Search

Theoretical calculations and numerical simulations play a crucial role in analyzing material properties and devising effective research strategies. In this study, the photonic band gap (PBG) of polymethyl methacrylate (PMMA) and polystyrene (PS) photonic crystals was successfully predicted using theoretical calculations and numerical simulations. The agreement between the predicted results and the actual reflection peaks reached an impressive level of 99%. Utilizing SEM images, the prediction of reflection peaks in acrylamide (AM)—based photonic hydrogels was conducted using theoretical formulas and Rsoft 2019–Bandsolve software v2019.09. The relationship between the actual reflection peaks and compressive strains in AM-based photonic hydrogels featuring 251 nm PMMA PCs exhibited a remarkable similarity of over 96% with the theoretical and simulated results. In conclusion, an exploration was conducted into the relationship between reflection peaks and compressive strains for AM-based 270 nm PMMA photonic hydrogels, allowing the prediction of the actual reflection peaks under compression. The consistency observed between theoretical/simulated reflection peaks and actual reflection peaks validates the efficacy of this approach in evaluating the optical properties of photonic materials and predicting their responsive effects. This method offers a straightforward and expeditious solution for the design and fabrication of photonic materials. [ABSTRACT FROM AUTHOR]

Photonic crystal has become a powerful technique for regulating electromagnetic waves due to its excellent features, such as structure designability and dynamic adjustability; in addition, it has great application value. In this paper, we visualize colors on the Ostwald color model and analyze the color differences of each group of color patches via the minimum color difference model. The manipulation law of particle size, temperature, and humidity on the color change of photonic crystal hydrogel is verified by these color analyses. [ABSTRACT FROM AUTHOR]

A photonic crystal material based on β-cyclodextrin (β-CD) with adsorption capacity is reported. The materials ((A-β-CD)-AM PC) consist of 3D poly (methyl methacrylate) (PMMA) colloidal microsphere arrays and hydrogels supplemented with β-cyclodextrin modified by acryloyl chloride. The prepared materials are then utilized for VOCs gas sensing. The 3D O-(A-β-CD)-AM PC was used to detect toluene, xylene, and acetone and the response was seen as the red-shift of the reflection peak. The 3D I-(A-β-CD)-AM PC was used to detect toluene, xylene, and acetone which occurred redshifted, while methanol, ethanol, and propanol and the peaks' red-shifting was observed. However, among these, methanol gave the largest red-shift response The sensor has broad prospects in the detection of alcohol and the detection of alcohol-loaded drug releases in the future. [ABSTRACT FROM AUTHOR]

The determination of lactic acid content has a guiding significance for disease diagnosis or food supervision. Herein, a hydrogel-based three-dimensional photonic crystal (PC) sensor for specific detection of lactic acid is introduced. The hydrogel was prepared by one-step copolymerization of N-isopropylacrylamide and acrylamide in the presence of oxamate derivative 2-((6-acrylamidohexyl) amino)-2-oxoacetic acid (AOA). An obvious color change from orange-red to purple and a 45-nm redshift of the reflection peak were obtained in 3 min when lactic acid concentration increased from 0 to 20 mM. The detection limit was confirmed as 0.1 mM, and the prepared sensor can be reused more than 20 times. Moreover, the affinity and selectivity of AOA to lactic acid were proven by both the interaction energy from density functional theory (DFT) study and the comparison to those of pyruvate and propionic acid. This sensor was proven to be cost-effective and convenient with rapid response time, good reusability, and selectivity. [ABSTRACT FROM AUTHOR]

Bletilla striata is an herb with a good medicinal value whose main active ingredient is Bletilla striata polysaccharide (BSP) in the tuber of Bletilla striata. In this study, a polysaccharide-based semi-interpenetrating network hydrogel was constructed by introducing BSP into polyacrylamide (PAM) hydrogel. The introduction of the BSP chain no only maintains the excellent mechanical properties of PAM, but also endows it with good biocompatibility. By implanting the colloidal crystal array into the above hydrogels, we obtained a novel biomass-based photonic crystal with good stimulus responsiveness that is sensitive to volatile organic compounds (VOCs), especially alcohol vapor. In addition, due to the scavenging ability of BSP to hydroxyl radicals, the photonic crystal hydrogel also has a good response to hydrogen peroxide ( H 2 O 2 ). [ABSTRACT FROM AUTHOR]

