Particulate Matter Sensor Spiral Winding Electrode Design
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Solution Overview
Problem
Existing particulate matter sensors face limitations in sensitivity and ease of production due to the distance between electrodes, with conventional methods like mask processes causing short circuits and laser electrode patterning increasing costs and complicating mass production.
Innovation Solution
A particulate matter sensor with a sensing unit featuring a laminate structure where electrodes and a porous layer are spirally wound on a base unit, reducing electrode distance and increasing measurement area for enhanced accuracy and sensitivity, while simplifying manufacturing and reducing directional sensitivity influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mask process is used to reduce the distance between electrodes, then sensitivity is improved, but short circuit between electrodes occurs after sintering
Solution Approach 1:
A porous insulation layer is introduced as an intermediary between the first and second electrodes. This insulation layer physically separates the electrodes while allowing particulate matter to pass through, preventing short circuits during sintering and operation. The porous structure maintains the necessary electrical isolation while preserving sensor functionality.
Solution Approach 2:
The patent employs a porous insulation layer made of ceramic material with controlled porosity. The porous structure allows exhaust gas and particulate matter to permeate through the layer, enabling the sensing function while the ceramic material provides electrical insulation to prevent short circuits between electrodes at high temperatures.
2Measurement precision
If laser electrode patterning process is used to reduce electrode distance, then sensitivity is improved, but cost increases and mass production becomes difficult
Solution Approach 1:
The sensor structure is segmented into distinct functional layers (electrodes, porous layer, insulation layer) that can be manufactured separately and assembled. This modular approach allows each component to be produced using standard, cost-effective processes rather than requiring complex laser patterning of the entire assembly, facilitating mass production.
Solution Approach 2:
The porous insulation layer serves as a mediator that defines the electrode spacing without requiring direct electrode patterning. By using this intermediate layer to control the gap between electrodes, the patent avoids the need for expensive and complex laser electrode patterning processes, enabling simpler and more scalable manufacturing.
3Ease of manufacture
If electrodes are formed only on one surface of substrate, then manufacturing is simplified, but sensitivity is low and influenced by mounting direction
Solution Approach 1:
The patent transitions from a two-dimensional single-surface electrode configuration to a three-dimensional structure with electrodes on opposite surfaces of the substrate. This dimensional change increases the effective sensing area and eliminates directional sensitivity issues, as the sensor now responds to particulate matter regardless of the flow direction through the porous layer.
Solution Approach 2:
The patent applies different functional properties to different locations: electrodes are placed on both surfaces of the substrate to maximize sensing area, while the porous layer is positioned between them to enable particulate matter passage. This localized functional distribution optimizes both sensitivity and manufacturing feasibility.
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 solution enhances measurement accuracy, reliability, and sensitivity by adjusting electrode distance through the thickness of the porous layer, simplifies production, and reduces costs, while minimizing the impact of sensor mounting direction on sensitivity.
Implementation Method 1
a porous layer stacked on one of the first electrode and the second electrode and having a structure which may pass exhaust gas
Implementation Method 2
measures capacitance between the first electrodes and the second electrodes using the area of particulate matter accumulated between the first electrodes
Implementation Method 3
signal change between the two electrodes due to an accumulation amount of the particulate matter occurs (i.e., resistance is reduced)
Data Source
AI summary
Disclosed is a particulate matter sensor having a structure which may achieve a reduction in distance between two electrodes and an increase in area of measurement electrodes so as to facilitate enhancement in measurement accuracy, reliability, and sensitivity, and reduce influence on sensitivity according to sensor mounting directions. The particulate matter sensor may include a housing provided with an inlet and an outlet, and a sensing unit installed within the housing so as to pass exhaust gas, the sensing unit may include a laminate including an electrically insulating substrate, a first electrode provided on one surface of the electrically insulating substrate, a second electrode provided on the other surface of the electrically insulating substrate, and a porous layer stacked on one of the first electrode and the second electrode and having a structure to pass the exhaust gas, and the laminate is spirally wound on a base unit.