Interdigital Comb Sensor With Non-Equidistant Electrodes
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Solution Overview
Problem
Existing particle sensors in internal combustion engines have low sensitivity due to only a fraction of particles accumulating on the sensor surface, leading to early saturation and inefficient signal formation, as they rely on equidistant finger electrode distances which limit the electrical field's effectiveness in attracting particles from various layers.
Innovation Solution
The sensor employs an interdigital comb structure with non-equidistant finger electrode distances, featuring alternating areas with larger and shorter distances to create a homogeneous electrical field, allowing particles from various layers to accumulate and contribute to signal formation, thereby increasing sensitivity without premature saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If equidistant finger electrode distances are used, then the electrical field has consistent direction and strength, but the sensor sensitivity is low and particles accumulate slowly
Solution Approach 1:
The patent applies asymmetry by using non-equidistant finger electrode distances instead of uniform spacing. The first area has larger distances between finger electrodes while the second area has smaller distances, creating an asymmetric electrical field distribution that enhances particle attraction efficiency and signal formation without requiring equidistant spacing throughout the entire electrode structure.
2Productivity
If finger electrodes are located closely adjacent to one another, then particle accumulation rate increases due to amplified field gradients, but conductive paths form rapidly causing early saturation
Solution Approach 1:
The patent segments the electrode structure into two distinct areas: a first area with larger finger electrode distances and a second area with smaller distances. This segmentation allows different regions to perform different functions - the first area provides extended operational duration by preventing rapid conductive path formation, while the second area maintains high particle accumulation rate through amplified field gradients.
Solution Approach 2:
The patent applies local quality by giving different spatial characteristics to different areas of the electrode structure. The first area has larger electrode distances suitable for extended operation, while the second area has smaller distances optimized for rapid particle accumulation. Each local region is optimized for its specific function rather than using a uniform design throughout.
3Measurement precision
If only a fraction of particles accumulate on the sensor surface, then the sensor structure is simple, but the signal formation is inefficient and sensitivity is low
Solution Approach 1:
The patent changes the geometric parameter of finger electrode distances from uniform to non-uniform distribution. By varying the distance parameter across different areas (larger in the first area, smaller in the second area), the electrical field distribution is optimized to enhance particle accumulation efficiency and signal formation without requiring additional complex components or structures.
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 design enhances the sensor's sensitivity by utilizing the entire electrode surface for signal formation, attracting particles from multiple layers and preventing early saturation, while maintaining dynamic performance.
Implementation Method 1
the sensor element which has an interdigital comb structure including finger electrodes situated equidistantly in relation to one another forms a symmetrical electrical field upon application of a voltage between the measuring electrodes
Implementation Method 2
particles which are entrained in the gas flow, in particular soot particles having this property, accumulate on the sensor element
Implementation Method 3
If electrically conductive particles which are entrained in the gas flow, in particular soot particles having this property, accumulate on the sensor element, the electrical resistance thus changes between the two measuring electrodes
Implementation Method 4
the concentration of the accumulated particles may be determined from a change over time of the particular measured variable, in particular the electrical resistance
Data Source
AI summary
A device for determining a concentration of particles in a gas flow, e.g., soot particles in exhaust gas of an internal combustion engine, includes a carrier and a sensor, which is situated on a surface of the carrier and can be exposed to the gas flow, the sensor including an electrode structure including at least two measuring electrodes that are of different polarity and that are formed as an interdigital comb structure including finger electrodes. In first areas of the interdigital comb structure, the finger electrodes have a first mutual distance in relation to each other, and in second areas of the interdigital comb structure, the finger electrodes have a second smaller mutual distance in relation to each other, the first areas and the second areas in the interdigital comb structure each at least partially adjoining each other alternately, occupying respective surface areas on the sensor.