Flexible wearable materials have frequently been used in drug delivery, healthcare monitoring, and wearable sensors for decades. As a novel type of artificially designed functional material, photonic crystals (PCs) are sensitive to the changes in the external environment and stimuli signals. However, the rigidity of the PCs limits their application in the field of biometric and optical sensors. This study selects silk fibroin (SF) and poly-N-isopropylacrylamide (PNIPAM) as principal components to prepare the hydrogel with the physical crosslinking agent lithium silicate (LMSH) and is then integrated with PCs to obtain the SF-PNIPAM dual-crosslinked nanocomposite for temperature and strain sensing. The structural colors of the PCs change from blue to orange-red by the variation in temperature or strain. The visual temperature-sensing and adhesion properties enable the SF-PNIPAM dual-crosslinked nanocomposite to be directly attached to the skin in order to monitor the real-time dynamic of human temperature. Based on its excellent optical properties and biocompatibility, the SF-PNIPAM dual-crosslinked nanocomposite can be applied to the field of visual biosensing, wearable display devices, and wound dressing materials. [ABSTRACT FROM AUTHOR]

Photonic glasses with infrared gaps can be used as surface coating materials to effectively change the infrared radiation characteristics of substrate. In this research, a photonic glass with an infrared broad gap could be prepared easily in thermostatic water bath by a simple and fast baking protocol. The photonic glass prepared had a broad gap from 4.25 to 4.57 μm, centering at 4.45 μm, which was slightly different from the result of numerical simulation due to the existence of the internal disordered structure. The infrared transmission diagram showed that the infrared transmittance of a substrate covered by the photonic glass can be reduced from 80 % to 25 % at infrared atmosphere window of 3∼5 μm, which proved the ability of the material to regulate and control the infrared electromagnetic wave. In addition, the material can significantly restrain the infrared radiation of the substrate at 60 °C, which was expected to achieve stealth under the infrared detection. [ABSTRACT FROM AUTHOR]

Colloidal photonic crystals (PCs), consisting of highly ordered monodisperse nanoparticles, have been carried out a great deal of research in recent decades due to the attributes of readable signal, easy modification and low cost. With these unique features, colloidal PCs have also gradually become a focus of candidates applied in sensing fields. In this review, an overview of recent advances in colloidal PCs including self-assemblies and sensing applications is illustrated. With respect to the development in self-assemblies of colloidal PCs, the review concentrates on the summary of responsive mechanisms, detection methods, responsive materials, unit cells and fabrication methods. In terms of advances in sensing application of colloidal PCs, various types of sensors are summarized based on the kinds and applications of target analytes. Furthermore, the current limitations and potential future directions of colloidal PCs in self-assemblies and sensing areas are also discussed. Image 1 • Colloidal PCs have come to the fore due to the unique feature of structures. • Recent developments in self-assemblies of colloidal PCs are highlighted. • Recent advances in sensing applications of colloidal PCs are introduced. • The prospect and current limitation of colloidal PCs are summarized. [ABSTRACT FROM AUTHOR]

Self‐monitoring of blood glucose is not only an effective method to treat diabetes, but also a painful invasive process to patients. To develop a noninvasive technique, we evaluated the clinical performance of a polymerized crystalline colloidal array (PCCA) sensor for glucose monitoring in urine. A two‐dimensional crystalline colloidal array (CCA) was assembled using polystyrene particles and further embedded into 3‐acrylamidophenylboronic acid functionalized hydrogel. 101 urine samples were tested, and the glucose concentrations was calculated by the particle spacing of PCCA. All the urine samples were also analyzed by automated urine analyzers. Pearson correlation and linear regression analyses showed a linear relationship between the PCCA results with a range of 0.4‐53.3 mmol L−1 and the Cobas® 8000 references (r=0.914; [PCCA]=0.9281 [HK] + 2.0585 mmol L−1). Cohen's kappa (κ) statistic with 0.65 (sig < 0.05) showed the PCCA results had moderate agreement with references. Also, Bland‐Altman plot showed that AX‐4030 sensor's systematic error was higher than PCCA sensor (mean=7.4813 > 0.5271 mmol L−1). The PCCA urine glucose biosensor has the advantages of fast fabrication, low cost, easy operation and high sensitivity, which provides a promising technique for noninvasive point‐of‐care glucose monitoring. [ABSTRACT FROM AUTHOR]

