Zinc-Silver Alloy Stent for Controlled Biodegradation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current biodegradable stents face issues with mechanical stability, rapid dissolution, and hydrogen release, which can lead to undesirable effects in the body, necessitating the development of a material with improved properties for medical implants.

Innovation Solution

A biodegradable alloy composed of high zinc content with added silver, specifically suited for stents, offering enhanced mechanical properties, anti-proliferative effects, and reduced hydrogen evolution, along with improved x-ray visibility, is produced using a method involving melting, vibration, quenching, and aging processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If polymer materials like polylactic acid are used for biodegradable stents, then the stent can be absorbed after fulfilling its function, but the mechanical stability of the stent is compromised

Engineering Contradiction:

ImprovebiodegradabilityVSAvoidmechanical stability

Core Design Contradiction:

Duration of action of stationary objectVSStrength

Solution Approach 1:

The patent uses zinc as the base metal and silver as an additive to create a composite alloy system. The zinc provides biodegradability and biocompatibility, while the silver (0.01-10 wt%) enhances mechanical strength and corrosion resistance, resolving the contradiction between biodegradability and mechanical stability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the silver content parameter within a specific range (0.01-10 wt%) to achieve the desired balance. By controlling this compositional parameter, the alloy achieves both adequate mechanical strength for stent support and controlled biodegradation rate for eventual absorption

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If magnesium-based alloys are used for biodegradable stents, then the dissolution rate is controlled, but hydrogen release occurs which is undesirable in the body

Engineering Contradiction:

Improvedissolution rate controlVSAvoidhydrogen release

Core Design Contradiction:

Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potential harm of hydrogen release into a benefit by using zinc's controlled corrosion behavior. Zinc corrodes to form zinc ions that are naturally excreted through urine, and the alloy's corrosion products form protective layers that prevent excessive hydrogen generation, transforming a harmful effect into a safe degradation process

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The silver component acts as an intermediary that modifies the corrosion mechanism. It slows down the corrosion rate and alters the corrosion products, preventing rapid hydrogen evolution while maintaining controlled biodegradation, thus mediating between the metal's reactivity and biological safety

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If stents are coated with medication to prevent restenosis, then antiproliferative effect is achieved, but the drugs are cytotoxic and require long-term concomitant therapy

Engineering Contradiction:

Improverestenosis preventionVSAvoidcytotoxicity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The zinc alloy stent provides self-service by inherently preventing restenosis through zinc's natural antiproliferative effect on smooth muscle cells. The zinc ions released during controlled corrosion directly inhibit excessive cell growth, eliminating the need for external drug coatings and their associated cytotoxicity and long-term therapy requirements

Inventive Principle:

Principle #25Self-service

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 zinc-silver alloy demonstrates superior mechanical stability, controlled dissolution kinetics, and reduced hydrogen release, ensuring the stent remains effective for 1-2 years without causing tissue damage or embolism, and its high density provides clear x-ray visibility for precise placement.