Electrochemical gas sensor

Abstract

A gas detector includes an electrochemical gas sensor. The sensor includes a plurality of electrodes. At least one of the electrodes is formed of a catalyst/binder slurry which is halftone printed onto a substrate. The composite printed element and substrate are sintered to form the electrode.

1 - 17 . (canceled) 
     
     
         18 . An apparatus comprising:
 a housing; and   an electrochemical gas sensor carried by the housing, wherein the electrochemical gas sensor comprises:   a plurality of electrodes comprising a printed portion, wherein the printed portion comprises a slurry halftone printed on a substrate, the slurry comprising a catalyst, the catalyst comprising at least one of: platinum, platinum black, graphite, carbon, carbon black, and a noble metal; and   an electrolyte in contact with the at least one of the plurality of electrodes.   
     
     
         19 . The apparatus of  claim 18 , wherein the slurry further comprises a binder, and wherein the slurry is sintered to the substrate to form the at least one of the plurality of electrodes. 
     
     
         20 . The apparatus of  claim 19 , wherein the binder comprises at least one of a perfluorinated ion electrolyte solution or a copolymer of tetrafluoroethylene and a sulfonic acid. 
     
     
         21 . The apparatus of  claim 19 , wherein the binder, at least in part, provides an interface between the catalyst in the slurry, a gas in contact with the substrate in the electrochemical gas sensor, and the electrolyte. 
     
     
         22 . The apparatus of  claim 19 , wherein the binder comprises at least one of a perfluorinated ion electrolyte solution or a copolymer of tetrafluoroethylene and a sulfonic acid. 
     
     
         23 . The apparatus of  claim 18 , wherein the substrate is a porous membrane. 
     
     
         24 . The apparatus of  claim 18 , wherein a composition of the slurry comprises 75% by weight Platinum black, 10% by weight graphite, and 15% by weight a perfluorinated ion electrolyte solution. 
     
     
         25 . The apparatus of  claim 18 , wherein a response time for the electrochemical gas sensor comprising the composition is less than 30 seconds for 20.9% oxygen in air. 
     
     
         26 . The apparatus of  claim 18 , further comprising a second housing which carries the housing and the electrochemical gas sensor, and which includes control circuits coupled to the electrodes to establish an ambient gas concentration. 
     
     
         27 . The apparatus of  claim 26 , further comprising an audible or visual output device, carried by the second housing, coupled to the control circuits to provide a gas concentration indicator. 
     
     
         28 . A gas detector comprising:
 an electrochemical gas sensor, wherein the electrochemical gas sensor comprises:   a plurality of electrodes comprising a printed portion, wherein the printed portion comprises a slurry halftone printed on a substrate, the slurry comprising a catalyst and a binder, wherein the binder comprises at least one of: tetrafluoroethylene, perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid, a perfluorinated ion electrolyte, polytetrafluoroethylene, sulfonic acid, and perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid, wherein a ratio of the catalyst to the binder is between 4:1 and 7.5:1; and   electrolyte in contact with the at least one of the plurality of electrodes.   
     
     
         29 . The gas detector of  claim 28 , wherein the slurry is sintered to the substrate to form the at least one of the plurality of electrodes. 
     
     
         30 . The gas detector of  claim 29 , wherein the catalyst comprises at least one of:
 platinum, platinum black, graphite, platinum, carbon, carbon black, and a noble metal.   
     
     
         31 . The gas detector of  claim 29 , wherein the binder, at least in part, provides an interface between the catalyst in the slurry, a gas in contact with the substrate in the electrochemical gas sensor, and the electrolyte. 
     
     
         32 . The gas detector of  claim 29 , wherein the binder comprises at least one of a perfluorinated ion electrolyte solution or a copolymer of tetrafluoroethylene and a sulfonic acid. 
     
     
         33 . The gas detector of  claim 28 , wherein the substrate is a porous membrane. 
     
     
         34 . The gas detector of  claim 28 , wherein a composition of the slurry comprises 75% weight Platinum black, 10% weight graphite and 15% weight perfluorinated ion electrolyte solution. 
     
     
         35 . The gas detector of  claim 28 , wherein a response time for the electrochemical gas sensor comprising the composition is less than 30 seconds for 20.9% oxygen in air 
     
     
         36 . A method comprising:
 halftone printing a slurry onto a porous substrate to form an electrode, said slurry being heated to greater than a predetermined temperature prior to said halftone printing, said slurry comprising a catalyst, a binder, and an electrolyte, wherein a ratio of the catalyst to the binder is between 4:1 and 7.5:1;   heating the electrode to above a sintering temperature of said slurry in order to sinter said slurry; and   after heating said electrode to sinter said slurry, forming an electrochemical gas sensor comprising said electrode as one of a working electrode, a sensing electrode, a reference electrode, or a counter electrode,   wherein a response time for the electrochemical gas sensor comprising said electrode is less than 30 seconds for 20.9% oxygen in air.   
     
     
         37 . The method of  claim 36 , wherein the binder comprises at least one of:
 tetrafluoroethylene, perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid, a perfluorinated ion electrolyte, polytetrafluoroethylene, sulfonic acid, and perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid, wherein at least one of: platinum, platinum black, graphite, carbon, carbon black, and a noble metal.