Directional water self‐transport plays a crucial role in diverse applications such as biosensing and water harvesting. Despite extensive progress, current strategies for directional water self‐transport are restricted to a short self‐driving distance, single function, and complicated fabrication methods. Here, a lubricant‐infused heterogeneous superwettability surface (LIHSS) for directional water self‐transport is proposed on polyimide (PI) film through femtosecond laser direct writing and lubricant infusion. By tuning the parameters of the femtosecond laser, the wettability of PI film can be transformed into superhydrophobic or superhydrophilic. After trapping water droplets on the superhydrophilic surface and depositing excess lubricant, the asymmetrical wetting ridge drives water droplets by an attractive capillary force on the LIHSS. Notably, the maximum droplet self‐driving distance can approach ≈3 mm, which is nearly twice as long as the previously reported strategies for direction water self‐transport. Significantly, it is demonstrated that this strategy makes it possible to achieve water self‐transport, anti‐gravity pumping, and chemical microreaction on a tilted LIHSS. This work provides an efficient method to fabricate a promising platform for realizing directional water self‐transport.

Wetting Ridge‐Guided Directional Water Self‐Transport

Tactile sensors with visible light feedback functions, such as wearable displays and electronic skin and biomedical devices, are becoming increasingly important in various fields. However, existing methods cannot meet the application requirements for the tactile perception of intensity feedback and extended intersection due to their limited light‐mapping performance and insufficient portability. Herein, a freely constructible self‐powered visual tactile sensor is proposed, which consists of a high‐output triboelectric nanogenerator (TENG) and a visual light source. The transferred charge of the TENG is enhanced to 746 nC by the structural design of the triboelectric material and device, which can easily drive the light source to generate a light signal with a brightness of 9.8 cd m−2. Notably, the application of the TENG enables to realization visual sensing of the palm‐grasp state and strength feedback without an external power supply. This visual feedback and power‐free tactile sensors are expected to have potential application in the field of artificial intelligence as a new interactive medium for smart protective clothing and robotics.

Wearable Triboelectric Visual Sensors for Tactile Perception

Triboelectric nanogenerator enhanced radical generation in a photoelectric catalysis system via pulsed direct-current

Synthetic polymer materials such as paraformaldehyde and polyamides are widely used in the field of energy engineering. However, they pose a challenge to environmental sustainability because they are derived from petrochemicals that are non‐renewable and difficult to degrade in the natural environment. The development of high‐performance natural alternatives is clearly emerging as a promising mitigation option. Inspired by natural bamboo, this research reports a “three‐step” strategy for the large‐scale production of triboelectric materials with special nanostructures from natural bamboo. Benefiting from the special hierarchical porous structure of the material, Bamboo/polyaniline triboelectric materials can reach short‐circuit current of 2.9 µA and output power of 1.1 W m–2 at a working area of only 1 cm2, which exceeds most wood fiber‐based triboelectric materials. More importantly, it maintains 85% energy harvesting after an extreme environment of high temperature (200 °C), low temperature (−196 °C), combustion environment, and multiple thermal shocks (ΔT = 396 °C). This is unmatched by current synthetic polymer materials. This work provides new research ideas for the construction and application of biomass structural materials under extreme environmental conditions.

Hierarchical Porous Cellulosic Triboelectric Materials for Extreme Environmental Conditions

Application and prospect of organic acid pretreatment in lignocellulosic biomass separation: A review.

Though visualizing perspiration constituents is crucial for physiological evaluation, inadequate material healing and unreliable power supply methods restrict its applications. Herein, a fully flexible self‐powered sweat sensor is fabricated from a cellulose‐based conductive hydrogel to address these issues. The hydrogel electrode is composed of a cellulose nanocomposite polymerized in situ with polyaniline and cross‐linked with polyvinyl alcohol/borax. The cellulose nanocomposites furnish the sweat sensor with tensile and electrical self‐healing efficiencies exceeding 95% within 10 s, a stretchability of 1530%, and conductivity of 0.6 S m−1. The sweat sensor quantitatively analyzes Na+, K+, and Ca2+ contents in perspiration, to sensitivities of 0.039, 0.082, and 0.069 mmol–1, respectively, in real time via triboelectric effect and wirelessly transmits the results to a user interface. This fabricated sweat sensor with high flexibility, stability, and analytical sensitivity and selectivity provides new opportunities for self‐powered health monitoring.

Stretchable Triboelectric Self‐Powered Sweat Sensor Fabricated from Self‐Healing Nanocellulose Hydrogels

Abstract The effective acquisition of clean water from atmospheric water offers a potential sustainable solution for increasing global water and energy shortages. In this study, an asymmetric amphiphilic surface incorporating self-driven triboelectric adsorption was developed to obtain clean water from the atmosphere. Inspired by cactus spines and beetle elytra, the asymmetric amphiphilic surface was constructed by synthesizing amphiphilic cellulose ester coatings followed by coating on laser-engraved spines of fluorinated ethylene propylene. Notably, the spontaneous interfacial triboelectric charge between the droplet and the collector was exploited for electrostatic adsorption. Additionally, the droplet triboelectric nanogenerator converts the mechanical energy generated by droplets falling into electrical energy through the volume effect, achieving an excellent output performance, and further enhancing the electrostatic adsorption by means of external charges, which achieved a water harvesting efficiency of 93.18 kg/m 2 h. This strategy provides insights for the design of water harvesting system. 

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Ying Qin

Papers

Stretchable Triboelectric Self‐Powered Sweat Sensor Fabricated from Self‐Healing Nanocellulose Hydrogels

Bioinspired asymmetric amphiphilic surface for triboelectric enhanced efficient water harvesting

Hierarchical Porous Cellulosic Triboelectric Materials for Extreme Environmental Conditions

Cellulose template-based triboelectric nanogenerators for self-powered sensing at high humidity

Air-permeable cellulosic triboelectric materials for self-powered healthcare products