Method and device for determining oxygen in gases

Claim 2

A dry electrolytic cell sensor for determining the oxygen content of a sample gas without the use of a reference gas, the sensor comprising: (a) first electrode means acting as an anode, for the conversion of O -- ions to O 2 gas, said anode being formed from a porous electroconductive material which is not conductive of ions; (b) second electrode means, acting as a cathode, for the conversion of O 2 to O -- ions, said cathode being formed from a nonporous electroconductive material which is not conductive of ions; (c) solid electrolyte means for conducting O -- ions between said anode and said cathode, the electrolyte separating said electrode means and being imperivous to the passage of O 2 , and the electrodes being positioned in electronic contact with the electrolyte; (d) power means for applying a DC voltage across said electrode means; wherein the anode and cathode are positioned on opposite facing sides of the electrolyte, and said electrolyte is from 50 to 500 μm in thickness; wherein the nonporous cathode material is shaped so as to expose said electrolyte directly to a sample gas, an area of sample gas/electrolyte contact being defined by a cathode/electrolyte junction boundary line; wherein the ionic resistance of said electrolyte is not greater than 10 3 ohm/cm of said cathode/electrolyte junction boundary line; wherein the voltage applied by said power means is from 0.2 to 12 volts/cm of said cathode electrolyte junction boundary line; and wherein the electrolyte is heated to a temperature such that the internal resistance of the electrolyte to the flow of O -- ions is about a tenth or less than the resistance associated with O 2 ionization, so that the current flowing across the electrode means of the sensor is controlled by the rate of ionization of said O 2 gas at the cathode area of contact.

Claim 3

A sensor as in claim 1 wherein said electrolyte comprises stabilized ZrO 2 having a thickness of from 100-300 μm.

Claim 4

A dry electrolytic cell sensor for determining the oxygen content of a sample gas without the use of a reference gas, the sensor comprising: (a) first electrode means acting as an anode, for the conversion of O -- ions to O 2 gas, said anode being formed from a porous electroconductive material which is not conductive of ions; (b) second electrode means, acting as a cathode, for the conversion of O 2 to O -- ions, said cathode being formed from a nonporous electroconductive material which is not conductive of ions; (c) solid electrolyte means for conducting O -- ions between said anode and said cathode, the electrolyte separating said electrode means and being impervious to the passage of O 2 , and the electrodes being positioned in electronic contact with the electrolyte; (d) power means for applying a DC voltage across said electrode means; wherein said anode and cathode are arranged on the same side of said electrolyte, separated by a distance of from 20-500 μm; wherein the nonporous cathode material is shaped so as to expose said electrolyte directly to a sample gas, an area of sample gas/electrolyte contact being defined by a cathode/electrolyte junction boundary line; wherein the ionic resistnce of said electrolyte is not greater than 10 3 ohm/cm of said cathode/electrolyte junction boundary line; wherein the voltage applied by said power means is from 0.2 to 12 volts/cm of said cathode electrolyte junction boundary line; and wherein the electrolyte is heated to a temperature such that the internal resistance of the electrolyte to the flow of O -- ions is about a tenth or less than the resistance associated with O 2 ionization, so that the current flowing across the electrode means of the sensor is controlled by the rate of ionization of said O 2 gas at the cathode area of contact.

