Polymer-stabilized liquid crystal indicator used in thermometry

Research on the biological effects and on critical-temperature alarm indicators for fire safety often requires the use of non-metallic and reliable temperature sensors. For such applications, we investigated the temperature dependence of the spectral response of a pure cholesteric liquid-crystal temperature indicator and of a polymer/liquid crystal mixture. We observed a modulation of the intensity of transmitted monochromatic light, in accordance with the temperature changes. We emphasize that the modulation occurs over a wide temperature range outside the active temperature of the thermochromic liquid-crystal indicator. Such behavior suggests the possibility of using these liquid crystals in a wider temperature range, under appropriate conditions. The spectral response of the liquid crystal in its active temperature range shows that a thermochromic liquid crystal indicator may be practically used as a precision thermometer.