Triboelectric Generator Research Articles

Design and analysis of a compliant 3D printed energy harvester housing for knee implants

Instrumented implants have the potential to detect abnormal loading patterns which could be deleterious to implant longevity, indicating a need for intervention which could reduce the need for more complicated revision surgeries. Reliably powering such devices has been one obstacle preventing widespread usage of instrumented implants in clinical populations. This study presents a 3D-printed titanium interpositional device designed to integrate triboelectric generators (TEGs) into a commercially available total knee replacement (TKR). The device's stiffness, durability, and efficacy as a TEG housing were determined. Surprisingly, the stiffness of the 3D printed prototype was 73% less than what was calculated in a corresponding computational model, and under long-term durability testing failed after approximately 30,000 cycles of simulated gait loading. Under cyclical compressive loading, TEGs embedded in the device were able to generate 10.05 μW of power which is sufficient to run the frontend electronics for a load measurement system. The stiffness discrepancy between the computational and experimental models and the premature fatigue failure are suspected to be a result of internal porosity, unfused material and surface roughness of the 3D printed metal. Further refinements in design and manufacturing of the compliant device are required to improve its durability and TEG power output.

Recent advancement in TENG polymer structures and energy efficient charge control circuits

Tribo-electric nanogenerator proved a better alternative energy resource for many electronic accessories because of its flexible nature and optimized device properties. It opens up the use of polymer materials (PMs) for harvesting mechanical energy. The disadvantage of the Tribo-Electric Nano Generator (TENG) is likely lower durability, limited short circuit output current, structural changes, post-stress conditions, etc. The purpose of this review article is more focused on systematic and detailed descriptions of TENGs. It gives an overview of tribo-electric polymer-based material formation and triboelectricity generation, structural modes of tribo-electric polymer-based nanogenerators, and its comparisons, measurement, and quantification of tribo-electric polymer-based nanogenerators based on structural and load conditions. Also, this article focused on TNEG efficiency enhancement techniques using various charge control circuit techniques. Possible applications of TNEG for various self-powered devices such as sensor, actuators and bio-harvesting utilities are discussed in detail.

Stretchable and self-healable catechol-chitosan-diatom hydrogel for triboelectric generator and self-powered tremor sensor targeting at Parkinson disease

With increasing interest in human health, stretchable and wearable sensors have attracted a lot of attention for real-time health monitoring. However, most wearable sensors require external power sources, show structural failures under repeated mechanical strains and are not suitable for sensing low-frequency body motion. Herein, we report that a highly stretchable and self-healable hydrogel conductor was newly synthesized with all ocean biomaterials including catechol, chitosan and diatom. The catechol-chitosan-diatom hydrogel (CCDHG) conductor was exploited as stretchable triboelectric nanogenerators (TENG) for energy harvesting from human motion and skin-attachable self-powered tremor sensors for monitoring the health condition of Parkinson’s disease (PD) patients. The catechol-chitosan-diatom hydrogel triboelectric nanogenerator (CCDHG-TENG) showed open-circuit voltage of 110 V, short-circuit current of 3.8 μA, and instantaneous power density of 29.8 mW/m 2 . Furthermore, a self-powered tremor sensor, which was specially designed with an M-shaped Kapton film and the CCDHG-TENG, was applied to identify the health conditions of PD patients using a machine learning algorithm. This study provides a new strategy to design stretchable TENGs with all ocean bio-materials and this can be utilized for various applications, including stretchable power sources, wearable electronics and health monitoring systems with artificial intelligence. Catechol-Chitosan-Diatom hydrogel (CCDHG) is developed to realize the stretchable triboelectric nanogenerator. The CCDHG, which is biocompatible, stretchable, self-healable and conductable hydrogel, is utlized as an electrode of TENG. Furthermore, the M-shaped tremor sensor is developed to evaluate low-frequency motion of Parkinson’s disease patients based on the CCDHG-TENG. • Catechol-chitosan-diatom hydrogel (CCDHG) was for the first time utilized as a stretchable electrode for TENGs. • The CCDHG can be attached to the hydrophobic polymer owing to the mussel-inspired catechol. • The tremor sensor can be used to identify the condition of Parkinson’s disease patients with machine learning.

Robust Triboelectric Generators by All-In-One Commercial Rubbers

Stretchable piezoelectric nanogenerators (PENGs), as well as triboelectric nanogenerators (TENGs), have become the topic of interest of many scientists for sustainable power generation and power su...

