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Triboelectric nanogenerator (TENG) provides a new cost‐effective strategy to harvest water wave energy due to the broad options of triboelectric materials and the high efficiency in low‐frequency energy harvesting. Here, a new triboelectric–electromagnetic hybrid nanogenerator (TEHG) consisting of a soft ball‐based triboelectric nanogenerator (SB‐TENG) and an electromagnetic generator (EMG) is reported for harvesting wave energy. The soft balls are utilized as one triboelectric layer to increase the contact area with the copper electrodes. The critical parameters that may affect the energy harvesting performance of the SB‐TENG are investigated, including the type of the filled liquids, the thickness of the silicone shell, the number of layers, and the added soft balls. Under an operating frequency of 1 Hz, the SB‐TENG and the EMG can reach a maximum output peak power of 0.5 and 8.5 mW, respectively. The TEHG has been demonstrated to power dozens of light‐emitting diodes and drives a digital temperature sensor to monitor the water temperature for an extended period. This study provides a new design and approach to improve the output performance of TENGs and presents an excellent prospect for building a self‐powered water‐sensing system driven by low‐frequency water waves. [ABSTRACT FROM AUTHOR]

Soft robots have attracted great attention in the past decades owing to their unique flexibility and adaptability for accomplishing tasks via simple control strategies, as well as their inherent safety for interactions with humans and environments. Here, a soft robotic manipulation system capable of stiffness variation and dexterous operations through a remotely controlled manner is reported. The smart manipulation system consists of a soft omnidirectional arm, a dexterous multimaterial gripper, and a self‐powered human–machine interface (HMI) for teleoperation. The cable‐driven soft arm is made of soft elastomers and embedded with low melting point alloy as a stiffness‐tuning mechanism. The self‐powered HMI patches are designed based on the triboelectric nanogenerator that utilizes a sliding mode of tribo‐layers made of copper and polytetrafluoroethylene. The novel soft manipulation system has great potential for soft and remote manipulation and human machine interactions in a variety of applications from elderly care to surgical operation to agriculture harvesting. [ABSTRACT FROM AUTHOR]

[Display omitted] • AE-mediated PDI effectively inactivated planktonic Staphylococcus aureus. • AE-mediated PDI damaged membrane integrity and genomic DNA. • Type II reaction mechanism was predominantly responsible in AE-mediated PDI process. • AE-mediated PDI reduced S. aureus contamination and maintained quality on apple juice. Aloe-emodin (AE) is a natural compound with photodynamic properties. The aim of this study was to investigate the inhibitory effect of AE-mediated photodynamic inactivation (PDI) on Staphylococcus aureus (S. aureus). The bacteriostatic efficiency under different photodynamic conditions and photosensitizing mechanism was studied in detail. The results showed that AE-mediated PDI exhibited a typical concentration and time-dependent characteristics. In terms of bactericidal mechanism, disruption of membrane integrity and increase of cell membrane permeability was observed. Type II reaction was assumed as the main photochemical reaction involved in AE-mediated PDI as evidenced by the action of different ROS quenching agents. Furthermore, AE-mediated PDI decreased the bacterial survival in freshly squeezed apple juice and maintained its quality. The combination of blue light and AE enlarged the application of AE as an effective natural photosensitizer suitable for a food system. [ABSTRACT FROM AUTHOR]

Forest fires present a great threat as they can rapidly grow and become large, resulting in tragic loss of life and property when occurring near occupied land. Here a self‐powered fire alarm system based on a novel multilayered cylindrical triboelectric nanogenerator (MC‐TENG) that can produce electrical power for the detection sensors by harvesting the kinetic energy of moving tree branches in a forest is presented. The major parameters for harvesting the kinetic energy using the proposed MC‐TENG are investigated, including the number of triboelectric layers, the frequency, the amplitude of external excitation, and the orientation between motion direction and device configuration. The fabricated MC‐TENG results in a peak power of 2.9 mW and a maximum average power of 1.2 mW at a low frequency of 1.25 Hz. The integrated self‐powered forest fire alarm system, consisting of fire sensors, a carbon‐based micro‐supercapacitor, and the MC‐TENG, is demonstrated to be able to report fire risk or hazard efficiently, accurately, and robustly. This study provides a new solution to reduce the forest fire risk through a portable and sustainable alarm system by effectively harvesting kinetic energies in natural environment with TENG technology. [ABSTRACT FROM AUTHOR]

