electrical energy using materials' contact motion. Objective: The purpose of this study is to produce electrical energy for different material pairs and under various contact frequencies using triboelectric separation mode. Methods: To produce electricity through triboelectric separation mode, a vibratory exciter was used to provide the contact frequency between the pairs of materials which were connected to an oscilloscope by a capacitive electric circuit containing a diode bridge. The studied materials are: Mica, Polyamide (Nylon), Polytetrafluoroethylene (PTFE), Polyvinylidene fluoride (PVDF), and Polyethylene terephthalate (PET). Mica and Nylon are positive charge materials, while PTFE, PVDF, and PET are negative charge materials. The material pairs are then: Nylon-PVC, Mica-PVC, Nylon-PET, Mica-PET, Nylon- PTFE, and Mica-PTFE. Results: The increase of the contact frequency improves the recovered electrical energy for all the material pairs. The produced electrical energy can reach 5μJ which allows supply for low consumption devices. Conclusion: The research results lead to identify favorable configurations of material pairs and contact frequencies, allowing to recover enough electrical energy supply to low-power devices.

Triboelectric Energy Harvesting for Self-powered Antibacterial Applications

Triboelectric Energy Harvesting for Self-powered Antibacterial Applications

Wide-bandwidth triboelectric energy harvester combining impact nonlinearity and multi-resonance method

This paper presents a novel wide-bandwidth triboelectric energy harvester (WBTEH) that takes advantage of impact nonlinearity and multi-resonance. The harvester features a triboelectric transducer that operates in contact and separation mode, with two cantilever beams of different resonant frequencies connected to it. By exploiting the relative motion of the beams, the harvester achieves a broad bandwidth through the resonance shift caused by the impact and multi-resonance. A WBTEH prototype with a 3 mm gap between the triboelectric pair shows a total bandwidth of 4.3 Hz even at a low base excitation of 3 m/s2. The matched peaks and bandwidth in the frequency up-sweep and down-sweep tests demonstrate the excellent stability of the WBTEH. The frequency locking phenomenon with strong resonance occurs in the WBTEH when the displacement amplitude/gap ratio exceeds 1.48, which is beneficial for obtaining a continuous bandwidth and a high power output. An electromechanical model is formulated for parametric studies that investigate the effects of contact stiffness and damping on the performance of WBTEH. It is found that large impact stiffness and small damping can cause quasi-periodic motion, leading to a non-constant voltage output that should be prevented in the harvester design. The WBTEH is capable of powering wireless sensors, making it a potential candidate for Internet of Things (IoT) applications.

Optimisation-driven design of sliding mode triboelectric energy harvesters

With the increasing demand of emerging technologies for autonomous sensing, the modelling and optimisation of complete energy harvesting systems are essential to achieve efficient power output. To date, most of the optimisation efforts in enhancing the performance of triboelectric energy harvesters have been focused on the improvement of material properties and on the establishment of figures of merit to assist in the definition of parameters. However, these efforts do not consider the complex relationship between the device structure and power output, physical constraints in place, and varying excitation conditions. This paper fills that gap for the first time by applying an optimisation algorithm to establish mechanisms for optimisation-driven design of sliding-mode triboelectric energy harvesters. A global optimisation methodology is developed to improve its performance, having experimentally validated the numerical model adopted. This work highlights the need for a more robust design framework for applications of triboelectric energy harvesting and proposes a hybrid approach combining the finite element method with analytical models to consider different energy harvesting parameters including the degradation of the charge transfer efficiency due to the edge effect. A novel high-power output sliding-mode triboelectric energy harvesting concept is proposed and its performance is optimised, using the proposed methodology.

Spent Catalyst‐Derived Mo‐MOF: Triboelectric Nanogenerators and Energy Harvesting

The spent catalysts discarded during chemical manufacturing can be a source of pollution and are classified as hazardous waste. Looking at the bright sides of the mission of waste management, such as recycling and reducing, reuse such types of the spent catalyst can be chemically treated to extract valuable salts and metals. Such a process not only reduces waste disposal issues but also promotes a circular economy ecosystem. This present study aims to extract MoO3 from the spent petroleum catalyst, Mo–Ni/Al2O3, and further processing of Mo‐metal organic framework (MOF) particles using extracted MoO3 and imidazole acting as an organic binder. The structural, morphology, and thermal properties of Mo‐MOF are evaluated. The surface roughness and positive surface potential of the Mo‐MOF are achieved. The Mo‐MOF/Kapton‐based triboelectric nanogenerators (TENG) generate a 148 V voltage, 470 nA current, and 17 nC charge. Further, TENG is utilized to charge the capacitors, and powering of the electronic devices is demonstrated. The repetition of the boxing punches and exercises can be monitored using TENGs and paves the way toward intelligent sports or healthcare.

