Ultra-High Sensitivity Real-Time Monitoring of Landslide Surface Deformation via Triboelectric Nanogenerator.

Monitoring surface deformation is crucial for the early warning of landslides, facilitating timely preventive measures. Triboelectric nanogenerator (TENG) demonstrates great potential for self-powered distributed monitoring in remote and power-scarce landslide areas. However, landslides deform typically at a rate of a few millimeters per day (mm d-1), making it challenging for TENG to directly monitor the deformation process. Herein, a method for monitoring surface deformation of landslides by constructing an ultra-low-speed triboelectric displacement sensor (US-TDS) is reported. Utilizing a force storage-release device and an accelerator, the US-TDS can produce obvious sensing signals at a linear input speed of 4.32 mm d-1. The coefficient of determination (R2) for the fitting curve of the pulse signals within the speed range of 21.6 to 129.6 mm d-1 reaches 0.999. Moreover, US-TDS can detect deformation displacement as small as 0.0382 mm. The stability of US-TDS displacement measurements is confirmed at a speed of 108 mm d-1, with relative errors under 1%. Ultimately, a real-time monitoring and early warning system for landslide surface deformation is constructed and verified through a combination of indoor simulations and outdoor experiments. This work provides a feasible solution for the scientific monitoring and early warning of the landslide development.

A Highly-Sensitive Omnidirectional Acoustic Sensor for Enhanced Human-Machine Interaction.

Acoustic sensor-based human-machine interaction (HMI) plays a crucial role in natural and efficient communication in intelligent robots. However, accurately identifying and tracking omnidirectional sound sources, especially in noisy environments still remains a notable challenge. Here, a self-powered triboelectric stereo acoustic sensor (SAS) with omnidirectional sound recognition and tracking capabilities by a 3D structure configuration is presented. The SAS incorporates a porous vibrating film with high electron affinity and low Young's modulus, resulting in high sensitivity (3172.9 mVpp Pa-1) and a wide frequency response range (100-20 000 Hz). By utilizing its omnidirectional sound recognition capability and adjustable resonant frequency feature, the SAS can precisely identify the desired audio signal with an average deep learning accuracy of 98%, even in noisy environments. Moreover, the SAS can simultaneously recognize multiple individuals in the auxiliary conference system and the driving commands under background music in self-driving vehicles, which marks a notable advance in voice-based HMI systems.

Regulating Contact-Electro-Catalysis Using Polymer/Metal Janus Composite Catalysts.

Interfacial contact electrification can catalyze redox reactions through a process called contact-electro-catalysis (CEC). The two main reaction paths for producing reactive oxygen species via CEC are the water oxidation reaction (WOR) and the oxygen reduction reaction (ORR). Herein, we designed a polymer/metal Janus composite catalyst that regulated the reaction rates of the WOR and ORR based on the catalyst composition. The ORR was preferentially enhanced when the polymer was negatively charged during contact electrification, while the WOR was preferentially enhanced when the polymer was positively charged. This phenomenon was observed for various conductive materials. The increase in the enhancement of the reaction rates depended on the conductivity and work function of the metal. We expect that this efficient CEC method can form a universal strategy for improving the performance of existing catalysts, as contact electrification is common in nature.

High-Performance Rotating Structure Triboelectric-Electromagnetic Hybrid Nanogenerator for Environmental Wind Energy Harvesting.

As environmental energy harvesting gains increasing importance in self-powered systems and large-scale energy demands, wind energy, as a clean, pollution-free, and renewable source, has garnered widespread attention. However, achieving efficient wind energy collection remains challenging. This study proposes a high-performance rotating structure triboelectric-electromagnetic hybrid nanogenerator designed for environmental wind energy harvesting. By optimizing the magnetic circuit design of the electromagnetic generator, the dispersed radial magnetic field is converted into a unified axial magnetic field, enabling efficient power generation with only a single annular coil, thereby simplifying the generator design and reducing manufacturing and maintenance costs. Additionally, a triboelectric nanogenerator design with soft contact friction between polycarbonate (PC) fur and fluorinated ethylene propylene (FEP) film was implemented, optimizing the spacing between the electrode and friction layers, thus enhancing output performance and device durability. Furthermore, we simulated and experimentally tested the output waveform of the designed hybrid generator structure, with the results showing a high degree of similarity, further validating the rationality of the device design and providing guidance for structural optimization. Subsequently, we achieved efficient energy storage using an energy management circuit (EMC). With the integration of the EMC, the generator successfully powered a Bluetooth temperature and humidity sensor at a wind speed of 10 m/s, achieving wireless transmission, and demonstrating its potential application in traffic signal systems and other natural environmental systems. This research provides an important reference for further exploration of novel wind energy harvesting technologies.

