How will a personal breathalyzer test BAC?

Let’s start with this simple fact: You should not drive if you’ve been drinking. Drinking and driving is dangerous to the driver and everyone on the road with them.

Knowing someone’s blood alcohol content (BAC) is of potential interest to family, friends, and to the individual him or herself. The only way to get an exact measurement of blood alcohol levels is through a blood sample, but since this is not always a practical method, a personal breathalyzer is used to estimate blood alcohol content.

How will a personal breathalyzer test BAC

How will a breathalyzer test BAC

A breathalyzer is used to measure the amount of alcohol in a person's breath, and that number is converted into an estimate of how much alcohol would be in a person's blood. Alcohol is not immediately digested or chemically changed upon absorption, and as the blood goes through the lungs, some of the alcohol in the lungs is exhaled into the air. The ratio of breath alcohol to blood alcohol is 2,100:1.

There are two main personal breathalyzers types:

Fuel cell technology uses fuel cell sensors to detect chemical reactions of alcohol. These fuel cells have two platinum electrodes on either side of a porous, acid-electrolyte material. As the air flows past one side of the fuel cell, the platinum oxidizes any alcohol that’s in the air and produces acetic acid, protons and electrons. The electrical current that is established between the two electrodes can reveal the presence of alcohol in the air sample. Fuel cells are better at providing both highly accurate and more consistent BAC results.

Semiconductor devices also use a current to determine the presence of alcohol. A small, charged bead of tin oxide is headed to 300 degrees Celsius. When alcohol comes into contact with the bead, the current changes. The degree of change determines the concentration of alcohol in the breath. Although not as accurate or reliable as their fuel cell counterparts, semiconductor breathalyzers — offer users a more affordable means to gauge their BAC.


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