Alcohol thermometer to give a background for reading the scale. The range of usefulness of the thermometer is set by the boiling point of the liquid used. In the case of the ethanol-filled thermometer, the upper limit for measurement is 78 °C (172.4 °F), which makes it useful for measuring daytime, nighttime and body temperatures, although not for anything much hotter than these. Ethanol-filled thermometers are used in preference to mercury for meteorological measurements of minimum temperatures and can be used down to −70 °C (-94 °F). The physical limitation of the ability of a thermometer to measure low temperature is the
Liquid crystal thermometer except for the analytic liquid crystal thermometer which shows the exact temperature between 35.5 to 40.5 Celsius. Liquid crystal thermometers are also commonly used in aquariums in homebrewing, and in mood rings. The Liquid crystal thermometer was invented by Bob Parker in California, one of many of the inventor's thermochromic applications patented in the 1970s. Liquid crystal thermometer A liquid crystal thermometer, temperature strip or plastic strip thermometer is a type of thermometer that contains heat-sensitive (thermochromic) liquid crystals in a plastic strip that change colour to indicate different temperatures. Liquid crystals possess the mechanical properties of a liquid, but