Temperature sensing using reversible thermochromic polymeric films

Temperature sensing membranes using Nafion® as the polymeric support matrix have been prepared incorporating common pH indicators and stains as visible indicators. These simple systems depend on the temperature sensitivity of the acid-base equilibria between the indicator and the acidic Nafion®. The films are able to sense temperature change through a change in film colour resulting from the equilibrium shift between different forms of the indicating dye. The dyes (phenolphthalein, methylene blue, safranin-O and crystal violet) studied covered a temperature range from 4 to 70 °C. © 2003 Elsevier Science B.V. All rights reserved