Self-Assembled Curved Macroporous Photonic Crystal-Based Surfactant Detectors

Abstract

Surfactants are extensively used as detergents, dispersants, and emulsifiers. Thus, wastewater containing high-concentration surfactants discharged to the environment pose a serious threat to the ecosystem. Unfortunately, conventional detection methods for surfactants suffer from the use of sophisticated instruments and cannot perform detections for various surfactants by a single analysis. The article reports the development of simple and sensitive surfactant detection using doctor-blade-coated three-dimensional curved macroporous photonic crystals on a cylindrical rod. The photonic crystals exhibit different hydrophobicities at various angular positions after surface modification. The penetration of aqueous surfactant solutions in the interconnected macropores causes red-shift as well as reduction in amplitude in the optical stop bands, resulting in surfactant detection with visible readout. The correlation between the surface tension, as well as the solution-infiltrated angular position, and the concentration of aqueous surfactant solutions has also been investigated in this study.

Photonic Crystal Reflectors with Ultrahigh Sensitivity and Discriminability for Detecting Extremely Low-Concentration Surfactants

“…Also, the detection of the SDS concentration in the range 0.01−1 wt % can be carried out through the variation of the solutioninfiltrated angular position with the concentration of SDS by using curved macroporous photonic crystals on a cylindrical rod. 41 In this study, our findings demonstrate that the sensitivity to the SDS surfactant can be significantly enhanced to 0.01 mM. Additionally, a wavelength shift of 111 nm is observed when the SDS concentration changes from 0 to 0.01 mM, allowing for a clear visualization of the color change in response to even a small variation in the SDS concentration.…”

“…As reported, when the concentration of the SDS surfactant is changed from 0 to 1 mM, a wavelength shift of approximately 30 nm is observed using a close-packed polystyrene 2-D array monolayer embedded in a poly­( N -isopropylacrylamide) (PNIPAAm)-based hydrogel film. Also, the detection of the SDS concentration in the range 0.01–1 wt % can be carried out through the variation of the solution-infiltrated angular position with the concentration of SDS by using curved macroporous photonic crystals on a cylindrical rod . In this study, our findings demonstrate that the sensitivity to the SDS surfactant can be significantly enhanced to 0.01 mM.…”

“…Therefore, the development of effective surfactant detection methods is of great significance. Although detection methods such as high-performance liquid chromatography, mass spectroscopy, evaporative light scattering, and charged aerosol detection are available, they are costly and inconvenient for the general public. − As a result, developing efficient and user-friendly detecting methods, such as direct visualization by stimuli-responsive visible-wavelength photonic crystals, has gained much attention. − Visible color change and sensitivity are essential for detecting surfactants by using photonic crystals. The selection of appropriate molecular weight BCPs and the modification of the composition of the constituent blocks are vital in obtaining the visible-wavelength of BCP-based photonic crystals and improving their sensitivity to surfactants.…”

Decoding Optical Responses of Contact-Printed Arrays of Thermotropic Liquid Crystals Using Machine Learning: Detection and Reporting of Aqueous Amphiphiles with Enhanced Sensitivity and Selectivity

“…The CNN models were implemented using PyTorch (version 1.2.0). 37 The major hyperparameters we varied include the kernel size (5,7,9), number of convolution layers (1,2,3), pooling function (max pooling or average pooling), and learning rate (0.0001,0.0005,0.001). The tested models were trained with cross-entropy loss, Adam optimizer, and a learning rate of 0.0001.…”

“…Surfactants are amphiphilic molecules that contain hydrophilic head groups and hydrophobic tail groups, the combination of which allows them to self-assemble both in solution and at interfaces (e.g., at solid surfaces or at interfaces between immiscible liquid phases) . Because of their unique properties, surfactants are used in a wide range of industrial and pharmaceutical products, including detergents and food additives, and as components of drug delivery vehicles. − Amphiphilic molecules also play essential roles in living organisms, and many have been identified as disease biomarkers. , As a result of their widespread use in practical applications, surfactants can also end up as contaminants in consumer or pharmaceutical products or may be discharged into the environment where they can harm surrounding ecosystems. − …”