Gas Sensor Linearization via Molar Mass Reference
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Solution Overview
Problem
Existing methods for gas sensor output signal linearization are inadequate as they fail to account for individual sensor non-linearity and changes over time, requiring additional hardware and not allowing for real-time verification.
Innovation Solution
A method utilizing an additional molar mass sensor to automatically determine the linearization curve of a specific gas sensor by using reference gases with differing molar mass values, allowing for a three-point calibration and subsequent polynomial fitting to correct non-linear responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed linearization curve is determined during sensor development and applied to all sensors, then the linearization process is simple and quick, but it does not account for individual sensor non-linearity differences and changes over time
Solution Approach 1:
The system performs preliminary characterization of the sensor's non-linear response by measuring output signals at multiple known gas concentrations during initial operation. This preliminary data collection enables subsequent automatic determination of the linearization curve specific to each sensor, resolving the contradiction between simplicity and accuracy by preparing the necessary measurement data in advance during normal operation rather than requiring complex external calibration equipment
Solution Approach 2:
The system uses the sensor itself to characterize its own non-linear response by measuring its output at multiple known concentrations during routine operation. This self-characterization eliminates the need for external calibration equipment and allows each sensor to automatically determine its own linearization parameters, achieving both ease of manufacture and measurement precision
2Measurement precision
If the linearization curve is determined individually for each sensor using defined gas mixtures during production, then individual sensor characteristics are accounted for, but it does not account for changes in sensor characteristics over time
Solution Approach 1:
The system transitions from static linearization curves determined during production to dynamic linearization that can be updated during the sensor's operational lifetime. By periodically remeasuring the sensor response at multiple known concentrations and recalculating the linearization parameters, the system adapts to aging and drift, maintaining accuracy throughout the sensor's life rather than only at the time of calibration
Solution Approach 2:
The system implements a feedback mechanism where the sensor's actual response to known gas concentrations is continuously monitored and used to update the linearization curve. This closed-loop approach allows the system to detect deviations from the original calibration and automatically correct for them, ensuring long-term accuracy without requiring manual intervention or replacement
3Measurement precision
If the linearization curve is determined during sensor operation using defined gas mixtures, then real-time verification is possible, but it requires at least one additional precision gas mix and therefore additional hardware
Solution Approach 1:
The system uses the existing gas sensor and control system to perform multiple functions: normal gas concentration measurement and self-characterization for linearization determination. By utilizing the sensor's own measurement capabilities and the existing microcontroller, the system eliminates the need for separate calibration equipment, achieving real-time verification without increasing hardware complexity
Solution Approach 2:
The system introduces a software-based intermediary process that coordinates the self-characterization measurements and calculates the linearization parameters. This software mediator orchestrates the measurement sequence, processes the data, and updates the linearization curve without requiring additional physical hardware, resolving the contradiction between verification capability and device complexity
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 accurate and adaptive linearization of gas sensor output signals, accounting for individual sensor characteristics and changes over time without the need for additional precision gases or hardware, improving measurement accuracy in applications like lung function diagnostics.
Implementation Method 1
using an additional molar mass sensor
Data Source
AI summary
The invention describes a method that is used to determine the linearization curve of a sensor for specific gas components by combining this sensor with an ultrasonic molar mass sensor. The described method uses the fact that the molar mass sensor exhibits a completely linear response when two gas compositions of differing molar mass values are mixed. Using this feature a non linear-response of a sensor for specific gas components can be determined and a linearization curve can be computed.