The Safety of Sensors, Part 3: Infrared

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Infrared Sensor

Technology is ever evolving, making the impossible plausible and the unreachable more accessible. Within the automotive industry, one where horsepower and engine RPM used to dominate, safety now reigns as king.

And the future of safety is infrared.

Some vehicles on the road take advantage of this technology, through infrared night vision and blind spot detection. Several industries use this technology in other ways: motion detection for automatic lights, entry detection for home security, heat detection to measure body temperature.

Some sensor technologies determine how to drive, breath sensors however suggest if you should drive.

Infrared breath sensors are mostly tailored for evidential breathalyzers, such as those used at police roadside checkpoints and stations. An infrared sensor measures the absorption of light by the ethanol molecule. Ethanol is a liquid that comprises the base of all alcohol. The absorption value is directly proportional to the alcohol concentration, which is used to calculate the Breath Alcohol Content (BrAC) of the breath sample.

Believe it or not, the first roadside evidential breathalyzer didn’t have a sensor, a screen or electrical power. The first roadside breathalyzer was invented by Dr. Bogen1, which involved a large football bladder filled with sulphuric acid and potassium dichromate. As you can imagine, problems emerged with this invention as both sulphuric acid and potassium dichromate are very corrosive and harmful if inhaled.

As time passed and breath sensing technologies became more intricate, problems surfaced in the public eye regarding breath testing ethics; some criticized the ethics behind what they deemed ‘push-button evidence’. The concept of being caught drinking while driving by a small handheld device stood to persecution, since breath alcohol is not the only factor to determine a person’s intoxication level. Criticisms shortly disappeared as vehicle ownership became more commonplace and the rates of drink-driving related fatalities increased to unprecedented heights.

In the world of breath alcohol testing, infrared is the most accurate; the measurement of light absorption proved to be more accurate than both semi-conductors and electrochemical sensors. Law enforcement officials tend to prefer using infrared breathalyzers because results from one can be used as evidence in a court of law.

The future is infrared and the future is now.


1 A.W. Jones. (1990). Physiological Aspects of Breath-Alcohol Measurement. Alcohol, Drugs and Driving, Volume: 6(2), 1-25. https://www.ncjrs.gov/App/publications/abstract.aspx?ID=131532