Columnar Sensor Substrate for Particulate Detection
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Solution Overview
Problem
Existing sensor substrates for detecting particulate matter in exhaust gases face challenges in achieving high accuracy and sensitivity due to limitations in electrode design and material resistance, particularly in high-temperature environments.
Innovation Solution
A sensor substrate with columnar sensing electrodes and embedded innerlayer wiring lines on an insulating ceramic substrate, featuring a heat-generating electrode and a passivation film to enhance detection sensitivity and resistance to oxidation, allowing for precise measurement of leakage current changes caused by particulate matter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electrode design and materials are used, then manufacturing simplicity is maintained, but detection sensitivity and accuracy decrease in high-temperature environments
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: a base electrode layer for electrical conduction, a heat-generating layer for thermal management, and a passivation film layer for oxidation protection. This segmentation allows each layer to perform its specific function optimally, improving detection sensitivity while maintaining manufacturing feasibility through sequential deposition processes
Solution Approach 2:
The electrode uses composite material structure combining different functional materials: conductive materials for electrical properties, heat-generating materials for thermal control, and oxidation-resistant materials for durability. This composite approach enables the electrode to withstand high-temperature exhaust environments while maintaining high detection sensitivity and accuracy
2Measurement precision
If electrode gap is reduced to increase sensitivity, then detection accuracy improves, but manufacturing precision requirements increase
Solution Approach 1:
The electrode structure extends into the depth dimension with multiple layered components rather than relying solely on lateral gap control. The columnar configuration and vertical layering allow sensitivity improvement through increased interaction volume with particulate matter, reducing the criticality of precise lateral gap control while maintaining manufacturing feasibility
3Reliability
If oxidation-resistant materials are used for electrodes, then reliability in high-temperature environments improves, but manufacturing complexity increases
Solution Approach 1:
A passivation film is applied in advance to the electrode surface before the electrode operates in the exhaust environment. This preliminary protective layer prevents oxidation during normal operation, ensuring long-term reliability in high-temperature conditions while allowing the use of standard electrode materials that are easier to manufacture
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 design significantly increases detection sensitivity and accuracy of particulate matter, including soot, by narrowing the gap between electrodes and using oxidation-resistant materials, enabling reliable operation in high-temperature exhaust gas environments.
Implementation Method 1
on the basis of variation in resistance value or current value caused by accumulation of detection targets contained in exhaust gas in between a pair of the sensing electrodes
Implementation Method 2
featuring a heat-generating electrode
Implementation Method 3
using oxidation-resistant materials
Data Source
AI summary
There are provided a sensor substrate and a sensor device which have high detection accuracy. A sensor substrate includes an insulating substrate; sensing electrodes disposed in the insulating substrate, the sensing electrodes being columnar and being composed of at least one pair of positive and negative sensing electrodes, in the at least one pair of positive and negative sensing electrodes, part of a positive electrode and part of a negative electrode being each exposed from one surface of the insulating substrate; and innerlayer wiring lines embedded within the insulating substrate, the innerlayer wiring lines corresponding to the positive electrode and the negative electrode, respectively, in the at least one pair of positive and negative sensing electrodes.