Soft end effectors or grippers capable of grasping objects dexterously and efficiently have attracted increasing attention in a broad range of applications. This article describes a smart soft finger‐like actuator with fast response, accurate control, self‐powered pressure, and bending sensing capability by combing the cable‐driven actuation with soft triboelectric nanogenerators (TENGs). The soft actuator, driven by a miniature DC motor, is designed to have multiple segments of elastomer body split with triangular cuts to facilitate the bending actuation and conformal contact with target objects. Two types of TENGs are integrated with the soft actuator: a single‐electrode‐mode TENG to measure the contact pressure and an inner contact–separation‐mode TENG to detect the bending. With micropyramid structures, the tribo‐skin patches possess high sensitivity and good compatibility with the actuator and can actively detect proximity, contact, and pressure via self‐generated electricity. Based on the modular design approach, a gripper with three fingers is fabricated and tested for its grasping, sensing, and self‐powering performance. This gripper is capable of picking up different kinds of objects, providing sensory feedback, and generating electricity, which shows great potential for use in robot–human and robot–environment interaction applications. [ABSTRACT FROM AUTHOR]

Grippers, human-machine interfaces, motion sensors, soft arms, soft robotics, triboelectric nanogenerators, variable stiffness Keywords: grippers; human-machine interfaces; motion sensors; soft arms; soft robotics; triboelectric nanogenerators; variable stiffness EN grippers human-machine interfaces motion sensors soft arms soft robotics triboelectric nanogenerators variable stiffness 1 1 1 05/07/21 20210501 NES 210501 In article number 2100084, Changyong Cao and co-workers develop a novel soft robotic manipulation system capable of stiffness variation and dexterous operation for safe human-machine interactions. Human-Machine Interfaces: Soft Robotic Manipulation System Capable of Stiffness Variation and Dexterous Operation for Safe Human-Machine Interactions (Adv. [Extracted from the article]

Additive manufacturing, i.e., 3D printing, is being increasingly utilized to fabricate a variety of complex‐shaped electronics and energy devices (e.g., batteries, supercapacitors, and solar cells) due to its excellent process flexibility, good geometry controllability, as well as cost and material waste reduction. In this review, the recent advances in 3D printing of emerging batteries are emphasized and discussed. The recent progress in fabricating 3D‐printed batteries through the major 3D‐printing methods, including lithography‐based 3D printing, template‐assisted electrodeposition‐based 3D printing, inkjet printing, direct ink writing, fused deposition modeling, and aerosol jet printing, are first summarized. Then, the significant achievements made in the development and printing of battery electrodes and electrolytes are highlighted. Finally, major challenges are discussed and potential research frontiers in developing 3D‐printed batteries are proposed. It is expected that with the continuous development of printing techniques and materials, 3D‐printed batteries with long‐term durability, favorable safety as well as high energy and power density will eventually be widely used in many fields. [ABSTRACT FROM AUTHOR]

Multifunctional metamaterials (MFMs) capable of energy harvesting and vibration control are particularly attractive for smart structures, wearable/biointegrated electronics, and intelligent robotics. Here, a novel MFM based on triboelectric nanogenerators (TENGs), which can harvest environmental energy and reduce vibration simultaneously, is reported. The unit cells of the MFM consist of a local resonator, an integrated contact‐ separation mode TENG, and spiral‐shaped connecting beams. A multiphysics theoretical model is developed for quantitatively evaluating the performance of the MFM by including the mechanical and electrical fields interactions, which is further validated by experimental testing. It is demonstrated that the TENG‐based MFM can not only effectively harvest vibration energy to power electronics but also dramatically suppress low‐frequency mechanical vibration. This work provides a new design and model for developing novel TENG‐based MFMs for advanced smart systems used in a variety of applications. [ABSTRACT FROM AUTHOR]