Claim 5

A dry electrolytic cell sensor for determining the oxygen content of a sample gas without the use of a reference gas, the sensor comprising: (a) first electrode means acting as an anode, for the conversion of O -- ions to O 2 gas, said anode being formed from a porous electroconductive material which is not conductive of ions; (b) second electrode means, acting as a cathode, for the conversion of O 2 to O -- ions, said cathode being formed from a nonporous electroconductive material which is not conductive of ions; (c) solid electrolyte means for conducting O -- ions between said anode and said cathode, the electrolyte separating said electrode means and being impervious to the passage of O 2 , and the electrodes being positioned in electronic contact with the electrolyte; (d) power means for applying a DC voltage across said electrode means; wherein said anode and cathode are arranged on the same side of said electrolyte, separated by a distance of from 20-500 μm; wherein the nonporous cathode material is shaped so as to expose said electrolyte directly to a sample gas, an area of sample gas/electrolyte contact being defined by a cathode/electrolyte junction boundary line; wherein the ionic resistnce of said electrolyte is not greater than 10 3 ohm/cm of said cathode/electrolyte junction boundary line; wherein the voltage applied by said power means is from 0.2 to 12 volts/cm of said cathode electrolyte junction boundary line; and wherein the electrolyte is heated to a temperature such that the internal resistance of the electrolyte to the flow of O -- ions is about a tenth or less than the resistance associated with O 2 ionization, so that the current flowing across the electrode means of the sensor is controlled by the rate of ionization of said O 2 gas at the cathode area of contact.

Claim 6

A sensor as in claim 3 wherein said anode and cathode are separated by a distance of from 50-100 μm.

Claim 7

A sensor as in claim 3 wherein an insulating strip is positioned on the surface of said electrolyte between said anode and said cathode, at a distance from each of between 1 and 10 μm.

Claim 8

A dry electrolytic cell sensor for determining the oxygen content of a sample gas without the use of a reference gas, the sensor comprising: (a) first electrode means acting as an anode, for the conversion of O -- ions O 2 gas, said anode being formed from a porous electroconductive material which is not conductive of ions; (b) second electrode means, acting as a cathode, for the conversion of O 2 to O -- ions, said cathode being formed from a nonporous electroconductive material which is not conductive of ions; (c) solid electrolyte means for conducting O -- ions between said anode and said cathode, the electrolyte separating said electrode means and being impervious to the passive of O 2 , and the electrodes being positioned in electronic contact with the electrolyte; (d) power means for applying a DC voltage across said electrode means; wherein openings which make up the area of sample gas/electrolyte contact at the cathode are of a size about one order of magnitude greater than the size of the pores in the anode; wherein the nonporous cathode material is shaped so as to expose said electrolyte directly to a sample gas, an area of sample gas/electrolyte contact being defined by a cathode/electrolyte junction boundary line; wherein the ionic resistance of said electrolyte is not greater than 10 3 ohm/cm of said cathode/electrolyte junction boundary line; wherein the voltage applied by said power means is from 0.2 to 12 volts/cm of said cathode electrolyte junction boundary line; and wherein the electrolyte is heated to a temperature such that the internal resistance of the electrolyte to the flow of O -- ions is about a tenth or less than the resistance associated with O 2 ionization, so that the current flowing across the electrode means of the sensor is controlled by the rate of ionization of said O 2 gas at the cathode area of contact.

Claim 9

A dry electrolytic cell sensor for determining the oxygen content of a sample gas without the use of a reference gas, the sensor comprising: (a) first electrode means acting as an anode, for the conversion of O -- ions O 2 gas, said anode being formed from a porous electroconductive material which is not conductive of ions; (b) second electrode means, acting as a cathode, for the conversion of O 2 to O -- ions, said cathode being formed from a nonporous electroconductive material which is not conductive of ions; (c) solid electrolyte means for conducting O -- ions between said anode and said cathode, the electrolyte separating said electrode means and being impervious to the passive of O 2 , and the electrodes being positioned in electronic contact with the electrolyte; (d) power means for applying a DC voltage across said electrode means; wherein openings which make up the area of sample gas/electrolyte contact at the cathode are of a size about one order of magnitude greater than the size of the pores in the anode; wherein the nonporous cathode material is shaped so as to expose said electrolyte directly to a sample gas, an area of sample gas/electrolyte contact being defined by a cathode/electrolyte junction boundary line; wherein the ionic resistance of said electrolyte is not greater than 10 3 ohm/cm of said cathode/electrolyte junction boundary line; wherein the voltage applied by said power means is from 0.2 to 12 volts/cm of said cathode electrolyte junction boundary line; and wherein the electrolyte is heated to a temperature such that the internal resistance of the electrolyte to the flow of O -- ions is about a tenth or less than the resistance associated with O 2 ionization, so that the current flowing across the electrode means of the sensor is controlled by the rate of ionization of said O 2 gas at the cathode area of contact.

