Polymeric Surgical Implant Multi-Layer Coating Osseointegration
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Solution Overview
Problem
Polymeric surgical implants, such as those made from PEEK, face challenges in osseointegration due to poor compatibility with soft and hard tissues, leading to potential migration or loosening, and existing surface modification techniques like titanium oxide coatings may not ensure adequate anchoring or maintain polymer properties.
Innovation Solution
A surgical implant with a substrate coated by a plurality of layers, including an activated substrate surface layer, a valve metal layer, and a porous valve metal oxide layer, where the valve metal layer is between the activated substrate and the porous oxide layer, with optional buffer and conductive layers, to enhance osseointegration and tissue compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick coating of titanium oxide powder is applied using vacuum plasma spray (VPS), then the bioactivity of the implant surface is improved, but the high process temperature deteriorates the properties of the polymer substrate
Solution Approach 1:
The coating is divided into multiple thin layers (typically 3-10 layers of 50-200 nm each) rather than one thick layer, allowing lower temperature deposition that does not damage the polymer substrate while still achieving the desired coating thickness and bioactivity
Solution Approach 2:
The deposition temperature parameter is changed from high (VPS) to low (PVD), and the layer thickness parameter is changed from thick (200 μm) to thin (50-200 nm per layer), resolving the contradiction between achieving bioactivity and protecting the polymer from thermal damage
2Reliability
If a thick VPS coating is applied, then the surface bioactivity is enhanced, but the fine structure of the implant surface is leveraged out
Solution Approach 1:
The coating is segmented into multiple thin layers that preserve the underlying fine surface structure rather than obscuring it with a thick coating, maintaining both bioactivity and surface geometry
Solution Approach 2:
The thin PVD coating maintains the local surface features and fine structures of the implant while providing the necessary bioactive surface properties, allowing both requirements to coexist
3Ease of manufacture
If titanium PVD thin layers are applied, then the coating process is simple and temperature-controlled, but the layers are dense and thin (approximately 1 micrometer or less) which is not satisfactory for implants
Solution Approach 1:
The coating is designed to be porous rather than dense, with controlled porosity (30-70%) and appropriate thickness (5-20 μm) to enable tissue ingrowth and improve implant reliability, while still using controlled PVD processes for manufacturing
Solution Approach 2:
The coating is structured as a composite of multiple materials (e.g., TiN, CrN, TiO2, Cr2O3) in alternating layers, combining the benefits of different materials to achieve both manufacturability and the required porosity/thickness for implant performance
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 multi-layered coating significantly improves the osseointegration of polymeric implants by creating a porous structure that enhances tissue anchoring and compatibility, addressing the limitations of existing surface modification techniques while maintaining the properties of the polymer substrate.
Implementation Method 1
a porous valve metal oxide layer, wherein the valve metal layer is disposed between the activated substrate layer and the porous valve metal oxide layer
Data Source
AI summary
A surgical implant comprising: a substrate having an exterior surface and a plurality of layers disposed over the substrate exterior surface. The substrate comprises a polymeric material, and the plurality of layers comprises: an activated substrate surface layer; a valve metal layer; and a porous valve metal oxide layer, wherein the valve metal layer is disposed between the activated substrate layer and the porous valve metal oxide layer. The disclosure provides for a method for producing a polymeric surgical implant. The exterior substrate surface is treated by one or more processes comprising: plasma activation; electron beam irradiation; ultraviolet light; and low energy Ar+ ion beam irradiation; producing an activated substrate surface layer. A plurality of layers is applied over the activated substrate surface layer. The surface is converted by a spark-anodization process in an alkaline bath containing Ca and P ions into a layer of porous valve metal oxide.