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L. N. Zavora¹, N. A. Kasyan¹, L. N. Lisetski¹, V. D. Panikarskaya¹, I. P. Terenetskaya², T. N. Orlova², S. I. Torgova³

Author affiliations
¹SSI “Institute for Single Crystals”. NAS of Ukraine. 60 Lenin Ave, Kharkov, 61001, Ukraine. lisetski@isc.kharkov.com ²Institute of Physics. Nauky av. 46, Kyiv 680028, Ukraine ³Institute of Physics RAS, 123995, GSP-5, Moscow D-242, B. Gruzinskaya st., 10-1, Russia

Abstract
UV-irradiation of liquid crystal mixtures based on cholesterol esters, which contain provitamin D as a non-mesogenic component and form, alongside with the cholesteric phase, smectic A-phase at lower temperatures, can lead to a photoinduced smectic A – cholesteric transition, with a corresponding appearance of visible color upon absorption of a certain dose of UV radiation. The presence of a biological component (provitamin D) makes this system a promising material for bioequivalent UV-dosimetry. Physico-chemical principles governing the process are discussed, which determine the effects of the mixture composition on the sensitivity of the sensor material.

Keywords: UV radiation detectors, bioequivalent UV dosimetry, vitamin D, cholesteric liquid crystals, selective reflection, sensor materials