Self-powered visualized tactile-acoustic sensor for accurate artificial perception with high brightness and record-low detection limit.

The growth of the Internet of Things has focused attention on visualized sensors as a key technology. However, it remains challenging to achieve high sensing accuracy and self-power ability. Here, we propose a self-powered visualized tactile-acoustic sensor (SVTAS) based on an elaborated triboelectrification-induced electroluminescence (TIEL) unit. To date, it features a high brightness of 0.5 mW cm-2 (32 cd m-2) and a record-low detection limit of 0.5 kPa in horizontal-sliding mode. Meanwhile, the SVTAS is applicable to convert acoustic waves into TIEL signals in contact-separation mode, showing the highest response to the 44.07 Hz sound, a high signal-to-noise ratio of 8.7 dB-1, and an ultrafast response time of 0.8 ms. Furthermore, advanced artificial visualized perception systems are constructed with excellent performance in recognizing motion trajectories and human speech with different words/sentences. This work paves the way for the highly efficient and sustainable development of new-generation self-powered visualized perception systems, contributing a solution to wireless communication free from electromagnetic interference.

Enhancing CAR-T cell therapy against solid tumor by drug-free triboelectric immunotherapy.

Chimeric antigen receptor (CAR) T cell therapy is a highly effective immunotherapy for hematological tumors, but its efficacy against most solid tumors remains challenging. Herein, a novel synergistic combination therapy of drug-free triboelectric immunotherapy and CAR-T cell therapy against solid tumor was proposed. A triboelectric nanogenerator (TENG) that can generate pulsed direct-current by coupling triboelectrification effect and electrostatic breakdown effect was fabricated. The TENG can generate up to 30 pulse direct-current peaks with peak current output ≈35 µA in a single sliding to power the triboelectric immunotherapy. The pulsed direct-current stimulation induced immunogenic cell death of tumor cells (survival rate of 35.9 %), which promoted dendritic cells maturation, accelerated the process of antigen presentation to CAR-T cells and enhanced the systemic adaptive immune response. Furthermore, triboelectric immunotherapy promoted M1-like macrophage polarization, reduced regulatory T cells differentiation and reprogrammed the tumor immunosuppressive microenvironment, which ultimately enhanced the efficacy of CAR-T cells to eradicate nearly 60 % of NALM6 solid tumor mass. Notably, considering that triboelectric immunotherapy is a safe and effective drug-free antitumor strategy, the combined therapy did not increase the burden of double-medication on patients.

Unveiling Contact-Electrification Effect on Interfacial Water Oscillation.

Water is crucial for various physicochemical processes at the liquid-solid interfaces. In particular, the interfacial water, mediating the electric field and solvation effect along with the solid, corporately determine the electrochemical properties. Understanding the interaction between solid properties and the interface water holds significant importance in interfacial dynamics. However, the impact of alterations in the charged state of solid surfaces induced by contact electrification on interfacial water remains unknown. Here, the evolution of atomic-level resolution maps of hydration layers are reported on charged surfaces using 3D atomic force microscopy (3D-AFM). These findings demonstrate that electrostatic interactions can reinforce, distort, or collapse the characteristic structure of hydration layers. More importantly, these interactions exhibit interlayer differences and sample specificity in hydration layer structures of different substrates. In addition, similar oscillations of the hydration layer are observed at the electrochemical interface under different voltage biases. This suggests that contact-electrification has the potential to serve as a novel method for manipulating and regulating chemical reactions at the interface.

Triboelectric Nanogenerator with the Double-Mass Pendulum Integrated Spacer for Galloping Energy Harvesting of Transmission Lines.

