Self-calibrating analyte sensor
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Solution Overview
Problem
Resonant chemical sensors are sensitive to humidity and prone to long-term drift, leading to inaccurate measurements and the need for costly and invasive manual calibration, especially in applications like indoor air quality monitoring.
Innovation Solution
A sensor device with a resonant mass transducer coated with a sensing material that adjusts its temperature according to a profile, using detectors and processors to correct for humidity effects and self-calibrate, eliminating the need for manual recalibration by comparing transducer responses to pre-measured reference data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration is performed periodically to compensate for drift, then measurement accuracy is maintained, but device complexity and operational cost increase
Solution Approach 1:
The sensor performs self-calibration by automatically comparing its output signal against pre-stored reference data corresponding to known analyte concentrations. The processor autonomously adjusts calibration parameters without requiring manual intervention, external calibration equipment, or user expertise, thereby maintaining measurement accuracy while eliminating operational complexity associated with manual calibration procedures
Solution Approach 2:
Reference data representing known analyte concentrations and corresponding transducer responses is pre-measured and stored in memory during manufacturing or initial setup. This preliminary preparation enables the sensor to perform rapid self-calibration by simply comparing current measurements against the pre-stored reference data, eliminating the need for time-consuming manual calibration procedures while maintaining measurement accuracy
2Measurement precision
If resonant mass transducers are used for gas detection, then sensitivity to analyte molecules is achieved, but sensitivity to humidity and water adsorption increases
Solution Approach 1:
The calibration process is segmented into multiple discrete concentration points stored as reference data. By dividing the measurement range into segments and storing reference responses for each segment, the system can accurately distinguish analyte signals from humidity interference through comparative analysis against the segmented reference data, maintaining analyte detection sensitivity while compensating for humidity effects
Solution Approach 2:
The system continuously monitors transducer responses and compares them against stored reference data, using feedback loops to automatically adjust calibration parameters. This feedback mechanism enables real-time compensation for humidity interference by detecting deviations from expected analyte responses and correcting measurements based on comparisons with reference data under various humidity conditions
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 device provides accurate, long-term stable measurements of analyte concentrations without manual calibration, reducing costs and expanding deployment in demand-controlled ventilation and indoor air quality monitoring.
Implementation Method 1
A sensor device is provided for determining a quantity of at least one analyte (e.g., a target gas) in an environment or sample
Implementation Method 2
the sensing material has an ability to adsorb or absorb an amount of the analyte that depends on a temperature of the sensing material
Implementation Method 3
At least one thermal element is arranged to heat and/or cool the sensing material according to at least one temperature profile
Implementation Method 4
At least one thermal element is arranged to heat and/or cool the sensing material according to at least one temperature profile
Implementation Method 5
The device further comprises at least one humidity sensor arranged to detect a humidity level of the environment or sample containing the analyte
Data Source
AI summary
A sensor device comprises at least one transducer and a sensing material disposed on the transducer. The sensing material adsorbs or absorbs an amount of analyte (e.g., a target gas) that depends on a temperature of the sensing material and a concentration of the analyte. At least one detector is arranged to measure responses of the transducer to sorption or desorption of the analyte in the sensing material while the sensing material is heated and/or cooled according to at least one temperature profile. The device also comprises a humidity sensor that is arranged to detect a humidity level of the environment or sample containing the analyte. A processor or controller is programmed to determine the quantity (e.g., concentration) of the analyte by comparing values of the transducer measurement signals to reference data indicative of expected or pre-measured responses of the transducer to known concentrations of the analyte at the same humidity level as indicated by the humidity sensor while the sensing material is subjected to the same or similar temperature profile.