Dual-Coil Telemetry Circuit for Implantable Medical Devices

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Solution Overview

Problem

The existing communication circuitry in implantable medical devices, such as spinal cord stimulation systems, faces challenges in optimizing the number of turns in telemetry coils for both transmission and reception, leading to suboptimal distances for reliable two-way communication between the external controller and the implantable pulse generator.

Innovation Solution

The use of two LC circuits with separate coils in either the external controller or the implantable pulse generator, where only one coil is used for transmission and both coils are used in series for reception, allowing for optimized coil configuration for each function without affecting the resonant frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a single telemetry coil is used for both transmission and reception in implantable medical devices, then the device structure remains simple, but the communication distance is suboptimal because the same coil cannot be optimized for both functions simultaneously

Engineering Contradiction:

Improvecommunication distanceVSAvoidcoil configuration

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The single telemetry coil is segmented into two separate coils: a first coil dedicated to transmission and a second coil dedicated to reception. This segmentation allows each coil to be independently optimized for its specific function, thereby extending the communication distance while maintaining manageable device complexity through modular architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The implantable medical device is designed with multi-functionality by incorporating both transmission and reception capabilities using separate coils. The system can operate in different modes (transmission-only, reception-only, or simultaneous) depending on the communication needs, providing universal adaptability while resolving the contradiction between communication performance and device simplicity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If the number of turns in the telemetry coil is increased to improve reception sensitivity, then reception distance improves, but transmission performance deteriorates due to increased resistance and reduced current

Engineering Contradiction:

Improvereception sensitivityVSAvoidtransmission current

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The coil system is segmented into a first coil with fewer turns optimized for transmission (maintaining low resistance and high current) and a second coil with more turns optimized for reception (achieving high sensitivity). This segmentation resolves the contradiction by allowing each coil to have different turn counts tailored to its specific function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different local qualities are applied to different coils: the first coil has local quality characteristics suited for transmission (lower turns, lower resistance), while the second coil has local quality characteristics suited for reception (higher turns, higher sensitivity). This local optimization resolves the contradiction between transmission power and reception sensitivity.

Inventive Principle:

Principle #3Local quality

3Power

If the number of turns in the telemetry coil is decreased to improve transmission current, then transmission distance improves, but reception sensitivity deteriorates due to reduced induced voltage

Engineering Contradiction:

Improvetransmission currentVSAvoidreception sensitivity

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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 extends the range of two-way communication between the devices, maintaining optimal transmission distances while improving reception distances, thus enhancing the reliability and effectiveness of data transfer.

Implementation Method 1

Two coils (antennas) are generally present in the IPG 10: a telemetry coil 36 used to transmit/receive data to/from an external controller 50

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The use of two LC circuits with separate coils in either the external controller or the implantable pulse generator

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9067072B2Switchable dual-coil communication circuitry for extending communication range in an implantable medical device system

Publication Date: 2015.06.30 BOSTON SCI NEUROMODULATION CORP

AI summary

Two LC circuits (each with its own coil) are used in either or both of an external controller or an implanted medical device to extend the range at which the two devices can communicate. Only one of the LC circuits (i.e., one of the coils) is used when the device is transmitting, while both LC circuits (i.e., both coils) are used when the device is receiving. When receiving, the LC circuits are preferably connected in series. The series connection of the LC circuits does not affect the resonant frequency, and thus this resonant frequency is the same for both transmission and reception despite the different LC circuits used. Switching circuitry is controlled to disconnect one of the LC circuits when the device is transmitting, and to connect the LC circuits in series during reception.