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Tunable devices constructed by ferroelectric thin films are often desired to possess a low dielectric loss while maintainging a high dielectric tunability over a broad operating temperature range in applications, for example, resonators, filters, or phase shifters. However, it is difficult to simultaneously achieve these characteristics by traditional strategies, such as doping and strain modifying. Here, we demonstrate that the dielectric tunability of the sol-gel-prepared Pb(Sc 1/2 Nb 1/2 ) 0.9 (Mg 1/3 Nb 2/3 ) 0.1 O 3 (PSNMN) thin film can be almost doubled from ~47% to ~80.0% (at 10 kHz) at a low electric field (~530 kV/cm), and the dielectric loss can be sharply reduced by more than an order of magnitude, from ~0.50 to ~0.037 (at 1 kHz) when the thin film was annealed in air at 650°C for 15 h under the help of an atmosphere-compensating-block (ACB) made from the proto-PSNMN gel. Moreover, the PSNMN thin film annealed with ACB also exhibited an extremely high thermally-stable dielectric tunability in an ultrabroad temperature range (>130 K), which could be attributed to the Maxwell-Wagner (MW) effect generated by the interface between the PSNMN disordered matrix and the B-site nanoscale-ordered structure formed during the long-term annealing process. The reduced dielectric loss is mainly benefited from the reduced concentration of oxygen vacancy and the possible MW effects, and the enhanced dielectric tunability could be ascribed to the weaker domain-pinning effect by oxygen vacancy. The breakthrough provides a new universal strategy to achieve utrahigh tunable performance in A(B’ 1/2 B” 1/2 )O 3 ferroelectric thin films with a B-site nanoscale-ordered structure, meanwhile it paves the way for ultraintergrated tunable thin-film-devices with great phase shifter performance in practical applications.

Conventional approaches to studying fish kinematics pose a great challenge for the real-time monitoring of fish motion kinematics. Here, a multifunctional fish-wearable data snooping platform (FDSP) for studying fish kinematics is demonstrated based on an air sac triboelectric nanogenerator (AS-TENG) with antibacterial coating. The AS-TENG not only can harvest energy from fish swimming but also serves as the self-powered sensory module to monitor the swimming behavior of the fish. The peak output power generated from each swing of the fishtail can reach 0.74 mW, while its output voltage can reflect the real-time behavior of the fishtail. The antibacterial coating on the FDSP can improve its biocompatibility and the elastic texture of the FDSP allows it to be tightly attached to fish. The wireless communication system is designed to transmit the sensory data to a cell phone, where the detailed parameters of fish motion can be obtained, including swing angle, swing frequency, and even the typical swing gestures. This FDSP has broad application prospects in underwater self-powered sensors, wearable tracking devices, and soft robots.

With the rapid development of human-machine interfaces, artificial acoustic sensors play an important role in the hearing impaired. Here, an ultrathin eardrum-like triboelectric acoustic sensor (ETAS) is presented consisting of silver-coated nanofibers, whose thickness is only 40 µm. The sensitivity and frequency response range of the ETAS are closely related to the geometric parameters. The ETAS endows a high sensitivity of 228.5 mV Pa

There is a critical shortage in research needed to explore a new class of multifunctional structural components that respond to their environment, empower themselves and self-monitor their condition. Here, we propose the novel concept of triboelectric nanogenerator-enabled structural elements (TENG-SEs) to build the foundation for the next generation civil infrastructure systems with intrinsic sensing and energy harvesting functionalities. In order to validate the proposed concept, we develop proof-of-concept multifunctional composite rebars with built-in triboelectric nanogenerator mechanisms. The developed prototypes function as structural reinforcements, nanogenerators and distributed sensing mediums under external mechanical vibrations. Experiential and theoretical studies are performed to verify the electrical and mechanical performance of the developed self-powering and self-sensing composite structural components. We demonstrate the capability of the embedded structural elements to detect damage patterns in concrete beams at multiscale. Finally, we discuss how this new class of TENG-SEs could revolutionize the large-scale distributed monitoring practices in civil infrastructure and construction fields.

