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.
Organic–inorganic lead halide perovskite materials have recently attracted much attention in the field of optoelectronic devices. Here, a hybrid piezoelectric nanogenerator based on a composite of piezoelectric formamidinium lead halide perovskite (FAPbBr3) nanoparticles and polydimethylsiloxane polymer is fabricated. Piezoresponse force spectroscopy measurements reveal that the FAPbBr3 nanoparticles contain well‐developed ferroelectric properties with high piezoelectric charge coefficient (d33) of 25 pmV−1. The flexible device exhibits high performance with a maximum recordable piezoelectric output voltage of 8.5 V and current density of 3.8 μA cm−2 under periodically vertical compression and release operations. The alternating energy generated from nanogenerators can be used to charge a capacitor and light up a red light‐emitting diode through a bridge rectifier. This result innovatively expands the feasibility of organic–inorganic lead halide perovskite materials for application in a wide variety of high‐performance energy harvesting devices.
a b s t r a c tProtected areas worldwide are facing increasing pressures to co-manage human development and biodiversity conservation. One strategy for managing multiple uses within and around protected areas is zoning, an approach in which spatial boundaries are drawn to distinguish areas with varying degrees of allowable human impacts. However, zoning designations are rarely evaluated for their efficacy using empirical data related to both human and biodiversity characteristics. To evaluate the effectiveness of zoning designations, we developed an integrated approach. The approach was calibrated empirically using data from Wolong Nature Reserve, a flagship protected area for the conservation of endangered giant pandas in China. We analyzed the spatial distribution of pandas, as well as human impacts (roads, houses, tourism infrastructure, livestock, and forest cover change) with respect to zoning designations in Wolong. Results show that the design of the zoning scheme could be improved to account for pandas and their habitat, considering the amount of suitable habitat outside of the core zone (area designated for biodiversity conservation). Zoning was largely successful in containing houses and roads to their designated experimental zone, but was less effective in containing livestock and was susceptible to boundary adjustments to allow for tourism development. We identified focus areas for potential zoning revision that could better protect the panda population without significantly compromising existing human settlements. Our findings highlight the need for evaluating the efficacy of zoning in other protected areas facing similar challenges with balancing human needs and conservation goals, not only in China but also around the world.
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