Hydrogen Sensor Porous Catalytic Layer Surface Area
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Solution Overview
Problem
Hydrogen gas sensitive semiconductor sensors based on the hydrogen dipole transducer principle face reduced sensitivity due to oxidation and contamination by oxygen and other substances, leading to shortened sensor life and inadequate initial sensitivity, especially when used in gas samples containing air or other contaminants.
Innovation Solution
The sensor design features a catalytic metal layer with an outer surface area at least 100% larger than the total surface area of the inner hydrogen atom adsorption surface portions, enhancing the adsorption and dissociation of hydrogen gas molecules and increasing the density of hydrogen dipoles, thereby improving initial sensitivity and extending sensor life without the need for additional purification or atmosphere modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor uses a conventional catalytic metal layer with standard surface area, then the sensor structure is simple, but the initial sensitivity to hydrogen gas is insufficient and sensor life is shortened due to oxidation and contamination
Solution Approach 1:
The patent applies dimensionality change by creating a porous catalytic metal layer structure that increases the effective surface area from a two-dimensional planar surface to a three-dimensional porous network. This porous structure provides numerous adsorption sites for hydrogen gas molecules while maintaining the same basic layer geometry, thereby enhancing sensitivity without fundamentally changing the sensor architecture.
Solution Approach 2:
The patent explicitly employs porous materials by forming a porous catalytic metal layer with controlled porosity. This porous structure increases the available surface area for hydrogen adsorption and dissociation, enhancing the sensor's initial sensitivity. The porous morphology allows gas molecules to access numerous active sites within the layer structure, improving measurement precision while the material itself remains relatively simple.
2Measurement precision
If the outer surface area of the catalytic metal layer is increased to enhance hydrogen adsorption, then initial sensitivity improves, but the sensor becomes more vulnerable to oxidation and contamination effects
Solution Approach 1:
The patent applies local quality by creating different functional zones within the catalytic metal layer. The outer surface is designed with high porosity and large surface area for maximum hydrogen adsorption, while the inner region maintains structural integrity and catalytic properties. This spatial differentiation allows the outer surface to be highly active for hydrogen detection while the inner structure provides stability and resistance to oxidation and contamination.
Solution Approach 2:
The patent employs composite materials by combining the porous catalytic metal layer with the semiconductor layer and insulator layer in a multi-layer composite structure. This composite architecture allows each layer to perform its specific function: the porous metal layer provides high surface area for hydrogen adsorption, the semiconductor layer provides the sensing mechanism, and the insulator layer provides electrical isolation. This composite structure enhances both sensitivity and reliability simultaneously.
3Speed
If the catalytic metal layer is made thinner to reduce contamination depth, then sensor response time improves, but the total surface area for hydrogen adsorption decreases
Solution Approach 1:
The patent applies porous materials to resolve this contradiction. By making the catalytic metal layer porous, the effective surface area is dramatically increased within a thin physical thickness. The porous structure provides numerous adsorption sites throughout the layer depth, maintaining a large effective surface area while keeping the overall layer thickness small, thus achieving both high sensitivity and fast response time.
Solution Approach 2:
The patent uses dimensionality change by transitioning from a planar surface to a three-dimensional porous network. This allows the catalytic metal layer to provide extensive surface area for hydrogen adsorption within a thin profile, enabling fast response time while maintaining high sensitivity. The porous structure effectively utilizes the vertical dimension to increase surface area without increasing lateral dimensions.
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 design results in a hydrogen gas sensitive semiconductor sensor with increased initial sensitivity and extended life, maintaining high performance even in the presence of contaminants, as the larger outer surface area provides more sites for hydrogen adsorption and dissociation, reducing the impact of oxygen and other contaminants on sensor functionality.
Implementation Method 1
the catalytic metal layer may adsorb some of them on its outer surface arranged to freely communicate with the ambient atmosphere
Implementation Method 2
The term 'catalytic metal' is herein used to denote a metal or an alloy being capable to dissociate hydrogen gas molecules and to absorb the hydrogen atoms thus formed
Implementation Method 3
the hydrogen atoms thus formed may be absorbed into the catalytic metal layer
Implementation Method 4
Some of the absorbed hydrogen atoms will subsequently be adsorbed at the interface between the catalytic metal layer and the insulator layer after diffusion through the catalytic metal layer
Implementation Method 5
hydrogen atoms adsorbed at the interface between the catalytic metal layer and the insulator layer are polarized with the positive end facing the insulator layer. The polarization implies that hydrogen dipoles are produced. The hydrogen dipoles generate an electrical field that shifts the effective work function of the catalytic metal layer
Data Source
AI summary
A hydrogen gas sensitive semiconductor sensor including a catalytic metal layer, a semiconductor layer and an insulator layer arranged between the catalytic metal layer and the semiconductor layer. The catalytic metal layer includes an outer surface and an inner surface including at least one hydrogen atom adsorption surface portion. Each hydrogen atom adsorption surface portion is arranged adjacent to the insulator layer. The surface area of the outer surface is at least 100% larger than the total surface area of all of the at least one hydrogen atom adsorption surface portion. A probe includes the sensor, A hydrogen gas detection system includes the sensor. Use of the sensor for detection of presence of and/or measurement of concentration of hydrogen gas in a gas sample.