Paper-Based Triboelectric Nanogenerators Made of Stretchable Interlocking Kirigami Patterns

The development of stretchable energy generation devices is indispensable for achieving stretchable, self-powered electronic systems. In this paper, a type of highly stretchable triboelectric nanogenerators made from conventional, inelastic materials such as paper is presented. It exploits a rationally designed interlocking kirigami structure and is capable of harvesting energy from various types of motions such as stretching, pressing, and twisting owing to the shape-adaptive thin film design. Energy harvested from the as-fabricated devices has been used for powering an LCD screen and lighting LED arrays. Furthermore, the paper-based devices have also been demonstrated for self-powered acceleration sensing and self-powered sensing of book opening and closing. This work introduces traditional kirigami into the development of stretchable triboelectric nanogenerators and verifies its promising applications in both power generation and self-powered sensing

Notepad-like Triboelectric Generator for Efficiently Harvesting Low-Velocity Motion Energy by Interconversion between Kinetic Energy and Elastic Potential Energy

Great attention has been paid to nanogenerators that harvest energy from ambient environments lately. In order to give considerable output current, most nanogenerators require high-velocity motion that in most cases can hardly be provided in our daily life. Here we report a notepad-like triboelectric generator (NTEG), which uses simple notepad-like structure to generate elastic deformation so as to turn a low-velocity kinetic energy into high-velocity kinetic energy through the conversion of elastic potential energy. Therefore, the NTEG can achieve high current output under low-velocity motion, which completely distinguishes it from tribogenerators previously reported. The factors that may affect the output performance are explored, including the number of slices, active length of slice, press speed, and vertical displacement. In addition, the working mechanism is systematically studied, indicating that the efficiency of the generator can be greatly enhanced by interconversion between kinetic energy and elastic potential energy. The short-circuit current, the open-circuit voltage, and power density are 205 μA and 470 V and 9.86 W/m², respectively, which is powerful enough to light up hundreds of light-emitting diodes (LEDs) and charge a commercial capacitor. Besides, NTEGs have been successfully applied to a self-powered door monitor

Harvesting Low-Frequency (<5 Hz) Irregular Mechanical Energy: A Possible Killer Application of Triboelectric Nanogenerator

Electromagnetic generators (EMGs) and triboelectric nanogenerators (TENGs) are the two most powerful approaches for harvesting ambient mechanical energy, but the effectiveness of each depends on the triggering frequency. Here, after systematically comparing the performances of EMGs and TENGs under low-frequency motion (<5 Hz), we demonstrated that the output performance of EMGs is proportional to the square of the frequency, while that of TENGs is approximately in proportion to the frequency. Therefore, the TENG has a much better performance than that of the EMG at low frequency (typically 0.1–3 Hz). Importantly, the extremely small output voltage of the EMG at low frequency makes it almost inapplicable to drive any electronic unit that requires a certain threshold voltage (∼0.2–4 V), so that most of the harvested energy is wasted. In contrast, a TENG has an output voltage that is usually high enough (>10–100 V) and independent of frequency so that most of the generated power can be effectively used to power the devices. Furthermore, a TENG also has advantages of light weight, low cost, and easy scale up through advanced structure designs. All these merits verify the possible killer application of a TENG for harvesting energy at low frequency from motions such as human motions for powering small electronics and possibly ocean waves for large-scale blue energy

Enhancing Performance of Triboelectric Nanogenerator by Filling High Dielectric Nanoparticles into Sponge PDMS Film

