Electro-chemical sensors for trace gases

Claim 1

AN ELECTRO-CHEMICAL SENSOR SYSTEM COMPRISING: A FIRST ELECTRO-CHEMICAL GAS SENSING CELL HAVING A DOPED CHALCOGENIDE GLASS CONSISTING OF ABOUT 60 MOLE PERCENT SELENIUM, 28 MOLE PERCENT GERMANIUM, 12 MOLE PERCENT ANTIMONY AND CONTAINING AS A DOPANT ABOUT 1% TO ABOUT 4% BY WEIGHT OF IRON, AN ELECTRICAL CONDUCTOR ELECTRICALLY CONNECTED TO SAID GLASS ON ONE SIDE, AN ELECTROLYTE CONTACTING THE OTHER SIDE OF SAID GLASS, AN AT LEAST ONE ELECTRODE CONTACTING SAID ELECTROLYTE, A SECOND ELECTRO-CHEMICAL GAS SENSING CELL HAVING A DOPED CHALCOGENIDE GLASS CONSISTING OF 15% MN-AS2S3, AN ELECTRICAL CONDUCTOR ELECTRICALLY CONNECTED TO SAID GLASS ON ONE SIDE, AN ELECTROLYTE CONTACTING THE OTHER SIDE OF SAID GLASS, AND AT LEAST ONE ELECTRDE CONTACTING SAID ELECTROLYTE, MEANS FOR INTRODUCING A GAS SAMPLE INTO SAID FIRST AND SECOND CELLS SO AS TO IMPINGE UPON THE RESPECTIVE GLASSES THEREOF, SAID FIRST CELL BEING RESPONSIVE TO THE PRESENCE OF GASEOUS NO2 AND MORE STRONGLY OXIDIZING GASES TO PRODUCE AN ELECTRICAL SIGNAL BETWEEN THE FIRST-MENTIONED ELECTRICAL CONDUCTOR AND ONE OF THE FIRST-MENTIONED AT LEAST ONE ELECTRODE AND SAID SECOND CELL HAVING RESPONSIVE TO THE PRESENCE OF GASES MORE STRONGLY OXIDIZING THAN NO2 TO PRODUCE AN ELECTRICAL SIGNAL BETWEEN THE SECOND-MENTIONED ELECTRICAL CONDUCTOR AND ONE OF THE SECOND-MENTIONED AT LEAST ONE ELECTRODE, AND MEANS FOR MEASURING THE ELECTRICAL SIGNALS DEVELOPED BY SAID FIRST AND SECOND CELLS IN RESPONSE TO THE INTRODUCTION OF THE GAS SAMPLE THEREINTO SO AS TO INDICATE WHETHER NO2 AND MORE STRONGLY OXIDIZING GASES ARE PRESENT IN THE GAS SAMPLE.