System and probe for monitoring pH levels of a sample medium

• US 7,182,847 B1
• Filed: 05/07/2003
• Issued: 02/27/2007
• Est. Priority Date: 05/07/2003
• Status: Expired due to Fees

• Current Assignee: Millar Instruments
• Original Assignee: Millar Instruments
• Inventors: Pauly, Robert L., Millar, Huntly D.
• Primary Examiner(s): Olsen; Kaj K.
• Application Number:
  US10/431,132
• Time in Patent Office: 1,392 Days
• Field of Search: 204/433, 204/435, 205/787.5
• US Class Current: 204/433
• CPC Class Codes: G01N 27/333 Ion-selective electrodes or membranes glass electrodes G01N27/36
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A system for monitoring a pH level of a sample medium is disclosed herein as including a pH probe having a pH-sensitive electrode, a reference electrode and a temperature electrode arranged within a housing of the pH probe. The probe housing generally includes a flexible inner tube and a flexible outer tube, the inner tube being concentrically arranged within the outer tube. Preferably, a size of the probe housing minimizes the amount of trauma introduced by insertion of the pH probe into physiological tissues, muscles or fluids. The system also includes a processing means, which is coupled to the pH probe for determining the pH of the sample medium. A method of forming a pH-sensitive electrode, a method of manufacturing a pH probe, and a method for using a pH probe are also disclosed herein.

Claims

1. A probe for determining a pH level of a sample medium, the probe comprising:

a flexible outer tube having a flexible inner tube concentrically arranged therein, wherein a lumen of the inner tube comprises a pH-sensitive electrode having a conducting portion and a sensing portion, which protrudes from a first end of the inner tube for detecting a signal used to determine the pH level of the sample medium, wherein;

the conducting portion comprises one or more antimony rods; and

the sensing portion comprises a smooth hemispherical tip formed by dipping one end of the antimony rods into liquefied antimony and allowing the sensing portion to harden while pointing in a downward direction;

wherein a space between the inner tube and the outer tube comprises;

a reference electrode configured to fill at least a portion of the space;

a temperature electrode arranged along one side of the space; and

wherein a sidewall of the outer tube comprises one or more diffusion windows located proximate to a first end of the outer tube to provide electrical coupling between the reference electrode and the sample medium.

2. The probe as recited in claim 1, further comprising a sealant applied to the first ends of the inner and outer tubes, wherein the sealant provides a hydrophobic seal extending between the sensing portion of the pH-sensitive electrode and the first ends of the inner and outer tubes.

3. The probe as recited in claim 1, wherein the temperature electrode comprises a temperature sensitive element configured to detect temperature values between about 0°

C. and about 100°

C., and wherein an outer diameter of the temperature sensitive element is substantially less than 0.5 mm.

4. The probe as recited in claim 1, wherein the reference electrode comprises:

a porous thread material arranged along the one side and extending in a continuous manner to an opposite side of the space;

an electrical conductor arranged along the one side or the opposite side of the space; and

an electrolytic solution filling at least a portion of the space and configured to provide an electrical connection between the porous thread material and the electrical conductor.

5. The probe as recited in claim 4, wherein portions of the porous thread material are arranged in the vicinity of the one or more diffusion windows.

6. The probe as recited in claim 4, wherein the porous thread material comprises a cotton wick.

7. The probe as recited in claim 4, wherein the electrical conductor comprises a metal wire containing at least some amount of silver and at least some amount of chloride.

8. The probe as recited in claim 4, wherein the electrolytic solution comprises a viscous fluid consisting of one or more chlorides selected from a group comprising potassium chloride, silver chloride and sodium chloride.

9. The probe as recited in claim 4, wherein the pH-sensitive electrode, the reference electrode and the temperature electrode each comprise a conductive portion, which extends outward from within corresponding second ends of the inner and outer tubes in a direction opposite to the first ends of the inner and outer tubes.

10. The probe as recited in claim 9, further comprising a sealant applied to the second ends of the inner and outer tubes, wherein the sealant provides a hydrophobic seal, which fills a space between the pH-sensitive electrode, the reference electrode, the temperature electrode and the second ends of the inner and outer tubes, such that only the conductive portions protrude from a surface of the sealant.

11. The probe as recited in claim 1, wherein an outer diameter of the probe is between about 0.5 mm and about 1.25 mm.

12. A system for monitoring a pH level of a sample medium, the system comprising:

a pH probe comprising;

a flexible probe housing comprising an inner tube concentrically arranged within an outer tube, which has one or more diffusion windows formed therein;

a pH-sensitive electrode arranged within the inner tube and partially protruding from a first end of the inner tube, wherein the pH-sensitive electrode comprises an antimony rod having a smooth hemispherical tip, which is configured to detect a voltage associated with the pH level of the sample medium;

a reference electrode arranged within a space between the inner tube and the outer tube, wherein the reference electrode is configured to detect a base voltage of the sample medium;

a temperature electrode arranged along one side of the space, wherein the temperature electrode is configured to detect a temperature value of the sample medium; and

a processing means coupled to the pH probe and configured to determine the pH level of the sample medium using the voltage, the base voltage, and the temperature value.

13. The system as recited in claim 12, wherein the processing means comprises an electrical potential measuring device.

14. The system as recited in claim 13, wherein the processing means comprises a processor, a display screen, and one or more user-actuated controls.

15. The system as recited in claim 14, wherein the processing means further comprises an output port for transmitting an analog signal to a display device.

16. The system as recited in claim 14, wherein the pH level and the temperature value are displayed upon the display screen.

17. The system as recited in claim 12, wherein the pH probe comprises an outer diameter of about 1.25 mm or less.