Silicon Nitride Laser Cladding for Stable Implant Osseointegration

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Solution Overview

Problem

Current surface functionalization methods for ceramics, biometals, and biopolymers, such as zirconia, titanium, and polyethylene, are inadequate for promoting effective osteointegration and bone tissue formation.

Innovation Solution

A method of laser cladding silicon nitride on the surface of biomedical implants, involving roughening the surface, applying silicon nitride powder, and using a laser to bond the powder to the substrate, repeated multiple times to achieve a thickness of at least 10 μm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If conventional surface functionalization methods (sandblasting, acid etching, coatings) are used on zirconia, titanium, and biopolymers, then surface roughness is improved, but bone tissue adhesion and osseointegration remain insufficient

Engineering Contradiction:

Improvesurface roughnessVSAvoidbone tissue adhesion

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The patent applies laser cladding with silicon nitride to fundamentally change the surface chemical composition and physical structure, transitioning from mere roughness modification to creating a bioactive surface layer that chemically promotes bone adhesion through silicon release and surface chemistry modification

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite surface structure by cladding silicon nitride onto the substrate (zirconia, titanium, or biopolymer), forming a multi-material surface that combines the mechanical properties of the substrate with the bioactive properties of silicon nitride

Inventive Principle:

Principle #40Composite materials

2Strength

If zirconia is sintered at high temperature to achieve tetragonal phase stability, then fracture toughness is improved, but low-temperature degradation in humid environments occurs

Engineering Contradiction:

Improvefracture toughnessVSAvoidresistance to low-temperature degradation

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent acknowledges that zirconia's inherent brittleness and LTD susceptibility are unavoidable material characteristics, but converts this challenge into an opportunity by applying a silicon nitride coating that provides the desired bioactivity and mechanical properties without exposing the zirconia substrate to degrading environments

Inventive Principle:

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

3Reliability

If titanium implants are functionalized with calcium phosphate or hydroxyapatite coatings, then osseointegration is improved, but coating delamination occurs at the interface

Engineering Contradiction:

ImproveosseointegrationVSAvoidcoating interface stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent replaces the mechanical bonding approach of conventional coatings with laser cladding, which uses laser energy to melt and fuse the silicon nitride powder to the substrate, creating a metallurgical or ceramic bond that is significantly stronger and more stable than conventional coating adhesion

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the bonding mechanism from physical adhesion (conventional coatings) to laser-induced fusion bonding, fundamentally altering the interface stability through thermal processing and material fusion

Inventive Principle:

Principle #35Parameter changes

4Reliability

If laser cladding is applied to achieve sufficient coating thickness (≥10 μm) for bone tissue integration, then osseointegration is improved, but manufacturing complexity and processing time increase

Engineering Contradiction:

ImproveosseointegrationVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary surface roughening before laser cladding to enhance surface area and mechanical interlocking, which improves coating adhesion and allows for more effective bone integration at the achieved coating thickness

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses continuous laser cladding processing to build up the silicon nitride coating to the required thickness in a controlled, systematic manner, ensuring uniform coverage and consistent bioactive properties throughout the coating layer

Inventive Principle:

Principle #20Continuity of useful action

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 laser-cladded silicon nitride coating enhances bone tissue production, increases osteocalcin and osteopontin distributions, and improves the osseous integration of biomedical implants, leading to better bone formation and integration with human tissue.

Implementation Method 1

laser cladding a coating of silicon nitride on the at least one roughened surface

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

laser cladding may include directing a laser beam to at least one roughened surface of the biomedical implant

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS12239761B2Methods of silicon nitride laser cladding

Publication Date: 2025.03.04 SINTX TECH INC

AI summary

Disclosed herein are methods for laser cladding a coating the surface of a biomedical implant. The biomedical implant may be an implant with a laser-cladded silicon nitride coating for promoting osteogenesis.