Claim 10

A sensor as in claim 6 wherein the opening at the cathode are at least 100 μm in diameter and the pores in said anode are 10 μm or less.

Claim 11

A dry electrolyte cell sensor for determining the oxygen content of a sample gas without the use of a reference gas, the sensor comprising: (a) first electrode means acting as an anode, for the conversion of O -- ions to O 2 gas, said anode being formed from a porous electroconductive material which is not conductive of ions; (b) second electrode means, acting as a cathode, for the conversion of O 2 to O -- ions, said cathode being formed from a nonporous electroconductive material which is not conductive of ions; (c) solid electrolyte means for conducting O -- ions between said anode and said cathode, the electrolyte separating said electrode means and being impervious to the passage of O 2 , and the electrodes being positioned in electronic contact with the electrolyte; (d) power means for applying a DC voltage across said electrode means; (e) means for measuring the intensity of an electrical signal representative of the oxygen content of a sample gas comprising a resistance connected in series between the cathode and the voltage source and a voltmeter connected in parallel with said resistance; wherein the nonporous cathode material is shaped so as to expose said electrolyte directly to a sample gas, an area of sample gas/electrolyte contact being defined by a cathode/electrolyte junction boundary line; wherein the ionic resistance of said electrolyte is not greater than 10 3 ohm/cm of said cathode/electrolyte junction boundary line; wherein the voltge applied by said power means is from 0.2 to 12 volts/cm of said cathode electrolyte junction boundary line; and wherein the electrolyte is heated to a temperature such that the internal resistance of the electrolyte to the flow of O -- ions is about a tenth or less than the resistance associated with O 2 ionization, so that the current flowing across the electrode means, of the sensor is controlled by the rate of ionization of said O 2 gas at the cathode area of contact.

Claim 12

A dry electrolyte cell sensor for determining the oxygen content of a sample gas without the use of a reference gas, the sensor comprising: (a) first electrode means acting as an anode, for the conversion of O -- ions to O 2 gas, said anode being formed from a porous electroconductive material which is not conductive of ions; (b) second electrode means, acting as a cathode, for the conversion of O 2 to O -- ions, said cathode being formed from a nonporous electroconductive material which is not conductive of ions; (c) solid electrolyte means for conducting O -- ions between said anode and said cathode, the electrolyte separating said electrode means and being impervious to the passage of O 2 , and the electrodes being positioned in electronic contact with the electrolyte; (d) power means for applying a DC voltage across said electrode means; (e) means for measuring the intensity of an electrical signal representative of the oxygen content of a sample gas comprising a resistance connected in series between the cathode and the voltage source and a voltmeter connected in parallel with said resistance; wherein the nonporous cathode material is shaped so as to expose said electrolyte directly to a sample gas, an area of sample gas/electrolyte contact being defined by a cathode/electrolyte junction boundary line; wherein the ionic resistance of said electrolyte is not greater than 10 3 ohm/cm of said cathode/electrolyte junction boundary line; wherein the voltge applied by said power means is from 0.2 to 12 volts/cm of said cathode electrolyte junction boundary line; and wherein the electrolyte is heated to a temperature such that the internal resistance of the electrolyte to the flow of O -- ions is about a tenth or less than the resistance associated with O 2 ionization, so that the current flowing across the electrode means, of the sensor is controlled by the rate of ionization of said O 2 gas at the cathode area of contact.

Claim 13

A sensor as in claim 8 wherein the cathode is an electrically conductive film coated on an electrolyte supporting member.