Exploring liquid-solid interface based triboelectrification, structures, and applications

Water wave energy is a promising renewable energy source that may alleviate the rising concerns over current resource depletion, but it is rarely exploited due to the lack of efficient energy harvesting technologies. In this work, a hybrid system with a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) based on an optimized inner topological structure is reported to effectively harvest water wave energy. The TENG with etched polytetrafluoroethylene films and Cu electrodes utilizing the contact‐freestanding mode is designed into a cubic structure, in which the EMG is well hybridized. An integration of TENG and EMG achieves mutual compensation of their own merits, enabling the hybrid system to deliver satisfactory output over a broad range of operation frequency. The output performance of TENG with varied inner topological structures is experimentally and theoretically compared, and a concept is proposed to further clarify the energy conversion efficiency, which should be considered in designing energy harvesting devices. The influences of oscillation frequency, amplitude, and dielectric materials on the output performance of the hybrid system are comprehensively studied on different platforms. Furthermore, the optimum operation frequency ranges for TENG and EMG are concluded. The proposed hybrid nanogenerator renders an effective approach toward large‐scale blue energy harvesting over a broad frequency range.

The technology of triboelectric nanogenerators (TENGs) has made great progress as a promising approach to generating electricity from ambient vibration energy. However, finding a way to generate enough electrical output efficiently from vibrations with a broadband of amplitudes is crucial when the relatively low current output of existing TENGs and the existence of natural vibrations with diverse amplitudes are considered. In this work, a freestanding and lightweight triboelectric nanogenerator with a capsule structure (namely, a capsule TENG) is demonstrated with an aim toward optional 3D integration and the efficient harvesting of energy from vibrations with a broadband of amplitudes. The capsule TENGs can be easily integrated to form 1D, 2D, and 3D structures to realize high electrical output. Under ideal conditions, the total output power of an integrated capsule-TENG pack can be approximately estimated as p × n2, where p is the peak output power per capsule TENG and n is the number of capsule TENGs. When capsule TENGs with hybrid structures, such as different lengths of the capsule tube and different numbers of paired electrodes, are assembled, energy can be more efficiently harvested from vibrations with a broadband of amplitudes. A total of three parameters (the active area-to-volume ratio, the power-to-volume ratio, and the power-to-weight ratio), which are important parameters for 3D-integrated TENGs, are proposed. The results of this research show that capsule TENGs are versatile devices that can potentially be used for the efficient harvesting of ambient vibration energy.

With the rapid development of the Internet of Things (IoT), the number of sensors utilized for the IoT is expected to exceed 200 billion by 2025. Thus, sustainable energy supplies without the recharging and replacement of the charge storage device have become increasingly important. Among various energy harvesters, the triboelectric nanogenerator (TENG) has attracted considerable attention due to its high instantaneous output power, broad selection of available materials, eco-friendly and inexpensive fabrication process, and various working modes customized for target applications. The TENG harvests electrical energy from wasted mechanical energy in the ambient environment. Three types of operational modes based on contact-separation, sliding, and freestanding are reviewed for two different configurations with a double-electrode and a single-electrode structure in the TENGs. Various charge transfer mechanisms to explain the operational principles of TENGs during triboelectrification are also reviewed for electron, ion, and material transfers. Thereafter, diverse methodologies to enhance the output power considering the energy harvesting efficiency and energy transferring efficiency are surveyed. Moreover, approaches involving not only energy harvesting by a TENG but also energy storage by a charge storage device are also reviewed. Finally, a variety of applications with TENGs are introduced. This review can help to advance TENGs for use in self-powered sensors, energy harvesters, and other systems. It can also contribute to assisting with more comprehensive and rational designs of TENGs for various applications.

The energy efficiency paradigm is a major bottleneck for the development of wireless sensor networks (WSNs) and Internet of Things (IoT) architectures and technologies. This edited book presents comprehensive coverage of energy harvesting sources and techniques that can be used for WSN and IoT systems

Electrospun materials are ideal substrates for wearable devices, offering high surface area, porosity, and mechanical flexibility. A polyimide/MXene (MXene) spinning film and cellulose acetate/polyamide 6 were used to fabricate a triboelectric nanogenerator (PC-TENG) for efficient mechanical energy harvesting. The results identify 5% MXene as the optimal weight fraction, achieving maximum performance by balancing material properties for enhanced energy conversion. The PC-TENG achieves a peak power output of 1.16 mW at an optimal load resistance of 10 MΩ. While the open-circuit voltage (VOC, ∼105 V) and transferred charge (QSC, ∼63.14 nC) remain stable across 2–6 Hz, the short-circuit current (ISC) increases significantly from 14.91 μA at 2 Hz to 41.41 μA at 6 Hz. A strong linear correlation between applied force and output performance is observed, with VOC rising from 63.41 V at 10 N to 148.14 V at 50 N, ISC from 7.31 to 17.98 μA, and QSC from 29.69 to 69.73 nC, demonstrating the device’s potential for precise force sensing. Integration into a table tennis paddle highlights its applicability in real-time sports monitoring, while its frequency-responsive current output underscores adaptability to dynamic sensing scenarios. This research demonstrates the PC-TENG’s potential for efficient energy harvesting and dynamic sensing, offering innovative solutions for self-powered devices and monitoring systems.

