Intercranial pressure transducer
First Claim
1. An intercranial pressure transducer of the passive type, including:
- a sealed capsule adapted to be housed in the thickness of a skull;
a movable permanent magnet within said capsule;
guide means for guiding displacement of said magnet axially within said capsule; and
said capsule including means for subjecting said magnet to a hydrostatic force generated by the intercranial pressure within said skull, whereby said magnet is displaceable by an external magnetic field applied thereto and which is sufficiently strong to overcome said hydrostatic force applied to said magnet and whereby the strength of the external magnetic field required to displace said magnet is a measure of said intercranial pressure.
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Abstract
The invention provides means for measuring the intercranial pressure of a patient. A small sealed capsule is located in a trephined hole in the patient'"'"'s skull, with its active face in the form of a diaphragm in contact with the dura mater. The capsule includes a small hollow cylindrical permanent magnet slidable for a short distance along a smooth rod and held against a stop by the diaphragm with a pressure proportional to the intercranial pressure of the liquid within the skull. When an alternating magnetic field of sufficient intensity is applied to the magnet by an external wound inductor, it vibrates on and off its stop, producing an audible signal and the current in the inductor, at this point, is proportional to the said intercranial pressure.
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Citations
10 Claims
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1. An intercranial pressure transducer of the passive type, including:
- a sealed capsule adapted to be housed in the thickness of a skull;
a movable permanent magnet within said capsule;
guide means for guiding displacement of said magnet axially within said capsule; and
said capsule including means for subjecting said magnet to a hydrostatic force generated by the intercranial pressure within said skull, whereby said magnet is displaceable by an external magnetic field applied thereto and which is sufficiently strong to overcome said hydrostatic force applied to said magnet and whereby the strength of the external magnetic field required to displace said magnet is a measure of said intercranial pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- a sealed capsule adapted to be housed in the thickness of a skull;
Specification