Abstract
A modern level of nanotechnology allows us to create conceptually new test systems for chemical analyses and to develop sensitive and compact sensors for various types of substances. However, at present, there are very few commercially available compact sensors for the determination of toxic and carcinogenic substances, such as organic solvents that are used in some construction materials. This article contains an overview of how 3D photonic crystals are used for the creation of a new test system for nonpolar organic solvents. The morphology and structural parameters of the photonic crystals, based upon a crystalline colloidal array with a sensing matrix of polydimethylsiloxane, have been determined by using scanning electron microscopy and by the results of specular reflectance spectroscopy based on the Bragg–Snell law. A new approach has been proposed for the application of this sensor in chemical analysis for the qualitative detection of saturated vapors of volatile organic compounds due to configuration changes of the photonic bandgap, recorded by diffuse reflectance spectroscopy. The exposure of the sensor to aromatic (benzene, toluene and p-xylene) and aliphatic (n-pentane, n-heptane, n-octane and n-decane) hydrocarbons has been analyzed. The reconstitution of spectral parameters of the sensor during the periodic detection of saturated vapors of toluene has been evaluated.
Highlights
Photonic crystals (PhCs) used for chemical sensors can be divided into three groups depending upon their structure, that is, one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) [1-10]. 2D and 3D structures used as chemical sensors are studied in most projects. 2D structures consist of a monolayer of spherical particles placed on a substrate. 3D struc
Tures, which appear in the form of a crystalline colloidal array (CCA), are called opal structures
A comparison between the specular reflectance and the diffuse reflectance spectra tested in the “specular component included (SCI)” and “specular component excluded (SCE)” modes has shown (Figure 1a) that the maximum of the diffuse reflectance spectra of the PhC sensor in the SCI mode coincides with the maximum of the specular reflection spectra resulting from flat (111) surfaces at an 8° angle
Summary
Photonic crystals (PhCs) used for chemical sensors can be divided into three groups depending upon their structure, that is, one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) [1-10]. 2D and 3D structures used as chemical sensors are studied in most projects. 2D structures consist of a monolayer of spherical particles placed on a substrate. 3D struc-Beilstein J. Photonic crystals (PhCs) used for chemical sensors can be divided into three groups depending upon their structure, that is, one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) [1-10]. 2D structures consist of a monolayer of spherical particles placed on a substrate. Tures, which appear in the form of a crystalline colloidal array (CCA), are called opal structures (spherical particles closepacked in an ordered structure). If the structure has been placed in a matrix and the particles have been removed, it is an inverse opal structure [11-13]. A photonic bandgap (PBG) appears in colloidal crystals due to the periodic modulation of the refractive index. Most of the configuration changes of the photonic bandgap in opal and inverse opal structures occur due to swelling or compression of the polymer matrix or gel
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