Ammonia sensor element, heater, and method for making the same

Abstract

A sensor element can comprise a co-fired heater section, a sensing section, and a third insulating layer disposed between the electrode portion and the temperature sensor. The heater section can comprise a heater, a shield, and a temperature sensor, with a first insulating layer disposed between the heater and the shield, and a second insulating layer disposed between the shield and the temperature sensor. The sensing section can comprise an electrode portion and a sensing portion, wherein the sensing portion is disposed on a side of the electrode portion opposite the heater section.

1 - 15 . (canceled)  
   
   
       16 . A method for making a sensor element, comprising: 
 disposing a shield between a heater and a temperature sensor to form a green laminate with a first insulating layer disposed between the heater and the shield, and a second insulating layer disposed between the shield and the temperature sensor;    co-firing the laminate to form a co-fired substrate;    printing a capacitor precursor on the temperature sensor side of the substrate;    firing the capacitor precursor;    patterning the capacitor precursor; and    disposing a sensor portion on a side of the patterned capacitor opposite the substrate.    
   
   
       17 . The method of  claim 16 , further comprising disposing a protective layer between the patterned capacitor and the sensor portion.  
   
   
       18 . The method of  claim 16 , wherein the heater comprises a serpentine comprising first inner legs and outer legs, and wherein the first inner legs have a varying inner leg width.  
   
   
       19 . The method of  claim 18 , wherein the first inner legs have a convexo-convex geometry.  
   
   
       20 . A heater, comprising: 
 a serpentine, wherein the serpentine comprises center inner legs, second inner legs, and outer legs, and wherein the second inner leg has a convexo-convex geometry; and    leads in electrical communication with the outer legs;    wherein, during operation, the heater has a longitudinal temperature gradient of less than or equal to about 5° C.    
   
   
       21 . The heater of  claim 20 , wherein the longitudinal temperature gradient is less than or equal to about 3° C.  
   
   
       22 . The heater of  claim 20 , wherein, during operation, the heater has a latitudinal temperature gradient of less than or equal to about 5° C.  
   
   
       23 . The heater of  claim 22 , wherein the latitudinal temperature gradient is less than or equal to about 3° C.  
   
   
       24 . The heater of  claim 20 , wherein the center inner legs have a center width that varies from about 0.20 mm to about 0.30 mm, prior to co-firing.  
   
   
       25 . The heater of  claim 24 , wherein the center inner legs have a center width that varies from about 0.27 mm to about 0.34 mm, prior to co-firing.  
   
   
       26 . The heater of  claim 20 , wherein the second inner legs have a second width that varies from about 0.30 mm to about 0.50 mm, prior to co-firing.  
   
   
       27 . The heater of  claim 26 , wherein the second width that varies from about 0.35 mm to about 0.45 mm, prior to co-firing.  
   
   
       28 . The heater of  claim 20 , wherein the outer legs have an outer width varies from about 0.20 mm to about 0.35 mm, prior to co-firing.  
   
   
       29 . The heater of  claim 28 , wherein the outer width varies from about 0.25 mm to about 0.32 mm, prior to co-firing.  
   
   
       30 . (canceled)