Implantable Printed Lead Structure for MRI Heating Reduction

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Solution Overview

Problem

Active implantable medical devices (AIMDs) face issues during magnetic resonance imaging (MRI) due to heating and damage caused by MRI fields, particularly due to radiofrequency energy and induced voltage, which can result in tissue burns and implant damage.

Innovation Solution

A method of manufacturing leads for AIMDs involving the deposition of biocompatible, electrically non-conductive material layers to form slots for biocompatible, electrically conductive material, which are retained by interference fit and designed to allow fluid passages for capacitive coupling with surrounding body fluid, reducing heating during MRI exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional conductive leads are used in AIMDs, then electrical connectivity is achieved, but heating and tissue damage occur during MRI exposure

Engineering Contradiction:

Improvesafety during MRIVSAvoidheating and tissue damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The lead incorporates a porous coating layer that allows body fluid to penetrate and establish capacitive coupling with the conductive elements. This porous structure enables the lead to function as an electrode, dissipating RF energy through capacitive coupling rather than conducting it, thereby reducing heating and tissue damage during MRI exposure while maintaining electrical connectivity when implanted.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The lead uses a composite structure combining biocompatible conductive materials (such as platinum or stainless steel) with a porous biocompatible coating material. This composite design allows the lead to exhibit both electrical conductivity for normal operation and capacitive coupling properties for MRI safety, resolving the contradiction between functionality and safety during imaging.

Inventive Principle:

Principle #40Composite materials

2Reliability

If conductive material is exposed to create electrodes, then electrical contact with tissue is improved, but MRI-induced heating increases

Engineering Contradiction:

Improveelectrical contact with tissueVSAvoidRF energy absorption

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The porous coating allows body fluid to penetrate and form capacitive coupling with the conductive elements, enabling the lead to function as an electrode for electrical contact while simultaneously providing a pathway for RF energy dissipation during MRI, thus reducing heating without compromising electrical contact.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The porous coating acts as an intermediary layer between the conductive elements and the tissue environment. It enables capacitive coupling with body fluid to achieve electrical contact while mediating the interaction with RF fields during MRI by allowing energy dissipation, thereby reducing harmful heating effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If lead structure is modified to reduce MRI heating, then safety during imaging improves, but manufacturing complexity increases

Engineering Contradiction:

ImproveMRI safetyVSAvoidlead structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The porous coating can be applied as a surface treatment or deposition layer on existing lead structures, modifying the lead to provide capacitive coupling capability without requiring complete structural redesign. This approach achieves MRI safety while minimizing increases in manufacturing complexity compared to traditional leads.

Inventive Principle:

Principle #31Porous 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 solution effectively reduces heating and damage to AIMDs during MRI by providing an additional electrical path for capacitive coupling with body fluids, ensuring the safety and functionality of the devices during imaging procedures.

Implementation Method 1

the slot is dimensioned to retain the biocompatible, electrically conductive material in the slot by interference fit

Methodology Applied

Scientific EffectInterference fit:

Implementation Method 2

designed to allow fluid passages for capacitive coupling with surrounding body fluid, reducing heating during MRI exposure

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 3

depositing biocompatible, electrically conductive material into the slot

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12121715B2Printed lead

Publication Date: 2024.10.22 SALUDA MEDICAL PTY LTD

AI summary

A method (100) of manufacturing a lead for an implantable medical device. The method includes: depositing (110) a base layer (3) of biocompatible, electrically non-conductive material; depositing (120) one or more complementary layers (5) of biocompatible, electrically non-conductive material to the base layer (3), wherein the base layer (3) and complementary layer (5) form at least one slot (7); and depositing (130) biocompatible, electrically conductive material (9) into the slot (7). There is also disclosed a lead for an implantable medical device and an apparatus (41) to manufacture the lead.