Importance

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Abstract

A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates on one side with the internal pressure to be measured and on the other side with an external pressure which is applied by an external pressurizer-control system and which is communicated to the sensor through the intact skin. An imbalance of the two opposing pressures causes a displacement of the movable element which changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit. This change is detected outside the body by an external detection system, such as a frequency swept radio frequency oscillator. The external pressure is varied until the external detector senses that the pressures are balanced on the movable element, at which point the external pressure equals the internal pressure, and the former is measured and read out.

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First Claim