Nanocomposites and nanomaterials
Liquid crystalline substances doped with carbon nanotubes as a sensitive medium of the CO2 sensor
Vistak M.V.1, Diskovkyi I.S.1, Kachurak Y.M. 2, Kuchmiy G.L.2 ,     Horina O.M. 2
1 Danylo Halytsky Lviv National Medical University. Pekarska str., 69, Lviv-79010, Ukraine. 
2 Lviv Polytechnic National University. Stepana Bandery str., 12, Lviv-79000, Ukraine. 
E-mail: yurii.m.kachurak@lpnu.ua

The creation of highly sensitive optical CO2 in air sensors is an urgent problem, as it allows control of CO2 content both indoors and in ambient air, where it’s level usually 600… 1000 ppm.
We propose to use a liquid crystalline substance[1-3] (nemato-cholesterol mixture based on E7 with impurities of cholesterol), supplemented with multi-walled carbon nanotubes, as a sensitive element of the CO2 sensor. The spectral characteristics of the liquid crystal mixture in the range of 400… 600 nm were studied. The content of carbon nanotubes varied in the range of 0.1… 0.5 wt.%. It is established that with increasing concentration in the range of 10… 100 mg/m3 the minimum transmission shifts to the long-wavelength region of the spectrum. The maximum spectral sensitivity in this range is 6 nm⁄mg⁄m3. The investigated material can be used as a sensitive element of the optical CO2 sensor. 

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2.	M. Vistak, Z. Mykytyuk, F. Vezyr, V. Polishchuk, Molecular Crystals and Liquid Crystals 672(1), 67 (2018).
3.	R.Politansryi,  M.Vistak,  G.Barylo,  A.Andrushak, Optical Materials, 102, art.no.109782, (2020).