Ultrasensitive triboelectric nanogenerator for weak ambient energy with rational unipolar stacking structure and low-loss power management

In this work, we present STONEHENGE - Suite for nonlinear analysis of energy harvesting systems, a comprehensive toolbox engineered to study nonlinear piezoelectric vibration energy harvesters. These harvesters can harness kinetic energy from the environment and convert it into electricity using the piezoelectric effect. By introducing nonlinearity through strategically placed magnets, their efficiency is enhanced across a wide frequency spectrum. However, it comes at the cost of increasing complexity in system dynamics. To investigate this complexity and comprehend the potential of nonlinear energy harvesting, the STONEHENGE library was created. It is tailored to analyze the harvesting performance and dynamic behavior of these systems and allows users to explore and characterize system dynamics across a diverse range of physical parameters and excitation conditions using advanced numerical simulations. The toolbox encompasses six key modules, (i) initial value problem, analysis of system behavior from initial conditions; (ii) dynamic animation: which provides visual representations of system dynamics, aiding in intuitive understanding and interpretation; (iii) nonlinear tools: equips users with tools to dissect and comprehend the nonlinear aspects of vibration harvesting systems, essential for comprehensive analysis; (iv) sensitivity analysis: facilitates the assessment of how system behavior responds to variations in parameters, offering insights into its robustness and performance under different conditions; (v) stochastic simulation: allows for the exploration of system behavior under stochastic excitation, crucial for understanding real-world operating conditions; (vi) chaos control: offers methods for mitigating chaotic behavior within the system, enhancing predictability and stability. Utilizing a bistable oscillator as a benchmark, STONEHENGE aims to serve as a valuable resource for the development and refinement of both existing and emerging nonlinear vibration-based energy harvesting systems. By providing a comprehensive toolkit for analysis and characterization, STONEHENGE seeks to catalyze advancements in this field, ushering in an era of more efficient and sustainable energy harvesting technologies. Moreover, this library was developed to be easily adaptable to different dynamic systems and can contribute to different application fields.

Flexible and wearable triboelectric nanogenerators (TENGs) are considered promising candidates for mechanical energy harvesting and self-powered sensing, yet simultaneously achieving high output performance together with environmental adaptability remains challenging. In this study, a hydrophobic nanofiber-reinforced paper-based TENG (HF-PTENG) was developed by integrating (3-aminopropyl)triethoxysilane (APTES)-modified polyacrylonitrile/aramid nanofiber (PANA) membranes and a flexible conductive paper electrode (FCPE). The HF-PTENG delivered an open-circuit voltage of 384.3V, a short-circuit current of 15.1µA, and a transferred charge of 149.5 nC, achieving a maximum instantaneous power destiny of 2.1mW/cm2. Stable electrical output was maintained over 11000 operation cycles, and efficient biomechanical energy harvesting was demonstrated from finger tapping, wrist bending, and knee motions to power capacitors, commercial LEDs, and sensors. A smart glove integrated with the HF-PTENG was designed to achieve wireless control of a miniature car via WiFi communication. In addition, a 3×3 TENG sensor array was constructed to visualize planar pressure distribution. Separately, convolutional neural network (CNN) analysis enabled the recognition of six finger-drawn patterns with an accuracy of 98.32%. This study offers a practical and scalable strategy for constructing high-performance, flexible TENGs with board potential for applications in wearable electronics, human-machine interfaces, and intelligent motion sensing.

Foot‐motion energy harvesting has emerged as a promising solution for powering wearable electronics, given the high frequency and amplitude of foot pressure during daily locomotion. Amino acids have shown great promise in enhancing triboelectric performance due to their unique molecular structure and environmental compatibility. Here, a high‐performance footstep‐driven energy harvesting system is reported by incorporating lysine into nylon‐based polymer network through electrospinning process. A peak power density of 10.67 W m −2 is achieved, which is over 26‐time higher than that of commercial nylon films. A stacked five‐layer triboelectric nanogenerator (SF‐TENG) is fabricated and strategically placed under the heel and forefoot regions to harvest energy from foot motion. The output exhibits a linear relationship with stepping frequency, and the device maintains a minimal phase difference between signals from the front and rear contact regions, enabling synchronized power generation. To demonstrate practical application, SF‐TENG is integrated with management circuit and successfully powers three parallel‐connected hygro‐thermographs. This system highlights the potential of amino acid‐enhanced tribo‐materials for efficient biomechanical energy harvesting and self‐powered sensing. This work not only introduces a sustainable and scalable pathway for enhancing triboelectric materials, but also establishes an efficient, durable, and application‐ready solution for wearable electronics, particularly in foot‐pressure‐driven scenarios.

