Lead Selenide Detector Thermistor Mounting for Capnography
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Solution Overview
Problem
Prior capnography systems face challenges in accurately measuring the temperature of Lead Selenide plate detectors due to thermal gradients and lag times caused by the use of thermistors on fused quartz substrates, which are poor thermal conductors, leading to inaccurate gas detection and measurement.
Innovation Solution
A micro-miniature chip thermistor is mounted directly onto the gold-plated electrode of the Lead Selenide detector without physical contact, allowing for precise temperature measurement and compensation, reducing thermal lag and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermistor is mounted on a fused quartz substrate near the Lead Selenide detector, then the temperature can be sensed, but large thermal gradient and thermal lag time occur due to poor thermal conduction
Solution Approach 1:
The patent uses the gold-plated electrode as an intermediary thermal conduction path between the Lead Selenide detector and the thermistor. The electrode serves as a thermal mediator that efficiently transfers heat from the detector to the thermistor, eliminating the need for thermal conduction through the poor conductor (fused quartz substrate) while maintaining electrical isolation where needed.
Solution Approach 2:
The patent segments the thermal measurement function from the mechanical mounting structure. Instead of mounting the thermistor directly on the substrate near the detector, the thermal measurement path is segmented to go through the electrode material, which has superior thermal conduction properties for this specific function.
2Measurement precision
If a thermistor is placed in proximity to the Lead Selenide film, then temperature sensing is achieved, but physical contact with the film causes measurement interference
Solution Approach 1:
The electrode acts as an intermediary that allows the thermistor to sense the detector temperature without direct contact with the Lead Selenide film. The thermal energy is transferred through the electrode, providing accurate temperature measurement while maintaining physical separation to avoid measurement interference.
Solution Approach 2:
The patent applies local quality by using different materials for different functions: the gold-plated electrode provides both electrical conduction and thermal conduction in the specific location where the thermistor is mounted, while the Lead Selenide film maintains its sensing function without direct thermal contact with the thermistor.
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 arrangement enhances the accuracy of temperature measurement and response time for Lead Selenide plate detectors, enabling better compensation for temperature variations and maintaining CO2 measurement accuracy in capnography systems.
Implementation Method 1
mounting a tiny chip thermistor onto the gold plated electrode of the Lead Selenide detector without coming into contact with the Lead Selenide film... places the temperature sensor at the closest position to the film on a surface that is highly thermally conductive with the film
Implementation Method 2
detecting a sample gas absorption wavelength... Lead Selenide detectors... infrared radiation detector
Data Source
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AI summary
An improved infrared-based gas detector apparatus is described in which a substantial improvement in temperature measurement and tracking accuracy is achieved by combining a temperature sensing element such as a Thermistor to the body of a Lead Selenide (PbSe) plate detector. This allows for as close to possible measurement of the actual Lead Selenide film temperature without coming directly in physical contact with the film surface itself.