NFC Coin Structure With Ferrite Shielding Against Eddy Currents
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Solution Overview
Problem
Existing technologies for making coins and medals smart are limited by QR codes, which allow only single responses and are space-constrained, and NFC tags in metallic objects face interference issues due to eddy currents, rendering them inoperable.
Innovation Solution
A miniature, custom-made NFC tag is developed with a ferrite and aluminum multilayer complex to neutralize eddy currents, embedded in a cavity and encapsulated with resin, integrated into metallic coins or medals, linked to a blockchain for secure digital certificates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an NFC tag is integrated into a metallic coin or medal, then digital certificates and dynamic data exchange are enabled, but eddy currents generated by the metallic object interfere with the NFC tag's operation, rendering it inoperable
Solution Approach 1:
A non-conductive intermediary material (resin or plastic) is introduced between the NFC tag and the metallic coin body. This intermediary layer prevents direct electrical contact between the NFC antenna and the conductive metal, thereby blocking eddy current generation while allowing the NFC tag to maintain its digital certificate and data exchange functions
Solution Approach 2:
The NFC tag is extracted from direct integration with the metallic structure and placed in a separate non-conductive housing or cavity within the coin. This spatial separation removes the harmful electromagnetic interaction between the NFC tag and the conductive metal, resolving the reliability issue while preserving adaptability
2Loss of information
If a QR code is used for identification, then the coin can store information, but the QR code only allows single response and is limited in information capacity and complexity
Solution Approach 1:
The information storage medium transitions from a static QR code with fixed parameters to a dynamic NFC tag that can change its response parameters based on reader requests. The NFC tag can provide different levels of information (basic identification, detailed certificates, dynamic data) depending on the interaction context, thereby increasing both information capacity and response versatility
3Device complexity
If the NFC tag is directly integrated into the metallic object, then the structure is simplified, but the metallic object generates eddy currents that degrade NFC performance
Solution Approach 1:
The coin structure becomes a composite object combining metallic material (for aesthetic and durability properties) with non-conductive material (resin or plastic housing the NFC tag). This composite structure allows the metal to maintain its traditional functions while the non-conductive portion provides an electromagnetically benign environment for the NFC tag, resolving the communication reliability issue without significantly increasing overall structural complexity
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
Enables secure, tamper-proof digital certificates and dynamic data exchange via blockchain, overcoming QR code limitations and NFC interference in metallic objects, allowing complex and readable data storage.
Implementation Method 1
NFC tags in metallic objects face interference issues due to eddy currents
Implementation Method 2
The NFC (Near Field Communication) system is a subset of RFID technology based on passive communication via a magnetic field
Data Source
Figure 1~2B
AI summary
The invention relates to a metallic device (100), of the medal or coin type, comprising an NFC (“Near Field Communication”) electronic tag element (110) housed in a cavity, encapsulated with resin and integrated into a ferrite complex (120) within said metallic device (100), and further comprising an aluminum layer (130) located under the ferrite complex (120).