# 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.

- **Patent:** US 2824789
- **Original title:** Apparatus for analyzing a gas
- **Owner:** Individual
- **Granted:** 1958
- **Status:** Public domain (expired)
- **Times cited:** 8
- **Field:** consumer_electronics, mechanical

## What it does

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 does NOT 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.

## Real-world examples

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

## 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.

## Frequently asked questions

### What does How the Breathalyzer Measures Alcohol in Your Breath cover?

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.

### Who owns patent US 2824789?

Individual owns this patent, granted in 1958.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 2824789 cited by?

This patent has been cited by 8 later patents that build on its ideas.

### What problem does this patent solve?

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.

### What does this patent NOT cover?

Does not cover modern digital fuel cell or infrared spectroscopy breath testing technology.

**Full plain-English explainer:** https://patentbrief.org/patent/us/2824789/breathalyzer-borkenstein

**Original patent:** https://patents.google.com/patent/US2824789

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


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