An ultra-stable all-weather service piezoelectric nanogenerator (PENG) with a wide operating temperature range (-80~80 ℃) and a wide operating relative humidity range (0~100%) is proposed. The PENG based on N doped 4H-SiC exhibits long-term service stability up to 50 days.The short circuit current density of PENG based on N doped 4H-SiC is enhanced significantly. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00779-0., Ultra-stable piezoelectric nanogenerator (PENG) driven by environmental actuation sources with all-weather service capability is highly desirable. Here, the PENG based on N doped 4H-SiC nanohole arrays (NHAs) is proposed to harvest ambient energy under low/high temperature and relative humidity (RH) conditions. Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance. The density of short circuit current of the assembled PENG reaches 313 nA cm−2, which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays. The enhancement can be attributed to the existence of nanohole sidewalls in NHAs. All-weather service capability of the PENG is verified after being treated at -80/80 ℃ and 0%/100% RH for 50 days. The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00779-0.

The electric double layer (EDL) at liquid-solid interfaces is fundamental to many research areas ranging from electrochemistry and microfluidics to colloidal chemistry. Here, we demonstrate the electricity generation by mechanically modulating the EDL at the hydrogel-dielectric polymer interfaces. It is found that contact electrification between the hydrogel and the dielectric polymer could charge the dielectric polymer surface at first; the mechanical deformation of the pyramid-shaped hydrogel results in the periodic variation of the EDL area and capacitance, which then induces an alternative current in the external circuits. This mechano-to-electrical energy conversion mechanism is then utilized to construct soft stretchable self-powered pressure sensors by designing dynamic EDL at hydrogel-dielectric elastomer interfaces. The sensitivity is optimized to 1.40 kPa

The pursuit to mimic skin exteroceptive ability has motivated the endeavors for epidermal artificial mechanoreceptors. Artificial mechanoreceptors are required to be highly sensitive to capture imperceptible skin deformations and preferably to be self-powered, breathable, lightweight and deformable to satisfy the prolonged wearing demands. It is still struggling to achieve these traits in single device, as it remains difficult to minimize device architecture without sacrificing the sensitivity or stability. In this article, we present an all-fiber iontronic triboelectric mechanoreceptor (ITM) to fully tackle these challenges, enabled by the high-output mechano-to-electrical energy conversion. The proposed ITM is ultralight, breathable and stretchable and is quite stable under various mechanical deformations. On the one hand, the ITM can achieve a superior instantaneous power density; on the other hand, the ITM shows excellent sensitivity serving as epidermal sensors. Precise health status monitoring is readily implemented by the ITM calibrating by detecting vital signals and physical activities of human bodies. The ITM can also realize acoustic-to-electrical conversion and distinguish voices from different people, and biometric application as a noise dosimeter is demonstrated. The ITM therefore is believed to open new sights in epidermal electronics and skin prosthesis fields.

As the world population structure has already exhibited an inevitable trend of aging, technical advances that can provide better eldercare are highly desired. Knee osteoarthritis, one of the most common age-associated diseases, can be effectively treated via total knee arthroplasty (TKA). However, patients are suffering from the recovery process due to inconvenience in post-hospital treatment. Here, a portable, modular, and wearable brace for self-assessment of TKA patients' rehabilitation is reported. This system mainly consists of a force transducer for isometric muscle strength measurement and an active angle sensor for knee bending detection. Clinical experiments on TKA patients demonstrate the feasibility and significance of the system. Specifically, via brace-based personalized healthcare, the TKA patients' rehabilitation process is quantified in terms of myodynamia, and a definite rehabilitation enhancement is obtained. Additionally, new indicators, that is, isometric muscle test score, for evaluating TKA rehabilitation are proposed. It is anticipated that, as the cloud database is employed and more rehabilitation data are collected in the near future, the brace system can not only facilitate rehabilitations of TKA patients, but also improve life quality for geriatric patients and open a new space for remote artificial intelligence medical engineering.

Although electrocoagulation technology has been widely researched in wastewater treatment, high energy consumption and electrode passivation are still the main challenges for its widespread applications. Here, we propose a self-powered electrocoagulation system based on a triboelectric nanogenerator (TENG) with alternating current (AC) outputs to solve these two issues, and thus enhance the removal efficiency of organic pollutants. Compared with the direct current source, the AC power source can reduce the electrode passivation, produce more aluminum hydroxide compounds after consuming an equal amount of charges, and thus improve the degradation efficiency. Moreover, the removal efficiency can be further enhanced by decreasing the frequency AC, in which a 5.7-fold improvement was achieved at 0.2 Hz compared to DC at 1.8 Hz. Inspired by the low frequency of ocean wave water, we developed a self-powered AC-electrocoagulation system to directly drive the electrocoagulation reaction by harvesting water wave energy, which can effectively remove 94.8% of xylenol orange and 98.8% of water-oil emulsion, and thus completely address the problem of energy consumption. This study further promotes the application of self-powered electrochemical systems in treating environmental pollution.

