Small glass electrode

• US 5,837,113 A
• Filed: 02/08/1996
• Issued: 11/17/1998
• Est. Priority Date: 12/06/1990
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Suzuki, Hiroaki, Kojima, Naomi, Sugama, Akio
• Primary Examiner(s): TUNG, TA HSUNG
• Application Number:
  US08/598,287
• Time in Patent Office: 1,013 Days
• Field of Search: 204/416-420, 204/435
• US Class Current: 204/420
• CPC Class Codes: G01N 27/36 Glass electrodes

Abstract

A small glass electrode and process for preparation thereof, the small glass electrode having a bonded structure and comprising a reference electrode composed of silver/silver chloride, a glass substrate having a pad embedded therein, the pad being composed of gold or platinum and circuit-connected to the reference electrode, and a silicon substrate having a (100) plane selectively etched by the anisotropic etching technique and comprising a groove for injecting an electrolyte composed of an aqueous solution containing chlorine such as KCA, or HCA, at least one hole for holding the electrolyte and a glass film formed in a portion corresponding to the reference electrode. The structure of the small glass electrode may be produced by the disclosed process easily and at low cost. Additionally, the small glass electrode, in differing embodiments, may include a reference electrode and a temperature sensor.

Claims

1. A small glass electrode having a bonded structure comprising:

a planar glass substrate having a first main surface and having embedded therein, from the first main surface, an inside reference electrode, a first pad and a first lead-in line interconnecting said inside reference electrode and said first pad, said planar glass substrate having a second main surface and having embedded therein, from the second main surface, an outside reference electrode, a second pad and a second lead-in line interconnecting said outside reference electrode and said second pad;

a first silicon semiconductor substrate bonded to the first main surface of said glass substrate and having a first main surface, at least one reservoir extending into the first silicon semiconductor substrate from the first main surface for holding an aqueous electrolyte and a groove forming a fluid passageway in communication with the reservoir for injecting the aqueous electrolyte into the reservoir, said groove and said reservoir being formed by anisotropic etching of the first silicon semiconductor substrate, the reservoir extending from the first main surface and toward a second opposite main surface of the first silicon semiconductor substrate and the reservoir having a sidewall defining an aperture at the second main surface of the first silicon semiconductor substrate to expose the interior of the reservoir, the aperture being disposed at a location corresponding to the position of the inside reference electrode embedded in the glass substrate;

a glass sensing film covering and sealing the aperture in the sidewall and thus at a position corresponding to said inside reference electrode; and

a second silicon semiconductor substrate bonded to the second main surface of said glass substrate and having a first main surface, at least one reservoir extending into the second silicon semiconductor substrate from the first main surface for holding an aqueous electrolyte and a groove for forming a salt bridge communicating between the reservoir and the exterior, said groove and reservoir being formed by anisotropic etching of the second silicon semiconductor substrate, the reservoir covering said outside reference electrode.

2. A small glass electrode according to claim 1, wherein an electrolyte occupies the electrolyte-holding reservoirs.

3. A small glass electrode according to claim 1, wherein said inside and outside reference electrodes are composed of silver/silver chloride.

4. A small glass electrode according to claim 1, wherein said first and second pads and lead-in lines are made of gold or platinum.

5. A small glass electrode according to claim 1, further comprising a temperature sensor.

6. A small glass electrode according to claim 5, wherein said temperature sensor comprises a thin film resistor formed between the glass substrate and the first or second silicon semiconductor substrate.

7. A small glass electrode according to claim 1, wherein the glass sensing film comprises two layers of glass film.

8. A small glass electrode according to claim 1, wherein said first and second silicon semiconductor substrates are (100) oriented silicon semiconductor substrates.

