Patent attributes
There is disclosed a method of operating a colorimetric gas detector system that comprises a substrate (1) bearing a material (12) that can react with a target gas to produce a change in the wavelength of radiation absorbed or transmitted by the material (“color-change material”). The method involves:a) applying onto a region (15) of the substrate that includes color-change material a chemical of predetermined concentration that reacts directly or indirectly with the color-change material to produce a change in the wavelength of the radiation absorbed or transmitted by the material;b) detecting the radiation absorbed or transmitted in said region (15) at a wavelength absorbed or transmitted by the reaction product of the color change material with the chemical, andc) generating a signal in accordance with the amount of radiation detected at the second wavelength, said signal being dependent on the amount of color-change material on the substrate.The signal can be used to correct the reading of the color change material when exposed to target gas to compensate for varying amounts of color-change material on the substrate.
