Adaptive Recharge Model for Implantable Medical Devices

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Solution Overview

Problem

Existing systems for recharging implantable medical devices with rechargeable power sources are inaccurate due to variations in inductive energy transfer caused by patient positioning and physiological changes, leading to inconsistent estimates of recharging time.

Innovation Solution

A system that adapts the recharge model by comparing estimated and actual recharging times, updating the model based on patient-specific factors such as positioning habits and physiological changes, to provide more accurate estimates of recharging duration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a predetermined recharge model is used to estimate recharging time, then the estimation process is simple and quick, but the accuracy of the time estimate deteriorates due to variations in patient positioning and physiological changes

Engineering Contradiction:

Improverecharging time estimate accuracyVSAvoidrecharge model complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system measures actual recharging time during charging sessions and uses this feedback to update the predetermined recharge model. The model is adjusted based on the difference between estimated and actual times, incorporating patient-specific factors such as positioning habits and physiological changes, thereby improving estimation accuracy over time without requiring complex real-time calculations

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary measurements of inductive energy transfer characteristics before actual charging sessions. These preliminary data are used to initialize and continuously refine the recharge model, allowing the system to account for patient-specific variations in coil positioning and tissue properties before they affect charging accuracy

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If the external charger is held in a consistent position for optimal energy transfer, then the inductive energy transfer efficiency is maximized, but the ease of operation deteriorates as the patient must maintain a fixed position

Engineering Contradiction:

Improveinductive energy transfer efficiencyVSAvoidcharger positioning flexibility

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The recharge model is made dynamic by continuously updating it with actual charging data from each session. This allows the system to adapt to varying patient positioning and physiological conditions over time, maintaining accurate time estimates even when the external charger position changes, thereby providing positioning flexibility without sacrificing energy transfer efficiency

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If the recharge model is updated frequently to improve accuracy, then the measurement precision improves, but the loss of time increases due to continuous model adjustments

Engineering Contradiction:

Improverecharging time estimate accuracyVSAvoidtime for model updates

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The recharge model is updated periodically based on accumulated charging data rather than continuously during each session. The system collects actual charging times and model predictions over multiple sessions, then performs model updates at appropriate intervals, balancing accuracy improvement with minimal time loss and avoiding unnecessary computational overhead

Inventive Principle:

Principle #19Periodic 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

The system progressively improves the accuracy of recharging time estimates by continuously updating the model, reflecting changes in patient behavior and physiological changes, resulting in more reliable and consistent charging sessions.

Implementation Method 1

An external power source may then be used to recharge the rechargeable battery, commonly transcutaneously via an inductive link between an external coil and an internal coil

Methodology Applied

Scientific EffectInductive energy transfer: Electromagnetic Induction

Data Source

PatentUS8193766B2Time remaining to charge an implantable medical device, charger indicator, system and method therefore

Publication Date: 2012.06.05 MEDTRONIC INC

AI summary

System and method for estimating a time to recharge a rechargeable power source of an implantable medical device. A plurality of measured parameters relating to the implantable medical device and an external charging device are applied to a model of recharging performance and an estimate is provided to a patient, perhaps in advance of charging. Once charging has begun, updated estimates can be provided until charging is complete. Once charging is complete, the model may be updated to reflect any differences in the estimated time to complete charging and the actual time required to complete charging. The model may be based on limitations to the rate at which charge may be transferred to the rechargeable power source over a plurality of intervals.