Gas Sensor Reference Lead Porous Structure
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Solution Overview
Problem
The variation in film thickness of the reference lead portion in gas sensors leads to increased voids, resulting in decreased detection accuracy due to gas discharge through these voids, affecting the sensor's characteristics.
Innovation Solution
Incorporating noble metal particles and ceramic particles with specific size relationships in the reference lead portion to control void formation, ensuring the film thickness is less than three times the maximum particle size, thereby minimizing void area variation and maintaining sensor accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the film thickness of the reference lead portion is increased, then the structural stability is improved, but the detection accuracy deteriorates due to increased voids causing gas discharge
Solution Approach 1:
The reference lead portion is designed with a controlled porous structure containing voids filled with reference gas. By carefully controlling the size and distribution of voids through particle size selection (ceramic particles with maximum diameter D and noble metal particles with maximum diameter d where d < 0.5D) and film thickness constraints (t < 3D), the patent creates an optimized porous material that maintains structural stability while preventing harmful gas discharge that would reduce detection accuracy.
Solution Approach 2:
The reference lead portion uses a composite material system combining ceramic particles (providing structural framework) and noble metal particles (providing conductivity and additional structural support). This composite structure allows simultaneous optimization of mechanical stability and gas permeability properties, resolving the contradiction between structural stability and detection accuracy by distributing functions across different material phases.
2Ease of manufacture
If the film thickness of the reference lead portion is increased, then the ease of manufacture is improved, but the characteristics of the gas sensor vary due to increased internal voids
Solution Approach 1:
The patent establishes specific parameter ranges for the reference lead portion: film thickness t < 3D (where D is the maximum diameter of ceramic particles), ceramic particle diameter D, and noble metal particle diameter d < 0.5D. These parameter constraints define an optimal manufacturing window that ensures consistent sensor characteristics while maintaining ease of manufacture through screen printing and sintering processes.
Solution Approach 2:
The patent performs preliminary design of the particle size distribution and film thickness before manufacturing. By pre-calculating the relationship between film thickness and void formation based on particle sizes, the manufacturing process can be optimized in advance to produce reference lead portions with controlled void structures, ensuring consistent sensor characteristics without requiring complex post-processing.
Data Source
AI summary
A sensor element 100 including: a detection electrode (106a) and a reference electrode 104a; and one pair of lead portions respectively connected to the detection electrode and the reference electrode, wherein out of the one pair of lead portions, a reference lead portion 104b that is connected to the reference electrode is configured to include noble metal particles 151 of one type or more selected from the group of Pt, Pd, Rh, and Au, ceramic particles 153 having an equivalent circle diameter larger than that of the noble metal particles, and a voids G1, G2, and when a cross section that crosses, in a longitudinal direction of, the reference lead portion is viewed, a relationship of a lead portion film thickness t<(a maximum particle size M of the ceramic particles×3)<a lead portion width W is satisfied.