a multilayered thermochromic display system is provided , wherein a thermochromic substance is applied to inert films in stacked layers with a non - invasive barrier between each layer of thermochromic substance . the thermochromic substance in each layer responds in a different temperature range so that as the temperature changes , the display exhibits repeated sequences of colors . the use of multiple layers with different temperature sensitivities enables the use of the displays over a broad range of temperatures .