Porous In2O3-Co3O4 CO Gas Sensor for Low-Concentration Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing metal oxide semiconductor gas sensors for detecting carbon monoxide (CO) have insufficient selectivity and sensitivity, particularly at low concentrations, necessitating an improvement in sensor performance.
Innovation Solution
A metal oxide semiconductor gas sensor comprising a sensing layer with specific composition and porosity ranges, including In2O3 and Co3O4, with porosities between 15.7% and 22.0%, and a thickness of 1.0 um or more, facilitating high sensitivity and rapid response to CO gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metal oxide semiconductor gas sensors are used for CO detection, then the sensor structure is simple, but the sensitivity and selectivity to CO gas are insufficient
Solution Approach 1:
The sensing layer uses a composite material consisting of In2O3 as the main component (65-99.5 vol%) and Co3O4 as the additive component (0.5-35 vol%). This composite structure combines the high sensitivity of In2O3 with the selective catalytic properties of Co3O4, achieving both high CO detection sensitivity and selectivity while maintaining a relatively simple two-component formulation.
Solution Approach 2:
The invention optimizes specific parameters including the volume ratio of In2O3 to Co3O4 (65:35 to 99.5:0.5), the average porosity (15.7-22.0%), and the average pore size (80-120 nm). By precisely controlling these parameters, the sensing layer achieves maximum sensitivity and selectivity to CO gas at low concentrations while keeping the device structure manageable.
2Speed
If the sensing layer porosity is increased to improve gas diffusion and sensitivity, then the response speed improves, but the mechanical strength decreases
Solution Approach 1:
The invention optimizes the average porosity to a specific range of 15.7-22.0%, which balances gas diffusion efficiency with mechanical integrity. This controlled porosity level allows sufficient CO gas diffusion to the sensing sites for rapid response while maintaining enough structural density to preserve mechanical strength and prevent layer degradation.
Solution Approach 2:
The sensing layer utilizes a porous structure with controlled porosity (15.7-22.0%) and pore size (80-120 nm) to facilitate gas diffusion. The porous architecture provides numerous pathways for CO gas molecules to reach the sensing interfaces between In2O3 and Co3O4 particles, enabling rapid response while the controlled pore dimensions maintain structural coherence.
3Measurement precision
If the sensing layer thickness is increased to improve sensitivity, then the detection capability at low concentrations improves, but the response time increases
Solution Approach 1:
The sensing layer employs a porous structure with 15.7-22.0% porosity and 80-120 nm pore size that enables efficient gas diffusion throughout the layer thickness. This porous architecture allows CO gas molecules to penetrate and reach sensing sites deep within the layer rapidly, maintaining fast response times even at optimal thicknesses for low-concentration detection.
Solution Approach 2:
The sensing layer exhibits local quality variations through its porous structure, where the distribution of In2O3 and Co3O4 particles creates numerous localized sensing interfaces throughout the thickness. This ensures that gas molecules can interact with active sensing sites at multiple locations simultaneously, achieving high sensitivity without requiring excessive thickness that would slow down the response.
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 sensor achieves high sensitivity and short response time for detecting CO gas at concentrations as low as 20 ppm, suitable for applications in home healthcare and combustion engine exhaust gas monitoring.
Implementation Method 1
a sensing layer in contact with both the first electrode and the second electrode, wherein the sensing layer contains In2O3 and Co3O4
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention pertains to a metal oxide semiconductor gas sensor having a first electrode, a second electrode, and a sensitive layer in contact with both the first electrode and the second electrode. The sensitive layer includes In2O3 and Co3O4. The average porosity in a cross section of the sensitive layer is 15.7-22.0%. The proportion of In2O3 and the proportion of Co3O4 in a region excluding pores of the sensitive layer are 65-99.5 vol% and 0.5-35 vol%, respectively.