Tunable current duration in triboelectric generators via capacitive air gaps

SummaryDespite the low cost, high power, and wide application areas, impact‐type triboelectric generators exhibit limited applicability due to the extremely short current duration, on the order of a millisecond. The high power, short lasting current peak not only results in reduced time‐averaged power output but also acts as triboelectric shock to the accompanying circuits, quickly degrading the usability of the generator. Here, we demonstrate tunable triboelectric current duration via controlling the air gap capacitance inserted between the two dielectric plates. In typical contact‐type triboelectric generator with nylon/air gap/Polydimethylsiloxane (PDMS) multilayers, decreasing the vertical speed of the dielectric plates from 0.5 cm/s to 0.05 cm/s result in increased current duration from 0.10 second to 0.81 second. The increased peak duration accompanies decreased peak current, resulting in the optimal charge density of 0.163 nC/cm2 at the vertical speed of 0.25 cm/s. Changing the air gap capacitance in noncontact mode or the relative permittivity in dielectric layers also results in similar change in peak duration. To explain the tunable current duration, an equivalent circuit model is constructed via serially connected capacitors and numerical solutions reproduce the trends in current duration associated with change in air gap capacitance. This study provides significant implications toward further optimizing triboelectric generators, in terms of optimal triboelectric charge density, accompanying circuit lifetime and broadened applicability.

A highly efficient triboelectric negative air ion generator

Negative air ions (NAIs) have been widely harnessed in recent technologies for air pollutant removal and their beneficial effects on human health, including allergy relief and neurotransmitter modulation. Herein, we report a corona-type, mechanically stimulated triboelectric NAI generator. Using the high output voltage from a triboelectric nanogenerator, air molecules can be locally ionized from carbon fibre electrodes through various movements, with the electron–ion transformation efficiency reaching up to 97%. Using a palm-sized device, 1 × 1013 NAIs (theoretically 1 × 105 ions cm−3 in 100 m3 space) are produced in one sliding motion, and particulate matter (PM 2.5) can be rapidly reduced from 999 to 0 µg m−3 in 80 s (in a 5,086 cm3 glass chamber) under an operation frequency of 0.25 Hz. This triboelectric NAI generator is simple, safe and effective, providing an appealing alternative, sustainable avenue to improving health and contributing to a cleaner environment. Negative air ions (NAIs) have been widely harnessed for air purification and environmental therapeutics. Herein, the authors construct a triboelectric NAI generator that produces NAIs with high efficiency, stimulated by mechanical motions.

Harvesting contact-separation-compression vibrations using a flexible and compressible triboelectric generator

Progress in renewable, portable, and sustainable energy sources for harvesting energy from ambient environments is of great importance in the Internet of Things (IoT) society. Recently, triboelectric nanogenerators (TENGs) have been proposed and developed by many research groups to convert mechanical energy, such as pressure, bending, stretching and vibration, into electrical energy at any given location and time. We must make clear relationships between contact-separation-compression process with external loads and electric performance of triboelectric generators, and should carefully clarify effects of separation-distance and separation-velocity on output voltage, and key parameters for the output voltage in more details.Here, we propose and develop a simple polymer-based flexible and compressible generator that employs a tribological process for sustainable energy such as wind, wave, current, and mechanical vibration. The proposed triboelectric nanogenerator, which is called FC-TENG (a flexible and compressible type of triboelectric nanogenerator), consists of laminated dielectric elastomer sheets and copper films. The characteristics of the working mechanism of the FC-TENG in the contact, separation, and compression modes are fundamentally elucidated in the vibration test, and it is found that the output voltage depends not on the separation distance but the separation velocity. The vertical strain rate of the FC-TENG is a key factor that influences efficient electrical power generation. A suitable initial separation distance must be selected to create a triboelectric potential layer and to achieve high electrical performance. Moreover, a theoretical model is proposed as a design tool, and the resulting average, maximum, and minimum output voltages exhibited good agreement with the experimental data. The proposed FC-TENG could act as a useful device for sustainable energy harvesting.

