You can freely build on Leonarde Keeler's Early Mechanical Blood Pressure Recorder
This patent expired in 1948. 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
1931
Expired
1948
Forward citations
4
What this patent covers
The device functions as a specialized mechanical apparatus for monitoring and documenting arterial blood pressure. It uses a pressure-sensitive mechanism to track fluctuations in a patient's pulse and blood flow. By translating these physical movements into a readable format, it allows clinicians to observe changes in pressure without constant manual observation.
What is now free to use
All 0 claims of US 1788434 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 electronic or digital blood pressure sensors.
Does not cover automated cuff inflation systems found in modern monitors.
Does not cover methods for analyzing blood pressure data using software or algorithms.
Who is building on this today
Modern medical device manufacturers like Omron and Welch Allyn have evolved these early mechanical concepts into highly sophisticated digital diagnostic tools used in hospitals worldwide.
Products built on expired version of this technology
Early mechanical sphygmograph prototypes
Analog clinical patient monitoring equipment
How to cite this patent in your documentation
Individual. US Patent 1788434. Apparatus for recording arterial blood pressure. Granted 1931, expired 1948. 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.