HEMT Gas Sensor with Ternary Alloy Barrier for Exhaust Analysis
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Solution Overview
Problem
Current NOx sensors in motor vehicle exhaust systems are non-selective, expensive, and have slow response times, failing to accurately distinguish between different nitrogen oxide components and operate effectively at high temperatures.
Innovation Solution
A high electron mobility transistor (HEMT) sensor with a ternary alloy barrier layer, a platinum/palladium functional layer, and a compact design capable of detecting NO, NO2, CO, and CO2, maintaining accuracy up to 600°C, integrated into the exhaust line for precise gas analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional NOx sensors are used to measure overall nitrogen oxide concentration, then the measurement covers all NOx components, but the response time is long and the cost is high
Solution Approach 1:
The patent divides the measurement of nitrogen oxides into separate detection channels: one for NO2 and another for NO, using distinct sensing elements with different selectivities. This segmentation allows each sensor to specialize in detecting its target gas, improving response time while maintaining comprehensive NOx measurement capability.
Solution Approach 2:
The sensor system uses a universal platform (semiconductor sensing element) that can be configured with different selective layers to detect multiple gas types (NO2, NO, and potentially other exhaust gases). This multi-functional approach enables a single device to provide comprehensive exhaust analysis without requiring multiple separate sensors.
2Measurement precision
If conventional NOx sensors are used to measure overall nitrogen oxide concentration, then the measurement covers all NOx components, but the sensor cost is high
Solution Approach 1:
The patent divides the measurement of nitrogen oxides into separate detection channels: one for NO2 and another for NO, using distinct sensing elements with different selectivities. This segmentation allows each sensor to specialize in detecting its target gas, improving response time while maintaining comprehensive NOx measurement capability.
Solution Approach 2:
The sensor system uses a universal platform (semiconductor sensing element) that can be configured with different selective layers to detect multiple gas types (NO2, NO, and potentially other exhaust gases). This multi-functional approach enables a single device to provide comprehensive exhaust analysis without requiring multiple separate sensors.
3Temperature
If a sensor is to operate in the high temperature exhaust environment, then the sensor can withstand temperatures up to 600°C, but the sensor materials must be thermally resistant and expensive
Solution Approach 1:
The patent modifies the semiconductor material parameters, specifically using wide-bandgap materials like silicon carbide (SiC) or gallium nitride (GaN) that maintain their electrical properties at high temperatures. This parameter change enables the sensor to operate reliably at exhaust temperatures up to 600°C while avoiding the need for expensive precious metal thermocouples or specialized high-temperature ceramics.
Solution Approach 2:
The sensor employs composite material structures combining semiconductor materials with appropriate protective and selective coatings. These composite structures provide both high-temperature stability and gas selectivity, achieving thermal resistance without relying on expensive single-material solutions.
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 provides selective and accurate detection of exhaust gases, enabling effective monitoring of pollution control devices and optimizing NH3 injection, while being cost-effective and thermally resistant.
Implementation Method 1
A high electron mobility transistor (HEMT) sensor with a ternary alloy barrier layer, a platinum/palladium functional layer
Implementation Method 2
The transistor includes a third layer and a fourth layer, both located between the first and second barrier layers, the third and fourth layers being composed of gallium nitride (GaN)
Implementation Method 3
a platinum/palladium functional layer, and a compact design capable of detecting NO, NO2, CO, and CO2
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a sensor (9) for the detection of a chemical species in a gas from an exhaust line of a motor vehicle, this sensor (9) comprising a transistor (14) having: - a substrate (16), - at least a first layer (17) and a second layer (18) barrier superimposed on the substrate (16), - a grid (19) coated with a functional layer made of a material having catalytic activity with at least one gaseous compound, the first layer (17), the second layer (18) and the grid (19) being made from element III nitride, the grid (19) being made of a ternary alloy.