Quantifying Wetting Dynamics with Triboelectrification

Wetting is often perceived as an intrinsic surface property of materials, but determining its evolution is complicated by its complex dependence on roughness across the scales. The Wenzel state, where liquids have intimate contact with the rough substrate, and the Cassie-Baxter state, where liquids sit onto air pockets formed between asperities, are only two states among the plethora of wetting behaviors. Furthermore, transitions from the Cassie-Baxter to the Wenzel state dictate completely different surface performance, such as anti-contamination, anti-icing, drag reduction etc.; however, little is known about how transition occurs during time between the several wetting modes. In this paper, we show that wetting dynamics can be accurately quantified and tracked using solid-liquid triboelectrification. Theoretical underpinning reveals how surface micro-/nano-geometries regulate stability/infiltration, also demonstrating the generality of our theoretical approach in understanding wetting transitions.Comment: Both Main and SI uploaded in a single fil

Innovative Technology for Self‐Powered Sensors: Triboelectric Nanogenerators

Abstract Internet of Things and wearable technology's quick development have opened up a vast market for sensor systems. However, typical sensors' external power supplies' short lifespan and expensive maintenance restrict them from being used more widely. Triboelectric nanogenerators (TENGs), a recently created mechanical energy harvesting and self‐powered sensing device, show enormous promise to get over these restrictions. TENG can be used not only to power sensors instead of conventional chemical batteries but also be utilized to actualize sensing by taking advantage of the unique characteristics of the friction layer itself. Triboelectric nanogenerators efficiently provide crucial infrastructure for a new generation of sensing devices that gather data using several self‐powered sensors in abundance. The recent progress in the development of TENGs applied in the sensor field is reviewed. First, the working mechanisms of solid‐solid TENG and solid–liquid TENG are introduced. Subsequently, the development of TENG‐based sensing systems and their application progress in self‐powered temperature sensors, self‐powered pressure sensors, self‐powered humidity sensors, self‐powered atmosphere sensors, self‐powered wireless sensors, interface wetting status monitoring, solution property monitoring, and friction condition monitoring are highlighted. Finally, current challenges and open opportunities are discussed

Concealed Wireless Warning Sensor Based on Triboelectrification and Human-Plant Interactive Induction

With the continuous development of artificial intelligence, the demand for sensors with simple preparation and strong concealment continues to increase. However, most of the high-sensitivity sensors have complex manufacturing methods, high costs, and single functions. In this paper, a sensitive motion sensor based on the triboelectric interaction between a living plant and the human body was designed to detect the real-time movements of human beings and provide danger warning. A certain relationship exists between the triboelectric signal and the distance between the plant and the human body, with effective signals being detected in the range of 1.8 m. In addition, the triboelectric signal generated by each person is unique like a fingerprint, which can be used for biometrics. On the basis of the triboelectric signal, a wireless character entry warning system is designed. This sensor can not only send out a wireless warning signal at a specific distance but also allow one to receive the warning information synchronously on a mobile phone in real time. The wireless movement sensor receives signals through a living plant, and it has the characteristics of convenient use, strong concealment, and shielding difficulty. This sensor has the potential to be widely used in person recognition, danger warning, and motion monitoring

A new synergetic system based on triboelectric nanogenerator and corrosion inhibitor for enhanced anticorrosion performance

A new synergetic anticorrosion system was constructed via combining a self-powered cathodic protection based on triboelectric nanogenerator (TENG) and a green corrosion inhibitor of zinc gluconate (ZnG). Wind-driven TENG with a sandwich-like structure was designed, exhibiting high output performance with the peak values of short circuit current, output voltage and corresponding power reaching about 155 mu A, 402 V and 13.5 mW, respectively, under a wind speed of 10 m/s. With the assistance of TENG, the migration of corrosion inhibitor can be accelerated and the formation of the protective layer becomes faster due to the driving force of electric field. The shielding effect of protective layer in turn improves the cathodic protection of TENG. The immersion experiment and electrochemical measurements including Tafel polarization curves and EIS were taken to evaluate the performance of synergetic anticorrosion system. FESEM and EDS measurements were performed to analyze the morphology and composition of the protective layer and confirm the mechanism of synergetic anticorrosion. This work expands the application of TENG in the anticorrosion field and proposes a new thought of synergetic anticorrosion method

