Device for the measurement of the pressure inside a body part relative to the outside pressure

摘要

For measurement of the pressure inside a body part relative to the outside pressure there is proposed a device which comprises a sensor housing, insertable into the body part, with two membranes by which a sensor oscillating circuit accommodated in the sensor housing and couplable to an external system can be influenced. The sensor housing and the membrane consist of an amagnetic, non-conducting material. The inside of the sensor housing is filled with an incompressible liquid osmotically equivalent to the environment. Furthermore, the sensor housing contains a ferromagnetic shell core and a movable ferrite plate placed on one of the two membranes. The position of the ferrite plate can be influenced within two stops by the deflection of the membrane. The sensor housing comprises two series-connected windings one of which is located inside the shell core and the other one of which is located on the outer edge thereof. An external emitting coil has such a high resistance and such a low inductance and capacity that its attenuation is greater, at least by a factor of 5, than the attenuation of the sensor oscillating circuit.