PHYSIOLOGICAL PRESSURE SENSING AND TELEMETRY MEANS EMPLOYING A DIODE CONNECTED TRANSISTOR TRANSDUCER

• US 3,757,770 A
• Filed: 02/22/1971
• Issued: 09/11/1973
• Est. Priority Date: 02/22/1971
• Status: Expired due to Term

• Current Assignee: Forrest G. Brayshaw, Theodore S. Roberts
• Original Assignee: Forrest G. Brayshaw, Theodore S. Roberts
• Inventors: Brayshaw, Forrest G., Roberts, Theodore S.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/117,589
• Time in Patent Office: 932 Days
• Field of Search: 128/2.5E,2.5R,2.6R,2.1A,2.1R,2R,2S
• US Class Current: 600/302
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/031 Intracranial pressure

Abstract

Pressure measurement apparatus and method, the apparatus having a pressure sensitive element, an audio oscillator, a transmitter, a receiver, a frequency-to-voltage converter and a read-out device. The pressure sensor is connected to and capable of varying the frequency of the audio oscillator as a function of the pressure applied to the sensor. The audio oscillator is connected to and capable of modulating the signal of the transmitter. The pressure sensor, audio oscillator and transmitter are implanted internal to the scalp of a living test subject, the pressure sensor being placed between the skull and the dura mater. Additionally, a remote receiver is connected to a frequency-to-voltage converter and is capable of receiving the radio frequency signal transmitter by the transmitter and supplying the detected audio oscillation of the radio frequency signal to the frequency-to-voltage converter. The frequency-tovoltage converter is capable of supplying a variable voltage to the read-out device, depending upon the frequency of the input signal delivered by the receiver. The read-out device is capable of optically displaying and/or recording the amount of signal voltage being fed to it by the frequency-to-voltage converter.

Claims

1. Apparatus for measuring static and dynamic physiological pressures within a living test subject, comprising:

pressure transducer means adapted to be implanted within the test subject, said transducer means comprising a diodeconnected pressure sensitive transistor, the resistance of which, between the emitter and commonly-connected base and collector, varies as a function of the pressure applied thereto;

an audio oscillator adapted to be carried by the test subject and connected for response to said transistor, said oscillator generating a signal the frequency of which varies as the resistance of said transistor;

a radio frequency transmitting means adapted to be worn by the test subject and connected for response to said audio oscillator, said transmitting means propagating an electromagnetic wave which is frequency-modulated at the frequency of said audio oscillator;

radio frequency receiver means adapted to be located remotely from and physically unconnected with the test subject, said receiver means receiving the frequency modulated electromagnetic wave propagated bp said transmitting means and providing a corresponding electric signal;

a frequency-to-voltage converting means connected for response to said receiver means for generating a voltage the amplitude of which varies according to the frequency of the signal applied thereto by said receiver means; and

indicating means connected for response to said freuqency-tovoltage converting means for providing, as a function of the voltage applied thereto, an indication of the pressure applied tsaid transistor.