A smart large-scale explosive-responsive amorphous photonic crystal sensor based on color analysis method

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.