Co-fired Gas Sensor RTD Integration
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Solution Overview
Problem
Existing gas sensors with integral resistance temperature detectors (RTDs) face challenges in accurately controlling temperature within the optimal operational range, leading to unreliable signals and increased assembly costs due to extra assembly steps and potential cracking from temperature gradients.
Innovation Solution
A gas sensor design where the RTD is co-fired with the heating and sensing sections, ensuring a single integral component with a coefficient of thermal expansion matching the ionically conductive and electrically insulating substrates, reducing assembly complexity and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RTD is glass bonded to an already sintered sensor, then temperature sensing capability is added, but assembly cost and assembly time increase due to extra assembly steps
Solution Approach 1:
The RTD is co-fired with the sensor components during the same sintering process, merging the temperature sensing function into the existing sensor structure. This eliminates the need for separate glass bonding assembly steps, reducing both assembly complexity and cost while maintaining temperature sensing capability.
Solution Approach 2:
The RTD is prepared and positioned on the green body (unsintered state) before the final sintering process. This preliminary placement allows the RTD to be integrated into the sensor structure during the sintering cycle itself, rather than requiring post-assembly bonding operations.
2Reliability
If the RTD is glass bonded to an already sintered sensor, then temperature sensing is enabled, but the glass bond is prone to cracking when exposed to temperature gradients or extreme temperatures
Solution Approach 1:
The RTD and sensor components are co-fired as a single integrated unit, eliminating the glass bond interface that is susceptible to cracking. The co-firing process creates a monolithic structure where the RTD is mechanically and thermally integrated with the sensor, removing the weak bonding interface.
Solution Approach 2:
The sintering temperature and atmospheric conditions are optimized to ensure the RTD material and sensor material are compatible during co-firing. By controlling the firing parameters, the RTD forms a strong, crack-resistant bond with the sensor substrate that can withstand temperature gradients and extreme temperatures.
3Ease of manufacture
If the RTD is bonded separately outward of the heater, then assembly is simplified, but readings of the RTD do not accurately reflect the actual temperatures experienced by the sensing element
Solution Approach 1:
The RTD is co-fired in close proximity to the sensing element and heater assembly, merging the temperature measurement function with the thermal environment of the sensing zone. This spatial integration ensures the RTD measures the actual temperature experienced by the sensing element while maintaining a unified manufacturing process.
Solution Approach 2:
The RTD is positioned at a specific location within the sensor structure where it can accurately sense the local temperature of the sensing element. The co-firing process allows precise positioning of the RTD in the green body, ensuring optimal thermal coupling with the sensing zone while maintaining manufacturing simplicity.
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
This design improves temperature control accuracy, reduces assembly costs, and enhances durability by eliminating the need for additional assembly steps and minimizing the risk of cracking, while allowing RTDs to be placed optimally for precise temperature sensing.
Implementation Method 1
a resistance temperature detector attached to the second green insulating substrate... based on a current or voltage signal from the RTD indicative of a temperature of the heater
Implementation Method 2
The heating component includes a heating element... During operation of the sensor, the heating component is energized to raise the temperature of the sensing component
Implementation Method 3
which are stacked together and then sintered to bond the two components
Data Source
AI summary
A sensor for detecting a gas is provided. The gas sensor may have a sensing section, a heating section, and a resistance temperature detector. The resistance temperature detector may be co-fired to be integral with at least one of the sensing section and the heating section.