Differential Channel Optical Readout System for Color Changes of Gas Sensitive Colorimetric Dyes

We present a simple sensor setup for detecting very small color changes of gasochromic materials. The sensor includes up to ten LEDs for capturing different spectral channels, ranging from ultraviolet to the near infrared. The System features a differential optical structure that intrinsically allows comparing the reflectance of the gas sensitive dye to that of a reference dye. This allows for detecting diminutive color changes of dyes at gas concentrations in the sub ppm range with a better signal-tonoise ratio and drift stability compared to single channel systems.