RFID Tag Assembly with Conductive Mounting Base for Metal Surfaces

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Solution Overview

Problem

Existing RFID tags for surgical instruments are large, impede surgical instrument use, and have limited communication distance when mounted on metal surfaces, particularly during sterilization and disinfection processes.

Innovation Solution

A method of manufacturing an RFID tag assembly using a mounting base made of electrically conductive material with a passive mount-on-metal RFID tag, where the tag is encapsulated in a moulded cover made of RF-transparent material, ensuring consistent grounding and increased communication distance without mechanical fixing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a passive RFID tag is mounted on a metal surface, then the tag can be used on surgical instruments, but the antenna performance deteriorates and communication distance reduces

Engineering Contradiction:
ImproveRFID tag functionality on metal surfaceVSAvoidcommunication distance
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The patent introduces a mounting base made of electrically conductive material as an intermediary between the RFID tag antenna and the metal surgical instrument surface. This mounting base acts as a mediator that provides consistent electrical grounding and impedance matching, preventing the antenna performance deterioration that would occur from direct mounting on the instrument surface. The mounting base enables reliable RFID communication while maintaining full contact with the metal surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the RFID tag is encapsulated in a moulded cover, then the tag is protected from temperature and humidity environments, but the manufacturing process becomes more complex

Engineering Contradiction:
Improveprotection from temperature and humidityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into a single moulded cover component: protection against temperature and humidity, mechanical securing of the RFID tag to the mounting base, and encapsulation of the entire assembly. This integration reduces the number of separate components and assembly steps, making the manufacturing process more efficient despite the added protection functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent specifies that the moulded cover is made from substantially RF transparent material, changing the material parameter to maintain RFID signal transmission while providing environmental protection. This material selection enables the cover to simultaneously protect the tag assembly and allow wireless communication without interference.

Inventive Principle:
Principle #35Parameter changes

3Volume of moving object

If the RFID tag assembly is made smaller, then it does not impede surgical instrument use, but the manufacturing precision requirements increase

Engineering Contradiction:
ImproveRFID tag assembly sizeVSAvoidmanufacturing precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent integrates the RFID tag, mounting base, and protective cover into a single compact assembly through moulding. This integration eliminates the need for separate mounting hardware and reduces overall assembly size, allowing the RFID tag to be mounted on surgical instruments without impeding their use while maintaining manufacturing feasibility.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If the mounting base is made of electrically conductive material, then consistent grounding is achieved, but the material selection becomes more restricted

Engineering Contradiction:
Improveconsistent groundingVSAvoidmaterial selection flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The mounting base made of electrically conductive material serves multiple functions simultaneously: it provides consistent electrical grounding for the antenna, acts as a mechanical support structure, and serves as a mounting interface for the surgical instrument. This multi-functionality justifies the restriction to conductive materials, as they are necessary to achieve the primary grounding function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 allows for smaller, more efficient RFID tags with improved communication distance and resistance to temperature and disinfection processes, enabling reliable tracking of surgical instruments without mechanical fixing, thus enhancing surgical instrument management.

Implementation Method 1

delivering a substantially RF transparent material in a molten state into the void between the mould tool and the RFID tag-mounting base sub-assembly. The method comprises allowing the substantially RF transparent material to cool into a solid state to thereby form a cover

Methodology Applied
Scientific EffectPhase change (molten to solid): Phase Change

Implementation Method 2

providing a mounting base made of an electrically conductive material... such that the mounting base and the cover together encapsulate the RFID tag

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

delivering a substantially RF transparent material in a molten state into the void... form a cover over the RFID tag-mounting base sub-assembly

Methodology Applied
Scientific EffectRF transparency: Electromagnetic Induction

Data Source

PatentEP3350752B1Method of manufacturing an RFID tag assembly and RFID tag assembly
Publication Date: 2021.12.15 SPA TRACK MEDICAL
  • EP3350752B1 patent drawingFigure 1
  • EP3350752B1 patent drawingFigure 2~3
  • EP3350752B1 patent drawingFigure 4~5

AI summary

A method (10) of manufacturing an RFID tag assembly, the method comprising: providing a mounting base made of an electrically conductive material (12); providing a passive mount-on-metal RFID tag, the RFID tag comprising an IC chip and an antenna provided on one side (12); mounting the RFID tag on the mounting base with said one side of the RFID tag coupled to a the mounting base, to form an RFID tag-mounting base sub-assembly (14); providing a mould tool comprising a mould cavity shaped to form a cover of the RFID tag assembly and locating the RFID tag-mounting base sub-assembly within the mould cavity (16); and delivering a substantially RF transparent material in a molten state into the void between the mould tool and the RFID tag-mounting base sub-assembly and allowing the material to cool into a solid state to form a cover over the RFID tag-mounting base sub-assembly, such that the mounting base and the cover together encapsulate the RFID tag (18). The substantially RF transparent material has a temperature in the molten state on delivery into the void that is higher than a maximum tolerable temperature of the IC chip and the molten material is delivered into the void at a position removed from IC chip. The IC chip position such that the temperature of the molten material does not exceed the maximum tolerable temperature of the IC chip when the substantially RF transparent material reaches the IC chip.