Wrapped Stainless Steel RFID Antenna Yarn for Flexible Textile Tags
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Solution Overview
Problem
Existing RFID antennas for textile applications are thick and stiff, leading to discomfort for users and potential interference with medical devices like MRI scanners, while also not providing optimal reading distance.
Innovation Solution
An RFID antenna comprising a stainless steel fiber yarn wrapped with electrically non-conductive yarns, which reduces the antenna's thickness and bending stiffness, providing better comfort and compatibility with medical devices by using a low-twist, thin stainless steel fiber configuration with minimal martensite content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extrusion coating is used to insulate the antenna, then electrical insulation is provided, but the antenna becomes thick and stiff
Solution Approach 1:
The patent uses a thin film wrapping yarn instead of thick extrusion coating to provide electrical insulation. The wrapping yarn forms a flexible thin layer around the antenna yarn, maintaining insulation properties while significantly reducing thickness and bending stiffness, thus improving comfort for wearable applications
Solution Approach 2:
The patent creates a composite structure by wrapping the antenna yarn with electrically non-conductive wrapping yarn. This composite approach combines the conductive antenna function with the insulating property of the wrapping yarn, achieving both electrical insulation and flexibility without the bulk of extrusion coating
2Reliability
If extrusion coating is used to insulate the antenna, then electrical insulation is provided, but the antenna diameter increases
Solution Approach 1:
The wrapping yarn forms a thin film-like layer around the antenna yarn, providing electrical insulation with minimal increase in diameter. This thin film approach is much more space-efficient than extrusion coating, keeping the antenna compact and thin for wearable applications
Solution Approach 2:
Instead of adding insulation radially through thick extrusion coating, the patent uses wrapping yarn that adds insulation in a circumferential dimension. The wrapping yarn winds around the antenna yarn, providing insulation coverage while maintaining a compact cross-sectional diameter
3Ease of operation
If multi-strand stainless steel wire is used, then flexibility is improved, but the antenna structure becomes complex
Solution Approach 1:
The patent changes the key parameter from multi-strand construction to single yarn construction. By using a single antenna yarn with appropriately selected material properties and twist, the patent achieves the desired flexibility without the structural complexity of assembling multiple strands, simplifying both manufacturing and the overall antenna structure
Data Source
Figure 1~3
AI summary
An antenna for use in an RFID tag comprises an antenna yarn. The antenna yarn comprises metal fibers. The metal fibers are stainless steel fibers. The antenna yarn is wrapped by at least one wrapping yarn thereby covering the full surface of the antenna yarn or of the metal wire or of the bundle of metal wires. The at least one wrapping yarn comprises non-electrically conductive fibers.