Method and device for eliminating electrode drift

• US 5,766,432 A
• Filed: 04/17/1996
• Issued: 06/16/1998
• Est. Priority Date: 04/17/1996
• Status: Expired due to Fees

• Current Assignee: University Of Massachusetts, Worcester Polytechnic Institute
• Original Assignee: University Of Massachusetts, Worcester Polytechnic Institute
• Inventors: Dunn, Raymond M., Harrington, Robert, Kun, Stevan, Peura, Robert
• Primary Examiner(s): Lacyk, John P.
• Assistant Examiner(s): ROLLINS, ROSILAND STACIE
• Application Number:
  US08/632,330
• Time in Patent Office: 790 Days
• Field of Search: 204/412, 204/406, 204/420, 204/433, 205/787.5, 128/635, 128/637, 128/640
• US Class Current: 204/412
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes

Abstract

A pH-measuring method and device for monitoring and then correcting for electrode drift is provided. The device includes a pH-measuring electrode and more than one reference electrode. During operation, the pH-measuring device is place in contact with a sample. The pH value measured at each electrode pair is due to the electrical potential difference between the pH electrode and the reference electrode. The maximum and minimum pH values are determined, and then the remaining pH values are averaged together to generate an overall average pH. The maximum and minimum pH values are subtracted from the average pH to generate a difference which is then compared to a user-defined drift level to determine if a particular electrode is deficient. The pH values from deficient electrodes are not considered when the overall pH of the sample is determined.

Claims

1. An electrode-containing device comprising:

a measuring electrode;

a plurality of reference electrodes in electrical contact with said measuring electrode, wherein each of the reference electrodes forms an electrode pair when electrically contacted with the measuring electrode; and

,

a microprocessor in electrical contact with each electrode pair, said microprocessor being programmed to;

receive an electrical signal from each electrode pair;

average together at least two of the electrical signals to determine an average electrical signal;

calculate an electrical signal difference between at least one electrical signal and the average electrical signal; and

compare each electrical signal difference to a predetermined drift level, wherein an electrical signal difference greater than the drift level existing for a time period greater than a predetermined drift time indicates a deficient reference electrode.

2. The device of claim 1, wherein said measuring electrode is a glass electrode.

3. The device of claim 1, further comprising a plurality of measuring electrodes each being in electrical contact with at least one of said plurality of reference electrodes.

4. The device of claim 1, wherein the measuring electrode is a pH-measuring electrode.

5. The device of claim 4, wherein the electrical signal received by the microprocessor indicates a pH value.

6. The device of claim 5, wherein the microprocessor is programmed to:

average together at least two of the electrical signals to determine an average pH;

calculate a difference between at least one pH value and the average pH; and

determine the pH of the sample by analyzing the pH values from the non-deficient reference electrodes.

7. The device of claim 1, wherein each of said reference electrodes is a non-invasive electrode or an electrical contact.

8. The device of claim 7, wherein each of said reference electrodes is a cutaneous or sub-cutaneous electrode.

9. The device of claim 8, wherein said cutaneous electrode is a skin-surface electrode.