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.

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The ability to topographically structure and fast controllably actuate hydrogel in two and three dimensions is the key for their promising applications in soft robots, microfluidic valves, cell and drug delivery, and artificial muscles. Inspired by evaporation-induced concentration differentiation phenomenon in the production process of beancurd sheet, we introduce a facile one-step evaporation process to create laminated layer/porous layer heterogeneous structure within graphene oxide-clay-poly­(N-isopropylacrylamide) hydrogel in vertical direction and pattern the heterogeneous structure in lateral direction to form tunable, fast, and robust hydrogel actuators. The laminated layer/porous layer architecture is highly stable and robust without possibility of delamination. The evaporation-programmed heterogeneous structures tune thermoresponsive actuations from global bending/unbending for global heterogeneous structure to local bending/unbending and site-specific folding/unfolding for segment-patterned heterogeneous structure, then to directional bending/unbending and chiral twisting/untwisting for stripe-patterned heterogeneous structure. These actuations are instant and reversible without detectable fatigue after many cycles.

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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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