9. A small glass electrode having a bonded structure comprising:

a glass substrate having a main surface and having embedded therein from the main surface, an inside reference electrode, a first pad, a first lead-in line interconnecting said inside reference electrode and said first pad, an outside reference electrode, a second pad, and a second lead-in line interconnecting said outside reference electrode and said second pad, said inside reference electrode, said first pad and said first lead-in line being electrically isolated from said outside reference electrode, said second pad and said second lead-in line;

a silicon semiconductor substrate having a first main surface, at least one first reservoir extending into the silicon semiconductor substrate from the first main surface for holding an aqueous electrolyte, a first groove forming a passageway in communication with the first reservoir for injecting the aqueous electrolyte into the first reservoir, at least one second reservoir extending into the silicon semiconductor substrate from the first main surface for holding an aqueous electrolyte, and a second groove for forming a salt bridge between the second reservoir and an exterior, said first and second reservoirs being formed by anisotropic etching of the silicon semiconductor substrate, the first reservoir extending from the first main surface of the silicon semiconductor substrate toward a second, opposite main surface of the silicon semiconductor substrate and the first reservoir having a sidewall defining an aperture at the second main surface of the silicon semiconductor substrate to expose the interior of the first reservoir, the aperture being disposed at a location corresponding to the position of the inside reference electrode embedded in the glass substrate; and

a glass sensing film covering and sealing the aperture in the sidewall and thus at a position corresponding to said inside reference electrode.

10. A small glass electrode according to claim 9, wherein an electrolyte occupies the electrolyte-holding reservoir.

11. A small glass electrode according to claim 9, wherein the glass sensing film comprises two layers of glass film.

12. A small glass electrode according to claim 9, wherein said reference electrode is comprised of silver/silver chloride.

13. A small glass electrode according to claim 9, wherein said first and second pads and said first and second lead-in lines are made of gold or platinum.

14. A small glass electrode according to claim 9, wherein said semiconductor substrate is a (100) oriented silicon substrate.

15. A small glass electrode according to claim 9, further comprising a temperature sensor.

16. A small glass electrode according to claim 15, wherein said temperature sensor comprises a thin film resistor formed between the glass substrate and the silicon semiconductor substrate, said resistor being insulated from the inside and outside reference electrodes.

17. A small glass electrode combined with a temperature sensor, comprising a planar glass substrate and a silicon semiconductor substrate, the glass substrate having a first main surface and the silicon semiconductor substrate having first and second opposite main surfaces, the first main surfaces of the substrates being bonded to each other, the bonded substrates having a first portion for a glass electrode and a second portion for a temperature sensor, the first and second portions being separated from each other,

i) said first portion comprising:

a reference electrode, a pad and a lead-in line, each embedded in the glass substrate, from the first main surface thereof, the lead-in line interconnecting said reference electrode and said pad;

at least one reservoir extending into the silicon semiconductor substrate from the first main surface of the silicon semiconductor substrate for holding an aqueous electrolyte, the reservoir having a sidewall defining an aperture at the second main surface of the silicon semiconductor substrate to expose the interior of the reservoir, the aperture being disposed at a location corresponding to the position of the reference electrode embedded in the glass substrate,

a groove forming a fluid passageway in communication with the reservoir for injecting the aqueous electrolyte into the reservoir, said groove and said reservoir being formed by anisotropic etching of the silicon semiconductor substrate, the reservoir extending from the first main surface toward the second main surface of the silicon semiconductor substrate; and

a glass sensing film covering and sealing the aperture in the sidewall and thus at a position corresponding to said reference electrode, and

ii) said second portion comprising a thin film resistor formed between the bonded substrates.

18. A small glass electrode according to claim 17, wherein an electrolyte occupies the electrolyte-holding reservoir.

19. A small glass electrode according to claim 17, wherein the glass sensing film comprises two layers of glass film.

20. A small glass electrode according to claim 21, wherein said semiconductor substrate is a (100) oriented silicon substrate.

21. A small glass electrode according to claim 17, wherein said reference electrode is comprised of silver/silver chloride.

22. A small glass electrode according to claim 17, wherein said pad and said lead-in line are made of gold or platinum.

23. A small glass electrode according to claim 17, wherein the first portion further comprises an aqueous electrolyte solution held within said at least one reservoir.