ELECTROCHEMICAL SENSOR WITH ZERO CALIBRATION FEATURE AND METHOD OF CALIBRATING

• US 20080251379A1
• Filed: 04/12/2007
• Published: 10/16/2008
• Est. Priority Date: 04/12/2007
• Status: Active Grant

• Current Assignee: MOCON, Inc. (Ametek Incorporated)
• Original Assignee: MOCON, Inc. (Ametek Incorporated)
• Inventors: Mayer, Daniel W.
• Granted Patent: US 9,128,045 B2
• Time in Patent Office: Days
• US Class Current: 204/406
• 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
• CPC Class Codes: G01N 27/4163 checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence
• CPC Class Codes: G01N 33/0006 Calibrating gas analysers

Abstract

An easily calibrated analytical instrument for sensing a target analyte. The instrument includes an electrochemical sensor and a switch. The electrochemical sensor includes a sensing electrode and a counter electrode. The switch is a normally open switch effective for creating a short circuit between the sensing and counter electrodes when closed. A zero calibration reading can be taken when the switch is closed.

Claims

1. An analytical instrument, comprising:

(a) an electrochemical sensor for sensing a target analyte, the electrochemical sensor comprising a sensing electrode and a counter electrode, and

(b) a normally open switch effective for creating a short circuit between the sensing and counter electrodes when closed, whereby a zero calibration reading can be taken when the switch is closed.

2. The instrument of claim 1 wherein the electrodes generate an electrical current proportional to the amount of target analyte to which the electrodes are exposed, and the instrument further includes a signaling module in electrical communication with the electrochemical sensor for receiving electrical current generated by the electrodes and producing an electrical output signal proportional to the electrical current.

3. The instrument of claim 2 further comprising a microprocessor containing a zero calibration value in memory and in electrical communication with the signaling module and the switch, wherein (i) when the switch is open the microprocessor receives the electrical output signal, zero calibrates the electrical output signal employing the zero calibration value in memory, and correlates the zero calibrated electrical output signal to a numerical value indicating the concentration of analyte in the test volume, and (ii) when the switch is closed the microprocessor receives the electrical output signal and replaces the zero calibration value in memory with the value of the received electrical output signal.

4. The analytical instrument of claim 1 wherein the target analyte is oxygen.

5. The analytical instrument of claim 2 wherein the signaling module includes a load resistor effective for converting the electrical current generated by the electrodes to a voltage.

6. An analytical instrument, comprising:

(a) an electrochemical sensor for sensing a target analyte in a test volume, the electrochemical sensor comprising a sensing electrode and a counter electrode, both in contact with an electrolyte and a test volume, for generating an electrical current proportional to the concentration of target analyte present in the test volume,

(b) a signaling module in electrical communication with the electrochemical sensor for receiving electrical current generated by the electrodes and producing an electrical output signal proportional to the electrical current,

(c) a normally open switch for providing a short circuit between the sensing and counter electrodes when closed, whereby electrical current generated by the electrodes bypasses the signaling module when the switch is closed, and

(d) a microprocessor containing a zero calibration value in memory, the microprocessor in electrical communication with the signaling module and the switch wherein;

(1) when the switch is open the microprocessor receives the electrical output signal and any background signal, and either;

(A) zero calibrates the electrical output signal employing the zero calibration value in memory in an effort to cancel the background signal, and correlates the zero calibrated electrical output signal to a numerical value indicating the concentration of analyte in the test volume, or

(B) correlates the electrical output signal to a numerical value indicating the concentration of analyte in the test volume, and zero calibrates the numerical value of concentration employing the zero calibration value in memory, and

(2) when the switch is closed the microprocessor receives any background signal and either (A) replaces the zero calibration value in memory with the value of the received background signal, or (B) correlates the received background signal to a numerical value indicating a concentration of analyte and replaces the zero calibration value in memory with the numerical value of concentration.

7. The analytical instrument of claim 6 wherein the target analyte is oxygen.

8. The analytical instrument of claim 6 wherein the signaling module includes a load resistor effective for converting the electrical current generated by the electrodes to a voltage.

9. A method of zero calibrating an electrochemical sensor, comprising the steps of:

(a) obtaining an electrochemical sensor having a sensing electrode and a counter electrode,

(b) short circuiting the electrodes, and

(c) taking a zero calibration reading with the electrodes short circuited.

10. The method of claim 9 wherein the electrochemical sensor is an oxygen sensor.

11. The method of claim 9 wherein the electrodes are short circuited by activation of a switch.

12. A method of zero calibrating an electrochemical sensor, comprising the steps of:

(a) obtaining an electrochemical sensor having (i) a sensing electrode and a counter electrode, both in contact with an electrolyte and a test volume, for generating an electrical current proportional to the concentration of target analyte present in the test volume, (ii) a signaling module in electrical communication with the electrodes for receiving electrical current generated by the electrodes and producing an electrical output signal proportional to the electrical current, and (iii) a microprocessor for receiving and processing the electrical output signal,

(b) short circuiting the electrodes, and

(c) recording any background signal received by the microprocessor with the electrodes short circuited as the zero calibration value.

13. The method of claim 12 wherein the background signal has a value and this value is recorded as the zero calibration value.

14. The method of claim 12 wherein the background signal is correlated to a numerical value indicating a concentration of analyte and the correlated numerical value of concentration is recorded as the zero calibration value.

15. The method of claim 12 wherein the electrochemical sensor is an oxygen sensor.

16. The method of claim 12 wherein the signaling module includes a load resistor effective for converting the electrical current generated by the electrodes to a voltage.

17. The method of claim 12 wherein the electrodes are short circuited by activation of a switch.