Electrification at water\u2013hydrophobe interfaces

The mechanisms leading to the electrification of water when it comes in contact with hydrophobic surfaces remains a research frontier in chemical science. A clear understanding of these mechanisms could, for instance, aid the rational design of triboelectric generators and micro- and nano-fluidic devices. Here, we investigate the origins of the excess positive charges incurred on water droplets that are dispensed from capillaries made of polypropylene, perfluorodecyltrichlorosilane-coated glass, and polytetrafluoroethylene. Results demonstrate that the magnitude and sign of electrical charges vary depending on: the hydrophobicity/hydrophilicity of the capillary; the presence/absence of a water reservoir inside the capillary; the chemical and physical properties of aqueous solutions such as pH, ionic strength, dielectric constant and dissolved CO2 content; and environmental conditions such as relative humidity. Based on these results, we deduce that common hydrophobic materials possess surface-bound negative charge. Thus, when these surfaces are submerged in water, hydrated cations form an electrical double layer. Furthermore, we demonstrate that the primary role of hydrophobicity is to facilitate water-substrate separation without leaving a significant amount of liquid behind. These results advance the fundamental understanding of water-hydrophobe interfaces and should translate into superior materials and technologies for energy transduction, electrowetting, and separation processes, among others.

Enhanced dielectric properties of halloysite/PVDF-HFP modified by Li-ion realizing superior energy conversion ability

High dielectric material has attracted interest in applications of triboelectric nanogenerators for its high charge-trapping capability. We reported the enhancement of both dielectric and piezoelectric properties by adding modified halloysite (HAL) into PVDF-HFP. Due to the combined effect of triboelectric generation by enhanced dielectric constant and piezoelectric generation by increase of β-phase, the HAL/PVDF-HFP composites film modified by Li+ and water exhibited superior generated current of 9.23 × 10−7 A compared to the pure PVDF-HFP with 1.65 × 10−7 A and unmodified HAL/PVDF-HFP with 2.68 × 10−7 A. This work is expected to inspire the design and fabrication of high dielectric and piezoelectric material for nanogenerators.

Recent Progress in Hybridized Nanogenerators for Energy Scavenging.

SummaryAs the world's demand for alternative energy increases, the development of green energy harvesters becomes ever more important. As a result, the creation of triboelectric (TENG), piezoelectric (PENG), and pyroelectric nanogenerators, electromagnetic generators (EMG), solar cells, and electrochemical cells is attracting interest in an effort to convert mechanical, thermal, magnetic, solar, and chemical energy into electricity. In order to take advantage of the ambient energies from our surrounding environment, the design of hybridized generator units that can simultaneously scavenge energy in a variety of forms continues to develop. These systems are being considered to satisfy the energy needs of a range of electronic devices and adapt to a variety of working environments. This review demonstrates the latest progress in hybridized nanogenerators in accordance with their structure, operating principle, and applications. These studies demonstrate new approaches to developing hybrid techniques and novel assemblies for efficiently harvesting environmental energy from a number of sources.

Triboelectric and Piezoelectric Nanogenerators for Future Soft Robots and Machines.

SummaryThe triboelectric nanogenerator (TENG) and piezoelectric nanogenerator (PENG) are two recently developed technologies for effective harvesting of ambient mechanical energy for the creation of self-powered systems. The advantages of TENGs and PENGs which include large open-circuit output voltage, low cost, ease of fabrication, and high conversion efficiency enable their application as new flexible sensors, wearable devices, soft robotics, and machines. This perspective provides an overview of the current state of the art in triboelectric and piezoelectric devices that are used as self-powered sensors and energy harvesters for soft robots and machines; hybrid approaches that combine the advantages of both mechanisms are also discussed. To improve system performance and efficiency, the potential of providing self-powered soft systems with a degree of multifunctionality is investigated. This includes optical sensing, transparency, self-healing, water resistance, photo-luminescence, or an ability to operate in hostile environments such as low temperature, high humidity, or high strain/stretch. Finally, areas for future research directions are identified.

