Colloidal photonic crystals (PCs) have been well developed because they are easy to prepare, cost-effective, and versatile with regards to modification and functionalization. Patterned colloidal PCs contribute a novel approach to constructing high-performance PC devices with unique structures and specific functions. In this review, an overview of the strategies for fabricating patterned colloidal PCs, including patterned substrate-induced assembly, inkjet printing, and selective immobilization and modification, is presented. The advantages of patterned PC devices are also discussed in detail, for example, improved detection sensitivity and response speed of the sensors, control over the flow direction and wicking rate of microfluidic channels, recognition of cross-reactive molecules through an array-patterned microchip, fabrication of display devices with tunable patterns, well-arranged RGB units, and wide viewing-angles, and the ability to construct anti-counterfeiting devices with different security strategies. Finally, the perspective of future developments and challenges is presented.

Patterned Colloidal Photonic Crystals.

Living organisms ubiquitously display colors that adapt to environmental changes, relying on the soft layer of cells or proteins. Adoption of soft materials into an artificial adaptive color system has promoted the development of material systems for environmental and health monitoring, anti-counterfeiting, and stealth technologies. Here, a hydrogel interferometer based on a single hydrogel thin film covalently bonded to a reflective substrate is reported as a simple and universal adaptive color platform. Similar to the cell or protein soft layer of color-changing animals, the soft hydrogel layer rapidly changes its thickness in response to external stimuli, resulting in instant color change. Such interference colors provide a visual and quantifiable means of revealing rich environmental metrics. Computational model is established and captures the key features of hydrogel stimuli-responsive swelling, which elucidates the mechanism and design principle for the broad-based platform. The single material-based platform has advantages of remarkable color uniformity, fast response, high robustness, and facile fabrication. Its versatility is demonstrated by diverse applications: a volatile-vapor sensor with highly accurate quantitative detection, a colorimetric sensor array for multianalyte recognition, breath-controlled information encryption, and a colorimetric humidity indicator. Portable and easy-to-use sensing systems are demonstrated with smartphone-based colorimetric analysis.

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Bioinspired Hydrogel Interferometer for Adaptive Coloration and Chemical Sensing.

Stimuli-chromism of photoswitches in smart polymers: Recent advances and applications as chemosensors

Biological photonic crystal (PC) patterns provide unique functionalities for the survival of creatures, such as the static identified patterns of butterfly wings, the mating function of the eye pattern of peacock feathers and the dynamic warning effect of the changing colour of a chameleon upon external stimulus. Inspired by these special functionalities, patterned PCs have been developed and have attracted considerable research interest due to their potential applications in sensors, catalysts, displays, information security and other fields. This review summarizes the preparation strategies, functional evolution and applications of patterned PCs. First, a series of preparation strategies for PC patterns are summarized, including template-induced assembly and direct writing without a template. Subsequently, the research progress in patterned PCs is sorted based on the evolution of their functionality, such as inactive and responsive (reversible, immobilized and programmed) PC patterns. Various applications of patterned PCs are also described in detail, such as sensing devices with a high sensitivity and fast response, PC displays based on external field regulation, information security anti-counterfeiting devices and shape memory intelligent systems. Finally, the outlook and challenges regarding PC patterns are presented. This review provides a significant foundation for the construction of new functional materials based on patterned PCs.

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Bio-inspired photonic crystal patterns

Recent advances in colloidal photonic crystal sensors: Materials, structures and analysis methods

Current multi-analytes chips are limited with requiring numbers of sensors, complex synthesis and compounds screen. It is expected to develop new principles and techniques to achieve high-performance multi-analytes testing with facile sensors. Here, we investigated the correlative multi-states properties of a photochromic sensor (spirooxazine), which is capable of a selective and cross-reactive sensor array for discriminated multi-analytes (11 metal ions) detection by just one sensing compound. The multi-testing sensor array performed in dark, ultraviolet or visual stimulation, corresponding to different molecular states of spirooxazine metal ions coordination. The facile photochromic microchip contributes a multi-states array sensing method, and will open new opportunities for the development of advanced discriminant analysis for complex analytes.