The transmission lines galloping severely threatens the safety operation of the power grid. A reliable operation and maintenance alternative is to monitor the transmission lines by wireless sensing and warning devices. In this work, a triboelectric nanogenerator with the double-mass pendulum integrated spacer (DMPS-TENG) is proposed for harvesting the galloping energy of transmission lines and powering the wireless monitoring devices. Specifically, by introducing a double-mass pendulum system, the response frequency of the DMPS-TENG is reduced, allowing it to harvest energy at lower frequencies in the range of transmission lines galloping (0-3 Hz). Hereby, enhancing the energy harvesting bandwidth and the efficiency. The experiments show that with the introduction of the double-mass pendulum, the optimum frequency of the harvester is reduced from 2.4 to 1.9 Hz, enhances the harvesting bandwidth by 18%, and enables an average power output of up to 0.32 mW. Additionally, to demonstrate the practical value, a prototype is designed and fabricated to perform three different application experiments in the multi-split transmission lines simulation system. This work presents an innovative approach for galloping energy harvesting of transmission lines, which can be used to inform further development of sensor networks and visualization of the power grid.

Biopolymer and Biomimetic Techniques for Triboelectric Nanogenerators (TENGs).

Triboelectric nanogenerators (TENGs) play a crucial role in attaining sustainable energy for various wearable devices. Polymer materials are essential components of TENGs. Biopolymers are suitable materials for TENGs because of their degradability, natural sourcing, and cost-effectiveness. Herein, the latest progress in commonly used biopolymers and well-designed biomimetic techniques for TENG is summarized. The applications of natural rubber, polysaccharides, protein-based biopolymers, and other common synthetic biopolymers in TENG technology are summarized in detail. Each biopolymer is discussed based on its electrification capability, polarity variations, and specific functionalities as active and functional layers of TENGs. Important biomimetic strategies and related applications of specific biopolymers are also summarized to guide the structural and functional design of TENG. In the future, the study of triboelectric biopolymers may focus on exploring alternative candidates, enhancing charge density, and expanding functionality. Various possible applications of biopolymer-based TENGs are proposed in this review. By applying biopolymers and related biomimetic methods to TENG devices, the applications of TENG in the fields of healthcare, environmental monitoring, and wearable/implantable electronics can be further promoted.

Visualization and standardized quantification of surface charge density for triboelectric materials.

Triboelectric nanogenerator (TENG) operates on the principle of utilizing contact electrification and electrostatic induction. However, visualization and standardized quantification of surface charges for triboelectric materials remain challenging. Here, we report a surface charge visualization and standardized quantification method using electrostatic surface potential measured by Kevin probe and the iterative regularization strategy. Moreover, a tuning strategy on surface charge is demonstrated based on the corona discharge with a three-electrode design. The long-term stability and dissipation mechanisms of the injected negative or positive charges demonstrate high dependence on deep carrier traps in triboelectric materials. Typically, we achieved a 70-fold enhancement on the output voltage (~135.7 V) for the identical polytetrafluoroethylene (PTFE) based TENG (neg-PTFE/PTFE or posi-PTFE/PTFE triboelectric pair) with stable surface charge density (5% decay after 140 days). The charged PTFE was demonstrated as a robot e-skins for non-contact perception of object geometrics. This work provides valuable tools for surface charge visualization and quantification, giving a new strategy for a deeper understanding of contact electrification.

Multi-Attribute Triboelectric Materials and Innovative Applications Via TENGs.

Triboelectric nanogenerators (TENGs) as an avant-garde technology that transforms mechanical energy into electrical energy, offering a new direction for green energy and sustainable development. By means of high-efficiency TENGs, conventional materials as new triboelectric materials have exhibited multi-attribute characteristics, achieving innovative applications in the field of micro-nano energy harvesting and self-powered sensing. The progress of TENGs technology with the triboelectric materials is complementary and mutually promoting. On the one hand, one of the cruxes of TENGs lies in the triboelectric materials, which have a decisive impact on their performance. On the other hand, as the research and application of TENGs continue to deepen, higher demands are placed on triboelectric materials, which in turn promotes the advancement of the entire material system as well as the fields of materials science and physics. This work aims to delve into the characteristics, types, preferred choices, and modification treatments of triboelectric materials on the performances of TENGs, hoping to provide guidance and insights for future research and applications.

Triboiontronics with temporal control of electrical double layer formation.