To meet the great need for distributed and sustainable power sources, mechanical energy in the environment is widely used for electricity generation. Based on the coupling effect of triboelectrification and electrostatic induction, triboelectric nanogenerator (TENG) as an innovative energy technology has advantages of collecting fluctuating amplitude and low-frequency mechanical energy. In this paper, a leaf-shaped TENG has been demonstrated to harvest multiple ambient mechanical energy. By the characterization with different mechanical energy sources, the leaf-shaped TENG has been proven as an effective tool to scavenge wind, vibration, and falling raindrop energy. Furthermore, based on numerous leaf-shaped TENGs, a leaf-shaped TENG tree has been developed, which can be used for continuous collection of environmental mechanical energy at large-scale. This paper has first exhibited a conformal structure for simultaneously harvesting various mechanical energy, which has bright potentials in environmental monitoring, Internet of things, and wireless sensor networks. [ABSTRACT FROM AUTHOR]

Abstract: The air breakdown phenomenon is generally considered as a negative effect in previous research on triboelectric nanogenerators (TENGs), which is always accompanied by air ionization. Here, by utilizing the air breakdown induced ionized air channel, a direct‐current triboelectric nanogenerator (DC‐TENG) is designed for harvesting contact‐separation mechanical energy. During working process, the charges first transfer from bottom to top electrodes through an external circuit in contact state, then flow back via the ionized air channel created by air breakdown in the separation process. So a unidirectional flow of electrical charges can be observed in the external circuit. With repeating contact‐separation cycles, continuous pulsed DC output through the external circuit can be realized. This working mechanism was verified by real‐time electrode potential monitoring, photocurrent signal detection, and controllable discharging observation. The DC‐TENG can be used for directly and continuously charging an energy storage unit and/or driving electronic devices without using a bridge rectifier. Owing to its simplicity in structure, the mechanism is further applied to fabricate the first flexible DC‐TENG. This research provides a significant fundamental study for DC‐TENG technology and may expand its application in flexible electronics and flexible self‐charging power systems. [ABSTRACT FROM AUTHOR]

Abstract: Growing demand in automobile safety system raises a requirement to electronic devices being self‐powered, stable, and durable. Herein, a self‐powered Hall vehicle sensor (SPHVS) is demonstrated for automobile safety system, which integrates the triboelectric nanogenerator, the management circuit, the magnet, and the Hall element. The tribotronic constant current source is proposed to steadily power the Hall element in rotational motion at any different speeds. Furthermore, the performances of the SPHVS for vehicle speed sensing and vehicle braking monitoring are systematically investigated, which exhibits wide sensing range, great stability, and excellent sensitivity. This work clearly proposes a promising solution for speed sensing and braking monitoring, and indicates the potential applications of power tribotronics for the self‐powered electronic devices in prospective automobile industry. [ABSTRACT FROM AUTHOR]

