Nature-Inspired Structural Materials for Flexible Electronic Devices

Abstract

Exciting advancements have been made in the field of flexible electronic devices in the last two decades and will certainly lead to a revolution in peoples' lives in the future. However, because of the poor sustainability of the active materials in complex stress environments, new requirements have been adopted for the construction of flexible devices. Thus, hierarchical architectures in natural materials, which have developed various environment-adapted structures and materials through natural selection, can serve as guides to solve the limitations of materials and engineering techniques. This review covers the smart designs of structural materials inspired by natural materials and their utility in the construction of flexible devices. First, we summarize structural materials that accommodate mechanical deformations, which is the fundamental requirement for flexible devices to work properly in complex environments. Second, we discuss the functionalities of flexible devices induced by nature-inspired structural materials, including mechanical sensing, energy harvesting, physically interacting, and so on. Finally, we provide a perspective on newly developed structural materials and their potential applications in future flexible devices, as well as frontier strategies for biomimetic functions. These analyses and summaries are valuable for a systematic understanding of structural materials in electronic devices and will serve as inspirations for smart designs in flexible electronics.

A Geologic Architecture System‐Inspired Micro‐/Nano‐Heterostructure Design for High‐Performance Energy Storage

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result, a series of helpful tools or apparatuses (like hacksaw-mantis, radar-bat, and gyrotron-fly) have been invented. [24][25][26][27][28] In addition, besides high-performance active materials, a flexible, porous, and self-supporting substrate is also crucial for developing a freestanding electrode without conductive or adhesive agents. [2,[4][5][6][7][8][9] For instance, directional water collection material, [10] antireflection film, [11,12] and superhydrophobic surface [13] have been designed and prepared by mimicking the microstructures of spider silk, transparent wings of glasswing butterfly/moth eye, and lotus leaf, respectively.

In the field of electrochemical energy storage, natural structures (like bamboo, [14] flower, [15,16] forest, [17,18] and honeycomb [19,20] ) have been and continue to be intriguing as models for molding similar micromorphologies of electrochemically active materials since these multiscale hierarchical structures exert enormous functions on electrochemical reactions (e.g., increasing reaction area, [21] providing fast electron paths, [22] and reducing diffusion path of electrolyte ions [23] ).

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A Self‐Folding Polymer Film Based on Swelling Metal–Organic Frameworks

“…[7] In these MOFs,t he swelling can be strongly influenced by the solvent and by the functional groups in the linkers. [13] Fori nstance,p lant tissues have developed diverse mechanisms for reversible and efficient shape transformations,w hich are typically driven by ambient humidity variations. [8b] Our group considered that the aforementioned phenomenon had been overlooked in the development of functional materials,sowebegan to reflect on how such swelling might be exploited to develop novel soft materials capable of reversible shape transformations.I nt his regard, self-folding materials,which are able to translate external stimuli such as thermal, light, electrical, or chemical energy into useful and predictable shape transformations,are garnering attention for their potential utility in applications such as robotics, [9] artificial muscles, [10] energy harvesting, [11] and encapsulation.…”

“…[8b] Our group considered that the aforementioned phenomenon had been overlooked in the development of functional materials,sowebegan to reflect on how such swelling might be exploited to develop novel soft materials capable of reversible shape transformations.I nt his regard, self-folding materials,which are able to translate external stimuli such as thermal, light, electrical, or chemical energy into useful and predictable shape transformations,are garnering attention for their potential utility in applications such as robotics, [9] artificial muscles, [10] energy harvesting, [11] and encapsulation. [13] Fori nstance,p lant tissues have developed diverse mechanisms for reversible and efficient shape transformations,w hich are typically driven by ambient humidity variations. [13] Fori nstance,p lant tissues have developed diverse mechanisms for reversible and efficient shape transformations,w hich are typically driven by ambient humidity variations.…”

Ultrasensitive, Low‐Voltage Operational, and Asymmetric Ionic Sensing Hydrogel for Multipurpose Applications

“…Generally, soft elastomer and conductive materials are indispensable components to build a highly sensitive tactile sensor . It is also found that structural design is critical to determine the sensitivity of tactile sensors . With micro/nanostructured elastomers or conductors, the tactile sensors can possess very high sensitivities and other functions.…”