Antimicrobial Set Screw Using Galvanic Ion Elution

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Solution Overview

Problem

Current orthopedic implant devices face challenges in achieving antimicrobial properties without requiring external operations or treatments, leading to increased patient burden due to microbial growth and infection risks.

Innovation Solution

An antimicrobial implant device made from a cobalt-based alloy and a titanium-based alloy, where the two materials form an electric circuit in vivo, allowing antimicrobial metal ions to be eluted from the cobalt-based alloy, providing an antimicrobial surface and surrounding area without external interventions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an implant device is made with antimicrobial metal components, then antimicrobial property is achieved, but device complexity increases due to requiring external power source and terminals

Engineering Contradiction:
Improveantimicrobial propertyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the external power source and terminal components from the antimicrobial implant system. By integrating the power generation function directly into the implant device itself through biocompatible metal components that generate electrical potential差 with body tissues, the system eliminates the need for separate external power sources and terminals, thereby reducing device complexity while maintaining antimicrobial efficacy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the power source function and antimicrobial metal component functions into a single integrated implant device. The biocompatible metals (silver, copper, or their alloys) serve dual purposes: maintaining structural integrity as implant components and generating electrical potential差 with surrounding body tissues to power the antimicrobial function, thereby combining multiple functions into one device and reducing overall system complexity

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If an implant device requires external power source and treatment to achieve antimicrobial property, then antimicrobial property is achieved, but patient burden increases due to external operations needed

Engineering Contradiction:
Improveantimicrobial propertyVSAvoidpatient burden
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements self-service functionality where the implant device autonomously generates its own power through the electrical potential差 created between the biocompatible metal components and surrounding body tissues. The device automatically activates and maintains its antimicrobial function without requiring external power sources, patient operations, or external control, thereby eliminating patient burden while ensuring reliable antimicrobial protection

Inventive Principle:
Principle #25Self-service

3Device complexity

If conventional implant devices are used without antimicrobial treatment, then device simplicity is maintained, but microbial growth and infection risk increase

Engineering Contradiction:
Improvedevice simplicityVSAvoidmicrobial growth
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces traditional mechanical or chemical antimicrobial treatments (such as coatings, heat treatment, or chemical impregnation) with an electrochemical mechanism. The biocompatible metal components generate electrical potential差 with body tissues to drive electrochemical reactions that release antimicrobial metal ions, providing a simpler, more effective antimicrobial mechanism that maintains device simplicity while preventing microbial growth

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 device effectively reduces patient burden by achieving antimicrobial properties upon implantation, significantly decreasing microbial growth and infection risks without the need for external treatments or operations.

Implementation Method 1

An antimicrobial implant device made from a cobalt-based alloy and a titanium-based alloy, where the two materials form an electric circuit in vivo, allowing antimicrobial metal ions to be eluted from the cobalt-based alloy

Methodology Applied
Scientific EffectGalvanic corrosion:

Data Source

PatentEP3424450B1Set screw for antibacterial device to be implanted in vivo
Publication Date: 2021.02.17 MEDTRONIC SOFAMOR DANEK
  • EP3424450B1 patent drawingFigure 1~2
  • EP3424450B1 patent drawingFigure 3~4
  • EP3424450B1 patent drawingFigure 5

AI summary

A set screw for an antimicrobial implant device comprising a set screw body having a screw portion and a head portion wherein the screw portion has a screw groove on the outer surface thereof and the head portion has an opening on the top thereof; and a cap having a leg portion for fitting the opening of the set screw body, wherein at least a surface of the opening of the set screw body and at least a surface of the leg portion of the cap comprise a first material and a second material that have a potential difference; the first material comprises an antimicrobial metal; the second material is nobler than the first material; an electric circuit is formed between the first material and the second material when the set screw is implanted in vivo for use; and ions of the antimicrobial metal are eluted from the first material under a presence of an electrolyte to impart an antimicrobial property to a surface and/or a surrounding area of the first material.