Soft/Hard-Coupled Amphiphilic Polymer Nanospheres for Water Lubrication

Amphiphilic polymer nanospheres of poly­(3-sulfopropyl methacrylate potassium salt-<i>co</i>-styrene) [P­(SPMA-<i>co</i>-St)] were prepared by a simple soap-free emulsion polymerization method and used as efficient water lubrication additives to enhance the antiwear behaviors of the Ti₆Al₄V alloy. The monodisperse and flexible P­(SPMA-<i>co</i>-St) bicomponent copolymer nanospheres were synthesized with a controllable manner by adjusting the mass fraction ratio of the monomers, with the hydrophobic polystyrene (PSt) as the hard skeletal carrier component and the hydrophilic PSPMA with a hydration layer structure as the soft lubrication layer in the course of friction. The influences of the monomer concentration, the copolymer nanosphere additive content, the load, and the frequency of the friction conditions on their tribological properties were studied in detail, and a probable antiwear mechanism of the soft/hard-coupled copolymer nanospheres under water lubrication was also proposed. The results show that compared with pure PSt, the P­(SPMA-<i>co</i>-St) polymer nanospheres exhibited better antiwear property as an additive for water lubrication, and the friction coefficient and the wear volume first decreased and then increased with the increase of the SPMA content, indicating that the hydrophilic SPMA has a significant effect on lubrication properties owing to its hydration performance. Furthermore, with the increase of polymer nanosphere concentration, the friction coefficient and wear amount also decreased to a stable and low value at a saturation concentration of 1 wt %. The flexible polymer nanospheres with a hydrophilic soft SPMA shell and a rigid PSt core exhibited good friction-reduction and antiwear performance as lubrication additives, indicating their promising and potential applications in water lubrication and biological lubrication

Visualization of Charge Dynamics when Water Droplets Bounce on a Hydrophobic Surface

Visualizing the motion of water droplets and understanding their electrification behavior holds significance for applications related to droplet transport, self-cleaning, and anti-icing/deicing and for providing a comprehensive explanation of the solid–liquid triboelectrification mechanism. Here, by constructing microcolumnar structures on the polytetrafluoroethylene surface, a water droplet-based single electrode triboelectric nanogenerator was fabricated for visualizing charge dynamics when a water droplet bounces on a hydrophobic surface. The motion state of the water droplet is closely linked to its electrification behavior through the integration of a high-speed camera and an ammeter. The electrification behavior stemming from the bounce of the water droplet is dynamically captured in real-time. The results show that the magnitude and polarity of the electrical signal have strong dependence on the motion state of the water droplet. For instance, when a water droplet approaches or moves away from the substrate in a single direction, a unipolar electrical signal is generated. However, when the water droplet reaches its limit in the initial motion direction, it signifies a static equilibrium state, resulting in the electrical signal being at zero. Furthermore, we examine the impact of factors such as impact speed, drop contact area, contact line spreading/retraction speed, and impact angle on electrification. Finally, based on the close relationship between poly­(ethylene oxide) (PEO) droplet bounce dynamics and electrical signals, the bouncing details of PEO droplets with different concentrations are tracked by electrical signals. This study digitally presents the whole process of droplet bounce in situ and provides a means for monitoring and tracking droplet movement

Visualization of Charge Dynamics when Water Droplets Bounce on a Hydrophobic Surface

Visualizing the motion of water droplets and understanding their electrification behavior holds significance for applications related to droplet transport, self-cleaning, and anti-icing/deicing and for providing a comprehensive explanation of the solid–liquid triboelectrification mechanism. Here, by constructing microcolumnar structures on the polytetrafluoroethylene surface, a water droplet-based single electrode triboelectric nanogenerator was fabricated for visualizing charge dynamics when a water droplet bounces on a hydrophobic surface. The motion state of the water droplet is closely linked to its electrification behavior through the integration of a high-speed camera and an ammeter. The electrification behavior stemming from the bounce of the water droplet is dynamically captured in real-time. The results show that the magnitude and polarity of the electrical signal have strong dependence on the motion state of the water droplet. For instance, when a water droplet approaches or moves away from the substrate in a single direction, a unipolar electrical signal is generated. However, when the water droplet reaches its limit in the initial motion direction, it signifies a static equilibrium state, resulting in the electrical signal being at zero. Furthermore, we examine the impact of factors such as impact speed, drop contact area, contact line spreading/retraction speed, and impact angle on electrification. Finally, based on the close relationship between poly­(ethylene oxide) (PEO) droplet bounce dynamics and electrical signals, the bouncing details of PEO droplets with different concentrations are tracked by electrical signals. This study digitally presents the whole process of droplet bounce in situ and provides a means for monitoring and tracking droplet movement