RADIO CAPSULE BATTERY

• US 3,791,377 A
• Filed: 06/30/1971
• Issued: 02/12/1974
• Est. Priority Date: 06/30/1971
• Status: Expired due to Term

• Current Assignee: Charles H. Rogers, Thomas E. Norby
• Original Assignee: Charles H. Rogers, Thomas E. Norby
• Inventors: Norby, Thomas E., Rogers, Charles H.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/158,294
• Time in Patent Office: 958 Days
• Field of Search: 128/2P,2R,2.1R,419R 136/177 204/195B
• US Class Current: 600/302
• CPC Class Codes: A61B 5/073 Intestinal transmitters

Abstract

A battery for an active radio capsule wherein one of the electrodes, a silver-silver chloride electrode, functions as the reference electrode for a sensor by means of an electrolytic path from the battery chamber to the solution external to the capsule. The reference electrode, which is stable and insensitive to foreign ions, is disposed in a closed chamber filled with an electrolyte which is immobilized by an absorptive powder. One or more fibrous plugs form an electrical connection between the chamber and the surrounding medium. The reference electrode is designed to have a low, stable internal impedance and has a high current capability.

Claims

2. A radio capsule in accordance with claim 1 wherein said fibrous material is wood.

3. A radio capsule in accordance with claim 2 wherein said chamber is substantially filled with a porous powder, said electrolyte being disposed within the voids between adjacent grains of said powder and within the pores thereof.

4. A radio capsule in accordance with claim 3 wherein said other of said electrodes comprises a silver wire which is bent at one end in the form of a substantially closed loop, said silver chloride filling the space within said loop and contacting that portion of said silver wire disposed on the inner surface of said loop.

5. A radio capsule in accordance with claim 4 wherein said loop is disposed in a first plane, that portion of said silver wire immediately adjacent to said loop being bent in a U-shaped manner in a second plane which intersects said first plane the volume within said loop and said U-shaped portion being filled with said silver chloride.

6. A radio capsule in accordance with claim 3 wherein said other of said electrodes comprises a sheet of silver foil, a thin layer of silver chloride disposed on one surface of said siLver foil, and a silver wire bonded to said silver foil.

7. A radio capsule in accordance with claim 6 wherein said silver foil-silver chloride composite is U-shaped.

8. A radio capsule in accordance with claim 1 wherein said chamber has an open end, said capsule further comprising an elastic cap disposed over said open end.

9. A radio capsule in accordance with claim 1 wherein said other of said electrodes comprises a silver wire which is bent at one end in the form of a substantially closed loop, said silver chloride filling the space within said loop and contacting that portion of said silver wire disposed in the inner surface of said loop.

10. A radio capsule in accordance with claim 9 wherein said loop is disposed in a first plane, that portion of said silver wire immediately adjacent to said loop being bent in a U-shaped manner in a second plane which intersects said first plane the volume within said loop and said U-shaped portion being filled with said silver chloride.

11. In a radio capsule for investigating a condition of a region that is readily accessible only by wireless probes, said capsule being of the type comprising a sensor for providing a voltage, the value of which is determined by said investigated condition, an oscillator for generating an rf signal modulated by said sensor voltage, and a battery adapted to be activated by an electrolyte prior to use, said battery having two electrodes for providing an operating voltage for said oscillator, one of said electrodes also functioning as the reference electrode for said sensor, said battery being characterized in that it comprises means defining a chamber in said capsule, said two electrodes being disposed in said chamber, said chamber being substantially filled with a porous powder, means defining at least one hole in said chamber defining means, means having low porosity disposed in said hole for permitting only an extremely limited diffusion of electrolyte to or from said chamber, one of said electrodes being a consumable electrode, and the other of said electrodes comprising a silver portion and a silver chloride portion contacting said silver portion, a part of said silver portion being exposed so that it is free to contact said electrolyte, that portion of said silver chloride which contacts said silver being thin in cross section so that the impedance of the electrode is relatively low.

12. A radio capsule in accordance with claim 11 wherein said porous powder is a crystalline zeolite.

13. A radio capsule in accordance with claim 12 wherein the voids between the grains of porous powder and the pores thereof are filled with an electrolyte.

14. A radio capsule in accordance with claim 13 wherein said electrolyte consists of a 5 to 10 sodium chloride solution.