How the Breathalyzer Measures Alcohol in Your Breath

A 1954 invention by Robert Borkenstein that uses a chemical reaction to estimate the amount of alcohol in a person's blood by testing their breath.

What it covers

The device captures a specific volume of a person's breath and passes it through a chemical solution containing potassium dichromate and sulfuric acid. If alcohol is present in the breath, it reacts with the solution, causing a color change from orange to green. The device then uses a photoelectric cell to measure the intensity of this color change, which correlates to the concentration of alcohol in the breath and, by extension, the bloodstream.

What it doesn't cover

• —Does not cover modern digital fuel cell or infrared spectroscopy breath testing technology.
• —Does not cover methods for testing alcohol concentration directly from blood or urine samples.
• —Does not cover automated data logging or wireless transmission of test results.

The clever bit

It cleverly used a simple color-changing chemical reaction as a proxy for blood alcohol content, allowing for a portable device that could be operated by police officers in the field rather than requiring a laboratory.

Why it matters

This invention transformed law enforcement by providing a portable, objective, and scientifically verifiable method for detecting drunk driving. It moved the legal standard for intoxication from subjective field sobriety tests to quantifiable chemical evidence.

Real-world examples

• 1.Original Breathalyzer 900 series
• 2.Early police sobriety checkpoints