03958558 is referenced by 81 patents and cites 6 patents.

A wireless, surgically implantable pressure transducer for measuring pressure of fluid or tissue in a body chamber such as brain ventricle of a patient suffering hydrocephalus or a severe head injury. The transducer includes a coaxial variable capacitor electrically connected across an inductor to form a parallel resonant L-C circuit. Alternatively, a coaxially variable inductor may be connected across a capacitor to form the L-C circuit. A bellows is mechanically connected to the variable component to vary the value of capacitance or inductance and hence the resonant frequency of the L-C circuit in response to pressure changes of the fluid in which the bellows is immersed. The transducer is electromagnetically coupled to an external source of variable-frequency oscillatory energy such as a grid-dip oscillator which enables external detection of the transducer resonant frequency which is in turn indicative of the level of fluid pressure being sensed.

Title
Implantable pressure transducer
Application Number
5/506217
Publication Number
3958558
Application Date
September 16, 1974
Publication Date
May 25, 1976
Inventor
Robert H Pudenz
Pasadena
CA, US
Leo A Bullara
Glendora
CA, US
Roderick R Dunphy
San Jose
CA, US
Agent
Christie Parker & Hale
Assignee
Huntington Institute of Applied Medical Research
CA, US
IPC
A61B 5/02
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