Transition metal dichalcogenides (TMDCs) with 2H phase are expected to be building blocks in next-generation electronics; however, they suffer from electrical anisotropy, which is the basics for multi-terminal artificial synaptic devices, digital inverters, and anisotropic memtransistors, which are highly desired in neuromorphic computing. Herein, the anisotropic carrier mobility from 2H WSe

In this paper, a quaternary dielectric soft-contact rotary triboelectric nanogenerator (QDSR-TENG) of low frictional resistance is fabricated for combining TENG with a shape memory alloy (SMA) engine. The introduction of rabbit fur brush and FEP brush results in charge pumps with a partially soft contact structure. Benefiting from the low friction loss of the structure, the QDSR-TENG can operate stably and continually for 100k cycles without significant output degradation. The SMA engine exhibits thermally induced phase transformation and super-elasticity and can be utilized for harnessing waste heat energy. The thermal-driven QDSR-TENG can operate with a water source of 43 °C with a distinguishable response to the variation of temperatures. Such a low starting temperature not only promotes the harvesting of low-grade thermal energy, but also results in a self-monitoring industrial cooling water system. The coupled elastocaloric power and cooling cycle proposed in the thermal-driven QDSR-TENG opens a new paradigm for the application in energy harvesting and smart sensing.

Triboelectric nanogenerators (TENGs) have attracted much interest in recent years, due to its effectiveness and low cost for converting high-entropy mechanical energy into electric power. The traditional TENGs generate an alternating current, which requires a rectifier to provide a direct-current (DC) power supply. Herein, a dynamic p-n junction based direct-current triboelectric nanogenerator (DTENG) is demonstrated. When a p-Si wafer is sliding on a n-GaN wafer, carriers are generated at the interface and a DC current is produced along the direction of the built-in electric field, which is called the tribovoltatic effect. Simultaneously, an UV light is illuminated on the p-n junction to enhance the output. The results indicate that the current increases 13 times and the voltage increases 4 times under UV light (365 nm, 28 mW/cm2) irradiation. This work demonstrates the coupling between the tribovoltaic effect and the photovoltaic effect in DTENG semiconductors, promoting further development for energy harvesting in mechanical energy and photon energy.

The lack of efficient, low-cost, distributed energy collection methods is a vital factor restricting the application of the Internet of Things (IoT) in smart agriculture. This paper proposes a method based on triboelectric nanogenerator and electromagnetic generator to realize self-powered IoT nodes and self-powered sensors at the same time. An energy harvesting and sensing device based on electromagnetic-triboelectric hybrid generator (ES-ETHG) is designed. The peak power of ES-ETHG is 32.4 mW, which can supply power to IoT nodes for a long time with power management circuits. In addition, ES-ETHG can critically measure wind speed and wind level within the range of 3-15 m/s, and accurately detect wind direction within 2 s. Furthermore, the self-powered distributed weather sensing system based on ES-ETHG is developed to realize the remote collection of wind speed, wind direction, temperature, and humidity. This work proposes a solution for developing self-powered IoT and sensor in the field of smart agriculture.

Contact electrification (CE) involves a complex interplay of physical interactions in realistic material systems. For this reason, scientific consensus on the qualitative and quantitative importance of different physical mechanisms on CE remains a formidable task. The CE mechanism at a water/polymer interface is a crucial challenge owing to the poor understanding of charge transfer at the atomic level. First-principle density functional theory (DFT), used in the present work, proposes a new paradigm to address CE. Our results indicate that CE follows the same trend as the gap between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of polymers. Electron transfer occurs at the outmost atomic layer of the water/polymer interface and is closely linked to the functional groups and atom locations. When the polymer chains are parallel to the water layer, most electrons are transferred; conversely, if they are perpendicular to each other, the transfer of charges can be ignored. We demonstrate that a decrease in the interface distance between water and the polymer chains leads to CE in quantitative agreement with the electron cloud overlap model. We finally use DFT calculations to predict the properties of CE materials and their potential for triboelectric nanogenerator energy harvesting devices.

