PHYSIOLOGICAL SIGNAL TRANSMITTER FOR USE INSIDE THE BODY

• US 3,682,160 A
• Filed: 10/16/1969
• Issued: 08/08/1972
• Est. Priority Date: 10/16/1969
• Status: Expired due to Term

• Current Assignee: Norio Murata
• Original Assignee: Norio Murata
• Inventors: Murata, Norio
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US04/866,818
• Time in Patent Office: 1,027 Days
• Field of Search: 128/2R,2.1A,2.1P,2.6R,419R,419P,2.1R 204/195 325/118 340/248P,253P 331/65,66,173
• US Class Current: 600/302
• CPC Class Codes: A61B 2018/1435 Spiral
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/073 Intestinal transmitters
• CPC Class Codes: A61B 5/42 Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems A61B1/00, A61B5/4857, A61B5/486, A61B5/4866, A61B5/4869 take precedence

Abstract

A miniature medical transmitter detects a physiological variable in a human body and transmits a signal to a receiver placed at the outside of a human body, more particularly to an orally swallawable minature transmitter for measuring pH value or any other variable in a gastro-intestinal tract. The transmitter comprises detecting means for generating a voltage relating to a physiological variable in a human body, limiting network means, a storing capacitor and oscillator means, and its operation is based on an arrangement wherein the voltage from the detecting means activates the oscillator means and, at the same time, modulates the oscillator means. Accordingly, the transmitter does not require conventional power supply means such as battery means and external energy sender means placed outside the body.

Claims

1. A medical transmitter adapted for transmission of an electric signal corresponding to a physiological variable in a human body, which comprises detecting means having two detecting terminals provided with a detected voltage E relating to said physiological variable;

limiting network means which has two input terminals connected with said two detecting terminals and which has two output terminals provided with a limiting current I therefrom;

a storing capacitor of a capacitance, Co, which is connected with said two output terminals; and

oscillator means which has two energizing terminals connected with two terminals of said storing capacitor and energizable by an electric charge stored in said storing capacitor which functions as a power source for said oscillator means, said oscillator means for starting oscillation in an oscillation frequency f when a voltage between said two energizing terminals rises up to a starting voltage Vt and for stopping said oscillation when said voltage between said two energizing terminals falls down to a stopping voltage Vp, and said oscillator means having a leakage current I1 adapted to flow therethrough upon the cessation of said oscillation and an actuating current Ia to flow therethrough during oscillation, said oscillating means having the following operating characteristic;

0 <

(I1)max <

(I)min <

(I)max <

(Ia<

(Ia)max <

<

Co.f.(Vt-Vp) where (I1)max is a maximum value of said leakage current I1, (I)min and (I)max are a minimum value and a maximum value of said limiting current I, respectively, and (Ia)min and (Ia)max are a minimum value and a maximum value of said actuating current Ia, respectively;

whereby said oscillator means is intermittently oscillating with an intermittent oscillation period which is variable with a change in said detected voltage.

2. A medical transmitter defined by claim 23, wherein said limiting network means comprises a limiting resistor having resistance Ro.

3. A medical transmitter defined by claim 2, wherein said oscillator means comprises a transistor tuned oscillator.

4. A medical transmitter defined by claim 3, wherein said detecting means comprises a pH sensor.

5. A medical transmitter defined by claim 4, wherein said pH sensor has a pH sensitive electrode comprising an antimony electrode, and a reference electrode comprising a zinc electrode.

6. A medical transmitter defined by claim 4, wherein said pH sensor has a pH sensitive electrode comprising an antimony electrode, and a reference electrode comprising a manganese electrode.

7. A medical transmitter as claimed in claim 4, wherein said pH sensor has a pH sensitive electrode comprising an antimony electrode, and a reference electrode comprising a magnesium-zinc alloy electrode.

8. A medical transmitter as claimed in claim 4, wherein said pH sensor has a pH sensitive electrode comprising an antimony electrode, and a reference electrode comprising a manganese dioxide electrode.

9. A medical transmitter as claimed in claim 4, wherein said pH sensor has a pH sensitive electrode comprising an antimony electrode and a reference electrode comprising a vanadium pentoxide electrode.

10. A medical transmitter defined by claim 3, wherein said transistor tuned oscillator has a tuning capacitor having a variable capacitance sensitive to an enviromental condition surrounding said medical transmitter.

11. A medical transmitter defined by claim 10, wherein said tuning capacitor is a temperature sensitive capacitor.

12. A medical transmitter defined by claim 3, wherein said transistor tuned oscillator has a tuning inductor, an inductance of which is variable depending upon a second physiological.

13. A medical transmitter defined by claim 12, wherein said second physiological variable is pressure and said tuning inductor has a magnetic core movable with a change in said pressure.

14. A medical transmitter defined by claim 1, wherein said storing capacitor is a voltage dependent capacitor.

15. A medical transmitter defined by claim 1, wherein said limiting network means comprises voltage dependent elements.

16. A medical transmitter defined by claim 1, wherein said storing capacitor consists essentially of a temperature sensitive capacitor capable of compensating a temperature dependence of said intermittent oscillation period of said medical transmitter.

17. A medical transmitter defined by claim 1, wherein said limiting network means comprises temperature sensitive elements capable of compensating a temperature dependence of said intermittent oscillation period of said medical transmitter.