Implantable Device Battery Charge Estimation
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Solution Overview
Problem
The capacity of rechargeable power sources in implantable medical devices degrades over time and with use, leading to unpredictable battery life and potential disruption of life-sustaining therapies.
Innovation Solution
A system and method to accurately determine the remaining charge in rechargeable power sources by measuring voltage and charge delivery, accounting for capacity fade due to age and usage, using a model specific to each type of rechargeable power supply to estimate present charge capacity and calculate the recharge interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the rechargeable power source is used continuously without accounting for capacity fade, then the device can operate for extended periods, but the battery life becomes unpredictable and therapy delivery may be disrupted
Solution Approach 1:
The system implements feedback by continuously monitoring the rechargeable power source voltage and comparing it against stored voltage-charge capacity relationships. The electronic componentry receives voltage information from the power source, determines charge capacity based on this voltage, and uses this information to predict remaining battery life and schedule recharges before capacity is depleted, ensuring reliable therapy delivery.
Solution Approach 2:
The system performs preliminary action by storing multiple voltage-charge capacity relationships in memory before the power source degrades. These pre-stored relationships serve as reference data that enable the system to accurately determine present charge capacity and predict battery life without requiring real-time complex calculations or external intervention.
2Measurement precision
If the system monitors voltage continuously to track capacity fade, then accurate charge level information is obtained, but device complexity increases
Solution Approach 1:
The system uses copying by storing multiple voltage-charge capacity relationships in memory as reference data. Instead of implementing complex real-time analysis algorithms, the system creates a simplified copy of the expected voltage-charge relationships under various conditions, allowing accurate charge level determination through simple voltage comparison against these stored reference values.
Solution Approach 2:
The system applies parameter changes by utilizing the relationship between voltage (a easily measurable parameter) and charge capacity. By monitoring voltage changes and comparing them against stored voltage-charge relationships, the system translates a simple voltage measurement into accurate charge capacity information without requiring direct measurement of charge or complex computational parameters.
Data Source
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AI summary
System and method for estimating the time before recharging the rechargeable power source of an implantable medical device. In a method, the present charge level of the power source is determined by determining the percentage of total charge consumed over a period of time. The present charge level is then divided by the expected power use to determine time remaining before recharging. Another method utilizes a model to determine the faded capacity of the rechargeable power source based on the number of times the rechargeable power source has been charged and the duration of the rechargeable power source's life.