Wind is a regenerative and sustainable green energy, but it is intermittent; especially, harvesting irregular wind energy is a great challenge for existing technologies. This study demonstrates a turbine vent triboelectric nanogenerator (TV-TENG), which can be utilized as both an irregular wind harvester and a self-powered environmental sensing system on the rooftops of buildings. At a wind speed of nearly 7 m/s, the TV-TENG delivers an open-circuit voltage of up to 178.2 V, a short-circuit current of 38.2 μA, and a corresponding peak power of 2.71 mW under an external load of 5 MΩ, which can be used to directly light up 120 green light-emitting diodes. Furthermore, a self-powered on-site industrial monitoring system has been developed, which can be improve the easiness and simpleness of the industry environment for temperature monitoring and safety warning. Increasing the fluidity of air inside and outside the device is a key factor in fabricating an efficient TV-TENG; it is a novel approach for harvesting irregular wind energy and is sensitive, reliable, waterproof, and easy to use. This work greatly expands the applicability of TENGs as energy harvesters for irregular wind and also as self-powered sensing systems for ambient detection.

It is known that the suspended liquid droplets in clouds can generate electrostatic charges, which finally results in the lightning. However, the detailed mechanism related to the contact-electrification process on the liquid-gas (L-G) interfaces is still poorly understood. Here, by introducing an acoustic levitation method for levitating a liquid droplet, we have studied the electrification mechanism at the L-G interface. The tribo-motion between water droplets and air induced by the ultrasound wave leads to the generation of positive charges on the surface of the droplets, and the charge amount of water droplets (20 μL) gradually reaches saturation within 30 s. The mixed solid particles in droplets can increase the amount of transferred charge, whereas the increase of ion concentration in the droplet can suppress the charge generation. This charge transfer phenomenon at L-G interfaces and the related analysis can be a guidance for the study in many fields, including anti-static, harvesting rainy energy, micro/nano fluidics, triboelectric power generator, surface engineering, and so on. Moreover, the surface charge generation due to L-G electrification is an inevitable effect during ultrasonic levitation, and thus, this study can also work for the applications of the ultrasonic technique.

Droplet motion state monitoring is important in microfluidic applications, such as biomedicine, drug delivery, and metal ion extraction. Here, a nonintrusion monitoring method of droplet motion state

The development of wearable electronic skins (E-skins) requires devices with high flexibility, breathability, and antibacterial activity, as in sports sensing technology. Here, we report a flexible, breathable, and antibacterial triboelectric nanogenerator (TENG)-based E-skin for self-powered sensing in volleyball reception statistics and analytics, which is fabricated by sandwiching a silver nanowire (Ag NW) electrode between a thermoplastic polyurethane (TPU) sensing layer and a poly(vinyl alcohol)/chitosan (PVA/CS) substrate. Benefiting from an outstanding breathability of 10.32 kg m-2 day-1 and biocidal properties of CS and Ag NW, the E-skin offers excellent thermal-moisture comfort and a remarkable antibacterial effect on Escherichia coli and Staphylococcus aureus. A pressure sensitivity of 0.3086 V kPa-1 is demonstrated in the sensing range of 6.65-19.21 kPa. Besides, a volleyball reception statistical and analytical system is further developed based on a 2 × 3 E-skin array. According to this work, the integration of wearable electronic devices with self-powered sensors may expand practical applications in sports.

Perovskite and semiconductor materials are always the focus of research because of their excellent properties, including pyroelectric, photovoltaic effects, and high light absorption. On basis of this, the design of combining BaTiO

The fast-spreading of novel coronavirus disease (COVID-19) has been sweeping arount the globe and brought heavy casualties and economic losses, which creats dire needs for technological solutions into medical preventive actions. In this work, triboelectric nanogenerator for respiratory sensing (RS-TENG) has been designed and integrated with facemask, which endows the latter with respiratory monitoring function. The output of RS-TENG for respiratory flow can reach up to about 8 V and 0.8 μA respectively although it varies with different respiratory status, which proves the high sensitivity of RS-TENG for respiratory monitoring. An apnea alarm system can be constructed by combining the smart facemask with circuit modules so that timely alarm can be transmitted after people stop breathing. Furthermore, RS-TENG can be used to control household appliances, which brings convenience to the life of the disabled people. Considering its incomparable advantages such as small volume, easy fabrication, simple installation and economical applicability, such design is helpful for developing multifunctional health monitoring gadgets during the COVID-19 pandemic., Graphical abstract This TENG-based facemask not only can real-time monitor human breath sensitively and accurately, but also can combine with different circuit module to realize different functions, such as control electric appliances by breath or apneal alarm. The research has proved that this facemask has a good prospect in the fields of wearable device, smart medical care systems and respiratory monitoring.