The nanoscale electrical double layer plays a crucial role in macroscopic ion adsorption and reaction kinetics. In this study, we achieve controllable ion migration by dynamically regulating asymmetric electrical double layer formation. This tailors the ionic-electronic coupling interface, leading to the development of triboiontronics. Controlling the charge-collecting layer coverage on dielectric substrates allows for charge collection and adjustment of the substrate-liquid contact electrification property. By dynamically managing the asymmetric electrical double layer formation between the dielectric substrate and liquids, we develop a direct-current triboiontronic nanogenerator. This nanogenerator produces a transferred charge density of 412.54 mC/m2, significantly exceeding that of current hydrovoltaic technology and conventional triboelectric nanogenerators. Additionally, incorporating redox reactions to the process enhances the peak power and transferred charge density to 38.64 W/m2 and 540.70 mC/m2, respectively.

A Triboelectric-Electromagnetic Hybrid Nanogenerator with Magnetic Coupling Assisted Waterproof Encapsulation for Long-Lasting Energy Harvesting.

Ocean energy harvesting based on a triboelectric nanogenerator (TENG) has great application potential, while the encapsulation of triboelectric devices in water poses a critical issue. Herein, a triboelectric-electromagnetic hybrid nanogenerator (TE-HNG) consisting of TENGs and electromagnetic generators (EMGs) is proposed to harvest water flow energy. A magnetic coupling transmission component is applied to replace traditional bearing structures, which can realize the fully enclosed packaging of the TENG devices and achieve long-lasting energy harvesting from water flow. Under the intense water impact, magnetic coupling reduces the possibility of internal gear damage due to excessive torque, indicating superior stability and robustness compared to conventional TENG. At the waterwheel rotates speed of 75 rpm, the TE-HNG can generate an output peak power of 114.83 mW, corresponding to a peak power density of 37.105 W m-3. After 5 h of continuous operation, the electrical output attenuation of TENG is less than 3%, demonstrating excellent device durability. Moreover, a self-powered temperature sensing system and a self-powered cathodic protection system based on the TE-HNG are developed and illustrated. This work provides a prospective strategy for improving the output stability of TENGs, which benefits the practical applications of the TENGs in large-scale blue energy harvesting.

Advanced Energy Harvesters and Energy Storage for Powering Wearable and Implantable Medical Devices.

Wearable and implantable active medical devices (WIMDs) are transformative solutions for improving healthcare, offering continuous health monitoring, early disease detection, targeted treatments, personalized medicine, and connected health capabilities. Commercialized WIMDs use primary or rechargeable batteries to power their sensing, actuation, stimulation, and communication functions, and periodic battery replacements of implanted active medical devices pose major risks of surgical infections or inconvenience to users. Addressing the energy source challenge is critical for meeting the growing demand of the WIMD market that is reaching valuations in the tens of billions of dollars. This review critically assesses the recent advances in energy harvesting and storage technologies that can potentially eliminate the need for battery replacements. With a key focus on advanced materials that can enable energy harvesters to meet the energy needs of WIMDs, this review examines the crucial roles of advanced materials in improving the efficiencies of energy harvesters, wireless charging, and energy storage devices. This review concludes by highlighting the key challenges and opportunities in advanced materials necessary to achieve the vision of self-powered wearable and implantable active medical devices, eliminating the risks associated with surgical battery replacement and the inconvenience of frequent manual recharging.

A Blade-Type Triboelectric-Electromagnetic Hybrid Generator with Double Frequency Up-Conversion Mechanism for Harvesting Breeze Wind Energy.

Triboelectric nanogenerators (TENGs) have garnered substantial attention in breeze wind energy harvesting. However, how to improve the output performance and reduce friction and wear remain challenging. To this end, a blade-type triboelectric-electromagnetic hybrid generator (BT-TEHG) with a double frequency up-conversion (DFUC) mechanism is proposed. The DFUC mechanism enables the TENG to output a high-frequency response that is 15.9 to 300 times higher than the excitation frequency of 10 to 200 rpm. Coupled with the collisions between tribomaterials, a higher surface charge density and better generating performance are achieved. The magnetization direction and dimensional parameters of the BT-TEHG were optimized, and its generating characteristics under varying rotational speeds and electrical boundary conditions were studied. At wind speeds of 2.2 and 10 m/s, the BT-TEHG can generate, respectively, power of 1.30 and 19.01 mW. Further experimentation demonstrates its capacity to charge capacitors, light up light emitting diodes (LEDs), and power wireless temperature and humidity sensors. The demonstrations show that the BT-TEHG has great potential applications in self-powered wireless sensor networks (WSNs) for environmental monitoring of intelligent agriculture.

Neuromorphic Computing-Assisted Triboelectric Capacitive-Coupled Tactile Sensor Array for Wireless Mixed Reality Interaction.

