The 'mood rings' popular in the 1970s showed, in a subdued way, that liquid crystals change colour with temperature. Now research at Pennsylvania State University is putting this trait to practical use: measuring heat flow in large machines under laboratory conditions.
By spraying a thin layer of liquid crystals from aerosol cans onto equipment, and using a video camera to record the colour changes as it heats up and cools down, the researchers can be accurate to 0.1 °C in every picture frame lasting 1/30th of a second. 'Our work is focused on heat transfer in aero-propulsion systems,' says Cengiz Camci, professor of aeronautical engineering.
The method should be cheaper and more accurate than the traditional method of applying thermocouples to surfaces. Camci, who has worked on the method since 1989 with Steve Hippensteele of NASA's Lewis Research Center in Cleveland, Ohio, says that liquid crystals have several advantages: 'The ...
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