Chemo-resistive Gas Sensor with Catalytic Filter for Selectivity
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Solution Overview
Problem
Chemo-resistive gas sensors face challenges in selectively detecting specific gases in gas mixtures due to shadowing effects, where a dominant gas like ozone (O3) masks the response to other gases, such as NO2, making precise concentration prediction impossible.
Innovation Solution
A gas sensing device incorporating a catalytic gas filter arrangement with membranes containing catalytic materials like Ni, Ti, and TiO2, which degrades shadowing gases like O3, allowing chemo-resistive gas sensing elements to detect gases like NO2 more accurately by reducing their concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemo-resistive gas sensors are used to detect gases in mixtures, then sensitive detection of environmental gases is enabled, but selectivity deteriorates due to shadowing effects from dominant gases
Solution Approach 1:
A catalytic filter layer is introduced as an intermediary component between the gas mixture and the chemo-resistive sensing elements. This filter layer selectively degrades dominant shadowing gases (such as O3) through catalytic reactions, allowing the sensing elements to detect target gases (such as NO2) with improved selectivity while maintaining high sensitivity
Solution Approach 2:
The gas sensing device employs different sensing elements with specific sensitivities to different gas types, and positions them in proximity to the catalytic filter. Each sensing element is optimized for detecting specific target gases, creating localized detection zones with enhanced selectivity for each gas type
2Adaptability or versatility
If multiple gas sensing elements are used to improve selectivity, then gas mixture analysis capability improves, but device complexity increases
Solution Approach 1:
The catalytic filter serves as a preprocessing intermediary that simplifies the gas mixture before it reaches the sensing elements by removing or degrading dominant interfering gases. This reduces the complexity of signal interpretation needed from the sensor array while maintaining multi-gas detection capability
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 catalytic gas filter arrangement ensures that shadowing gases are degraded in proximity to the sensing elements, enhancing the prediction sensitivity of target gases, enabling precise analysis of complex gas mixtures with improved selectivity and continuous operation without material consumption.
Implementation Method 1
a surface defining the pores comprises a catalytic material for degrading at least one of the gases of the plurality of the gases
Implementation Method 2
the at least one membrane comprises gas permeable pores
Implementation Method 3
The relevant dimensions are for example the pore diameter, the cross-sectional area of the pores, the perimeter of the pores, the length of the pores and the number of the pores
Implementation Method 4
the gases need to adsorb on the active sensor material and either undergo chemical reactions, such as oxidation/reduction of MOX materials
Implementation Method 5
the gases need to adsorb on the active sensor material
Data Source
AI summary
A sensor chip includes a substrate and one or more chemo-resistive gas sensing elements attached to the substrate. Each gas sensing element provides a signal depending on one or more gases to be sensed. A catalytic gas filter arrangement includes one or more filter sections, each filter section including a cavity covered with at least one membrane. The at least one membrane is supported by a support structure and includes gas permeable pores. A surface defining the pores includes a catalytic material for degrading one or more of the gases. The gas filter arrangement is arranged so at least one of the chemo-resistive gas sensing elements is exposed to a filtered mixture of the gases in the cavity of one of the filter sections. The filtered mixture of gases is obtained by filtering the ambient mixture of the one or more gases with the one of the filter sections.