You can freely build on How the Breathalyzer Measures Alcohol in Your Breath
This patent expired in 1975. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Individual
Patent granted
1958
Expired
1975
Forward citations
8
What this patent 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 is now free to use
All 0 claims of US 2824789 are in the public domain. Specifically:
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
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.
Who is building on this today
While the original chemical-based Breathalyzer is largely obsolete, companies like Draeger and Intoximeters have built upon the foundational principle of breath-based alcohol detection using more advanced fuel cell and infrared sensors.
Products built on expired version of this technology
Original Breathalyzer 900 series
Early police sobriety checkpoints
How to cite this patent in your documentation
Individual. US Patent 2824789. Apparatus for analyzing a gas. Granted 1958, expired 1975. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.