Miniaturized Gas Sensor With Selective Membrane for Humidity Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional miniaturized gas sensors lack sufficient sensitivity to measure air pollutant concentrations in outdoor environments, particularly for gases like NO2 and O3, which are present at low ppb levels. Additionally, these sensors are prone to interference from ambient temperature and relative humidity changes, leading to inaccurate measurements.
Innovation Solution
The proposed solution involves an apparatus and method for measuring gas concentration using a sensing unit with a first selective water vapour-permeable membrane and two working electrodes. The first electrode detects changes in ambient relative humidity, while the second electrode detects a superimposed signal from both humidity changes and gas molecule reactions. The processing unit isolates the gas-related signal by subtracting humidity and baseline terms, enabling accurate gas concentration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional miniaturized gas sensors are used, then device size is reduced, but measurement precision deteriorates due to insufficient sensitivity for ppb-level gas concentrations
Solution Approach 1:
The sensor is segmented into multiple functional components: a selective water vapour-permeable membrane that separates water molecules from gas molecules, a working electrode that detects electrochemical signals, and a reference electrode that provides baseline correction. This segmentation allows the small sensor to independently measure and correct for humidity interference, thereby maintaining ppb-level measurement precision while keeping the device miniaturized.
2Adaptability or versatility
If electrochemical sensors operate in outdoor environments, then adaptability improves, but measurement precision deteriorates due to temperature and humidity interference
Solution Approach 1:
A selective water vapour-permeable membrane is introduced as an intermediary component between the outdoor environment and the sensor electrodes. This membrane selectively allows water molecules to pass through while blocking gas molecules, thereby mediating the interference from ambient humidity and temperature. The membrane enables the sensor to adapt to outdoor conditions while maintaining measurement precision by isolating the electrochemical detection from humidity fluctuations.
3Measurement precision
If correction algorithms are applied to temperature and humidity interference, then measurement precision improves, but device complexity increases
Solution Approach 1:
The sensor implements self-service correction by incorporating a reference electrode that automatically measures baseline drift caused by temperature and humidity changes. The working electrode signal is then corrected by subtracting the reference electrode signal, providing real-time compensation without requiring external correction algorithms or additional processing complexity. This self-correcting mechanism maintains measurement precision while keeping the device simple.
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 effectively corrects for temperature and relative humidity-induced interferences, allowing for precise measurement of gas concentrations at ppb levels. The method provides a wide range of applicability and improves the accuracy of gas concentration measurements in outdoor environments.
Implementation Method 1
The first selective water vapour-permeable membrane may be configured to allow the first working electrode to be in contact with ambient water molecules but not with gas molecules to be measured
Implementation Method 2
the first working electrode may be configured to generate an electrical signal caused by change in ambient relative humidity
Implementation Method 3
the second working electrode may be configured to generate a superimposed electrical signal caused by both the change in ambient relative humidity and reaction of the gas molecules to be measured
Data Source
AI summary
An apparatus, method and sensor for measuring gas concentration. The apparatus includes a sensing unit and a processing unit. The sensing unit includes a first selective water vapour-permeable membrane, a first working electrode and a second working electrode. The first selective water vapour-permeable membrane allows the first working electrode to be in contact with water molecules while to prevent this first working electrode from being in contact with the gas molecules to be measured. The first working electrode generates an electrical signal caused by change in relative humidity, the second working electrode generates a superimposed electrical signal caused by the change in relative humidity and the gas molecules to be measured, and the processing unit acquires concentration of the gas based on the electrical signal and the superimposed electrical signal.