Thermochromic Liquid Crystals (LCs) can be highly temperature sensitive, change to many colors, and are more expensive than leuco dyes. LC's start black below their temperature range, go through the colors of a rainbow, and then black again above the temperature range. LC's are reversible in that they can be used over and over again. The picture below shows an example of a liquid crystal sheet response to warming.
Popular liquid crystal applications include aquarium thermometers, medical forehead thermometers, and "stress" cards. We offer a wide range of LC thermometers as stock products, but the majority of our business is custom thermometers and private label manufacturing.
LC's are very similar to the liquid crystal displays used in watches and laptop computers, but our thermochromic LC's change color with temperature instead of voltage. LC's can be formulated to change temperature from -25 to +250ºF (-30 to 120ºC), and can be sensitive enough to detect changes as small as 0.2ºF. If kept out of UV light and away from high temperatures and strong solvents, LC products last years.