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The widespread vibration is one of the most promising energy sources for IoT and small sensors, and broad-frequency vibration energy harvesting is important. Triboelectric nanogenerators (TENGs) can convert vibration energy into electrical energy through triboelectricity and electrostatic induction, providing an effective solution to the collection of broad-frequency vibration energy. Also, the power supply in constrained and compact spaces has been a long-standing challenge. Here, a miniaturized power supply (MPS) based on a broad-frequency vibration-driven triboelectric nanogenerator (TENG) is developed. The size of the MPS is 38 mm × 26 mm × 20 mm, which can adapt to most space-limited environments. The TENG device is optimized through theoretical mechanical modeling for the external stimuli, it can efficiently harvest vibrational energy in the frequency range of 1–100 Hz and has a high output power density of 134.11 W/cm3. The developed device demonstrates its practical application potential in powering small electronics like LEDs, watches, and timers. [ABSTRACT FROM AUTHOR]

In-plane micro-supercapacitors (MSCs) possess the capabilities of easy integration with planar circuits and feasible flexibility when they are used in flexible and wearable electronics. However, their unsatisfactory energy density limits their wide application. The Zn-ion hybrid supercapacitor is an ideal candidate as it assimilates the high energy-density of the zinc metal anode and high power-density of the pseudocapacitive material cathode. In view of the fact that multiple-metal MXenes could exhibit great potential compared to the single-metal MXenes in energy storage capability, here, Zn//V3CrC3Tx supercapacitors are fabricated. It is found that the partial replacement of Cr atoms for V atoms in V4C3Tx triggers an expansion of layer spacing of the MXene, the adsorption of Zn ions increases, and ion diffusion is promoted, which dramatically improve the capacitance, discharging potential, and cycle stability. Furthermore, in-plane Zn//V3CrC3Tx MSCs on paper demonstrate outstanding electrochemical properties and mechanical flexibility with an ultra-high area energy-density of 51.12 μW h cm−2, long cycle life of 20 000 cycles (84.5% capacitance retention), and outstanding bendability of 10 000 cycles (80.2% capacitance retention). The areal energy density and flexibility outperform most of the reported in-plane flexible MSCs. Owing to the emerging materials design and consummate flexible nature of the scheme, it can inject fresh strength into the development of flexible electronics. [ABSTRACT FROM AUTHOR]

With increasing global warming, catastrophic floods have threatened people's lives seriously and caused huge economic losses. However, present water hazard alarming systems generally rely on commercial batteries, limiting the intelligent development of disaster prevention planning and maintenance costs. In order to break the limitation, this work applies triboelectric nanogenerators (TENGs) to water hazard alarming. A spherical TENG device with four spiral units is designed to harvest water wave energy, and charge excitation modules (CEMs) are created and integrated with the TENG to improve its electric output. The output current and output power of the spherical TENG with CEMs can reach 15.09 mA and 24.48 mW, which are increased by 250.5 and 4.0 times, compared to the TENG without CEMs. Based on the charge excitation TENG, a self‐powered intelligent buoy is constructed. Utilizing the buoy to transmit 433 MHz radio frequency signals to 25 meters away, a water level alarm system and a water level information exchange system with a mobile phone are successfully realized. This work extends applications of TENGs toward water wave energy harvesting and provides a new strategy for water hazard alarming, which is conducive to the fields of carbon neutralization, Internet of Things, and disaster prevention. [ABSTRACT FROM AUTHOR]

Although graphitic carbon nitride nanosheets (CNs) with atomic thickness are considered as promising materials for hydrogen production, the wide band gap (3.06 eV) and rapid recombination of the photogenerated electron–hole pairs impede their applications. To address the above challenges, we synergized atomically thin CNs and graphene quantum dots (GQDs), which were fabricated as 2D/0D Van der Waals heterojunctions, for H2 generation in this study. The experimental characterizations indicated that the addition of GQDs to the π-conjugated system of CNs can expand the visible light absorption band. Additionally, the surface photovoltage spectroscopy (SPV) confirmed that introducing GQDs into CNs can facilitate the transport of photoinduced carriers in the melon chain, thus suppressing the recombination of charge carriers in body. As a result, the H2 production activity of the Van der Waals heterojunctions was 9.62 times higher than CNs. This study provides an effective strategy for designing metal-free Van der Waals hetero-structured photocatalysts with high photocatalytic activity. [ABSTRACT FROM AUTHOR]