Triboelectricity and textile structures

Triboelectricity is a natural phenomenon with limited applications in the past. Wide research over the last decade introduced it mainly in energy harvesting and sensing. The use of textiles in triboelectric applications mainly focuses on the energy harvesting field. The textile fabrics as active parts of wearable triboelectric generators are promising concerning the structural simplicity and the performance of the product. The clothes are made of textile fabrics and the textile-based triboelectric generator is benefitted by the large contact areas and the continuous activation thanks to the lasting movement of the wearer. Simultaneously, the textile character of the triboelectric parts supports the flexibility, elasticity, breathability etc of the clothes, maintaining the comfort of the user. The study of the triboelectric phenomenon on textile structures gives an indication of their suitability for energy harvesting applications. The present research work investigates the influence of parameters like the contact time duration of the fabrics, the force applied upon their contact, their relative orientation and their weave as well as the material type on the efficiency of the triboelectric unit. Additionally, the lack of a standard testing method imposed the design and development of a suitable testing apparatus. It operates in the vertical contact-separation mode and it allows the testing of different samples under the same conditions or of the same sample under different conditions. Textile fabric samples were paired and tested in order to evaluate their influence on the amount of energy harvested.

Triboelectric generator using mesoporous polydimethylsiloxane and gold layer

This paper presents a triboelectric generator using mesoporous (PDMS) polydimethylsiloxane and gold layer which was demonstrated in energy harvesting applications. The performance of power generation by the means of triboelectric principle at a small dimension, namely triboelectric generator is characterized. In this paper, triboelectric generator device adapted vertical contact-separation operation mode, whereby the device derives power generation based on contact electrification caused by cyclic tapping motion. Being primarily a two-layer structure, this device comprises a top layer of aluminum (Al) electrode coated with mesoporous polydimethylsiloxane (PDMS) film and another bottom layer of Al electrode coated with gold (Au) deposit. The characterization of this device is done by varying frequencies and cyclic compression force applied to triboelectric generator. The optimal performance of the 2 cm x 2 cm triboelectric generator contact surface area generated an open-circuit voltage of 4.4 V and a current of 0.1 µA at 5 Hz frequency. This research and device can be improved by magnifying the effective surface area of triboelectric generator to generate significant power for small base area.

Experimental and Analytical Investigation of the Response of a Triboelectric Generator Under Different Operating Conditions

This article provides experimental and theoretical studies on the effect of operating conditions on the output response of triboelectric generators. The influence of specific parameters is examined in detail, including vibration frequency, impact separation distance, and the type of adhesive between the dielectric and the electrode for a single dielectric layer device operating in contact‐separation mode, with Teflon and copper being the dielectric and electrode materials, respectively. A scotch‐yoke mechanism is designed and fabricated in an effort to understand the effect of varying the operating conditions on the output voltage behavior. The voltage output is compared with an analytical capacitor model at drive frequencies ranging from 1 to 5 Hz and separation distances from 5 to 40 mm to evaluate the model's effectiveness in predicting generator output. The experimental results provide new insights into the behavior of triboelectric generators and how the type of adhesive between the dielectric material and the electrode affects the output signal.

A Triboelectric Nanogenerator Design for the Utilization of Multi-Axial Mechanical Energies in Human Motions

As the use of mobile devices increase, there is public interest in the utilization of the human motion generated mechanical energy. The human motion generated mechanical energies vary depending on the body region, type of motion, etc., and an appropriate device has to be designed to utilize them effectively. In this work, a device based on the principles of triboelectric generation and inertia was assessed in order to utilize the multi-axial mechanical energies generated by human motions. To improve the output performance we confirm the changes in the output that vary with the structural design, the reasons for such changes, and variations in performance based on the parts of the human body. In addition, the level of electrical energy generated based on motion type was measured; a maximum voltage of 30 V and a current of 2 μA were generated. Finally, the proposed device was utilized in LEDs used for lighting, thus demonstrating that multi-axial mechanical energies can be harvested effectively. Based on the results, we expect that the developed device can be utilized as a sensor to detect mechanical energies, to sense changes in motion, or as a generator for auxiliary power supply for mobile devices.

Recent advances in wearable textile‐based triboelectric generator systems for energy harvesting from human motion

AbstractLarge‐area, flexible, and light‐weight textile‐based triboelectric generator (TTEG) technologies are promising power supplier by harvesting energy from human motions, wind, and water current. Numerous TTEG systems have been demonstrated. However, the challenges in their applications include the low electric output power, failure under wearing conditions, and adverse effects on the wearable performance like comfort and durability. What is the influence of system integration on the output performance of the TTEGs? What kinds of textile‐structures have the most promising performance? How to make an effective TTEG system? In an attempt to answer these important questions, a critical review is presented on the recent advances of wearable TTEG systems in terms of textile structures, selection of materials, working modes, mechanisms of triboelectrification and charge transfer, energy storage, and their integrations. Furthermore, the major approaches or directions for improving the total conversion efficiency and performance of wearable TTEG systems are systematically summarized.image

