A relationship exists between the concentration of ethanol in human breath and blood. Ethanol absorbs infrared energy in the region of 3.46 mu. In this method the concentration of ethanol in breath is measured by collecting a sample in a chamber and passing through it a filtered, directional, and interrupted...http://www.google.fr/patents/USRE31246?utm_source=gb-gplus-shareBrevet USRE31246 - Determination of the alcohol content of blood