UFO‐Shaped Integrated Triboelectric Nanogenerator for Water Wave Energy Harvesting

AbstractThe triboelectric nanogenerator (TENG), which is suitable for low‐frequency and high‐entropy mechanical energy harvesting, has great advantages in ocean energy collection and potential blue energy applications. The rational structural design can ensure the best working state of TENG in complex marine environment. Herein, an unidentified flying object (UFO) shaped integrated triboelectric energy harvester (U‐TENG) is proposed for complex and random ocean wave energy harvesting. The U‐TENG is assembled in a vertical structure by combining a coping TENG in a rotational structure and a bottom TENG in a rolling‐ball design. The proposed vertically integrated TENG structure can increase the efficiency of space utilization and improve the entirety output performance compared with the single device structure. A sophisticated auxiliary facility has also been pioneerily designed to simulate the ocean waving during the experiment tests. The prepared U‐TENG can easily light up dozens of light emitting diodes and power a commercial hygrothermograph at a low operating frequency. This work provides a highly efficient means to the development of high‐performance and robust TENG for ocean energy harvesting.

Self-Assembled Ultrathin Polymeric Multilayers for Triboelectric Energy Harvesting Coatings

Self-Assembled Ultrathin Polymeric Multilayers for Triboelectric Energy Harvesting Coatings

The Advances in Conversion Techniques in Triboelectric Energy Harvesting: A Review

A triboelectric nanogenerator (TENG) is a new transducer utilizing contact electrification and electrostatic induction to transform mechanical energy into electric energy. Due to its high energy density and flexibility, it can be employed to make electronic devices self-powered by harvesting ambient mechanical energy in many application scenarios, such as biomedical devices, wearable electronics, and Internet-of-Things (IoT) sensors. However, due to the time-varying and low internal capacitance of a TENG, it is challenging to extract electrical energy from it. Hence, good power conversion techniques are crucial in TENG energy harvesting systems. Currently, studies on dedicated integrated power conversion techniques are very limited. Due to the exponentially increasing research interests in TENG, a comprehensive study on the TENG energy harvesting system, emphasizing integrated-circuit (IC) power conversion techniques, is urgently needed. This paper summarizes and compares the state-of-the-art triboelectric energy harvesting systems, focusing on different power conversion techniques for output power enhancement. Some techniques, which have been widely used in other relevant energy harvesting systems, are also mentioned to inspire innovative design strategies for TENG systems.

A Two-Degree-of-Freedom Vibro-impact Triboelectric Energy Harvester for larger bandwidth

The efficiency of the energy harvesters can be improved by increasing the harvester bandwidth. Toward this, we presented a Two-Degree of Freedom (2-DOF) Vibro-impact Triboelectric Energy Harvester by combining multi-modality and piecewise linearity of two close resonant frequencies. The harvester structure consists of a primary cantilever beam attached to a secondary cantilever beam through a tip mass. The secondary beam is attached in the opposite direction to the primary beam. The secondary beam’s bottom surface acts as a triboelectric generator’s upper electrode. A lower electrode with bonded Polydimethylsiloxane (PDMS) insulator is attached at some gap separation distance underneath the upper electrode to create an impact structure. When the system vibrates, an impact between the triboelectric layers generates an alternating electrical signal. A 2-DOF system with lumped parameter theoretical model was developed to extract the governing equations. In addition, the experimental results were extracted to validate the theoretical model. Afterward, parametric analysis based on the variation of gaps, resistance, and surface charge density was theoretically investigated. Finally, the proposed harvester demonstrated an increase in the maximum output voltage by more than 300%, and a 250% increase in the bandwidth, by changing the excitation level from 0.1 g to 0.7 g. The result of this study can pave the way for an efficient energy harvester that can scavenge ambient vibrations over a wide range of excitation frequencies.

Surface-enhanced fully nanofiber-based self-cleanable ultraviolet resistive triboelectric energy harvester for wearable smart garments

Wearable triboelectric nanogenerators (TENGs) with high electrical performance have recently prompted great expectations. However, charge diffusion and recombination affect the electric field strength, resulting in a weak electrostatic potential in the displacement region. Current research on film-type dielectric interlayers indicates that charge trapping can prevent charge recombination, although surface charge air breakdown has not been addressed, and becomes a crucial demand in wearable energy applications. In the present study, the surface charge density of poly(vinylidene fluoride) (PVDF) nanofibers is greatly improved by co-electrospraying PDMS-PVDF (PDPV) charge-trapping microbeads; this new approach prolongs the lifetime of surface charges. In particular, the PDPV beads prevent charge recombination, and the interlocking mechanism enhances the tensile property of the PVDF nanofibers. These result in a two-fold increase in the open-circuit voltage and peak power density to 305 V and 124.3 mW m−2, respectively. The device is successfully employed in portable electronic gadgets. Ag-nanoparticle-grafted styrene-butadiene-styrene (SBS) fiber is used as an electrode because it has favorable stretchability with low resistance and is antibacterial. The addition of TiO2/multiwalled carbon nanotube to PVDF nanofiber membrane shows excellent electricfield-induced photocatalyst and ultraviolet protection. Our surface-enhanced fully fiber-based TENG is a promising energy harvester for flexible smart garments applications.