The internet of things in the context of the ocean is vitally important. For ships sailing on the wide ocean in adverse weather conditions, evasion of marine islands and reefs is crucial to ensure safe navigation. Here, a hybrid wave energy harvesting nanogenerator is proposed (HW‐NG) as a power source for long‐distance wireless transmission, and demonstrated a self‐powered route avoidance warning system for ocean navigation. The HW‐NG is developed based on a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG), integrated by a pendulum structure. The TENG based on a contact‐separation mode is designed into a spring‐assisted multilayered structure, in which the EMG unit is well hybridized. Simply relying on the energy extracted from water waves, the HW‐NG can establish long‐distance (1.5 km) communication nodes on the sea. In application, a large HW‐NG network could be developed in the adjacent water areas of islands or reefs. With a network formed by hundreds of thousands of HW‐NGs, the forewarning signal transmission could be realized per second on the sea. More importantly, the wireless emitting is spontaneous through the designed automatic switch module. This work demonstrates a practicable strategy for ensuring safety of sea transportation based on wave energy collection. [ABSTRACT FROM AUTHOR]

Wind is one of the most important sources of green energy, but the current technology for harvesting wind energy is only effective when the wind speed is beyond 3.5–4.0 m s−1. This is mainly due to the limitation that the electromagnetic generator works best at high frequency. This means that light breezes cannot reach the wind velocity threshold of current wind turbines. Here, a high‐performance triboelectric nanogenerator (TENG) for efficiently harvesting energy from an ambient gentle wind, especially for speeds below 3 m s−1 is reported, by taking advantage of the relative high efficiency of TENGs at low‐frequency. Attributed to the multiplied‐frequency vibration of ultra‐stretchable and perforated electrodes, an average output of 20 mW m−3 can be achieved with inlet wind speed of 0.7 m s−1, while an average energy conversion efficiency of 7.8% at wind speed of 2.5 m s−1 is reached. A self‐charging power package is developed and the applicability of the TENG in various light breezes is demonstrated. This work demonstrates the advantages of TENG technology for breeze energy exploitation and proposes an effective supplementary approach for current employed wind turbines and micro energy structure. [ABSTRACT FROM AUTHOR]

Abstract: A tactile sensor should be able to detect both normal and tangential forces, which is mandatory for simulating human hands, but this fundamental function has been overlooked by most of the previous studies. Here, based on a triboelectric nanogenerator (TENG) with single‐electrode mode, the fully elastic and metal‐free tactile sensor that can detect both normal and tangential forces is proposed. With tiny burr arrays on the contact interface to facilitate the elastic deformation, the detected normal pressure by the device can reach to 1.5 MPa with a sensitivity of about 51.43 kPa V−1, and a large range of tangential forces can be detected ranging from 0.5 to 40 N with rough sensitivity of 0.83 N V−1 (0.5–3 N) and 2.50 N V−1 (3–40 N). Meanwhile, the applied tangential forces from different directions can also be clearly distinguished by the four‐partitioned electrode structure. Moreover, a shield film is coated on the top surface of the device, which can screen the electrostatic interference and enhance the repeatability of the device. The demonstrated concept of this self‐powered tactile sensor has excellent applicability for industrial robotics, human–machine interactions, artificial intelligence, etc. [ABSTRACT FROM AUTHOR]

By integrating a triboelectric nanogenerator (TENG) and a simple circuit board, the motion of water droplets can be controlled by the output of the TENG, which demonstrates a self-powered microfluidic system toward various practical applications in the fields of microfluidic system and soft robotics. This paper describes a method to construct a physical model for this self-powered system on the basis of electrostatic induction theory. The model can precisely simulate the detailed motion behavior of the droplet under driving of TENG, and it can also reveal the influences of surface hydrophobicity on the motion of the droplet, which can help us to better understand the key parameters that decide the performance of the system. The experimental observation of the dynamic performance of the droplet has also been done with a high speed camera system. A comparison between simulation results and real measurements confirms that the proposed model can predict the velocity and position of the water droplet driven by high voltage source as well as TENG. Hence, the proposed model in this work could serve as a guidance for optimizing the self-powered systems in future studies. [ABSTRACT FROM AUTHOR]