/pdf/a-photochromic-sensor-microchip-for-high-performance-1p45ti4tpz.pdf

A photochromic sensor microchip for high-performance multiplex metal ions detection.

A Photochromic Sensor Microchip for High-performance Multiplex Metal Ions

All 20 natural amino acids identification shows crucial importance in biochemistry and clinical application while it is still a challenge due to highly similarity in molecular configuration of the amino acids. Low efficiency, complicated sensing molecules and environment hindered the successful identification. Here, we developed a facile sensor chip composed of one photochromic molecule with metal ions spotted to form spirooxazine-metallic complexes, and successfully recognized all the 20 natural amino acids as well as their mixtures. The sensor chip gives distinct fluorescent fingerprint pattern of each amino acid, based on multistate of spirooxazine under different light stimulations and discriminated interaction between various metal ions and amino acids. The sensor chip demonstrates powerful capability of amino acids identification, which promotes sensing of biomolecules.

Twenty natural amino acids identification by a photochromic sensor chip.

The invention belongs to the technical field of electronic printing materials, and discloses silver-wrapped-in-gold and graphene based aqueous ink and an application of a transparent patternconduction electrode obtained through ink-jet printingof the silver-wrapped-in-gold and graphene based aqueous ink. The prepared silver-wrapped-in-gold and graphene based aqueous inkcomprises an ink active component, a solvent and an additive, wherein the ink active component adopts composition of graphene and silver-wrapped-in-gold nano-particles or composition of graphene oxide and silver-wrapped-in-gold nano-particles; the mass percentage of the ink active component is 0.1%-30%, the mass ratio of the silver-wrapped-in-gold nano-particles to the grapheneor the graphene oxide is smaller than or equal to 100%, and the volume of the additive is 0%-2% of that of a solvent; and the diameter of each of the graphene and the graphene oxide is smaller than 2 mu m. Compared with the prior art, the prepared silver-wrapped-in-gold and graphene based aqueous ink has the characteristics of environmental protection, simple preparation process and low aftertreatment temperature, the electrode with better conductivity and stability can be acquired, and the ink can be applied to the technical field of electronic printing materials.

Silver-wrapped-in-gold and graphene based aqueous ink and application of transparent patternconduction electrode obtained through ink-jet printingof silver-wrapped-in-gold and graphene based aqueous ink

Electrochemical reduction (ER) is a promising approach to safely remove pollutants. However, sluggish reaction kinetics and significant side reactions considerably limit the applicability of this green process. Herein, we uncovered the previously ignored role of interfacial hydrophilicity in determining the ER performance through electron microscopy observations, contact angle (CA) analysis, and electrochemical measurements. A Pd/C electrocatalyst forms dense nanopores on the electrode surface, rendering it highly hydrophobic and achieving a CA of up to 145°. This imposes a large mass-transfer barrier for the diffusion of water and pollutants into Pd sites. Moreover, the release of H2 is suppressed, which changes the solid-liquid (Pd-polluted water) interface into a solid-gas (H2)-liquid interface. This further slows down mass transfer and the decontamination process. This dilemma can be easily alleviated by adding hydrophilic polymers like polyethylene glycol to increase hydrophilicity and improve mass transfer. By this way, the activity and Faraday efficiency of Pd/C in the electrochemical hydrodehalogenation of 2,4-dichlorophenol could be increased by 4-5 times. Moreover, this interfacial microenvironment modulation strategy is parallel to other approaches, such as Pd structural engineering, and therefore these strategies can be combined to further increase the electrochemical decontamination performance of electrocatalysts.

Wei Ran

Papers

A photochromic sensor microchip for high-performance multiplex metal ions detection.

A Photochromic Sensor Microchip for High-performance Multiplex Metal Ions

Twenty natural amino acids identification by a photochromic sensor chip.

Silver-wrapped-in-gold and graphene based aqueous ink and application of transparent patternconduction electrode obtained through ink-jet printingof silver-wrapped-in-gold and graphene based aqueous ink

Enhancing Electrocatalytic Hydrodechlorination through Interfacial Microenvironment Modulation.