Carbon Dioxide Gas Sensors and Method of Manufacturing and Using Same

Abstract

A gas sensor includes a substrate and a pair of interdigitated metal electrodes selected from the group consisting of Pt, Pd, Au, Ir, Ag, Ru, Rh, In, and Os. The electrodes each include an upper surface. A first solid electrolyte resides between the interdigitated electrodes and partially engages the upper surfaces of the electrodes. The first solid electrolyte is selected from the group consisting of NASICON, LISICON, KSICON, and β″-Alumina (beta prime-prime alumina in which when prepared as an electrolyte is complexed with a mobile ion selected from the group consisting of Na + , K + , Li + , Ag + , H + , Pb 2+ , Sr 2+ or Ba 2+ ). A second electrolyte partially engages the upper surfaces of the electrodes and engages the first solid electrolyte in at least one point. The second electrolyte is selected from the group of compounds consisting of Na + , K + , Li + , Ag + , H + , Pb 2+ , Sr 2+ or Ba 2+ ions or combinations thereof.

1 - 23 . (canceled) 
     
     
         24 . A process for fabricating a carbon dioxide sensor including the following steps:
 depositing platinum interdigitated finger electrodes on an Alumina substrate, said electrodes having an upper surface;   depositing solid electrolyte NASICON between said finger electrodes and on a portion of said upper surface of said interdigitated finger electrodes; and,   depositing an auxiliary electrolyte material comprising by a compound selected from the group consisting of Sodium Carbonate, Barium Carbonate, and mixtures thereof on top of the electrodes.   
     
     
         25 . A process for fabricating a carbon dioxide sensor as claimed in  claim 24  wherein said step of depositing interdigitated finger electrodes includes the following steps:
 patterning said alumina substrate with photoresist and an interdigitated finger electrode photomask; 
 developing and removing imidized photoresist; 
 depositing a layer of 50 A of material selected from the group consisting of Platinum Oxide and Titanium on said Alumina substrate; 
 depositing a layer of 4000 A of Platinum on said Alumina substrate; 
 patterning said alumina substrates again to cover said upper surface of said interdigitated finger electrodes and said Alumina substrate with photoresist; and, 
 developing and removing imidized photoresist. 
 
     
     
         26 . A process for fabricating a carbon dioxide sensor as claimed in  claim 25  wherein said step of depositing solid electrolyte NASICON between said finger electrodes and on a portion of said upper surface of said interdigitated finger electrodes includes the following steps:
 depositing solid NASICON over said Alumina substrate, said interdigitated finger electrodes and the unimidized photoresist; 
 removing said unimidized photoresist with acetone to remove NASICON from said upper surface of said interdigitated finger electrodes exposing said upper surfaces of said interdigitated electrodes; and, 
 heating said substrate in an oven at a temperature range of 850° C. 
 
     
     
         27 . A process for fabricating carbon dioxide sensor as claimed in  claim 26  wherein the step of the depositing an auxiliary electrolyte material comprising sodium carbonate and barium carbonate on top of the electrodes includes the steps of:
 sputtering solid auxiliary electrolyte layer between said interdigitated finger electrodes and on said NASICON using a shadow mask; and, 
 heating said substrates in an oven at approximately 686° C. for 10 minutes and at approximately 710° C. for 20 minutes. 
 
     
     
         28 . A process for fabricating a carbon dioxide sensor as claimed in  claim 26  wherein said step of depositing solid NASICON over said Alumina substrate, said interdigitated finger electrodes and the unimidized photoresist said NASICON solid electrolyte is deposited by e-beam evaporation. 
     
     
         29 . A process for fabricating a carbon dioxide sensor as claimed in  claim 26  wherein said step of depositing solid NASICON over said Alumina substrate, said interdigitated finger electrodes and the unimidized photoresist NASICON solid electrolyte is deposited by sputtering. 
     
     
         30 . A process for fabricating a carbon dioxide sensor as claimed in  claim 24  wherein said step of depositing solid electrolyte NASICON between said finger electrodes and on a portion of said upper surface of said interdigitated finger electrodes is performed by e-beam evaporation. 
     
     
         31 . A process for fabricating a carbon dioxide sensor as claimed in  claim 24  wherein said step of depositing solid electrolyte NASICON between said finger electrodes and on a portion of said upper surface of said interdigitated finger electrodes is performed by sputtering. 
     
     
         32 . (canceled) 
     
     
         33 . (canceled) 
     
     
         34 . A process for fabricating a carbon dioxide sensor including the following steps:
 applying photoresist on Alumina substrate;   applying, selectively, imidizing ultraviolet light using an interdigitated finger electrode photomask, developing, and removing the immidized photoresist;   sputtering a 50 A layer of Titanium to the Alumina substrate and unimidized photoresist;   sputtering a 4000 A layer of Platinum to the Titanium;   lifting off with solvent the unimidized photoresist, titanium, and platinum thereover forming electrodes on the alumina substrate;   applying photoresist to the Alumina substrate and electrodes;   applying, selectively, imidizing ultraviolet, light using an interdigitated finger electrode photomask, developing, and removing the imidized photoresist;   depositing NASICON over the Alumina substrate, the electrodes, and the unimidized photoresist;   lifting off with solvent the unimidized photoresist and NASICON thereover; and   depositing secondary electrolyte using a shadow mask over the NASICON and the electrodes.   
     
     
         35 . A process for fabricating a carbon dioxide sensor as claimed in  claim 34  wherein said step of depositing NASICON over the Alumina substrate, the electrodes, and the unimidized photoresist, is performed using electron beam evaporation. 
     
     
         36 . A process for fabricating a carbon dioxide sensor as claimed in  claim 34  wherein said step of depositing NASICON over the Alumina substrate, the electrodes, and the unimidized photoresist is performed using sputter deposition. 
     
     
         37 . A process for fabricating a carbon dioxide sensor gas sensor as set forth in  claim 24  using microfabrication processing with fault tolerant processing and maximization of three boundary contacts.