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

Integration of a porous wood-based triboelectric nanogenerator and gas sensor for real-time wireless food-quality assessment

UV illumination-enhanced ultrasensitive ammonia gas sensor based on (001)TiO2/MXene heterostructure for food spoilage detection.

UV illumination-enhanced ultrasensitive ammonia gas sensor based on (001)TiO2/MXene heterostructure for food spoilage detection

Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices, food packaging, biomedical application, and so forth, owing to their various advantages such as good flexibility, tunable light transmittance, high thermal stability, low thermal expansion coefficient, and superior mechanical properties. Herein, recent progress on the fabrication and applications of cellulose nanopaper is summarized and discussed based on the analyses of the latest studies. We begin with a brief introduction of the three types of nanocellulose: cellulose nanocrystals, cellulose nanofibrils and bacterial cellulose, recapitulating their differences in preparation and properties. Then, the main preparation methods of cellulose nanopaper including filtration method and casting method as well as the newly developed technology are systematically elaborated and compared. Furthermore, the advanced applications of cellulose nanopaper including energy storage, electronic devices, water treatment, and high-performance packaging materials were highlighted. Finally, the prospects and ongoing challenges of cellulose nanopaper were summarized. 

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Cellulose Nanopaper: Fabrication, Functionalization, and Applications

Chemically tailored molecular surface modification of cellulose nanofibrils for manipulating the charge density of triboelectric nanogenerators

Excellent triboelectric charge density and hydrophobicity are achieved on cellulose nanofibrils (CNFs) by employing a simple and environmentally friendly approach to aminosilane modification of a C...

Chemically Functionalized Cellulose Nanofibrils for Improving Triboelectric Charge Density of a Triboelectric Nanogenerator

Using clean and sustainable stochastic energy from the environment to eliminate pollution caused by gaseous aldehydes would be an effective strategy to achieve the sustainable development of energy and preserve the environment. Here, a piston-based triboelectric nanogenerator (P-TENG) was used to enhance gaseous acetaldehyde absorption and photocatalytic degradation. An external electric field could be generated on a conductive substrate by the P-TENG, converting wind energy into electricity. This made it possible to efficiently degrade gaseous acetaldehyde in the photocatalytic system. Driven by a light breeze (3.0 m/s), the acetaldehyde removal rate of the system reached 63% within 30 min. The presence of an external electric field could generate more hydroxyl radicals (•OH), superoxide radicals (•O2-), and holes (h+), which has a positive effect on the photocatalytic degradation of acetaldehyde. The design and concept of this study not only realized the efficient conversion of renewable and sustainable random energy but also could be applied to the efficient removal of gaseous aldehydes, providing an effective way to create a cleaner environment.

Chenchen Cai

Papers

Integration of a porous wood-based triboelectric nanogenerator and gas sensor for real-time wireless food-quality assessment

Chemically tailored molecular surface modification of cellulose nanofibrils for manipulating the charge density of triboelectric nanogenerators

Chemically Functionalized Cellulose Nanofibrils for Improving Triboelectric Charge Density of a Triboelectric Nanogenerator

Improved Capture and Removal Efficiency of Gaseous Acetaldehyde by a Self-Powered Photocatalytic System with an External Electric Field.

Advanced triboelectric materials for liquid energy harvesting and emerging application