Gas Sensor Element Stabilization via Pre-Inspection Driving
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The instability of oxidation-reduction states in electrodes within gas sensor elements during the manufacturing process leads to unreliable sensitivity characteristics and measurement accuracy, resulting in defective products and reduced yield.
Innovation Solution
A method is introduced to stabilize the electrode state by performing a pre-process that involves driving the sensor element and allowing it to stabilize in air before inspecting device characteristics, ensuring that sensitivity characteristics are determined under stable conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inspection of device characteristics is performed immediately after aging process, then productivity is improved, but measurement precision deteriorates due to unstable electrode state
Solution Approach 1:
The patent applies preliminary action by introducing a stabilization process before inspection. The sensor element is driven in a rich atmosphere for a predetermined period to stabilize the electrode state before sensitivity characteristics are determined. This ensures accurate measurement while maintaining productivity by automating the stabilization step.
2Ease of operation
If sensitivity characteristics are determined before shipment, then ease of operation is improved, but reliability deteriorates due to electrode state changes during use
Solution Approach 1:
The patent stabilizes the electrode state through a preliminary driving process in rich atmosphere before determining sensitivity characteristics. This preliminary stabilization ensures that the characteristics determined before shipment remain reliable during actual use, preventing drift and maintaining measurement accuracy.
Solution Approach 2:
The patent changes the operational parameters by driving the sensor in a rich atmosphere (low oxygen concentration) for a predetermined period before inspection. This parameter change stabilizes the electrode oxidation-reduction state, ensuring that sensitivity characteristics determined afterward remain reliable during subsequent use under different conditions.
3Manufacturing precision
If aging process is performed in rich atmosphere, then manufacturing precision is improved by reducing oxidation, but stability worsens due to unexpected decomposition of rich components
Solution Approach 1:
The patent introduces a preliminary stabilization driving process after the aging process in rich atmosphere. This additional step allows the electrode state to stabilize by completing the reduction process and eliminating unstable rich components, ensuring both manufacturing precision and long-term stability.
Solution Approach 2:
The patent extends the useful action by maintaining the rich atmosphere condition for a predetermined continuous period during the stabilization drive. This continuous exposure ensures complete stabilization of the electrode state, preventing subsequent decomposition and ensuring composition stability.
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 approach prevents erroneous defective product identification, ensures reliable sensitivity characteristics, and improves product yield by stabilizing the electrode state during the inspection and usage of gas sensors.
Implementation Method 1
the degree of oxidation at the time of baking an element
Implementation Method 2
the degree of reduction caused by a subsequent aging process performed in a rich atmosphere
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To realize a gas sensor having high reliability and capable of improving the yield of the product, a method for manufacturing a sensor element for a gas sensor is provided. The method includes the steps of: (a) printing and forming a wiring pattern of a conductive paste on a green sheet containing, as a main component, ceramic which is an oxygen-ion conductive solid electrolyte; (b) laminating a plurality of green sheets including the green sheet having been subjected to the step (a) and integrating the plurality of green sheets; (c) cutting out a plurality of element bodies from a laminated body obtained by the step (b); (d) baking the element body cut out by the step (c); (e) heating the element body having been subjected to the step (d), in a reducing atmosphere; (f) driving the element body having been subjected to the step (e), in an inspection-purpose gas atmosphere for a predetermined time period; and (g) inspecting electrical characteristics of the element body having been subjected to the step (f). The element body having passed the inspection of step (g) is assembled as a sensor element in a gas sensor.