G-series nerve agents, such as sarin, tabun, and soman, would cause tremendous harm in military and terrorist attacks, so it is necessary to develop a simple method for the rapid and efficient detection of these hazardous substances. We have developed a tunable acetylcholinesterase (AChE)-functionalized two-dimensional photonic crystal (2D PhC) for the detection of a real nerve agent, sarin. In accordance with the 2D PhC previously prepared by our group, the AChE-functionalized 2D PhC was optimized by adjustment of the amount of monomer in the hydrogel, which not only increased the sensitivity of the 2D PhC, with the detection limit decreasing by two orders of magnitude, but also ensured the structural color spanned the whole visible region in the detection range. A linear relationship between the logarithm of the sarin concentration and the particle spacing of the AChE-functionalized 2D PhC was observed from 7.1 × 10-17 to 7.1 × 10-4 mol/L. The AChE-functionalized 2D PhC also responded to mimics of G-series nerve agents, including dimethyl methylphosphonate, diisopropyl methylphosphonate, and isodipropyl methylphosphonate, to various degrees. The proposed 2D-PhC hydrogel has potential for low-cost, trace-level, and on-site monitoring of other G-series nerve agents. Graphical abstract [ABSTRACT FROM AUTHOR]

We developed a simple and efficient method to construct 3D and 2D opal and inverse opal cellulose photonic crystal films (CPCF) by embedding 3D or 2D polymethyl methacrylate (PMMA) colloidal arrays into carboxymethyl cellulose (CMC), respectively. The morphology and optical performance of CPCFs were characterized by SEM, diffraction spectra, Debye rings, and structural color. The brilliant structural colors of CPCFs are visible to the eye in the entire visible spectrum, and can be tuned by changing the particle diameters or the pore sizes. Attributed to decreased particle spacing and lower average refractive index caused by air spheres instead of polymer spheres, the stopbands of the inverse opal CPCFs blue-shifted. To the contrary, the particle spacing of 2D inverse opal CPCFs increased due to the losing of the connection force of 2D arrays, along with decreasing of Debye ring diameters. By alternately being exposed to organic solvents of methanol, acetonitrile, butanol, dioxane, and carbon tetrachloride, the 3D inverse opal CPCFs displayed an excellent sensing performance with instantaneously reversible color changes from violet to red. Their high stability and flexibility, efficient visual detection, and wide range of analytes promises a new opportunity for optical switching and sensing applications. [ABSTRACT FROM AUTHOR]

A novel polymerized crystalline colloidal array (PCCA) sensing material for the detection of urine glucose was developed by embedding a two-dimensional (2-D) polystyrene crystalline colloidal array (CCA) in 3-acrylamidophenylboronic acid (3-APBA)-functionalized hydrogel. After adjusting the cross-linker concentration, this material showed significant sensitivity for glucose under lab conditions, the particle spacing of the PCCA changed from 917 to 824 nm (93 nm) within 3 min as the glucose concentration increased from 0 to 10 mM, and the structural color of the PCCA changed from red through orange, to green, and finally, to cyan. In further experiments, this material was used to semi-quantitatively detect glucose in 20 human urine (HU) samples. Compared with the traditional dry-chemistry method, which was applied widely in clinical diagnosis, the PCCA method was more accurate and cost-effective. Moreover, this method can efficiently avoid the errors induced by most of the urine-interfering elements like vitamin C and ketone body. With a homemade portable optical detector, this low-cost intelligent sensing material can provide a more convenient and efficient strategy for the urine glucose detection in clinical diagnosis and point-of-care monitoring. [ABSTRACT FROM AUTHOR]

