Implantable Device Battery Capacity Determination via RF Voltage Drop
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Solution Overview
Problem
Existing methods for determining the usable capacity of active implantable medical device batteries with RF communication functionality are inadequate, as they rely on manufacturer-provided data that does not account for dynamic current profiles, leading to overestimation or underestimation of battery life, potentially compromising device operation during RF communication.
Innovation Solution
A method that utilizes the instantaneous voltage drop during a short current draw to determine battery capacity, allowing for regular monitoring of battery longevity without significantly impacting battery life, using a pulse of shorter duration than RF data transmission to measure high and low peak voltages and compare them to a predetermined threshold, ensuring reliable communication and alerting medical personnel of battery depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manufacturer-provided battery data (voltage at rest and voltage under strong current) is used to determine usable capacity, then the determination process is simple, but the result is inaccurate because it does not account for dynamic current profiles during RF communication
Solution Approach 1:
The patent changes the measurement parameters from static manufacturer data to dynamic in-device measurements. Specifically, it measures voltage during actual RF communication operation and calculates voltage drop (ΔV) under dynamic current profiles, rather than relying on fixed voltage-at-rest and voltage-under-strong-current specifications. This parameter transformation enables accurate determination of usable capacity while maintaining operational simplicity.
2Measurement precision
If continuous monitoring of battery voltage or impedance during RF communication is performed to check threshold, then real-time battery status is known, but the device cannot provide accurate residual longevity information between monitoring sessions lasting months or years
Solution Approach 1:
The patent performs preliminary characterization of the battery's voltage drop behavior during RF communication at the time of implantation or during initial device setup. By measuring and storing the relationship between current draw and voltage drop (ΔV) under various RF communication conditions, the device establishes a reference profile that can be used to predict remaining longevity without requiring continuous monitoring. This preliminary action enables accurate residual capacity calculation years later when the battery is depleted.
3Reliability
If manufacturer data with considerable margins is used to ensure safe operation, then device reliability is improved, but the usable capacity is seriously affected and RF communication may be interrupted prematurely
Solution Approach 1:
The patent implements feedback by continuously measuring the actual voltage drop (ΔV) during RF communication operations and comparing it against the characterized battery behavior. This feedback mechanism allows the device to dynamically determine when the battery reaches its usable capacity limit based on real-time performance data rather than relying on conservative manufacturer margins. The feedback loop enables precise tracking of battery depletion and timely notification to practitioners without premature interruption of RF communication.
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 optimizes battery longevity by avoiding excessive margins in usable capacity calculations, enabling daily monitoring of battery state and ensuring continued RF communication functionality until the battery can no longer transmit data, thus preventing device malfunction.
Implementation Method 1
a battery (26) to enable the RF communication unit (24) to transmit data
Implementation Method 2
The instantaneous drop observed is mainly linked to the resistive part of the battery
Data Source
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AI summary
The present invention relates to a method for determining the usable capacity of a battery of an implantable active medical device, in particular a pacemaker, comprising a radio frequency (RF) communication unit for transmitting data for a duration of RF transmission, and wherein the battery of the implantable active medical device enables the transmission of data by RF through the RF communication unit, the method comprising a) a step of measuring a voltage value VBi representative of an instantaneous drop of a voltage dVBi of the battery of said device following a stress on the battery, b) a step of comparing said voltage VBi of the battery to a predetermined voltage threshold VBs, and c) a step of transmitting an alert message to another device when said measured voltage VBi of the battery crosses the predetermined voltage threshold VBs.The invention also relates to an implantable medical device performing the process.