Stitched Conductive Wire RFID Antenna on Fabric
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Solution Overview
Problem
RFID devices in wearable electronics face issues with loose cables and poor performance due to high electrical resistance in conductive ink, which is also prone to damage from washing and environmental stresses.
Innovation Solution
An RFID device assembly is created by coupling an electrically conductive wire with a pattern forming an antenna to a fabric using a non-electrically conductive thread for securing, with options for metal wire, insulated wire, or metal plated polymer thread, and using adhesives or soldering for attachment, along with an encapsulation layer for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conductive ink is printed onto the fabric to form an RFID antenna, then the antenna can be integrated into the fabric, but the electrical resistance is high and performance is poor
Solution Approach 1:
The patent changes the material parameter from conductive ink to electrically conductive wire, which fundamentally alters the electrical conductivity property while maintaining the integration capability into fabric through stitching methods
Solution Approach 2:
The patent uses a composite structure combining non-conductive fabric with conductive wire elements, creating a hybrid system that leverages the advantages of both materials - the flexibility and comfort of fabric with the high conductivity of metal wire
2Ease of manufacture
If conductive ink is used to form the antenna, then the antenna can be printed directly on fabric, but the ink is damaged by washing or environmental stresses
Solution Approach 1:
The patent changes the material from printed ink to stitched wire, fundamentally altering the durability parameter while maintaining ease of manufacture through standard textile stitching processes
Solution Approach 2:
The conductive wire is formed into a pattern that follows the curvature and shape of the fabric, allowing the antenna to conform to the fabric's three-dimensional form while maintaining electrical continuity and mechanical durability
3Reliability
If metal wire is used as electrical conductor, then electrical conductivity is improved, but loose cables become a nuisance and ungainly
Solution Approach 1:
The patent merges the electrical conductor (metal wire) with the fabric structure by stitching the wire directly onto the fabric, combining the functionality of separate cable and fabric into a unified integrated structure
Solution Approach 2:
The patent uses flexible conductive wire that can be conformally attached to the fabric surface, creating a thin, flexible antenna structure that maintains comfort and aesthetics while providing excellent electrical conductivity
4Ease of manufacture
If printed ink antenna is used, then the antenna can be formed by printing process, but laser trimming is required to improve electrical performance
Solution Approach 1:
The patent changes the material parameter from printed ink to conductive wire, which eliminates the need for laser trimming since the wire itself provides sufficient conductivity and can be directly stitched into the final configuration
Solution Approach 2:
The patent extracts the laser trimming step from the manufacturing process by using conductive wire that does not require post-printing modification, simplifying the overall manufacturing workflow while maintaining or improving electrical performance
Data Source
AI summary
An RFID device assembly is fabricated by positioning an electrically conductive wire onto a fabric as a pattern that forms an antenna, and securing the wire to the fabric by stitching a non-electrically conductive thread over the wire and to the fabric. The two ends of the electrically conductive wire are positioned for coupling to antenna contact pads on an RFID device. The RFID device is attached to the fabric either before or after the electrically conductive wire is secured to the fabric by the stitched non-electrically conductive thread.