Gas Sensor Humidity Control Circuit
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Solution Overview
Problem
Existing gas constituent measuring apparatuses face challenges in accurately measuring concentrations of gases in exhaled air and skin gas due to humidity dependence of semiconductor gas sensors, requiring complex and costly gas chromatography or inefficient humidity control.
Innovation Solution
A gas constituent measuring apparatus with a cell, a gas sensor, a humidity regulator, and an integrated circuit that controls humidity within a predetermined range, allowing for accurate concentration determination by using a constant water vapor reference, thereby minimizing humidity dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas chromatography is used to measure gas concentrations, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for complex gas chromatography systems by using a simplified semiconductor gas sensor-based measurement approach. The core function of gas concentration measurement is achieved through a much simpler device architecture that uses multiple gas sensors in parallel rather than complex chromatographic separation.
Solution Approach 2:
The patent replaces expensive, complex gas chromatography equipment with inexpensive semiconductor gas sensors that can be mass-produced and replaced easily. The measurement system uses multiple low-cost sensors instead of one expensive chromatography instrument, making the overall system more affordable and maintainable.
2Device complexity
If semiconductor gas sensors are used, then device complexity is reduced, but measurement precision deteriorates due to humidity dependence
Solution Approach 1:
The patent applies different functional characteristics to different parts of the sensor array. Specifically, it uses multiple gas sensors with different humidity sensitivities or response characteristics, and processes their signals differently to compensate for humidity effects. Each sensor contributes specific local information that helps cancel out the harmful humidity dependence when combined through the evaluation circuit.
Solution Approach 2:
The patent implements feedback mechanisms where the evaluation circuit continuously monitors and adjusts measurements based on humidity sensor readings. By using the humidity information to correct the gas sensor readings in real-time, the system compensates for humidity-induced measurement drift and maintains high precision despite the inherent humidity sensitivity of semiconductor sensors.
3Measurement precision
If complex humidity control systems are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables the measurement system to self-compensate for humidity effects without requiring external humidity control equipment. The system uses its own internal humidity sensors and evaluation circuitry to automatically correct measurement drift caused by humidity changes, making the system self-sufficient and eliminating the need for separate climate control subsystems.
Solution Approach 2:
The patent introduces humidity sensors as intermediary elements that indirectly measure humidity's effect on the gas sensors. Rather than directly controlling humidity, the system uses humidity sensors to detect moisture levels and then uses this information as a mediator to correct the gas concentration measurements, avoiding the need for complex active humidity control mechanisms.
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
Enables high-accuracy, simple, and cost-effective measurement of gas concentrations without relying on gas chromatography, improving operational efficiency and reducing the need for complex humidity control systems.
Implementation Method 1
a gas sensor that responds to one or more types of constituent gases present in the cell
Implementation Method 2
a humidity sensor that detects the humidity in the cell
Data Source
AI summary
A gas constituent measuring apparatus includes a cell that draws in a first gas to be measured, gas sensors that respond to one or more types of constituent gases in the cell, a regulator that controls humidity in the cell, a pump, a humidity sensor that detects the humidity in the cell, and an integrated circuit. The integrated circuit controls the regulator and pump on the basis of a detection result of the humidity sensor so that the humidity is within a predetermined range before the first gas is drawn into the cell or after the first gas is discharged from the cell, acquires first response values from the gas sensors with humidity being controlled, acquires second response values from the gas sensors with the first gas being in the cell, and determines concentrations of the one or more types of constituent gases from the first and second response values.