Capacitive Sensor Using Metal-Plated Mesh Fabric for Stretching
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Solution Overview
Problem
Conventional capacitive sensors for vehicle seats and steering systems face reliability issues due to cracking of non-woven fabrics under stretching stress, leading to increased resistance and decreased sensing accuracy.
Innovation Solution
A capacitive sensor with a metal-plated mesh fabric substrate, where the sensor electrode is made by applying electroless and electrolytic plating on a mesh fabric with a high proportion of openings, allowing for greater elongation without cracking and maintaining contact pressure, thereby enhancing robustness and sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-woven fabric is used as the sensor electrode substrate, then the sensor can be manufactured with simpler process and lower cost, but the fabric cracks under stretching stress leading to increased resistance and decreased sensing accuracy
Solution Approach 1:
The patent applies a mesh fabric with a specific open work structure (opening area ratio of 30-70%) as the sensor electrode substrate. This porous structure allows the fabric to stretch without cracking while maintaining electrical conductivity through the metal plating on the mesh strands, thereby resolving the contradiction between manufacturing simplicity and sensing reliability.
Solution Approach 2:
The patent creates a composite structure by applying metal plating (copper, nickel, or stainless steel) on the mesh fabric strands. This composite material combines the flexibility and stretchability of the mesh structure with the electrical conductivity and durability of metal, preventing cracks under stretching stress while maintaining manufacturing feasibility.
2Strength
If the mesh fabric has larger opening area ratio to allow greater elongation, then the robustness and stretchability improve, but the electrical conductivity may decrease
Solution Approach 1:
The patent optimizes the opening area ratio parameter to be within 30-70%, which balances the elongation capability and electrical conductivity. Additionally, the metal plating thickness and mesh strand diameter are controlled within specific ranges to ensure adequate conductivity even with larger opening ratios, resolving the contradiction between stretchability and electrical performance.
3Reliability
If metal plating is applied on mesh fabric to improve conductivity and crack resistance, then the sensor robustness increases, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent specifies controlled parameter ranges for metal plating thickness (5-50 μm) and mesh strand diameter (0.1-1.0 mm) to optimize the balance between crack resistance and manufacturing complexity. These parameter controls ensure adequate durability while maintaining manufacturability through standardized production processes.
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 effectively reduces the occurrence of cracks in the sensor electrode, maintains sensing accuracy, and improves the robustness of the capacitive sensor by allowing it to stretch without increasing resistance, while also providing high corrosion resistance and reducing manufacturing costs.
Implementation Method 1
the sensor electrode is a conductive fabric made by applying a metal plating on a mesh fabric
Implementation Method 2
applying electroless and electrolytic plating on a mesh fabric
Data Source
AI summary
A capacitive sensor includes: a substrate that is in the form of a sheet; and a sensor electrode that is capacitive and disposed on a frontside of the substrate. The sensor electrode is a conductive fabric made by applying a metal plating on a mesh fabric that is woven of a plurality of warps and a plurality of wefts and that has openings each formed by two adjacent warps among the plurality of warps and two adjacent wefts among the plurality of wefts. An area defined by a maximum outside diameter of a warp or weft is smaller than an area of an opening space of each of the openings.