Modulating Polarization Voltage of Amperometric Sensors

• US 20110180426A1
• Filed: 09/14/2009
• Published: 07/28/2011
• Est. Priority Date: 09/23/2008
• Status: Active Grant

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Inventors: Milesky, Lawrence, Chan, Andy
• Granted Patent: US 8,518,237 B2
• Time in Patent Office: Days
• US Class Current: 205/782.5
• CPC Class Codes: G01N 27/404 Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid , e.g. Clark-type oxygen sensors

Abstract

The service life of amperometric electrochemical oxygen sensors is increased by operating the electrodes of such sensors at a polarization voltage suitable for measuring the oxygen content of samples only during calibration or when measuring such samples and thereafter modulating the polarization voltage to a lower voltage such that substantially no electrical current is produced by the electrodes.

Claims

1. A method of extending the service life of amperometric oxygen sensors having planar electrodes covered with a polymer electrolyte and a membrane permeable to oxygen, the improvement comprising operating said sensors at a polarization voltage suitable for measuring the oxygen content of a sample placed adjacent said oxygen permeable membrane only during the periods of time when said electrodes are being calibrated or testing samples, the polarization voltage being modulated to a lower polarization voltage at other times such that substantially no electrical current is produced by said electrodes.

2. The method of claim 1 wherein said operating polarization voltage is about −

0.4 to −

1.2 volts.

3. The method of claim 2 wherein said operating polarization voltage is about −

0.8 volts.

4. The method of claim 1 wherein said polarization voltage is modulated to less than −

0.4 volts except during periods of time wherein said electrodes are being calibrated or testing samples.

5. The method of claim 4 wherein the polarization voltage is modulated to about −

0.1 volts except during periods of time wherein said electrodes are being calibrated or testing samples.

6. The method of claim 1 wherein said polarization voltage is modulated to a lower voltage for about 96% of the sensor'"'"'s service life.

7. A method of measuring the oxygen content of liquid samples comprising:

(a) acquiring a liquid sample;

(b) introducing said liquid sample into an electrochemical sensor, said sensor comprising a working electrode, a counter electrode, and a reference electrode, each of said electrodes disposed on a dielectric substrate and covered by an electrolyte layer and an oxygen-permeable membrane layer disposed between said electrolyte layer and said sample;

(c) polarizing said electrodes at a voltage sufficient to induce an electrical current to flow resulting from reduction of oxygen from said sample;

(d) measuring the electrical current produced in (c) and correlating said current with the oxygen content of said sample;

(e) modulating the polarization voltage of said electrodes to a value such that substantially no electrical current flows between said electrodes;

(f) introducing a wash solution to said sensor to displace said sample;

(g) polarizing said electrodes to the voltage of (c) and introducing at least one calibration solution of known oxygen content to said sensor;

(h) measuring the electrical current produced in (g) and confirming the oxygen content of said at least one calibration solution; and

(i) repeating steps (a)-(h).

8. The method of claim 7 wherein said sample is blood.

9. The method of claim 8 wherein the polarization voltage of (c) is about −

0.8 volts.

10. The method of claim 8 wherein said polarization voltage of (e) is about −

0.1 volts.

11. A method of operating amperometric sensors used to measure a target component in biological fluids comprising operating said sensors at a polarization voltage suitable for measuring the target component in a sample of said biological fluid only during periods of time when the electrodes of said sensors are being calibrated or testing samples, the polarization voltage being modulated to a lower polarization voltage at other times such that substantially no electrical current is produced by said electrodes.

12. The method of claim 11 wherein said target component is oxygen, glucose, or lactate.

13. The method of claim 12 wherein said target component is oxygen in blood.