Highly sensitive reflection based colorimetric gas sensor to detect CO in realistic fire scenarios

For early fire detection, the measurement of low and small rising concentrations of the fire typical gas carbon monoxide (CO) is essential. The approach presented herein integrates a highly sensitive colorimetric material into a low cost gas sensor system. The gas sensitive color dye is hosted by silica nanoparticle based supraparticles and then processed to a so-called gas sensor stripe. Changes in the CO concentration enable a change of the sensor stripes color, which is easily detectable as a change of the light that is reflected by the stripe. A diffusion chamber protects the gas sensitive film against harmful environmental influences and interfering light. The capability of the gas sensor system is demonstrated in lab as well as real fire tests. In case of the latter, standardized real fire tests are conducted, as well as realistic mixtures of plastics and wood are smoldered. The developed sensors react in real time to the slowly rising CO concentration during the test fires. Even small amounts of CO (<20 ppm) are reliably detectable.