With the rapid evolution of emerging technologies like artificial intelligence, Internet of Things, big data, robotics, and novel materials, the landscape of global ocean science and technology is undergoing significant transformation. Ocean wave energy stands out as one of the most promising clean and renewable energy sources. Triboelectric nanogenerators (TENGs) represent a cutting‐edge technology for harnessing such random and ultra‐low frequency energy toward blue energy. A high‐performance TENG incorporating a double‐spiral zigzag‐origami structure is engineered to achieve continuous sensing and signal transmission in marine environment. Integrating the double‐spiral origami into the TENG system enables efficient energy harvesting from the ocean waves by converting low‐frequency wave vibrations into high‐frequency motions. Under the water wave triggering of 0.8 Hz, the TENG generates a maximum peak power density of 55.4 W m−3, and a TENG array with six units can generate an output current of 375.2 μA (density of 468.8 mA m−3). This power‐managed TENG array effectively powers a wireless water quality detector and transmits signals without an external power supply. The findings contribute to the development of sustainable and renewable energy technologies for oceanic applications and open new pathways for designing advanced materials and structures in the field of energy harvesting.

Hybrid harvesting of wind and wave energy based on triboelectric-piezoelectric nanogenerators

Triboelectric nanogenerators (TENGs) have recently emerged as a promising technology for efficient water wave energy harvesting. However, there is a paucity of clear guidance regarding the optimal designs of TENGs and their shells to achieve efficient absorption and conversion of water wave energy in real random waves. Herein, from the perspective of wave-body interaction and energy transfer, this paper proposes a structural quality factor (Qunit) for the quantitative evaluation of both the motion of floating triboelectric nanogenerator (Flo-TENG) shells and their capability to absorb and convert water wave energy efficiently. The factor is further subdivided into the amplitude structural quality factor (Qacc), which characterizes shell motion amplitude, and the frequency structural quality factor (Qf), which describes shell motion frequency. This paper systematically investigates the impact of various shell parameters such as bow shapes, curvatures, inclinations, and immersion ratios on Qacc and Qf. The findings indicate that variations in shell shape result in distinct Qunit values along different axial directions of wave propagation. These variations directly influence energy absorption efficiency in these directions. These results provide fundamental guidance for the design of high-performance Flo-TENG shells and the selection of internal energy harvesting directions to enable more efficient energy conversion.

A high-performance triboelectric nanogenerator (TENG) has been developed for breath sensing applications, utilizing tribopositive electrospun nylon-6 nanofibers and tribonegative fluorinated ethylene propylene (FEP). The optimization toward the development of electrospun nylon-6-based TENG includes a range of factors such as the applied force and frequency on tribo responses, the thickness of the fiber mat, the concentration of nylon-6 in the fiber mats, and the selection of the tribonegative material for pairing with nylon-6 nanofiber. Among these parameters, the nanofiber prepared with 18 wt% nylon-6, characterized by a uniform fiber distribution, the highest surface area of 55.69 m2 g−1, and an optimal thickness of 0.169 mm, demonstrated excellent TENG performance, among others. The TENG module constructed using nanofiber in a 4 cm2 area showed the TENG responses of more than 30 μA short-circuit current, 200 V open-circuit voltage, and 90 nC charge when hand-pressed. It achieved a substantial power density of 890 mW m−2 at 20 MΩ by applying a constant force of 10 N at a 10 Hz frequency. Charging a 1 μF capacitor to approximately 30.1 V in just 30 s highlights the potential of electrospun nylon-6 as a promising material for nanogenerator energy harvesting and sensing applications. The TENG device was found to be sufficient to power small, portable electronics such as LEDs and digital watch displays. A wearable belt was fabricated to showcase its breath-sensing capabilities by pairing it with FEP. The microcontroller connected to the TENG in the wearable belt is used to analyze the output produced through breathing patterns, subsequently activating a buzzer and LED by the nature of the breathing.

A real-time, self-powered wireless pressure sensing system with efficient coupling energy harvester, sensing, and communication modules

Three‐dimensional printed (3DP) triboelectric nanogenerators (TENGs) provide a versatile approach for complex and customizable microstructures tailored for efficient energy harvesting and sensing. Here, we demonstrate the fabrication of flexible microstructured TENGs produced via stereolithography 3D printing and subsequently coated with a conducting polymer, PEDOT:PSS (P:P). Three geometries are investigated: pillars, pyramids, and arches, with the arch configuration emerging as a new design combining enhanced mechanical adaptability and improved triboelectric performance. The arch‐shaped TENGs exhibit superior flexibility, structural stability, and a high active surface area, which collectively facilitate efficient energy conversion under repetitive deformation. Furthermore, the incorporation of P:P coating substantially enhances performance, resulting in a more than twentyfold increase in voltage output compared to uncoated counterparts. Among the 3DP structures, the arch geometry consistently delivers better performance, confirming the geometry‐driven performance of 3DP‐TENGs. The optimized arch configuration is found to yield a peak voltage output of ∼101 V, corresponding to a maximum power output of ∼193.6 mW/m 2 . By exploiting the spring‐like behavior of the arch‐shaped tribolayer, a “zero‐gap” TENG architecture is presented, offering a compact and adaptable energy‐harvesting platform as well as pressure‐sensing capabilities. Finally, a wireless pressure‐sensing platform configured as a vehicle parking counter is demonstrated, showcasing the potential of this development for integration into smart infrastructure and environmental monitoring systems.