practically any substrate to which the temperature indicating composition can be applied can be used including paper cardboard glass ceramic plastic and metal suitable plastic substrates include polyvinyl chloride films polyolefin films such as polyethylene and polypropylene polyethylene terephthalate polyvinylidene chloride and polyurethane mylar film is one suitable example of substrate which can be used for application of the compounds in accordance with the present invention using mylar film having a thickness of about 0 0005 inch as a substrate an extremely sensitive temperature indicating device can be obtained this type of device can be used for thermal mapping of the human body or an animal body to aid in diagnosis of abnormal conditions such as gall bladder or kidney malfunction blocked arteries sprains and a wide variety of other abnormal conditions that produce extremely small thermal changes in the body these very thin film temperature indicating devices can be applied either by the use of pressure sensitive adhesive or other means to hold each device to a desired location the temperature indicating devices of the present invention represented by fig3 through 7 can be designed to indicate almost any temperature desired different combinations of cholesteric substances have been used to measure temperatures ranging from minus 20 u00b0 c to plus 250 u00b0 c these substances have been fabricated into flexible films or tapes that can be applied to surfaces to record temperature gradients in several directions this technique can be extended to the inspection of opaque materials for certain structural flaws that would conduct heat unevenly and so produce different patterns of color in a cholesteric substance applied to the surface for certain warning applications for example a simple badge not illustrated which indicates a single temperature condition is all that is required for example.