Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
121 words
An oxygen sensor which comprises an electrochemical cell including (a) a gas diffusion electrode as the cathode, or working electrode, (b) a counter electrode as anode, (c) a reference electrode, and (d) a mass of salt which when molten constitutes an electrolyte in contact with said electrodes, the sensor also comprising (e) means for maintaining the working electrode (a) at a constant potential with reference to the reference electrode, and (f) means for determining the current flowing in the electrochemical cell due to reduction at the oxygen diffusion electrode (a) of oxygen present in the environment of the oxygen sensor, wherein the counter electrode (b) is a noble metal and the reference electrode (c) is a noble metal/noble metal oxide electrode.
Claim 2
Dependent Claim
121 words
An oxygen sensor which comprises an electrochemical cell including (a) a gas diffusion electrode as the cathode, or working electrode, (b) a counter electrode as anode, (c) a reference electrode, and (d) a mass of salt which when molten constitutes an electrolyte in contact with said electrodes, the sensor also comprising (e) means for maintaining the working electrode (a) at a constant potential with reference to the reference electrode, and (f) means for determining the current flowing in the electrochemical cell due to reduction at the oxygen diffusion electrode (a) of oxygen present in the environment of the oxygen sensor, wherein the counter electrode (b) is a noble metal and the reference electrode (c) is a noble metal/noble metal oxide electrode.
Claim 3
Dependent Claim
25 words
An oxygen sensor as claimed in claim 1 and wherein the noble metal of the counter eletrode (b) and the reference electrode (c) is platinum.
Claim 4
Dependent Claim
21 words
An oxygen sensor as claimed in claim 2 and wherein the gas diffusion electrode (a) is a silver metallised polytetrafluoroethylene membrane.
Claim 5
Dependent Claim
53 words
An oxygen sensor as claimed in claim 3 and wherein the gas diffusion electrode (a) is a film of polytetrafluoroethylene 6 μm thick, one side of which has been covered by a coating of evaporated or sputtered gold followed by one of silver to ensure good adhesion between the silver and the polytetrafluoroethylene.
Claim 6
Dependent Claim
68 words
An oxygen sensor as claimed in claim 1 and wherein the reference electrode (c) is a platinum/platinum oxide electrode prepared by the steps of: (1) boiling a platinum wire in aqua regia to thoroughly clean it, and (2) immersing the cleaned wire in molten potassium nitrate at a temperature in excess of 400° C. for at least one hour while bubbles of gas evolve from around the wire.
Claim 7
Dependent Claim
23 words
An oxygen sensor as claimed in claim 1 and wherein the salt electrolyte (d) is an eutectic of sodium, potassium, and lithium nitrates.
Claim 8
Dependent Claim
43 words
An oxygen sensor as claimed in claim 1 and which includes a heating means and a thermostatic means arranged to cooperate so that the sensor may operate in an environment having an ambient temperture below the melting point of the salt electrolyte (d).