A new approach to the creation of an active medium of optical gas sensors for the detection of carbon monoxide is proposed. The approach is based on the use of a liquid crystal host doped with iron compounds. Cholesteric liquid crystal CLC-2103L was doped by Fe₃O₄ magnetite nanoparticles with a concentration of 0.30-0.67% to develop the primary transducer of a carbon monoxide sensor. The proposed gas sensor registers the optical signal in the visible region of the spectrum, corresponding to the optical reflection by the helical structure of a cholesteric liquid crystal (CLC).

The influence of ammonia on the optical absorption of polyaniline films obtained by the electrochemical method is studied. In the presence of ammonia, the optical spectra of a polymer are found to change due to the appearance of a new absorption band with a maximum at 2.07 eV and a simultaneous decrease in the intensity of bands at 1.57 and 2.91 eV. The kinetics of changes showing the presence of an isobestic point at 2.71 eV is elaborated. The results can be used to optimize the ammonia gas sensors for monitoring the biotechnological processes in the food industry and the environment.

The composition of the surface and electrical properties of silicon oxide nanocomposites of porous silicon were investigated by FTIR spectroscopy in the range of 400 – 4000 cm^-1 and by impedance spectroscopy in the frequency range of 25 Hz – 1 MHz. It was revealed the different dispersion of electrical capacitance in different frequency bands and the complex relaxation processes that affect the electrical transport properties of nanocomposites. The correlations between the IR absorption spectra of silicon oxide composites and processes of charge transfer was defined. On the basis of analysis of spectra of thermal stimulated depolarization it was shown that oxidation of the surface of porous silicon nanocrystals gives rise to changing the density of states in different energy ranges.

The influence of ammonia on the optical absorption spectra of thin films of polyaniline (PANI), poly-3,4-ethylenedioxythiophene (PEDOT), mixtures thereof, and the bilayer film structures based on PANI and PEDOT obtained by electrochemical method were studied. The kinetics of changes in the optical absorption of these structures under the action of ammonia was explored in the spectral range of 350 … 900 nm. It was shown that thin film bilayer structure PANI / PEDOT significantly broaden the range of spectral sensitivity to ammonia compared to individual films.

In this study, we have manufactured sensory films based on poly(3,4-ethylenedioxythiophene)/carbon nanotubes/reduced graphene oxide nanocomposite. The charge transport in obtained films was analyzed using impedance spectroscopy and temperature dependence of conductivity in the 90–325 K temperature range. The activation mechanism of charge transfer was established and the activation energy of conductivity was determined. The percolation effect in the nanocomposite was found with increasing the content of carbon nanoparticles. A decrease in resistance and an increase in the capacity of hybrid films due to the adsorption of water and ammonia molecules were revealed. Found features of the charge transport processes can expand the prospects of application of nanocomposite films for sensor electronics.

The effect of an integrated polymer on the luminescence characteristics of porous silicon (PS)-conducting polymer (CP) heterostructures has been studied. Both n-(100) and p-type (111) PS has been employed in order to prepare the heterostructures. To obtain the integrated polymer layers (polyaniline, polymethoxyaniline, polyphenylacetylene, poly-para-phenylene, poly-N-epoxy-propylcarbazol), the methods of electrochemical polymerization, vacuum deposition, and spin coating have been used. The obtained structures were studied using atom force microscopy and were examined as to the capability to photoluminescence (PL) and cathodoluminescence (CL). It has been found that the presence of a CP layer on the PS surface preserves the “red” PL, but weakens it to 50–90%. The CL spectra of the obtained heterostructures allow us to suggest their capability of electroluminescence in the visible region of the spectrum.