Telemetry Signal Strength for Implantable Medical Device Recharging

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Solution Overview

Problem

Current methods for transcutaneously charging implantable medical devices (IMDs) are inefficient, leading to prolonged charging times, tissue heating, and inconvenience due to suboptimal alignment of external and internal coils, often requiring manual adjustments and measurements that do not occur in real-time.

Innovation Solution

The use of telemetry signal strength to position the primary recharge coil relative to the secondary coil, employing a signal strength map to correlate signal strength with recharge coupling efficiency, allowing for real-time adjustments and efficient energy transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual alignment methods are used to position the primary coil relative to the secondary coil, then coil alignment can be achieved, but the process is time-consuming and does not occur in real-time

Engineering Contradiction:
Improvecoil alignment precisionVSAvoidcharging time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system uses telemetry signal strength as real-time feedback to guide the positioning of the primary coil. The IMD continuously transmits telemetry signals, and the external device measures signal strength to determine optimal coil alignment during the charging process, enabling dynamic adjustment rather than static manual alignment.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces manual mechanical alignment methods with an automated electromagnetic field-based positioning system. Instead of physically adjusting coil positions based on external measurements, the system uses real-time telemetry signal strength measurements to automatically determine optimal alignment, substituting mechanical adjustment with electromagnetic field sensing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Power

If inductive coupling is used for transcutaneous energy transfer, then power can be delivered to the IMD, but tissue heating occurs around the coils

Engineering Contradiction:
Improvepower transfer efficiencyVSAvoidtissue heating
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The system employs real-time feedback through telemetry signal strength measurements to monitor and adjust the charging process. By continuously assessing the coupling efficiency via telemetry signals, the system can optimize power transfer while preventing excessive energy accumulation that would cause tissue heating.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent utilizes changes in telemetry signal strength parameters to dynamically adjust charging conditions. By monitoring signal strength variations in real-time, the system can modulate power delivery parameters to maintain efficient energy transfer while staying within safe thermal limits for surrounding tissue.

Inventive Principle:
Principle #35Parameter changes

3Power

If the IMD uses higher power for therapeutic functions, then therapeutic effectiveness is improved, but the charging time and energy requirements increase

Engineering Contradiction:
Improvetherapeutic power outputVSAvoidrecharge time
Core Design Contradiction:
PowerVSLoss of time

Solution Approach 1:

The real-time telemetry feedback mechanism allows the system to continuously monitor coupling efficiency and adjust charging parameters accordingly. This ensures maximum power transfer efficiency during recharge, reducing the time required to recharge high-capacity batteries needed for high-power therapeutic functions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent enables continuous monitoring and adjustment of the charging process through ongoing telemetry communications. This continuous action ensures that power transfer remains optimized throughout the entire charging cycle, minimizing recharge time for high-power IMDs without interrupting the therapeutic function.

Inventive Principle:
Principle #20Continuity of useful action

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 enables faster, more efficient charging sessions by providing real-time feedback for optimal coil alignment, reducing charging time and tissue heating, and improving the practical use of IMDs with higher power requirements.

Implementation Method 1

The primary coil is driven by the external power source with an alternating current. This induces a current in the secondary coil through inductive coupling.

Methodology Applied
Scientific EffectInductive coupling: Electromagnetic Induction

Implementation Method 2

at least one telemetry signal is transmitted between a telemetry coil of the recharging unit and a telemetry coil of the IMD

Methodology Applied
Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Data Source

PatentEP2279025B1Using telemetry coupling as a surrogate for recharger coupling
Publication Date: 2016.11.23 MEDTRONIC INC
  • EP2279025B1 patent drawingFigure 1
  • EP2279025B1 patent drawingFigure 2
  • EP2279025B1 patent drawingFigure 3

AI summary

Techniques for using telemetry signal strength for positioning a primary recharge coil of a recharging unit at a location proximate to an Implantable Medical Device (IMD) in preparation to recharge a rechargeable power source of the IMD are disclosed. An antenna of the recharging unit is positioned proximate to the IMD, a telemetry session is initiated between the two devices, and a value indicative of the telemetry signal strength is obtained. Using a known correspondence between telemetry signal strength and recharge coupling efficiency for the IMD/recharging unit pair, the telemetry signal strength value is used to determine whether adequate recharge coupling may be achieved between the pair of devices. If so, a recharge session may be established. Otherwise, the antenna is repositioned and the process is repeated. The correspondence between telemetry signal strength and recharge coupling efficiency for the device pair may be developed empirically or using modeling.