Understanding of the triboelectric charge accumulation from the view of materials plays a critical role in enhancing the output performance of triboelectric nanogenerator (TENG). In this paper, we have designed a feasible approach to modify the tribo-material of TENG by filling it with high permittivity nanoparticles and forming pores. The influence of dielectricity and porosity on the output performance is discussed experimentally and theoretically, which indicates that both the surface charge density and the charge transfer quantity have a close relationship with the relative permittivity and porosity of the tribo-material. A high output performance TENG based on a composite sponge PDMS film (CS-TENG) is fabricated by optimizing both the dielectric properties and the porosity of the tribo-material. With the combination of the enhancement of permittivity and production of pores in the PDMS film, the charge density of ∼19 nC cm^–2, open-circuit voltage of 338 V, and power density of 6.47 W m^–2 are obtained at working frequency of 2.5 Hz with the optimized film consisting of 10% SrTiO₃ nanoparticles (∼100 nm in size) and 15% pores in volume, which gives over 5-fold power enhancement compared with the nanogenerator based on the pure PDMS film. This work gives a better understanding of the triboelectricity produced by the TENG from the view of materials and provides a new and effective way to enhance the performance of TENG from the material itself, not just its surface modification

Self-Powered Triboelectric Micro Liquid/Gas Flow Sensor for Microfluidics

Liquid and gas flow sensors are important components of the micro total analysis systems (μTAS) for modern analytical sciences. In this paper, we proposed a self-powered triboelectric microfluidic sensor (TMS) by utilizing the signals produced from the droplet/bubble <i>via</i> the capillary and the triboelectrification effects on the liquid/solid interface for real-time liquid and gas flow detection. By alternating capillary with different diameters, the sensor’s detecting range and sensitivity can be adjusted. Both the relationship between the droplet/bubble and capillary size, and the output signal of the sensor are systematically studied. By demonstrating the monitoring of the transfusion process for a patient and the gas flow produced from an injector, it shows that TMS has a great potential in building a self-powered micro total analysis system

An Ultrarobust High-Performance Triboelectric Nanogenerator Based on Charge Replenishment

Harvesting ambient mechanical energy is a green route in obtaining clean and sustainable electric energy. Here, we report an ultrarobust high-performance triboelectric nanogenerator (TENG) on the basis of charge replenishment by creatively introducing a rod rolling friction in the structure design. With a grating number of 30 and a free-standing gap of 0.5 mm, the fabricated TENG can deliver an output power of 250 mW/m² at a rotating rate of 1000 r/min. And it is capable of charging a 200 μF commercial capacitor to 120 V in 170 s, lighting up a G16 globe light as well as 16 spot lights connected in parallel. Moreover, the reported TENG holds an unprecedented robustness in harvesting rotational kinetic energy. After a continuous rotation of more than 14.4 million cycles, there is no observable electric output degradation. Given the superior output performance together with the unprecedented device robustness resulting from distinctive mechanism and novel structure design, the reported TENG renders an effective and sustainable technology for ambient mechanical energy harvesting. This work is a solid step in the development toward TENG-based self-sustained electronics and systems

Novel Spiral-Like Electrode Structure Design for Realization of Two Modes of Energy Harvesting

A planar spiral-like electrodes (PSE) based triboelectric generator has been designed for harvesting rotary mechanical energy to translate into electricity. The performance of the PSE-triboelectric generator with different cycles of spiral-like electrode strip at different rotating speeds is investigated, which demonstrates the open-circuit voltage and short-circuit current of 470 V and 9.0 μA at rotating speed of 500 r/min with three cycles. In addition, a novel coaxially integrated multilayered PSE-triboelectric generator is built, which can enhance the output of the power effectively. The short-circuit current, the open-circuit voltage, and output power reach to 41.55 μA, 500 V, and 11.73 mW, respectively, at rotating speed of 700 r/min. The output power of the multilayered PSE-triboelectric generator can drive 200 LEDs connected in antiparallel and charge a 110 μF commercial capacitor to 6 V in 23 s. Besides, due to the spiral-like electrode structure, the PSE-generator can work simultaneously in the modes of triboelectricity and electromagnetic induced electricity by sticking a small magnet on the rotating disk. The electromagnetic induced output power reaches to 21 μW at a loading resistance of 2 Ω at a rotating rate of 200 r/min. The spiral-like electrode structure not only broadens the electrode structure design but also adds a new function to the electrode

Enhancing the Output Charge Density of TENG via Building Longitudinal Paths of Electrostatic Charges in the Contacting Layers