Flexible tactile sensors show promise for artificial intelligence applications due to their biological adaptability and rapid signal perception. Triboelectric sensors enable active dynamic tactile sensing, while integrating static pressure sensing and real-time multichannel signal transmission is key for further development. Here, we propose an integrated structure combining a capacitive sensor for static spatiotemporal mapping and a triboelectric sensor for dynamic tactile recognition. A liquid metal-based flexible dual-mode triboelectric-capacitive-coupled tactile sensor (TCTS) array of 4 × 4 pixels achieves a spatial resolution of 7 mm, exhibiting a pressure detection limit of 0.8 Pa and a fast response of 6 ms. Furthermore, neuromorphic computing using the MXene-based synaptic transistor achieves 100% recognition accuracy of handwritten numbers/letters within 90 epochs based on dynamic triboelectric signals collected by the TCTS array, and cross-spatial information communication from the perceived multichannel tactile data is realized in the mixed reality space. The results illuminate considerable application possibilities of dual-mode tactile sensing technology in human-machine interfaces and advanced robotics.

Viscoelastic blood coagulation testing system enabled by a non-contact triboelectric angle sensor.

Thromboelastography (TEG) remains a convenient and effective viscoelastic blood coagulation testing device for guiding blood component transfusion and assessing the risk of thrombosis. Here, a TEG enabled by a non-contact triboelectric angle sensor (NTAS) with a small size (∼7 cm3) is developed for assessing the blood coagulation system. With the assistance of a superelastic torsion wire structure, the NTAS-TEG realizes the detection of blood viscoelasticity. Benefiting from a grating and convex design, the NTAS holds a collection of compelling features, including accurate detection of rotation angles from -2.5° to 2.5°, high linearity (R 2 = 0.999), and a resolution of 0.01°. Besides, the NTAS exhibits merits of low cost and simplified fabrication. Based on the NTAS-TEG, a viscoelastic blood coagulation detection and analysis system is successfully constructed, which can provide a graph and parameters associated with clot initiation, formation, and stability for clinicians by using 0.36 mL of whole blood. The system not only validates the feasibility of the triboelectric coagulation testing sensor, but also further expands the application of triboelectric sensors in healthcare.

Dynamic interfacial electrostatic energy harvesting via a single wire.

Spontaneously occurred electrostatic breakdown releases enormous energy, but harnessing the energy remains a notable challenge due to its irregularity and instantaneity. Here, we propose a revolutionary method that effectively harvests the energy of dynamic interfacial electrostatic breakdown by simply imbedding a conductive wire (diameter, 25 micrometers) beneath dielectric materials to regulate the originally chaotic and distributed electrostatic energy resulted from contact electrification into aggregation, effectively transforming mechanical energy into electricity. A point-charge physical model is proposed to explain the power generation process and output characteristics, guide structural design, and enhance output performance. Furthermore, a quantified triboelectric series including 72 dielectric material pairs is established for materials choice and optimization. In addition, a high voltage of over 10 kilovolts is achieved using polytetrafluoroethylene and polyethylene terephthalate. This work opens a door for effectively using electrostatic energy, offering promising applications ranging from novel high-voltage power sources, smart clothing, and internet of things.

Effective Charging of Commercial Lithium Cell by Triboelectric Nanogenerator with Ultrahigh Voltage Energy Management.

It is an increasingly mature application solution that triboelectric nanogenerator (TENG) supplies power to electronic devices through its power management system (PMS). However, the previous PMS is able to manage a limited voltage magnitude and the energy storage elements are limited to capacitors. This work proposes an ultrahigh voltage PMS (UV-PMS) to realize the charging of commercial lithium cells (LCs) by TENG. The design of UV-PMS enables energy management of TENGs with ultrahigh open-circuit voltages up to 3500 V and boosts the peak charging current from 30.9 µA to 2.77 mA, an increase of 89.64 times. With the introduction of UV-PMS, the effective charging capacity of LC charged by a TENG at a working frequency of 1.5 Hz for 1 h comes to 429.7 µAh, making a 75.3 times enhancement compared to charging by TENG directly. The maximum charging power comes to 1.56 mW. The energy storage efficiency is above 97% and the overall charge efficiency can be maintained at 81.2%. This work provides a reliable strategy for TENG to store energy in LC, and has promising applications in energy storage, LC's life, and self-powered systems.