A Nonlinear Impact-Driven Triboelectric Vibration Energy Harvester for Frequency Up-Conversion.

Energy harvesting effectively powers micro-sensors and wireless applications. However, higher frequency oscillations do not overlap with ambient vibrations, and low power can be harvested. This paper utilizes vibro-impact triboelectric energy harvesting for frequency up-conversion. Two magnetically coupled cantilever beams with low and high natural frequencies are used. The two beams have identical tip magnets at the same polarity. A triboelectric energy harvester is integrated with the high-frequency beam to generate an electrical signal via contact-separation impact motion between the triboelectric layers. An electrical signal is generated at the low-frequency beam range achieving frequency up-converter. The two degrees of freedom (2DOF) lumped-parameter model system is used to investigate the system's dynamic behavior and the corresponding voltage signal. The static analysis of the system revealed a threshold distance of 15 mm that divides the system into monostable and bistable regimes. In the monostable and bistable regimes, softening and hardening behaviors were observed at low frequencies. Additionally, the threshold voltage generated was increased by 1117% in comparison with the monostable regime. The simulation findings were experimentally validated. The study demonstrates the potential of using triboelectric energy harvesting in frequency up-converting applications.

Development of a flexible piezoelectric and triboelectric energy harvester with piezo capacitive sensing ability from barium tungstate nanorod-dispersed PVDF nanofabrics

Lead-free flexible piezoelectric nanogenerator (PNG) and triboelectric nanogenerator (TENG) are sought after due to their ability to produce electricity by harnessing wasteful mechanical energy. A comprehensive understanding of additives and processing techniques is crucial for fine-tuning the performance of such energy systems. We have investigated in detail the effect of the addition of reverse microemulsion synthesized barium tungstate nanorods (BWN) on morphology, crystallinity, polymorphism of electrospun nanofabrics of poly(vinylidene fluoride) (PVDF). The electroactive phase content of the nanofabrics was enhanced upon the addition of BWN and the highest electroactive phase content of 86.5% was observed in the nanofabric containing 3 wt% of BWN. The dielectric constant of the nanofabric containing 5 wt% BWN was ∼1.96 times higher than that of pristine electrospun PVDF nanofabric (EPVDF). The ratio of relative change in the capacitance to initial capacitance of the sensor fabricated from the same system was ∼4 times greater than that of EPVDF. Consequently, its piezoelectric and triboelectric performances were improved. The PNG fabricated using the nanofabric containing 3 wt% BWN produced the highest open-circuit voltage of 8 V under an applied load of 8 N. A TENG made using the same system was able to produce a voltage output of 200 V, which was 1.77 times as high as that of EPVDF under one-finger tapping in contact-separation mode. The same composite nanofabric produced piezoelectric and triboelectric power densities of 4.3 µW cm−2 and 646 µW cm−2, respectively. The TENG was able to light 40 LEDs under one finger tapping. Fluttering-driven TENG fabricated using the aforementioned nanofabric was able to produce a triboelectric voltage of 84 V at a wind speed of 7 m s−1. Overall, these nanofabrics could be a potential material for energy harvesting devices for powering wearable devices, environmental sensors, and internet of things.

Magnetic Bistability for a Wider Bandwidth in Vibro-Impact Triboelectric Energy Harvesters.

Mechanical energy from vibrations is widespread in the ambient environment. It may be harvested efficiently using triboelectric generators. Nevertheless, a harvester's effectiveness is restricted because of the limited bandwidth. To this end, this paper presents a comprehensive theoretical and experimental investigation of a variable frequency energy harvester, which integrates a vibro-impact triboelectric-based harvester and magnetic nonlinearity to increase the operation bandwidth and improve the efficiency of conventional triboelectric harvesters. A cantilever beam with a tip magnet was aligned with another fixed magnet at the same polarity to induce a nonlinear magnetic repulsive force. A triboelectric harvester was integrated into the system by utilizing the lower surface of the tip magnet to serve as the top electrode of the harvester, while the bottom electrode with an attached polydimethylsiloxane insulator was placed underneath. Numerical simulations were performed to examine the impact of the potential wells formed by the magnets. The structure's static and dynamic behaviors at varying excitation levels, separation distance, and surface charge density are all discussed. In order to develop a variable frequency system with a wide bandwidth, the system's natural frequency varies by changing the distance between the two magnets to reduce or magnify the magnetic force to achieve monostable or bistable oscillations. When the system is excited by vibrations, the beams vibrate, which causes an impact between the triboelectric layers. An alternating electrical signal is generated from a periodic contact-separation motion between the harvester's electrodes. Our theoretical findings were experimentally validated. The findings of this study have the potential to pave the way for the development of an effective energy harvester that is capable of scavenging energy from ambient vibrations across a broad range of excitation frequencies. The frequency bandwidth was found to increase by 120% at threshold distance compared to the conventional energy harvester. Nonlinear impact-driven triboelectric energy harvesters can effectively broaden the operational frequency bandwidth and enhance the harvested energy.