Biomolecule-based materials have attracted increasing attention for the fabrication of environmental-friendly triboelectric nanogenerators (TENGs) owing to the inductive effect with strong electron-donating ability from NH 2 groups. However, understanding the relationship between molecular packing and performance is extremely challenging due to the complex structures, thus limiting the designability of highly efficient triboelectric biomaterials at the molecular level. Here, we describe minimalistic yet mechanically robust ordered amino acid crystals formed by physical vapor deposition and utilized as positive triboelectric materials. The morphologies and electrostatic potential could be optimized by rationally tuning the chirality-dependent supramolecular spatial arrangement, which results in a 50% increase in the output voltage of the corresponding TENGs. Interestingly, the electric field-induced directional molecular packing results in a surface comprising charged amino groups that could easily lose electrons for charge separation, which more than doubled the output voltage of TENGs. The amino acid crystal-based TENG showing enhanced performance could serve as a micro-power source to drive light-emitting diodes and as a sensor to detect body movements. Our work provides insight into exploring the triboelectric effect of biomaterial crystals and paves an avenue to high-performance electric devices for bioengineering applications by designing biomolecule-based functional materials. [Display omitted] • Chirality-dependent amino acid crystals were obtained by physical vapor deposition. • The morphology, structure, and electrostatic potential of crystals were optimized by tuning molecular spatial arrangement. • The electric field-engineering of molecular packing during crystal growth leads to further enhanced triboelectric effect. • The optimized triboelectric nanogenerator could serve as a micro-power source and a sensor. [ABSTRACT FROM AUTHOR]

The sensor devices based on triboelectric nanogenerator (TENG) have been proved to have both high sensitivity and good self‐powered capability. Inspired by the cockroach antennae, a bionic‐antennae‐array (BAA) sensor based on the working principle of TENG is proposed for identifying the noncontact motions and a data processing module is specially designed for outputting electrostatic signal to the microcontroller unit (MCU). Based on the amplifying effect of antennae array, the detected maximum distance by this BAA sensor can reach 180 mm with a displacement resolution of 1 mm and maximum sensitivity of about 5.6 V mm−1 (at approaching angle of 90°). The influences of several critical factors, such as approaching angle, motion velocity, and target materials, to the performance of this BAA sensor are systematically studied. Meanwhile, the BAA sensor is integrated with proximity switch, intelligent robot, and mobile vehicles for realizing the function of motion alarming and obstacle detecting. The high sensitivity and the easy fabrication process of this TENG‐based BAA sensor show great application potentials in the field of industrial robotics, human–machine interactions, artificial intelligence, etc. [ABSTRACT FROM AUTHOR]

Here, a smart microfluidic system that can realize both long distance transport of micro‐/nanodroplets and precise patterning of microfluidics is designed based on triboelectric nanogenerator (TENG) and a photocontrollable adhesion surface (PCAS). The high output voltage from TENG can eject a microdroplet to a maximum distance of 640 mm (a maximum distance/diameter ratio of 300), while TENG can also manipulate the microdroplet under a thick dielectric layer (2 mm). Meanwhile, water adhesion as well as contact angle of the PCAS changes significantly with a short period of UV treatment and thus it can help to capture the moving microfluidics at the designated position. Moreover, microfluidic patterning with a variety of patterns and arrays on this PCAS can be obtained by using UV imprinting and the combination of TENG and PCAS can achieve an effective self‐powered microfluidic patterning system. Finally, a tunable gripper probe for 3D transport of microdroplets is demonstrated as another application of TENG and PCAS. These smart microfluidic systems based on TENG and PCAS have excellent applicability for many fields, such as drug/cell delivery, controllable chemical reaction for liquid testing, and production of microdroplets. A smart microfluidic system that can realize long distance transport of droplets and precise microfluidic patterning is designed based on triboelectric nanogenerator (TENG) and photocontrollable adhesion surface (PCAS). The high voltage from TENG can eject a microdroplet to a maximum distance of 640 mm. With UV treatment, the PCAS can capture the moving microfluidics at the designated position. [ABSTRACT FROM AUTHOR]

Tactile recognition is a critical technology for many applications. Here, it is found that the ambient electromagnetic signal, which is usually regarded as electromagnetic noise, can be a good triggering source to realize tactile detection. A circuit consisting of two light emitting diodes (LEDs) is designed as sensor unit and human contact can amplify the electrostatic signal induced by electromagnetic wave in this circuit, which enhances the brightness of the LEDs. Hence, visualizing tactile perception can be achieved based on this strategy. Accordingly, a stretchable and semi‐transparent sensor matrix is established for mapping detailed contact positions, on which the contact force can be smaller than 0.001 N. The detection and the visualization of sliding trajectory and pressure change are also demonstrated by using this sensory method, indicating its good applicability for different purposes. Electromagnetic wave universally exists in the working places and tactile sensors based on this strategy can be possibly applied to many fields such as factory automation, intelligent robotics, human–machine interaction, etc. Here, visualizing tactile perception and ultrasensitive tactile sensors by utilizing body‐enhanced induction of ambient electromagnetic waves are demonstrated. Coupled with a stretchable array of conductive nodes, a strip of conductive hydrogel, and a pressure‐sensitive conductor, the visualization of contact position mapping, sliding trajectory, and contact pressure are realized, respectively. [ABSTRACT FROM AUTHOR]