Miura-origami-inspired electret/triboelectric power generator for wearable energy harvesting with water-proof capability

One of the critical issues for electret/triboelectric devices is the poor charge viability and stability in humid environments. Herein, we propose a new origami-inspired “W-tube”-shaped triboelectric nanogenerator (W-TENG) with two thin-film electrets folded based on Miura-origami. The Miura-origami fold is capable of transforming flat materials with large surface areas into reduced and compressed complex 3D structures with parallelogram tessellations. The triboelectric power generation components can thus be hermetically sealed inside the “W-tube” to avoid contact with the external humid environment. Furthermore, the elastic nature of the Miura-origami fold endows the proposed W-TENG device with excellent deformability, flexibility, and stretchability. Therefore, it is capable of harvesting kinetic energy from various directions and forms of movement, including horizontal pressing, vertical tapping, and lateral bending. The compact, light weight, and self-rebounding properties of the origami structure also make it convenient for integration into wearable devices. Various parameters of the W-TENG are intensively investigated, including the number of power generation units, original height of the device, acceleration magnitude, excitation direction, and water-proof capability. Triggered by hand tapping impulse excitation in the horizontal and vertical directions, the instantaneous open-circuit voltages can reach 791 V and 116 V with remarkable optimum powers of 691 μW at 50 MΩ and 220 μW at 35 MΩ, respectively. The outcomes of this work demonstrate the fusion of the ancient art of origami, material science, and energy conversion techniques to realize flexible, multifunctional, and water-proof TENG devices.

Encapsulated Triboelectric–Electromagnetic Hybrid Generator for a Sustainable Blue Energy Harvesting and Self-Powered Oil Spill Detection

Hybridizing the triboelectric and electromagnetic generator shows a great potential in harvesting the water wave energy in a wide frequency range from low to high upon water wave motions. The tribo...

Large-area fabrication and applications of patterned surface with anisotropic superhydrophobicity

Recently, anisotropic superhydrophobic surfaces have aroused much attention due to their promising applications. However, large-area fabrication of low-cost superhydrophobic surfaces with obvious anisotropicity is still a huge challenge. In this work, a home-made melt hot-pressing method was proposed to facilely fabricate aligned micro-patterns on high-density polyethylene surface. Such surface displays anisotropic superhydrophobic characteristic with a static water contact angle of 152°and 145° respectively in parallel and perpendicular direction. Moreover, it has low surface adhesion and decent mechanical stability, showing promising applications for hydraulic triboelectric generator with self-cleaning ability, milk residue reduction and drag reduction. Considering the facile fabrication process and inexpensive thermoplastic polymer used, this study not only provides the possibility of large-area and low-cost preparation of orderly patterned surfaces with anisotropic superhydrophobicity, but also opens a new pathway toward wide application of anisotropic superhydrophobic surface.

3D printed stretchable triboelectric nanogenerator fibers and devices

Abstract Triboelectric generators and sensors have a great potential as self-powered wearable devices for energy harvesting, biomedical monitoring, and recording human activity. Here, we report a process for 3D printing stretchable membranes, meshes, and hollow 3D structures on planar, rotating, and non-planar anatomical substrates using elastomeric metal-core triboelectric nanogenerator (TENG) fibers. The triboelectric performance of single 3D-printed elastomeric metal-core silicone-copper (Cu) (cladding-core) fibers and 3D-printed membranes was quantified by cyclic loading tests, which showed maximum power densities of 31.39 and 23.94 mW m−2, respectively. The utility of the flexible silicone-Cu TENG fibers and 3D printing process was demonstrated through applications to wearable mechanosensors for organ and human activity monitoring, specifically, monitoring of perfused organs and speech recognition in the absence of sound production by the speaker (i.e., ‘silent speech’), respectively. 3D-printed wearable triboelectric mechanosensors, in the form of stretchable form-fitting meshes and membranes, in combination with machine-learning signal processing algorithms, enabled real-time monitoring of perfusion-induced kidney edema and speech recognition in the absence of sound production by human subjects (99% word classification accuracy). Overall, this work expands the conductive and functional materials palette for 3D printing and encourages the use of 3D-printed triboelectric devices for self-powered sensing applications in biomanufacturing, medicine, and defense.