Air Quality Sensor Calibration via Cavity Isolation
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Solution Overview
Problem
Air quality sensors in wearable devices face challenges in maintaining accuracy due to variations in humidity, temperature, and aging components, requiring regular recalibration but are difficult for users to implement effectively.
Innovation Solution
A device with a cavity that can switch between open and closed states, allowing for calibration by consuming air compounds within the cavity, ensuring reliable measurements by setting a new baseline when the compound concentration falls below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the air quality sensor is recalibrated regularly to maintain measurement accuracy, then the measurement precision is improved, but the ease of operation deteriorates due to the difficult and burdensome calibration process for users
Solution Approach 1:
The device performs calibration automatically without requiring user intervention. The microprocessor controls the cavity to isolate the sensor, introduces zero air through the membrane, and adjusts the baseline automatically, allowing the system to calibrate itself while the user continues normal usage
Solution Approach 2:
The calibration process is initiated and completed in advance during periods when the user is not actively using the device for measurements. The system prepares the cavity and performs baseline adjustment before the user needs accurate readings, ensuring readiness without interrupting user workflow
2Duration of action of moving object
If the cavity internal volume is reduced to enable faster calibration by consuming air compounds more quickly, then the duration of action is improved, but the volume of the cavity is reduced which may affect sensor performance
Solution Approach 1:
The system changes the concentration parameter of air compounds in the cavity over time by isolating it and allowing consumption through the membrane. By controlling the isolation duration and membrane properties, the system achieves sufficient concentration change for calibration without requiring a large initial volume
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 approach enables reliable air quality measurements by recalibrating the sensor when the user is unlikely to use it, ensuring accurate data over time without burdening the user with complex calibration processes.
Implementation Method 1
the air quality sensor is adapted to produce an electric current by consuming the air compound present in the internal volume of the cavity
Data Source
AI summary
A device (1) comprising a cavity (5) defining an internal volume, an air quality sensor (9) being adapted to measure a concentration of at least one air compound present in the internal volume, the cavity (5) can be alternatively in:an open state in which air can enter into the cavity (5) from the outside of the cavity (5), anda closed state in which no air can circulate between the outside and the inside of the cavity (5),the air quality sensor (9) being adapted to be calibrated when the cavity (5) is in the closed state and once the internal volume no longer comprises the air compound or comprises a concentration of the air compound that is below a predefined threshold.