The surface charge density of the tribolayer is the most parameter for developing a high performance triboelectric nanogenerator (TENG). Most previous works focused on the surface structural/chemical modification. Nevertheless, the internal space of the tribolayer and its mechanism exploration were less investigated. Herein, in this work, internal-space-charge zones are built through imbedding ravines and gullies in criss-crossed gold layers in the near-surface of the tribolayer, which leads to the high output performance of TENG. As experimental results manifest, the transfer charge density of gold-PDMS TENG (G-TENG) reaches 168 μC m^–2. Through theoretical analyses, it is determined that gold layers act as the passageways and traps of the triboelectric charges when the charges drift to the internal space of the tribomaterial. Moreover, the transport and storage process of triboelectric charges in the frictional layer are investigated comprehensively by quantum mechanics for the first time. The calculation method of the output current of TENG is proposed, and the theoretical calculation results coincide with the test results well. The results verify the application of the theoretical model and help with the construction and development of the theoretical system of TENG. Meanwhile, the relative results can be directly attained by this new theoretical model, and it is possible to make full use of the theoretical analysis to achieve a better performance for TENG. This study paves an easy and novel way for enhancing the charge density of the tribolayer by internal space construction and a new underlying theoretical model

Fully Packaged Blue Energy Harvester by Hybridizing a Rolling Triboelectric Nanogenerator and an Electromagnetic Generator

Ocean energy, in theory, is an enormous clean and renewable energy resource that can generate electric power much more than that required to power the entire globe without adding any pollution to the atmosphere. However, owing to a lack of effective technology, such blue energy is almost unexplored to meet the energy requirement of human society. In this work, a fully packaged hybrid nanogenerator consisting of a rolling triboelectric nanogenerator (R-TENG) and an electromagnetic generator (EMG) is developed to harvest water motion energy. The outstanding output performance of the R-TENG (45 cm³ in volume and 28.3 g in weight) in the low-frequency range (<1.8 Hz) complements the ineffective output of EMG (337 cm³ in volume and 311.8 g in weight) in the same range and thus enables the hybrid nanogenerator to deliver valuable outputs in a broad range of operation frequencies. Therefore, the hybrid nanogenerator can maximize the energy conversion efficiency and broaden the operating frequency simultaneously. In terms of charging capacitors, this hybrid nanogenerator provides not only high voltage and consistent charging from the TENG component but also fast charging speed from the EMG component. The practical application of the hybrid nanogenerator is also demonstrated to power light-emitting diodes by harvesting energy from stimulated tidal flow. The high robustness of the R-TENG is also validated based on the stable electrical output after continuous rolling motion. Therefore, the hybrid R-TENG and EMG device renders an effective and sustainable approach toward large-scale blue energy harvesting in a broad frequency range

Automatic Mode Transition Enabled Robust Triboelectric Nanogenerators

Although the triboelectric nanogenerator (TENG) has been proven to be a renewable and effective route for ambient energy harvesting, its robustness remains a great challenge due to the requirement of surface friction for a decent output, especially for the in-plane sliding mode TENG. Here, we present a rationally designed TENG for achieving a high output performance without compromising the device robustness by, first, converting the in-plane sliding electrification into a contact separation working mode and, second, creating an automatic transition between a contact working state and a noncontact working state. The magnet-assisted automatic transition triboelectric nanogenerator (AT-TENG) was demonstrated to effectively harness various ambient rotational motions to generate electricity with greatly improved device robustness. At a wind speed of 6.5 m/s or a water flow rate of 5.5 L/min, the harvested energy was capable of lighting up 24 spot lights (0.6 W each) simultaneously and charging a capacitor to greater than 120 V in 60 s. Furthermore, due to the rational structural design and unique output characteristics, the AT-TENG was not only capable of harvesting energy from natural bicycling and car motion but also acting as a self-powered speedometer with ultrahigh accuracy. Given such features as structural simplicity, easy fabrication, low cost, wide applicability even in a harsh environment, and high output performance with superior device robustness, the AT-TENG renders an effective and practical approach for ambient mechanical energy harvesting as well as self-powered active sensing