Triboelectric nanogenerator (TENG) has presented the huge potential application in distributed energy field which can realize the conversion from dispersed mechanical energy to electric energy. However, the natural characteristic of pulse output for conventional TENG, which means high crest factor, is defective for directly driving electronics. Here, a strategy to convert the pulse alternate current of TENG into a direct current with low crest factor is achieved through introducing a phase difference design into the structure of TENG. As a result, a direct current with a crest factor of 1.07 is obtained in a rotational free-standing TENG (RF-TENG) array at optimum phase difference, where 3D digital printing technology is used to accurately control the parameter of phase difference. Moreover, an adaptable contact mode structure between tribolayer and electrode improves the durability of the RF-TENG array, which can present a stable performance after working 1.2 million cycles. This work provides a combined strategy to obtain a long-lifetime and low crest-factor TENG for its large-scale application in energy harvesting.

Description, The contact-electrification induced interface photon emission spectroscopy is revealed by electrons transfer at the interface., Contact electrification (CE) (or triboelectrification) is the phenomena where charges are produced through physical contact between two materials. Here we report the atomic featured photon emission spectra during CE between two solid materials. Photon emission provides the evidence that electron transfer takes place at the interface from an atom in one material to another atom in the other material during CE. This process is the contact electrification induced interface photon emission spectroscopy (CEIIPES). It naturally paves a way to a spectroscopy corresponding to the CE at an interface, which might impact our understanding of the interaction between solids, liquids, and gases. The physics presented here could be expanded to Auger electron excitation, x-ray emission, and electron emission in CE for general cases, which remain to be explored. This could lead to a general field that may be termed as contact electrification induced interface spectroscopy (CEIIS).

Scanning transmission electron microscopy (STEM) tomography is widely used to reveal three-dimensional (3D) structure of the specimens from nanometers to atomic resolution. Advances in transmission electron microscope enable high resolution and low dose data acquisition for 3D reconstruction to resolve 3D coordinates of single atoms. Meanwhile, the developments of reconstruction algorithms increase the reconstruction quality. However, the as-acquired raw datasets often require alignments before they can be used as inputs to feed a reconstruction algorithm. The effect of post-acquisition data misalignments on the final reconstruction quality of STEM tomography is less discussed. Here, using phantom datasets with a focus on atomic features, we simulate a range of misalignments on each alignment step and correlate the level of misalignments to the final reconstruction quality. The study pinpoints that accurate alignments of tilt angles and stack positions and minimizing scan distortion are important to the reconstruction quality, while the sequence of alignment steps do not affect the reconstruction quality. The study not only emphasizes the most important alignment steps that should be pay attention to for a high-quality 3D reconstruction, but also summarizes post-acquisition data alignment procedures as a primer for new practitioners to use STEM tomography.

Description, An all-in-one fully self-powered wireless sensing e-sticker was designed for smart sensing, robotics, smart city, and Industry 4.0., The rapid development of the Internet of Things depends on wireless devices and their network. Traditional wireless sensing and transmission technology still requires multiple modules for sensing, signal modulation, transmission, and power, making the whole system bulky, rigid, and costly. Here, we proposed a paradigm shift wireless sensing solution based on the breakdown discharge–induced displacement current. Through that, we can combine the abovementioned functional modules in a single unit of self-powered wireless sensing e-sticker (SWISE), which features a small size (down to 9 mm by 9 mm) and long effective transmission distance (>30 m) when compared to existing wireless sensing technologies. Furthermore, SWISEs have functions of multipoint motion sensing and gas detection in fully self-powered manner. This work proposes a solution for flexible self-powered wireless sensing platforms, which shows great potential for implantable and wearable electronics, robotics, health care, infrastructure monitoring, human-machine interface, virtual reality, etc.