The cylindrical surface with Bragg-enhanced Fresnel reflectivity constructed from non-close-packed photonic crystals (NPCs) was designed for spectral selectivity and optical gain, which broke through the limitations of traditional Fresnel curved mirror with lowest central reflectivity and inability to perform spectral selectivity, and was conducive to expending the application of Fresnel mirror in the fields of signal transmission, optical measurement and instrument design. [Display omitted] According to the Fresnel theory, the reflectivity intensity of spherical and cylindrical convex surfaces decreases from their edge to center, and it is noteworthy and interesting for optical gain to study the enhancement of center reflectance. In this paper, a polydimethylsiloxane (PDMS) − encapsulated cylindrical non-closed-packed photonic crystals (NPCs) composite with Bragg-enhanced Fresnel reflectance was designed for spectral selectivity and optical gain. Theoretically and experimentally, the periodically ordered structure of NPCs achieved high-reflection of light in photonic bandgap and high-transmission in other bands, which enhanced Fresnel reflectivity of the convex center to specific bands. Furtherly, the cylindrical NPCs hydrogel with stretchability was applied for the dynamic tuning of optical signals. The reflection peak of the PDMS-encapsulated cylindrical NPCs composite blue-shifted from 608 nm to 413 nm with 50 % tensile strain and achieved a rapid transition of structural color from orange to blue-violet in 60 cycles. The new kind of photonic crystals composite for optical gain and spectral selection broke through the limitations of traditional Fresnel curved mirrors with the lowest central reflectivity and inability to perform spectral selectivity, and have great significance and application prospects in fields of signal transmission, optical measurement, and instrument design. [ABSTRACT FROM AUTHOR]

A cross-responsive molecularly imprinted photonic crystal (MIPC) sensor array was established for the detection of RDX, HMX, CL-20 and TNT. The MIPC sensor red shifted and the structural color changed with the increasing concentration of the analytes. Using Pattern Recognition (PR) and principal component analysis (PCA), the sensor array could discriminate four different explosives. • Nitramine explosives were visually detected by molecularly imprinted photonic crystal (MIPC) sensors. • Nitramine explosives could be discriminated by pattern recognition. • Alkaline solution softened MIPC, and improved the mass transfer and the sensitivity. Colorimetric, selective and sensitive screening of explosives is important not only to military action but also to public security. Normal explosives detection is mainly targeted for nitroaromatic compounds, however, ntiramine explosive is used more widely due to its outstanding performance. Herein, molecularly imprinted photonic crystal (MIPC) sensors were made to detect typical nitramine explosives: 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), cyclotetramethylenete-tranitramine (HMX) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20). And 2,4,6-trinitrotoluene (TNT) templated MIPC was also made to discriminate not only nitramines but also nitrobenzene explosives. With explosives concentration increase, the diffraction peak and structure color of MIPC sensors both red shifted within 5 min. By adding alkaline solution, the MIPC sensors were softened, and the mass transfer and the sensitivity were improved. The MIPC sensors could respond to lower than 0.05 mM explosives with the limit of detection of 0.01 mM. A MIPC sensor array with the above MIPCs was constructed to achieve a semi-quantitative detection, and Pattern Recognition with a 48 × 4 multivariate data matrix was using to discriminate different explosive molecules. According to principal component analysis, the response of RDX, HMX, CL-20 and TNT scattered in separate areas, and the sensor array could discriminate with a LOD of 1 mM. [ABSTRACT FROM AUTHOR]

Abstract With the development of infrared detection technology, the threat of infrared detection technology to military targets in the battlefield is becoming more and more serious. Novel infrared stealth materials are in urgent demand. Photonic crystals are promising infrared stealth materials because they can prohibit the propagation of electromagnetic waves in a certain frequency range. This paper outlines a simple and fast method to fabricate three-dimensional photonic crystals for stealth material. Monodisperse polystyrene colloid microspheres with a particle size of 2 μm were prepared and used in a gas–liquid interface self-assembly to form a three-dimensional photonic crystal infrared stealth material. The infrared absorption peak wavelengths of the material were 3.30 μm and 3.42 μm. The band gap is in good agreement with the photon forbidden band (3.24–3.44 μm) obtained from simulation and calculation using Rsoft software. The material meets the requirements of an infrared stealth material and realizes the modulation of the infrared radiation characteristics of the detectable band of 3–5 μm. The process provides a simple, economical, fast, and efficient new method for the preparation of large diameter, three-dimensional photonic crystal infrared stealth materials. [ABSTRACT FROM AUTHOR]

