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Home > Fuel Cell vs. Semiconductor Oxide Breathalyzer Sensors

Fuel Cell vs. Semiconductor Oxide Breathalyzer Sensors

So what's the difference between Fuel Cell and Semiconductor breathalyzers?

The difference between fuel cell andsemiconductor technology is simply the way that the alcohol that is found inthe breath sample is tested.

Alcohol breathalyzers work by testing the BAC (Blood Alcohol Content) of the breath sample. It measures how many grams of alcohol there are in your bloodstream. The current legal upper limit for Canada is 0.08, which means the maximum is 0.08 g/100ml or 80 mg/100ml. Most of the time however, the BAC is referred to as 0.08% or 0.05% etc.

Alcohol is not digested when you consume it, it's absorbed into your blood stream. As the blood travels through the lungs some of the alcohol moves across the membrane of the lung’s alveoli (air sacks). When the alcohol is exposed to the air in your lungs, it evaporates and mixes with the air in your lungs and is expelled when you exhale.

Through exhaustive experimentation, there has been a correlation found between the ratio of vaporized alcohol (found in your lungs) and the alcohol content in the bloodstream. It has been accepted that there is a ratio of 2,100:1 (air volume to blood volume).

Using this ratio, a properly calibrated alcohol breathalyzer can accurately determine a person BAC without having to draw blood and have it analyzed in a laboratory.

Fuel Cell

Fuel cell technology works by creating a chemical reaction thatoxidizes the alcohol in the breath sample. This oxidization produces anelectrical current and the device measures this electrical current todetermine the blood-alcohol content (BAC) of the sample.

Of the two, fuel cell technology is more accurate and more reliable forthe following reasons:

  • Fuel cells are not affected by environmental pollutants andother chemicals.
  • Less likely to provide a false positive when testingsomeone with diabetes (because of acetone secretions).
  • Require less calibration and maintenance.
  • The sensing technology provides a more accurate BAC.
  • Can be used in a testing environment where multiple testswill be performed successively.
Fuel Cell Image


Semiconductor technology uses an oxide sensor to measure the reactivitybetween the tin dioxide (SnO2) in the sensor and the ethanol moleculesin the breath sample. When the ethanol molecules come in contact withthe tin dioxide the reaction changes the electrical resistance of thesensor. The semiconductor measures this difference and calculates anestimate of the BAC of the sample.

However, semiconductor breathalyzers offer these benefits:

  • The lower cost of manufacturing the semiconductor sensor results in a more affordable device.
  • The semiconductor units require less power and parts allowing them to be smaller and more easily carried.
  • These units have a larger consumer based product line versus the fuel cell breathalyzers that are targeted towards professionals and organizations requiring a device that can handle higher test volumes.


In summary, if you require the most accurate and reliable device werecommend that you choose a fuel cell breathalyzer that meets yourneeds.

But, keep in mind that all of the semiconductor models we sell are of veryhigh quality and will produce accurate results and are the better value.