You can freely build on How the Iron Lung Artificial Respirator Works
This patent expired in 1951. 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
1933
Expired
1951
Forward citations
7
What this patent covers
The device, commonly known as an iron lung, creates a sealed environment around a patient's body, leaving only the head exposed. By using a pump to rhythmically lower and raise the air pressure inside the chamber, the device forces the patient's chest to expand and deflate. This mechanical action mimics the natural process of breathing for individuals who have lost the ability to control their own diaphragm muscles.
What is now free to use
All 0 claims of US 1906844 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 positive-pressure ventilators that push air directly into the lungs through a tube.
Does not cover portable or wearable breathing assistance devices.
Does not cover electronic sensors or automated feedback loops for monitoring blood oxygen levels.
Who is building on this today
Modern respiratory care has largely moved toward positive-pressure ventilation, with companies like Medtronic and Philips leading the development of advanced ventilators. The iron lung is now a historical artifact, though its principles influence modern non-invasive ventilation techniques.
Products built on expired version of this technology
The Drinker Respirator
Historical polio ward iron lung machines
How to cite this patent in your documentation
Individual. US Patent 1906844. Artificial respirator. Granted 1933, expired 1951. 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.