We developed a photonic crystal (PhC) sensor for the quantification of 2,4,6-trinitrotoluene (TNT) in solution. Monodisperse (210 nm in diameter) molecularly imprinted colloidal particles (MICs) for TNT were prepared by the emulsion polymerization of methyl methacrylate and acrylamide in the presence of TNT as a template. The MICs were then self-assembled into close-packed opal PhC films. The adsorption capacity of the MICs for TNT was 64 mg TNT/g. The diffraction from the PhC depended on the TNT concentration in a methanol/water (3/2, v/v) potassium dihydrogen phosphate buffer solution (pH = 7.0, 30 mM). The limit of detection (LOD) of the sensor was 1.03 μg. The color of the molecularly imprinted colloidal array (MICA) changed from green to red with an 84 nm diffraction red shift when the TNT concentration increased to 20 mM. The sensor response time was 3 min. The PhC sensor was selective for TNT compared to similar compounds such as 2,4,6-trinitrophenol, 2,4-dinitrotoluene, 2,6-dinitrotoluene, 2-nitromesitylene, 4-nitrotoluene, 2-nitrotoluene, 1,3-dinitrobenzene, methylbenzene, 4-nitrophenol, 2-nitroaniline, 3-aminophenol and 3-nitroaniline. The sensor showed high stability with little response change after three years storage. This sensor technology might be useful for the visual determination of TNT. [ABSTRACT FROM AUTHOR]

[Display omitted] • A pH-responsive discoloration photonic crystal sensor was proposed for amniotic fluid recognition. • The sensor showed the high accuracy and sensitivity, rapid response and visual detection. • Compared with pH test paper, a noticeable color difference and extraordinary accuracy were obtained. In this study, we proposed a pH-responsive photonic crystal hydrogel sensor (PCHs) to conveniently and accurately recognize the amniotic fluid from urine of parturient women, which was constituted by three-dimensional polymethyl acrylamide (PMMA) array and optimized hydrogel. PMMA array was self-assembled by 180 nm monodispersed nanoparticles with vertical sedimentation method. The functional hydrogel containing N-acryloyl phenylalanine (APA), acrylamide (AM) and N, N'-methylene bis(acrylamide) (BIS) as co-monomer and crosslinking agent respectively, was photo-polymerized by the precursor under 365 nm UV light. This hydrogel significantly shrank or swelled corresponding to the acidity and alkalinity of the aqueous solution, which resulted in both the reflection peak position (λ max) of the prepared sensor and its structural color changing with the pH value. The λ max of PCHs redshifted from 514 nm to 606 nm in 60 s while the pH value of testing solution increased from 4.5 to 8.0, which exactly covered the pH value of amniotic fluid and urine. Correspondingly, its structure color gradually changed from pale-green to red ensuring their naked-eye determination. Furthermore, an extremely high sensitivity as 26.3 nm/pH of Δ λ max was obtained which was linearly related to pH value. The prepared sensor possessed steady accuracy and extraordinary sensitivity compared with the pH test strip which was generally used in amniorrhexis diagnosis nowadays besides the advantages of the low cost, simple operation, rapid response and visual detection mode. The reliability of this PCHs was further confirmed by the real sample detection which relative standard deviation was below 5.0 %, suggesting its potential clinical applications. [ABSTRACT FROM AUTHOR]

As a typical antibiotic that is harmful to the health of human beings and widely used in animal husbandry, oxytetracycline (OTC) has a potential threat to the food safety. Therefore, the design of portable sensors for efficiently monitoring trace amounts of OTC in foods is vital to maintain safe food supply in our daily life. Herein, a two-dimensional (2D) molecularly imprinted photonic crystal hydrogel (MIPCH) sensor for the detection of OTC was fabricated by combining the photonic crystal (PC) method and molecular imprinting technique. In this regard, OTC was used as imprinted template to form the MIPCH sensor with specific binding sites during polymerization. After the removal of template, the obtained MIPCH possessed the specific nanocavities that were complementary to target compound, OTC. In addition, the response of the MIPCH to tetracyclines (TCs) in aqueous solution was monitored through a readable change of Debye diffraction ring, which is related to the particle spacing variation of MIPCH in response to the target molecules. As the concentration of OTC increased from 0 to 60 μM, the particle spacing of MIPCH sensor increased to about 94 nm and the structural color redshifted from blue to red. More importantly, the detection of OTC in milk sample by this portable, cost-effective MIPCH sensor has also been achieved at the same range of OTC. With the increasing concentration of OTC in milk sample, the particle spacing of MIPCH sensor increased about 92 nm and the structural color of MIPCH changed from blue through green to orange. Image 1 • A novel 2D molecularly imprinted PC was developed for the fast screening of trace level residues of OTC in milk. • The detection could be realized by naked eyes through observing the diffraction ring or structural color. • The sensor also showed advantages in easy preparation and specificity towards the targets. [ABSTRACT FROM AUTHOR]

