Electrochemical multigas sensor
First Claim
1. An electrochemical measuring cell for the simultaneous detection of different gas components in a gas sample, the measuring head comprising:
- a diffusion barrier;
a plurality of measuring electrodes behind said diffusion barrier;
a common reference electrode comprised of a sintered mixture of metal and its metal oxide;
a common counterelectrode;
an acid electrolyte, said common reference electrode and said common counterelectrode being in said acid electrolyte;
a potentiostatic evaluating circuit maintaining electric potentials of said measuring electrodes at a predetermined value relative to said reference electrode independently from one another for the combined detection of CO and O2, wherein one of said measuring electrodes is a CO-measuring electrode with an electric potential relative to said reference electrode set at a value of about 0 mV to 300 mV; and
one of said measuring electrodes is an O2 -measuring electrode with an electric potential set at a value between -300 and -800 mV.
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Accused Products
Abstract
An electrochemical measuring cell for the simultaneous detection of different gas components in a gas sample, with a plurality of measuring electrodes (4, 5, 6) behind a diffusion barrier (7), with a common reference electrode (8) and counterelectrode (9) in an acid electrolyte, and with a potentiostatic evaluating circuit. Improvements in terms of service life for a sensor for the simultaneous detection of oxygen and carbon monoxide is provided with a reference electrode formed of a sintered mixture of metal and its metal oxide, preferably from the platinum group, the iridium group or gold and the potential of the CO-measuring electrode (5) relative to the reference electrode (8) is set at about 0 to 300 mV, and that of the O2 -measuring electrode (4) is set at a value between -300 and -800 mV.
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Citations
13 Claims
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1. An electrochemical measuring cell for the simultaneous detection of different gas components in a gas sample, the measuring head comprising:
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a diffusion barrier; a plurality of measuring electrodes behind said diffusion barrier; a common reference electrode comprised of a sintered mixture of metal and its metal oxide; a common counterelectrode; an acid electrolyte, said common reference electrode and said common counterelectrode being in said acid electrolyte; a potentiostatic evaluating circuit maintaining electric potentials of said measuring electrodes at a predetermined value relative to said reference electrode independently from one another for the combined detection of CO and O2, wherein one of said measuring electrodes is a CO-measuring electrode with an electric potential relative to said reference electrode set at a value of about 0 mV to 300 mV; and
one of said measuring electrodes is an O2 -measuring electrode with an electric potential set at a value between -300 and -800 mV.
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2. The electrochemical measuring cell in accordance with claim 1, wherein said sintered mixture of metal and its metal oxide is from the platinum group, the iridium group or is gold.
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3. The electrochemical measuring cell in accordance with claim 1, wherein one of said measuring electrodes is a H2 S-measuring electrode formed of gold, iridium or carbon/graphite, with an electrical potential relative to said reference electrode set at a value of about 0 to 200 mV;
- and further comprising cross sensitivity means for compensating for cross sensitivity.
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4. The electrochemical measuring cell in accordance with claim 3, further comprising a gas-selective filter provided before said CO-measuring electrode as a means of compensating H2 S at said CO-measuring electrode.
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5. An electrochemical measuring cell for the simultaneous detection of different gas components in a gas sample, the measuring head comprising:
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a diffusion barrier; a plurality of measuring electrodes behind said diffusion barrier; a common reference electrode comprised of a sintered mixture of metal and its metal oxide; a common counterelectrode; an acid electrolyte, said common reference electrode and said common counterelectrode being in said acid electrolyte; a potentiostatic evaluating circuit maintaining electric potentials of said measuring electrodes at a predetermined value relative to said reference electrode independently from one another for the combined detection of H2 S and O2, one of said measuring electrodes being a H2 S-measuring electrode with an electric potential set relative to the said reference electrode at a value of about 0 to 200 mV, and another of said measuring electrodes is an O2 -measuring electrode with an electric potential set at a between -300 mV and -800 mV, said H2 S-measuring electrode being formed of gold, iridium or carbon/graphite.
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6. The electrochemical measuring cell in accordance with claim 5, further comprising a gas-selective filter provided before said CO-measuring electrode as a means of compensating H2 S at said CO-measuring electrode.
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7. Electrochemical measuring cell in accordance with claim 5, wherein said cross sensitivity means is an electrolyte barrier within said diffusion barrier.
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8. The electrochemical measuring cell in accordance with claim 5, wherein said sintered mixture of metal and its metal oxide is from the platinum group, the iridium group or is gold.
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9. A method for simultaneous detection of gases in a sample, the method comprising;
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providing a housing; providing an acid electrolyte in said housing; providing a diffusion barrier in said housing; providing a CO measuring electrode in said electrolyte and against said diffusion barrier; providing a O2 measuring electrode in said electrolyte and against said diffusion barrier; providing a common reference electrode in said electrolyte and formed of a sintered mixture of metal and metal oxide; providing a common counterelectrode in said electrolyte; setting an electric potential of said CO measuring electrode relative to said reference electrode to a value in a range of approximately 0 mV to 300 mV; setting an electric potential of said O2 measuring electrode relative to said reference electrode to a value in a range of approximately -300 mV to -800 mV wherein the detection of CO and O2 in the sample are obtained.
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10. A method in accordance with claim 9, wherein:
said metal of said reference electrode is formed from one of a platinum group, an iridium group and a gold group.
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11. A method in accordance with claim 9, further comprising:
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providing a H2 S measuring electrode in said electrolyte and formed of one of gold, iridium and carbon graphite; setting an electric potential of said H2 S measuring electrode relative to said reference electrode to a value in a range of approximately 0 mV to 200 mV; providing means for compensating H2 S at said CO measuring electrode wherein detection of H2 S in the sample is obtained.
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12. A method for simultaneous detection of gases in a sample, the method comprising;
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providing a housing; providing an acid electrolyte in said housing; providing a diffusion barrier in said housing; providing a H2 S measuring electrode in said electrolyte and against said diffusion barrier, said H2 S measuring electrode being formed of one of gold, iridium and carbon/graphite; providing a O2 measuring electrode in said electrolyte; providing a common reference electrode in said electrolyte formed of a sintered mixture of metal and metal oxide; providing a common counterelectrode in said electrolyte; setting an electric potential of said H2 S measuring electrode relative to said reference electrode to a value in a range of approximately 0 mV to 200 mV; setting an electric potential of said O2 measuring electrode relative to said reference electrode to a value in a range of approximately -300 mV to -800 mV wherein the detection of H2 S and O2 in the sample are obtained.
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13. A method in accordance with claim 12, wherein:
said metal of said reference electrode is formed from one of a platinum group, an iridium group and a gold group.
Specification