Multilayer Titanium Nitride Coating for Implantable Devices

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Solution Overview

Problem

Implantable medical devices (IMDs) face challenges in reducing post-shock recovery time while maintaining capacitance and improving color and abrasion characteristics, as previous approaches with single titanium nitride layers either prioritize capacitance or surface properties, but not both.

Innovation Solution

A conductive coating comprising a layer of large grain titanium nitride and a layer of small grain titanium nitride is applied to the IMD, including an adhesion layer, a titanium nitride base layer, a titanium intermediate layer, and a titanium nitride top layer, which increases surface area and enhances electrical properties, reducing impedance and improving post-shock recovery time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a single homogenous titanium nitride layer with coarse grain structure, large branching and high porosity is used, then capacitance is increased, but color and abrasion characteristics deteriorate

Engineering Contradiction:
ImprovecapacitanceVSAvoidcolor and abrasion characteristics
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The coating is divided into multiple distinct layers with different grain structures. The base layer has large grain size and high porosity for capacitance, while the top layer has fine grain size and low porosity for color and abrasion resistance. This segmentation allows each layer to optimize for its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the coating have different properties tailored to their functional requirements. The base layer region is designed with large grains and high porosity to maximize capacitance, while the top layer region is designed with fine grains and low porosity to maximize color stability and abrasion resistance. Each local region has optimized quality for its specific purpose.

Inventive Principle:
Principle #3Local quality

2Reliability

If a single homogenous titanium nitride layer with fine grain structure, limited branching and dominantly columnar structure is used, then color and abrasion characteristics are improved, but capacitance decreases

Engineering Contradiction:
Improvecolor and abrasion characteristicsVSAvoidcapacitance
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The coating is divided into multiple distinct layers with different grain structures. The base layer has large grain size and high porosity for capacitance, while the top layer has fine grain size and low porosity for color and abrasion resistance. This segmentation allows each layer to optimize for its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the coating have different properties tailored to their functional requirements. The base layer region is designed with large grains and high porosity to maximize capacitance, while the top layer region is designed with fine grains and low porosity to maximize color stability and abrasion resistance. Each local region has optimized quality for its specific purpose.

Inventive Principle:
Principle #3Local quality

3Reliability

If the coating surface area is increased to decrease impedance and improve post-shock recovery, then electrical properties are improved, but manufacturing complexity increases

Engineering Contradiction:
Improvepost-shock recovery timeVSAvoidcoating structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The coating is divided into multiple distinct layers with different grain structures. The base layer has large grain size and high porosity for capacitance, while the top layer has fine grain size and low porosity for color and abrasion resistance. This segmentation allows each layer to optimize for its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The coating uses a composite structure combining titanium nitride layers with different grain sizes and porosity characteristics. This composite approach integrates multiple material properties within a single coating system, achieving enhanced electrical performance and durability while maintaining a manageable manufacturing process through sequential deposition.

Inventive Principle:
Principle #40Composite materials

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 coating decreases post-shock recovery time while maintaining desirable color and abrasion characteristics, allowing IMDs to rapidly resume sensing cardiac or neurological signals after therapy delivery.

Implementation Method 1

The coating can include an adhesion layer formed on at least a portion of the metallic outer surface

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

a titanium nitride base layer formed on at least a portion of the adhesion layer, a titanium intermediate layer formed on at least a portion of the titanium nitride base layer, and a titanium nitride top layer formed on at least a portion of the titanium intermediate layer

Methodology Applied
Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Data Source

PatentEP3113840B1Implantable medical device having a conductive coating
Publication Date: 2018.12.19 CAMERON HEALTH INC
  • EP3113840B1 patent drawingFigure 1
  • EP3113840B1 patent drawingFigure 2~3
  • EP3113840B1 patent drawingFigure 4~5

AI summary

An implantable medical device including a coating and associated method are disclosed. The implantable medical device can include a metallic housing. An adhesion layer formed on at least a portion of the metallic housing. A titanium nitride base layer formed on at least a portion of the adhesion layer. An intermediate layer formed on at least a portion of the titanium nitride base layer, and a titanium nitride top layer formed on at least a portion of the intermediate layer.