The detection of the human immunodeficiency virus-1 (HIV) at an early stage is vital and could be realized through its cell surface glycoprotein-120 (gp120) without virus preprocessing. Here, we present an ssDNA-aptamer-linked photonic crystal (APC) hydrogel sensor for HIV detection which is comprised of photonic crystals (PCs) made of polystyrene nanoparticles embedded in the polyacrylamide hydrogel. ssDNA aptamers specific for gp120 are crosslinked in the hydrogel which can selectively bind to gp120 by hydrogen bonding increasing the PCs particle spacing and swelling of the hydrogel. The binding response can be visually monitored as a color change due to the diffraction of light from PCs and can eventually be measured (1–1000 ng mL−1 of gp120) and 100 to 108 VP mL−1 of HIV by the Debye's ring diameter or a UV/Vis spectrometer. APC-hydrogel can be regenerated by Tris-HCl and EDTA washing buffer system. The sensor demonstrates LOD of 7.1 ± 1.55 ng mL−1 for gp120 and 4 VP mL−1 for the whole HIV, a rapid response of 5 min, reusability up to 70 % (in fifth use), and recovery of 95.4 ± 0.1 % to 99.0 ± 0.2 % in plasma samples. The sensor is cost-effect and stable compared to antibody-based sensors and can be utilized to develop point-of-care testing (POCT) devices for HIV diagnosis. [Display omitted] • A novel ssDNA aptamer linked photonic crystal sensor for rapid, sensitive, and onsite quantitative detection of HIV. • Specific binding of the aptamer to gp120 results in reversible swelling of the hydrogel. • Photonic crystals embedded in the polyacrylamide hydrogel provide a vibrant optical response visible to the naked eye. [ABSTRACT FROM AUTHOR]

The indiscriminate use of nerve agents by terrorist groups has attracted attention of the scientific communities toward the development of novel sensor technique for these deadly chemicals. A photonic crystal (PhC) hydrogel immobilized with butyrylcholinesterase (BuChE) was firstly prepared for the sensing of Sarin agents. Periodic polystyrene colloidal (240 nm) array was embedded inside an acrylamide hydrogel, and then BuChE was immobilized inside the hydrogel matrix via condensation with 3-(diethoxyphosphoryloxy)−1,2,3-benzotriazin-4(3 h)-one (DEPBT). It indicated that a total of 3.7 units of BuChE were immobilized onto the PhC hydrogel. The functionalized hydrogel recognized the Sarin agent and then shrunk, thus the diffraction of PhC hydrogel blue shifted significantly, and a limit of detection (LOD) of 10 −15 mol L −1 was achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • A large-scale amorphous photonic crystal (APC) array was cast by a robotic arm. • The APC arrays had non-iridescent structural colors and can be used in painting. • Molecularly imprinted APC sensors group was fabricated to detect explosives. • A qualitative and semi-quantitative result was obtained via color analysis methods. Leveraging advances in nanoscience and intelligent technology to engineer large-scale and stimuli-response amorphous photonic crystals (APCs) for use in inexpensive and portable sensing system for the detection of explosives. Polymethyl methacrylate (PMMA) colloidal microspheres with uniform particle size and good mono-dispersion were used to prepare APCs by spraying method. The structural color of APCs was angle-independent and changed with different microspheres size. Meanwhile, a robotic arm was designed to achieve an automatic and large-scale preparation of APCs, and this more accurate and cost-effective method not only provides an automatic process for large-scale APCs pattern painting in chemical industry, but also gives chemical sensors an access to be smart devices in life. Then 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and cyclotetramethylenete-tranitramine (HMX) molecularly imprinted APCs (MIAPCs) were fabricated in the same way. The results showed that the response time of MIAPCs was 10 s, and the limit of detection was 0.01 mM with NaOH swollen. Specially, by using the more convenient HSB (Hue-Saturation-Brightness) and CIE (Commission Internationale de L'Eclairage) color analysis methods, combined with principal component analysis and pattern recognition methods, a sensor group with higher selectivity and sensitivity than a single sensor was constructed. A qualitative and semi-quantitative result was realized by responding to the changes of structural color before and after. Compared with traditional PhCs sensor, the APCs sensor has angle-independent structural color, which provides more accurate results and simplifies the detection based on the color analysis. This novel large-scale APCs sensor represents a potential of highly selective and real-time on-site visual explosive detection. In the meanwhile, the automatic APCs casting also offers chemical materials an access to combining with intelligent technology. [ABSTRACT FROM AUTHOR]

