Shielding Coil for Implantable Device Telemetry Noise Reduction

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Solution Overview

Problem

Electromagnetic interference from capacitive coupling between metallic housings and telemetry antennas in implantable medical devices, such as pacemakers and defibrillators, poses a significant challenge in maintaining reliable performance, with existing conductive shields being difficult to work with and unreliable.

Innovation Solution

A shielding coil is disposed between the housing and the telemetry antenna, with one end electrically terminated in the device's circuitry, providing a simple and effective mechanism to reduce noise interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conductive spray coating or adhesive conductive shields are used to surround the telemetry antenna, then electromagnetic noise shielding is improved, but manufacturing difficulty and reliability issues increase

Engineering Contradiction:

Improveelectromagnetic noise interferenceVSAvoidmanufacturing difficulty

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

A coil shield is introduced as an intermediary component between the telemetry antenna and the housing. This coil shield serves as a mediator that blocks electromagnetic noise from reaching the antenna, while being easier to manufacture and more reliable than conductive spray coatings or adhesive shields.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical form and electrical properties of the shielding material from conductive coatings/adhesives to a coil structure with specific inductance values (0.5-5 microhenries). This parameter change enables the shield to be both effective against electromagnetic interference and easier to manufacture with consistent results.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If conductive spray coating or adhesive conductive shields are used to surround the telemetry antenna, then electromagnetic noise shielding is improved, but reliability and variability increase

Engineering Contradiction:

Improveelectromagnetic noise interferenceVSAvoidshielding reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The coil shield acts as a reliable intermediary component with defined electrical characteristics (inductance between 0.5-5 microhenries). Unlike variable conductive coatings, the coil shield provides consistent and predictable shielding performance across all devices, improving reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of using conductive materials to create a Faraday cage, the invention inverts the approach by using an inductive coil structure that generates a magnetic field to counteract electromagnetic noise. This inverted approach provides more reliable and consistent shielding.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If a coil shield is disposed between the housing and telemetry antenna, then manufacturing ease and reproducibility are improved, but device complexity increases

Engineering Contradiction:

Improvemanufacturing easeVSAvoiddevice complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The coil shield serves multiple functions: it provides electromagnetic noise shielding, acts as an inductive element that can be tuned to specific frequencies, and can be integrated with existing device components. This multi-functionality justifies the added complexity by eliminating the need for separate shielding materials.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

By specifying a narrow range of inductance values (0.5-5 microhenries), the invention standardizes the coil shield parameters, making it easier to manufacture reproducibly while controlling the complexity through defined electrical characteristics rather than open-ended design parameters.

Inventive Principle:

Principle #35Parameter changes

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

This approach results in a reproducible and reliable noise reduction of up to 40 dB, improving the performance of telemetry systems in implantable medical devices.

Implementation Method 1

employing conductive spray coating or adhesive conductive shields to surround the inductive telemetry antenna coil in a Faraday cage like manner

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

capacitive coupling between metallic housings of implantable medical devices and inductive coils, such as telemetry antennas, disposed within the housings

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 3

inductive coils, such as telemetry antennas

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS7912551B2Telemetry noise reduction

Publication Date: 2011.03.22 MEDTRONIC INC

AI summary

A device includes a housing and electronics disposed in the housing. A telemetry antenna is disposed in the housing and is operably coupled to the electronics. A shielding coil is disposed between the housing and the telemetry antenna. The shielding coil has a first end and a second end. The second end is electrically terminated in circuitry of the electronics.