Alcohol Detector: Easily check the drunk driving

Lead: Speaking of alcohol detectors may be a little unfamiliar to everyone, but the following scene we should have seen it: when the traffic police on the roadside check drunk driving, usually holding an instrument to allow the driver to exhale, and then after shaking the instrument You know if the driver has alcohol. The instrument used by the traffic police is the alcohol detector. Does it know the reaction principle?

Usually after drinking, alcohol is absorbed by the body through the digestive system, and then through the blood circulation, about 90% of the alcohol is exhaled through the lungs. The alcohol concentration of the exhaled gas and the alcohol concentration in the blood will show a certain positive proportional relationship: blood alcohol concentration = breath alcohol concentration × 2200, so use an alcohol detector to measure the alcohol content in the exhalation to determine the degree of intoxication.

When an oxide having N-type conductivity is exposed to the atmosphere, its internal resistance is increased due to the adsorption of oxygen to reduce its internal electrons. When the surface of the alcohol tester adsorbs a reducing gas (such as alcohol-generated organic solvent vapor), the ratio of the conductive electrons of the semiconductor microcrystalline particle-contacting interface changes, so that the resistance value depends on the concentration of the measured gas. Change and change. As a result, the value on the alcohol detector changes, and at the same time, this reaction is reversible.

Know the reaction principle of the alcohol detector, is it right? Here also to remind everyone: For the sake of their own and others' safety, we must not drunk driving!