There are some cheap MQ-3 sensors reactive to alcohol contained in air. I wouldn't expect them to be useful for anything else, but fun. The devices used by the Police need to be certified and regularly calibrated.
A few years ago, the Police (at least in our country) used chemical reaction that changed colour of a stripe included in an inflating balloon inflated by a person to be checked.
However, for precise alcohol measurement (contained in blood), a different method is used. Two samples of blood need to be taken after a while (not sure how the alcohol volume is measured) and then compared to some typical absorption curve to estimate alcohol level at the some specific time.
There are some cheap MQ-3 sensors reactive to alcohol contained in air. I wouldn't expect them to be useful for anything else, but fun. The devices used by the Police need to be certified and regularly calibrated.
A few years ago, the Police (at least in our country) used chemical reaction that changed colour of a stripe included in an inflating balloon inflated by a person to be checked.
However, for precise alcohol measurement (contained in blood), a different method is used. Two samples of blood need to be taken after a while (not sure how the alcohol volume is measured) and then compared to some typical absorption curve to estimate alcohol level at the some specific time.