• A biodegradable, transparent, and antibacterial sodium alginate-based triboelectric nanogenerator is proposed. • A vacuum filtration method was used for preparing patterned transparent conductive sodium alginate/AgNWs electrodes. • Sodium alginate/glycerol substrate have good adhesion to realize the complete transfer of the AgNWs pattern. • The triboelectric nanogenerator has been used as a self-powered tactile sensor. The utilization of natural biomaterials in the construction of triboelectric nanogenerators (TENG) has significant implications for the advancement of sustainable self-powered devices. Sodium alginate (SA), an eco-friendly and biodegradable triboelectric material with excellent transparency, is considered an ideal material for wearable TENGs. In this work, we report a biodegradable, transparent, and antibacterial SA-based TENG for mechanical energy harvesting and self-powered tactile sensing. The addition of glycerol, an environment-friendly additive, can enhance flexibility and adhesiveness of the SA, which resulted in well-transferred AgNWs/SA electrodes with high transparency and conductivity. The major parameters that affect the output performance of the fabricated TENG are investigated, including the frequency, thickness and area of the triboelectric layers. The output voltage, transferred charge, and peak power of the TENG could reach up to 53 V, 18 nC, and 4 μW, respectively, which is sufficient to power small electronic devices. In addition, the fabricated TENG device also shows excellent antibacterial and biodegradable capabilities. Finally, the TENG is demonstrated to be an effective self-powered tactile sensor for pressure mapping, human movement monitoring, and wearable human–machine interfacing. This work provides a new strategy to design flexible transparent TENGs with biodegradable SA and paves the way for developing next-generation self-powered transient electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Salt-resistant wood-based solar steam generator with downward water supply is designed. • High-yield and long-term desalination of seawater and high salinity water is achieved. • The solar-driven water evaporator achieves a high evaporation rate of 4.31 kg m−2 h−1. • The rate reaches 4.24 kg m−2 h−1 during desalinating 15 wt% brine water over 100 h. • Downward water supply avoids salt deposition and has long-term performance stability. To realize high-yield and long-term desalination of seawater and high salinity water, salt-resistant wood-based solar steam generators with a special top-down water supply device are developed by delignification of balsa wood for enhancing its hydrophilicity followed by vacuum-assisted impregnation of polyvinyl alcohol (PVA) and MXene nanosheets and lyophilization. Thanks to the incidental gain of environmental energy, the sufficient top-down water supply, the porous channels and intrinsic hydrophilicity of the delignified wood, and the efficient solar light absorption and solar-thermal energy conversion of the dispersed MXene nanosheets, the resultant PVA/MXene-decorated wood (WPM) solar-driven water evaporator achieves a water evaporation rate of as high as 4.31 kg m−2 h−1 under 1-sun irradiation. A superior solar-driven desalination rate of 3.83 kg m−2 h−1 is achieved during evaporating a brine water with 25 wt% of NaCl for 8 h. The sufficient top-down water supply dilutes the high concentration of brine on the WPM evaporator surface and drains it promptly, avoiding the salt deposition and hence achieving the performance stability during the long-term solar-driven desalination. The high evaporation efficiency and the satisfactory long-term salt-resistance are demonstrated by desalinating an aqueous solution of 15 wt% NaCl over 100 h under 1-sun irradiation with an exceptional average evaporation rate of 4.24 kg m−2 h−1. [ABSTRACT FROM AUTHOR]

A novel tribotronic transistor has been developed by vertically coupling a single-electrode mode triboelectric nanogenerator and a MoS2 field effect transistor. Once an external material contacts with or separates from the device, negative charges are induced by triboelectrification on the surface of the polymer frictional layer, which act as a 'gate' voltage to modulate the carrier transport in the MoS2 channel instead of the conventional applied gate voltage; the drain-source current can be tuned in the range of 1.56-15.74 μA, for nearly ten times. The application of this MoS2 tribotronic transistor for the active smart tactile switch is also demonstrated, in which the on/off ratio can reach as high as ≈16 when a finger touches the device and the increased drain-source current is sufficient to light two light-emitting diodes. This work may provide a technique route to utilize the 2D materials based tribotronic transistors in MEMS, nanorobotics, and human-machine interfacing. [ABSTRACT FROM AUTHOR]

The triboelectric nanogenerator (TENG) is a promising mechanical energy harvesting technology, but its pulsed output and the instability of input energy sources make associated energy‐storage devices necessary for real applications. In this work, feasible and efficient charging of Li‐ion batteries by a rotating TENG with pulsed output current is demonstrated. In‐depth discussions are made on how to maximize the power‐storage efficiency by achieving an impedance match between the TENG and a battery with appropriate design of transformers. With a transformer coil ratio of 36.7, ≈72.4% of the power generated by the TENG at 250 rpm can be stored in an LiFePO4–Li4Ti5O12 battery. Moreover, a 1 h charging of an LiCoO2–C battery by the TENG at 600 rpm delivers a discharge capacity of 130 mAh, capable of powering many smart electronics. Considering the readily scale‐up capability of the TENG, promising applications in personal electronics can be anticipated in the near future. [ABSTRACT FROM AUTHOR]

The front cover page of the journal is presented.