Microchip Oxygen Sensor for Control of Internal Combustion Engines or Other Combustion Processes

Abstract

A microchip oxygen sensor for sensing exhaust gases from a combustion process, and related methods. The microchip oxygen sensor includes a dielectric substrate and a heater pattern affixed to the substrate. A first electrode is affixed to the substrate and has a first plurality of fingers forming a first comb. A second electrode is affixed to the substrate and has a second plurality of fingers forming a second comb. The second electrode is disposed in spaced relation to the first electrode such that the first and second combs face each other. A semiconducting layer is disposed over the first and second electrodes so as form a physical semiconductor bridge between the first and second electrodes. The semiconducting layer comprises an n-type semiconducting material or a p-type semiconducting material. A porous dielectric protective layer, advantageously containing a catalytic precious metal, may cover the semiconducting layer.

What is claimed is: 
     
         1 . A microchip oxygen sensor for sensing exhaust gases from a combustion process, comprising:
 a dielectric substrate;   a heater pattern affixed to the substrate;   a first electrode affixed to the substrate and having a first plurality of fingers forming a first comb;   a second electrode affixed to the substrate and having a second plurality of fingers forming a second comb, the second electrode disposed in spaced relation to the first electrode such that the first and second combs face each other;   a semiconducting layer disposed over the first and second electrodes so as form a physical semiconductor bridge between the first and second electrodes; wherein the semiconducting layer comprises an n-type semiconducting material.   
     
     
         2 . The microchip oxygen sensor of  claim 1 , further comprising a porous dielectric protective layer covering the semiconducting layer. 
     
     
         3 . The microchip oxygen sensor of  claim 1 , wherein the porous dielectric protective layer contains a catalytic precious metal. 
     
     
         4 . The microchip oxygen sensor of  claim 1 , wherein the substrate is disposed between the first and second electrodes and the heater pattern. 
     
     
         5 . The microchip oxygen sensor of  claim 1 :
 wherein the heater pattern is disposed between the first and second electrodes and the substrate;   further comprising an additional dielectric layer disposed between the heater pattern and first and second electrodes.   
     
     
         6 . The microchip oxygen sensor of  claim 1 , wherein the combustion process is associated with an internal combustion engine; wherein the heater pattern comprises platinum. 
     
     
         7 . A microchip oxygen sensor for sensing exhaust gases from a combustion process, comprising:
 a dielectric substrate;   a heater pattern affixed to the substrate;   a first electrode affixed to the substrate and having a first plurality of fingers forming a first comb;   a second electrode affixed to the substrate and having a second plurality of fingers forming a second comb, the second electrode disposed in spaced relation to the first electrode such that the first and second combs face each other;   a semiconducting layer disposed over the first and second electrodes so as form a physical semiconductor bridge between the first and second electrodes; wherein the semiconducting layer comprises a p-type semiconducting material.   
     
     
         8 . The microchip oxygen sensor of  claim 7 , further comprising a porous dielectric protective layer covering the semiconducting layer. 
     
     
         9 . The microchip oxygen sensor of  claim 7 , wherein the porous dielectric protective layer contains a catalytic precious metal. 
     
     
         10 . The microchip oxygen sensor of  claim 7 , wherein the substrate is disposed between the first and second electrodes and the heater pattern. 
     
     
         11 . The microchip oxygen sensor of  claim 7 :
 wherein the heater pattern is disposed between the first and second electrodes and the substrate;   further comprising an additional dielectric layer disposed between the heater pattern and first and second electrodes.   
     
     
         12 . The microchip oxygen sensor of  claim 7 , wherein the combustion process is associated with an internal combustion engine; wherein the heater pattern comprises platinum. 
     
     
         13 . A method of sensing oxygen in exhaust gases from a combustion process, comprising:
 simultaneously heating a substrate of a microchip oxygen sensor and passing current through a sensing circuit of the microchip oxygen sensor;   measuring a resistance of the oxygen sensing circuit;   wherein the heating the substrate comprising passing a first current through a heater pattern affixed to the substrate;   wherein the sensing circuit comprises:
 a first electrode affixed to the substrate and having a first plurality of fingers forming a first comb; 
 a second electrode affixed to the substrate and having a second plurality of fingers forming a second comb, the second electrode disposed in spaced relation to the first electrode such that the first and second combs face each other; 
 a semiconducting layer disposed over the first and second electrodes so as form a physical semiconductor bridge between the first and second electrodes; 
   wherein passing the current through the sensing circuit comprises passing the current from the first electrode to the second electrode via the semiconducting layer.   
     
     
         14 . The method of  claim 13 , wherein the combustion process occurs in a combustion chamber of an engine, and wherein the microchip oxygen sensor is exposed to exhaust gases from the engine. 
     
     
         15 . The method of  claim 14 , wherein the engine is a multi-cylinder engine. 
     
     
         16 . The method of  claim 14 , wherein the measuring the resistance of the oxygen sensing circuit comprises applying a voltage to the oxygen sensor via a voltage divider circuit contained in a wire harness connector operatively disposed between the microchip oxygen sensor and an electronic control unit of the engine. 
     
     
         17 . The method of  claim 14 , wherein the measuring the resistance of the oxygen sensing circuit comprises applying a voltage to the microchip oxygen sensor via a voltage divider circuit contained in an electronic control unit of the engine. 
     
     
         18 . The method of  claim 13 :
 wherein the semiconducting layer comprises a p-type semiconducting material;   further comprising performing at least one of following in response to detecting rich exhaust gases based on a resistance of the microchip oxygen sensor:
 generating an alarm; 
 disabling the combustion process.