The most common examples of liquid crystal (LC) materials in routine use are as the display medium in LCD televisions, computer screens and calculators. They have also become important as thermometers, an application that takes advantage of the colour changes that they can undergo as the temperature varies.
Linkam's LTS420 temperature stage for the study of liquid crystals (above) and an image showing the power and detail revealed using a hot stage to view phase changes of liquid crystals – smectic to cholesteric phase change (below).
The Hallcrest Group is a leading manufacturer in the application of such thermographic materials for temperature measurement. Notably, Hallcrest's LC room thermometers are being used in the British Gas Help the Aged 'Winter Deaths' campaign.
Scientifically, the Hallcrest Group's Technology Centre has found Linkam's LTS420 heating microscope stages to be invaluable tools for accurately determining the temperature at which the phase transitions that cause the colour changes occur. With six systems in use, this has allowed them to develop some of the most accurate LC thermometers on the market.
The high degree of control over heating and cooling rates, along with the accuracy and long term stability, make Linkam's LTS420 the preferred choice. With LC applications ranging from medical thermometers, refrigeration indicators to novelty and promotional products, an LC thermometer may contain 12 different LC formulations to give the most appropriate temperature range for an application. The Linkam LTS420 can be programmed with up to 100 temperature ramps, controlled to +/- 0.1°C, and when integrated with digital image capture, enables full temperature characterisation of the new LC formulations.
In addition to new product development, the Linkam stages are routinely used for calibration and quality control of LC temperature indication devices.