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.

The emulation of human sensation, perception and action processes has become a major challenge for bio-inspired intelligent robotics, interactive human-machine interfacing and advanced prosthetics. Reflex actions, enabled through reflex arcs, are important for human and higher animals to respond to stimuli from environment without the brain processing and survive the risks of nature. An artificial reflex arc system that emulates the functions of the reflex arc simplifies the complex circuit design needed for "central-controlonly" processes and becomes a basic electronic component in an intelligent soft robotics system. Herein, we report an artificial somatic reflex arc that enables the actuation of electrochemical actuators in response to the stimulation of tactile pressures. Only if the detected pressure by the pressure sensor is above the stimulus threshold, the metal-organic framework-based threshold controlling unit (TCU) can be activated and triggers the electrochemical actuators to complete the motion. Such responding mechanism mimics the all-or-none law in the human nervous system. As a proof of concept, we successfully

Resistive switching memory constitutes a prospective candidate for next-generation data storage devices. Meanwhile, naturally occurring biomaterials are promising building blocks for a new generation of environmentally friendly, biocompatible, and biodegradable electronic devices. Recent progress in using proteins to construct resistive switching memory devices is highlighted. The protein materials selection, device engineering, and mechanism of such protein-based resistive switching memory are discussed in detail. Finally, the critical challenges associated with protein-based resistive switching memory devices are presented, as well as insights into the future development of resistive switching memory based on natural biomaterials.

The increasing need for smart systems in healthcare, wearable, and soft robotics is creating demand for low-power sensory circuits that can detect pressure, temperature, strain, and other local variables. Among the most critical requirements, the matrix circuitry to address the individual sensor device must be sensitive, immune to disturbances, and flexible within a high-density sensory array. Here, a strategy is reported to enhance the matrix addressing of a fully integrated flexible sensory array with an improvement of 10 fold in the maximum readout value of impedance by a bidirectional threshold switch. The threshold switch shows high flexibility (bendable to a radius of about 1 mm) and a high nonlinearity of ≈10 by using a nanocontact structure strategy, which is revealed and validated by molecular dynamics simulations and experiments at variable mechanical stress. Such a flexible electronic switch enables a new generation of large-scale flexible and stretchable electronic and optoelectronic systems.

The emergence, amplification, and manipulation of chiroptical activity in self-assembled nanostructures, including circularly polarized absorbance and luminescence (CPL), remain considerable challenges. Here, we report the high-throughput synthesis of nanostructures with finely tailored chiroptical activities. Two fully π-conjugated benzimidazoles formed H-bonded complexes with natural hydroxyl acids (tartaric acid and mandelic acid), which self-assembled into diversified macroscopically chiral nanostructures. Synergistic coassembly allows for the emergence of Cotton effects and CPL with high dissymmetry g-factors (g abs up to 8 × 10 −3 , g lum up to 3 × 10 −3 ). The tartaric acid coassembled system exhibits enantiomer-independent left-handed CPL, which transforms into a cooperative ternary coassembly appended with enantiomerresolved CPL with extended emission wavelength upon selective transition metal ion chelation. This H-boned coassembly system provides a vast number of chiral nanostructures with flexibly tuned Cotton effects and CPL, which also behaves as a selective chiroptical sensor to metal ions.

wileyonlinelibrary.comfast-paced life. [ 22 ] For instance, although millions of miles of electrical cables have been used for providing electrical connections, the electrical energy produced from various physical or chemical sources to be distributed to users still need additional energy storage equipment, which causes unnecessary trouble and high cost. Moreover, people are possibly confronted with the inconvenience of sudden loss of power when using indoor electric appliances, and bothered by carrying heavy portable electronic accessories such as batteries and power cords simultaneously during a trip. Integrating the energy storage devices into appropriate energy transmission circuits should be an effective strategy to solve the problem of tiring energy distribution, sudden power off, and further lighten the weight of portable electronics, but current research barely involves the integration of energy storage devices and energy transit system, and these two systems still work independently with each other. [ 37,38 ] Supercapacitor, a promising class of energy storage device, is appealing because of its high power density, long cycle life time, and high energy effi ciency. [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] More importantly, supercapacitor can be easily fabricated in various confi gurations for ease of compatibility and integration with diversifi ed architectures of electronic devices. [55][56][57][58][59][60][61][62][63][64] From this, it can be expected that the integration of appropriate supercapacitor confi guration into proper circuit could achieve synchronous energy storage and energy transmission. Besides the confi guration, the exploration of naturally abundant and renewable biomaterials with high energy density for the new-generation green supercapacitors is intensively desired. [65][66][67][68][69] Thus, considering the issues of both the materials and confi guration, constructing an ideal integrated supercapacitor system based on renewable biomaterials for synchronous energy storage and transmission should be of scientifi c and technological importance due to their additional desirable economic, biocompatible and environmental friendly merits.Herein, we report the development of biocomposite-based fl exible integrated electrical cable for synchronous energy transmission and storage. In this unique integrated confi guration, the fi ber electrodes were alternately winded along the twisted electric wires, which worked not only as scaffolding to support and strengthen the slight electrodes but also as separators to spatially confi ne them to avoid short circuit ( Scheme 1 ). Distinct from the conventional electric wires used in a serial It becomes increasingly important to develop integrated systems with the aim of achieving maximum functionality for the state-of-the-art electronic devices. Here, a fl exible integrated electrical cable is reported by incorporating biomaterials based fi ber supercapacitors into a resistor-capacitor circuit. In this unique integrated confi gura...

The somatosensory system in the skin plays an essential role for human hands to perform adaptive interactions with external environments, such as tactile sensing and handling objects. For artificial pressure...

In this paper, a correction method is introduced to make a more accurate calculation of winding eddy-current losses of high-voltage direct current (HVDC) converter transformer. The assumption that winding eddy-current losses of HVDC converter transformers follow the frequency with the exponent 2 proposed by IEC 61378-2 Std. is thought to be inappropriate and the skin effect should be taken into consideration. The frequency characteristic of winding eddycurrent losses is proposed by analysing the distribution of magnetic flux in conductors, in which skin effect is taken into consideration. The correction method with a correction factor is then introduced to correct the assumption. To verify the validity of the correction method, a two-dimension axisymmetric finite element analysis of a HVDC converter transformer is conducted. The geometrical complexity of windings and electrical connection are fully taken into account, it is shown that the correction method shows a significant advantage. Influence of different methods is revealed by applying the actual non-sinusoidal load current and it is shown that the error of correction method is the least. At last, harmonic losses measurements are conducted on three coils to investigate the limits of the correction method.