There is currently enormous and growing demand for flexible electronics for personalized mobile equipment, human–machine interface units, wearable medical‐healthcare systems, and bionic intelligent robots. Cellulose is a well‐known natural biopolymer that has multiple advantages including low cost, renewability, easy processability, and biodegradability, as well as appealing mechanical performance, dielectricity, piezoelectricity, and convertibility. Because of its multiple merits, cellulose is frequently used as a substrate, binder, dielectric layer, gel electrolyte, and derived carbon material for flexible electronic devices. Leveraging the advantages of cellulose to design advanced functional materials will have a significant impact on portable intelligent electronics. Herein, the unique molecular structure and nanostructures (nanocrystals, nanofibers, nanosheets, etc.) of cellulose are briefly introduced, the structure–property–application relationships of cellulosic materials summarized, and the processing technologies for fabricating cellulose‐based flexible electronics considered. The focus then turns to the recent advances of cellulose‐based functional materials toward emerging intelligent electronic devices including flexible sensors, optoelectronic devices, field‐effect transistors, nanogenerators, electrochemical energy storage devices, biomimetic electronic skins, and biological detection devices. Finally, an outlook of the potential challenges and future prospects for developing cellulose‐based wearable devices and bioelectronic systems is presented.

A dynamic gel composed of cellulose, ionic liquids, and H 2 O with reversible Turing-pattern microstructures is realized via the construction of a switchable hydrogen-bond topological network. The dynamic gel exhibits diverse tunable, reversible properties including mechanical strength and toughness, viscoelasticity, self-healing, and ionic conductivity. These dynamic features can be facilely tuned through changing the water content in the gel material. The flexible, transparent, and designable dynamic gel material shows great potential in electronic skin and smart devices.

With the aid of DFT calculation, deep eutectic solvents can be designed more powerful for the pretreatment of lignocellulose and the production of biochemicals.

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In nature, stiffness‐changing behavior is essential for living organisms, which, however, is challenging to achieve in synthetic materials. Here, a stiffness‐changing smart material, through developing interchangeable supramolecular configurations inspired from the dermis of the sea cucumber, which shows extreme, switchable mechanical properties, is reported. In the hydrated state, the material, possessing a stretched, double‐stranded supramolecular network, showcases a soft‐gel behavior with a low stiffness and high pliability. Upon the stimulation of ethanol to transform into the coiled supramolecular configuration, it self‐adjusts to a hard state with nearly 500‐times enhanced stiffness from 0.51 to 243.6 MPa, outstanding load‐bearing capability (over 35 000 times its own weight), and excellent puncture/impact resistance with a specific impact strength of ≈116 kJ m−2 (g cm−3)−1 (higher than some metals and alloys such as aluminum, and even comparable to the commercially available protective materials such as D3O and Kevlar). Moreover, this material demonstrates reconfiguration‐dependent self‐healing behavior and designable formability, holding great promise in advanced engineering fields that require both high‐strength durability and good formability. This work may open up a new perspective for the development of self‐regulating materials from supramolecular‐scale configuration regulation.

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Structural design and self‐assembly at the molecular level provide feasible strategies for constructing materials with novel and unique properties. Cellulose is one of the most abundant bioresources and is renewable, biodegradable, biocompatible, and environmentally friendly. The formation of hydrogen‐bonding networks between the cellulose molecular chains on the one hand gives cellulose a rigid crystalline region and high mechanical strength and on the other hand it causes inconvenience to material design based on the molecular scale. The emergence of eco‐friendly solvents such as ionic liquids and alkali/urea solutions breaks the hydrogen bonds and allows the design of various cellulose‐based functional materials, such as membranes, gels, fibers, and nano/microspheres via structural optimization and molecular self‐assembly. Such functional materials have promising applications in flexible electronic devices, such as electrochemical energy storage devices, sensors, biomimetic electronic skins, and optoelectronic devices. In this review, green solvents for cellulose, the dissolution–recombination process, molecular self‐assembly strategies, advanced applications, and future development prospects for high‐performance cellulose‐based functional materials with unique structures are presented.

Electronic skin (e-skin), a new generation of flexible electronics, has drawn interest in soft robotics, artificial intelligence, and biomedical devices. However, most existing e-skins involve complex preparation procedures and are characterized by single-sensing capability and insufficient scalability. Here, we report on a one-step strategy in which a thermionic source is used for the in situ molecularization of bacterial cellulose polymeric fibers into molecular chains, controllably constructing an ionogel with a scalable mode for e-skin. The synergistic effect of a molecular-scale hydrogen bond interweaving network and a nanoscale fiber skeleton confers a robust tensile strength (up to 7.8 MPa) and high ionic conductivity (up to 62.58 mS/cm) on the as-developed ionogel. Inspired by the tongue to engineer the perceptual patterns in this ionogel, we present a smart e-skin with the perfect combination of excellent ion transport and discriminability, showing six stimulating responses to pressure, touch, temperature, humidity, magnetic force, and even astringency. This study proposes a simple, efficient, controllable, and sustainable approach toward a low-carbon, versatile, and scalable e-skin design and structure–performance development.