Abstract: A label free molecularly imprinted photonic crystal (MIPC) was developed to detect the degradation product of nerve agents. Mono-dispersed poly-methyl methacrylate colloidal particles with the diameter of 280nm were used to fabricate a closely packed colloidal crystal array (CCA), and a methyl phosphonic acid (MPA) imprinted hydrogel was prepared within the CCA using 2-hydroxyethyl-methacrylate and N-isopropylacrylamide as monomers, ethyleneglycol dimethacrylate and N, N′-methylenebisacrylamide as cross-linkers, a mixture of n-octanol and acetonitrile as porogen. The diffraction intensity of the MIPC decreased significantly upon the MPA adsorption with a limit of detection (LOD) of 10−6 molL−1. Furthermore, the diffraction intensity decreased and blue shifted with the increase of temperature, decreased and red shifted with the increase of ionic strength. At higher pH, the diffraction intensity increased without obvious diffraction shift. The MIPC provides an indirect path to detect nerve agents (Sarin, Soman, VX and R-VX) by monitoring the MPA released from the hydrolysis of nerve agents, with LODs of 3.5×10−6 molL−1, 2.5×10−5 molL−1, 7.5×10−5 molL−1 and 7.5×10−5 molL−1 for Sarin, Soman, VX and R-VX, respectively. [Copyright &y& Elsevier]

• A rapid self-assembly method was proposed to prepare the 3D-photonic crystal (PhC). • The effect of microspheres, heating and nitrogen blowing have been also studied. • Using this method, a p-nitrophenol-molecular imprinted PhC sensor was prepared. To overcome the long period of three-dimension photonic crystal colloidal array preparation, a rapid self-assembly method is proposed. The effect of microspheres diameter and concentration, heating and nitrogen blowing have been also studied. According to the results, when the microspheres suspension concentration is 0.2 wt% and heating temperature of 70 °C, a highly regular 3D face-centered cubic colloidal crystal array structure self-assembles on the gas-liquid interface within 3 min. Then using this method, a p-nitrophenol-molecular (p-NP) imprinted photonic crystal sensor with high selectivity and sensitivity is prepared. The p-NP imprinted sensor presents twice signal intense than the non-imprinted sensor towards the target, and the structural color changes from blue to green. Meanwhile, the sensor responds in 3 min and can be reversible more than 9 times. This rapid self-assembly method provides a suitable way for large-area colloidal photonic crystal preparation with higher efficiency and good repeatability, which has a high value for practical applications. [ABSTRACT FROM AUTHOR]

• The sensitivity of the IOPC increases due to the inverse opal structure and the infiltration of dimethyl sulfoxide. • The sensing mechanism of the IOPC is simulated by RSoft, and the experimental results are highly consistent with the simulated experimental results. • The reflection wavelength redshift of the IOPC increases with the concentration of alcohol vapors. • The reflection-peak of IOPC shifted when exposed to acetone and hydrogen peroxide, which provide a potential method for the detection of peroxide explosives. Colorimetric sensors were fabricated by embedding three dimensional (3D) inverse opal photonic crystal (IOPC) structure inside a dimethyl sulfoxide (DMSO) infiltrated carboxymethyl cellulose membrane for gas sensing. The DMSO infiltrated IOPC (DMSO-IOPC) carboxymethyl cellulose sensors can perform visual, on-site monitoring for analytes including alcohols, acetone and hydrogen peroxide (H 2 O 2). After exposed to alcohols and acetone, the mean effective refractive index (RI) and lattice constant of DMSO-IOPCs were changed, which led to a redshift of diffraction peak of the incident light. Sequentially their structural color changed remarkably. The limit of detection (LOD) for methanol and ethanol vapors are 110 ppm and 102 ppm, respectively. The H 2 O 2 sensor is also achieved by using DMSO-IOPCs, and the diffraction blue-shifted when they were exposed to H 2 O 2 vapor. In addition, this DMSO-IOPC sensor shows excellent selectivity and reversibility. The sensing mechanism of the DMSO-IOPC membranes was explained and simulated using finite-different time-domain (FDTD) method, and the experimental results were consistent with the simulated results. The DMSO-IOPCs demonstrate promising potential for in-situ monitoring of alcohol vapors, and could be used for peroxides detection and as a cheap and minimally invasive breathalyzer. [ABSTRACT FROM AUTHOR]