Intrinsically stretchable electronics have gained extensive interest recently, due to their promising application in wearable electronics, bio-integrated electronics, and healthcare devices. All of the components of such stretchable electronics need to be stretchable and mechanically robust to accommodate complex movements. The design and fabrication of robust intrinsically stretchable electronic materials represent a critical challenge in this emerging field. In this review, we focus on the latest studies of intrinsically stretchable electronics, covering the strategies for achieving intrinsically stretchable electronic materials, the recent progresses in the key electronic materials including intrinsically stretchable conductors, semiconductors, dielectrics, and the devices produced by them. Finally, some suggestions and prospects for the future development of intrinsically stretchable electronics are proposed.
Intelligent materials with responsive behaviors toward external stimuli, such as light, temperature, pH, redox, and solvent have been increasingly fascinating. Reversible noncovalent interactions provide an efficient way to construct stimuliresponsive materials. Macrocyclic compounds, such as cyclodextrins, cucurbit[n]urils, calix[n]arenes, crown ethers, and related macrocycles, are useful skeletons for constructing such materials through host–guest interactions. Pillar[n]arenes are pillar-shaped macrocyclic hosts developed by our groups in 2008, in which the repeated 1,4-dialkoxybenzene units are connected by methylene bridges at the para position. The versatile functionality, easy modification, excellent size-dependent host–guest complexation, and adjustable electron density of the cavity endow pillar[n]arenes with excellent properties compared with other cyclic host molecules. Moreover, the unique planar chirality and chirality inversion generated by unit rotation make pillar[n]arenes ideal platforms for investigating chirality inversion, induction, and transformation. In this review, we describe stimuli-responsive topological, optical, chiroptical, supramolecular assemblies, and solid-state materials based on the host–guest complexation and structural regulation of pillar[n]arenes.
Compared with traditional rigid actuators, soft actuators exhibit a large number of advantages, including enhanced flexibility, reconfigurability, and adaptability, which motivate us to develop artificial soft actuators with widespread applications. Soft actuators with MXene nanomaterials are regarded as highly promising candidates for advancing the development of bioinspired soft robotics as a consequence of their unprecedented physicochemical characteristics, such as high electronic conductivity, thermal conductivity, photothermal conversion capability, and abundant surface functional groups. Herein, a comprehensive overview of the recent advancement of soft actuators with MXene nanomaterials and their extensive applications from the perspective of bioinspiration is provided. First, synthetic methods of MXene and their properties are briefly summarized. Subsequently, soft actuators with MXene nanomaterials (including photoresponsive soft actuators, electroresponsive soft actuators, and chemoresponsive soft actuators) are sequentially investigated with a focus on the fabrication approaches, actuation properties, underlying mechanisms, and promising applications. At the end, the future challenges and opportunities for the rapid development of soft actuators with MXene nanomaterials are discussed.
Stimuli-responsive fluorescent hydrogels are three-dimensional networked polymeric materials with tunable luminescence and dynamic properties, which play an important role as a water-rich soft material in the fields of information encryption, bionic actuation, bioimaging, environmental monitoring, and luminescent materials. Compared with conventional hydrogels, their unique luminescent properties allow the visualization of microscopic dynamics within the polymer network. By rational inclusion of dynamic motifs, such as photoswitches, AIEgens, lanthanide complexes, and host–guest complexes, these materials are endowed with tunability of emission, shape, and phase in time and space in response to environmental effectors. In this review, we summarize the fabrication strategies that are mainly used by recently reported stimuli-responsive fluorescent hydrogels and the applications of these materials.
For centuries, humans have never stopped exploring the nature of light and manipulating it, since light carries multiple information through its intrinsic waveparticle dualism, including wavelength, amplitude, phase, polarization, spin/orbital angular momentum, etc., which determines the physical language and basic manners we perceive the objective world. Conventional optical devices, such as lenses, prisms, and lasers, are composed of solid elements that are bulky, making it difficult to manipulate light dynamically with multiple degrees-of-freedom. Comparatively, some responsive soft matters, especially represented by liquid crystals (LCs), possess distinctive orientational order and spontaneous self-assembled superstructures, enabling the digital programming of microstructures and multiple degrees-of-freedom manipulation of their optical characteristics. The optical manipulation based on these soft superstructures, that is, the “soft-matter-photonics”, is playing an impressive role in integrated functional devices, especially in the present age of information explosion. Herein, we review the latest advances, respectively, in the microstructure configurations, multiple degrees-of-freedom manipulations, and the relevant prospective applications. Additionally, scientific issues and technical challenges that hinder the programing operation and optical manipulations are discussed. Toward a four-dimensional optical manipulation of soft condensed matter, this review may have wide implications on a variety of applications, including the integrated fabrication of compact elements, multi-channel information processing and high-capacity optical communications.
Liquid crystal polymers (LCPs) have gained tremendous attention in recent years due to their great potentials from fabrication of responsive actuators and sensors to construction of intelligent soft robotic and light modulators. However, conventional LCPs with permanent cross-links present tedious and unmodifiable stimuliresponsiveness. Recently, dynamic bonds capable to reversibly break and reform have been integrated into LCP, imparting intrinsic dynamic characteristics. The dynamic LCP possesses unprecedented diverse functionalities including reprogrammability, recyclability, and self-healing ability, becoming much more adaptive to surrounding environmental changes compared with the conventional counterpart. In this review, recent progress of dynamic bond-based LCPs is summarized. The mechanism, preparation, and functionalities of dynamic LCPs based on dynamic noncovalent bond (DNCB) and dynamic covalent bond (DCB) are poised to be discussed, followed by introducing emergent LCPs combining both of DNCB and DCB. Consequently, the unique functionalities of dynamic bond-based LCPs will be given. Finally, outlooks of development of the dynamic bond-based LCPs are presented.
Commodity fraud poses significant economic and public health risks while jeopardizing market stability. A promising avenue for addressing this issue involves the incorporation of physical unclonable function (PUF) in anti-counterfeiting labels for commodity authentication purposes. PUFs are a large number of unbreakable security labels generated through a random process, which exhibit unique physical pattern responses that are impervious to replication. In particular, a novel kind of a PUF model, called structural color-based PUFs, combing the structural color characteristics of angle-dependent stability and brightness with unclonable property, offers unassailable encryption capabilities and serves as a formidable safeguard against forgery. This review undertakes a comprehensive summary of recent advancements in PUF technology leveraging structural color materials. Moreover, it provides a systematic description of the recognition and authentication technology employed in optical structural color PUFs. Finally, a prospective summary and outlook is proposed to explain existing challenges, and highlight potential developments in anti-counterfeiting technology incorporating structural color PUF labels.
Bio-enabled and bio-mimetic nanomaterials represent functional materials, which use bio-derived materials and synthetic components to bring the better of two, natural and synthetic, worlds. Prospective broad applications are flexibility and mechanical strength of lightweight structures, adaptive photonic functions and chiroptical activity, ambient processing and sustainability, and potential scalability along with broad sensing/communication abilities. Here, we summarize recent results on relevant functional photonic materials with responsive behavior under mechanical stresses, magnetic field, and changing chemical environment. We focus on recent achievements and trends in tuning optical materials’ properties such as light scattering, absorption and reflection, light emission, structural colors, optical birefringence, linear and circular polarization for prospective applications in biosensing, optical communication, optical encoding, fast actuation, biomedical fields, and tunable optical appearance.