Microchip Oxygen Sensor with Intermeshing Electrodes for Small Engine Control
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Solution Overview
Problem
Current oxygen sensors for internal combustion engines, particularly those used in small engines, are cost-prohibitive and unsuitable for small engine markets due to their expensive nature and limited size reduction potential, making them ineffective for emission control and safety applications in motorcycles, ATVs, and hybrid engines.
Innovation Solution
A sub-miniature microchip oxygen sensor is developed using a thin ceramic substrate with multiple thin heater patterns and intermeshing comb-shaped electrodes, a semiconducting layer, and a porous protective dielectric layer, allowing for reduced size and cost while maintaining functional characteristics such as resistance changes and chemical stability, enabling individual cylinder control and safety features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional oxygen sensors are used for emission control in small engines, then measurement precision is improved, but cost increases making them prohibitive for small engine markets
Solution Approach 1:
The patent employs a resistive sensor design using titania-based semiconductor material that can be manufactured at lower cost compared to conventional zirconia sensors. The sensor utilizes a simpler structure without requiring heated elements or complex voltage generation mechanisms, enabling cost-effective production for small engine applications while maintaining functional capability for emission control
Solution Approach 2:
The patent transitions from voltaic sensor technology (voltage-based measurement) to resistive sensor technology (resistance-based measurement). This parameter change in the sensing mechanism allows for simplified construction and reduced manufacturing cost while still providing the necessary measurement precision for air-fuel ratio control in small engines
2Measurement precision
If conventional oxygen sensors are used in small engines, then measurement precision is improved, but device size remains large limiting size reduction potential
Solution Approach 1:
The resistive sensor design inherently allows for miniaturization compared to conventional sensors. The titania-based semiconductor layer can be deposited on small substrates, and the sensor structure does not require large heated elements or complex internal geometry, enabling significant size reduction for compact small engine installations
Solution Approach 2:
The patent utilizes thin film deposition techniques to create the titania-based semiconductor sensing layer on a substrate. This thin-film approach enables the sensor to be made extremely compact while maintaining the necessary sensing surface area and electrical properties for accurate measurement
3Measurement precision
If heated oxygen sensors are used to improve functionality, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The resistive sensor operates at ambient temperature without requiring heated elements. The titania-based semiconductor material exhibits resistance changes in response to oxygen concentration variations directly at operating temperature, eliminating the need for continuous heating and thus reducing power consumption significantly compared to heated oxygen sensors
Solution Approach 2:
The patent replaces the thermal heating mechanism with an electrical resistance measurement mechanism. Instead of using heat to activate the sensor and maintain its functionality, the sensor directly measures oxygen concentration through resistance changes at ambient temperature, substituting a thermal system with an electrical measurement system that consumes less power
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The microchip oxygen sensor provides cost-effective and compact solutions for small engine markets, enabling precise air-fuel ratio control and safety features, such as preventing noxious gas production, with reduced power requirements and interchangeability with conventional zirconia sensors.
Implementation Method 1
A heater pattern is affixed to the substrate
Implementation Method 2
A second type of sensor known as a resistive sensor relies on a step-wise change in resistance of a semiconductor material
Data Source
AI summary
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.