Implantable Charger Housing Temperature Estimation During Charging
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges in accurately monitoring and controlling the temperature of their external housing during charging, as existing temperature sensors are often not thermally coupled to the housing, leading to inaccurate temperature readings and potential tissue damage due to elevated temperatures.
Innovation Solution
A system and method that estimates the temperature of an IMD's housing using temperature sensors not directly thermally coupled to it, employing algorithms and transfer functions to determine temperature differentials, allowing for controlled charging to maintain safe temperatures and reduce charging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are placed inside the IMD housing to monitor temperature during charging, then temperature monitoring capability is provided, but the sensors are not thermally coupled to the housing and thus cannot accurately measure housing temperature
Solution Approach 1:
The patent introduces a thermal coupling structure that acts as an intermediary between the temperature sensor and the housing. This structure thermally connects the sensor to the housing without requiring direct attachment, enabling accurate temperature measurement while maintaining design flexibility and reducing complexity.
2Productivity
If charging power levels are increased to reduce charging time, then charging speed improves, but temperature of the housing and surrounding tissue increases causing safety concerns
Solution Approach 1:
The patent implements a feedback control system that continuously monitors housing temperature during charging and dynamically adjusts charging power levels. When temperature approaches threshold values, the system automatically reduces power to prevent tissue heating, enabling safe and optimized charging operations.
Solution Approach 2:
The charging system transitions from static fixed power levels to dynamic adjustable power levels that adapt in real-time based on temperature conditions. This allows the system to operate at high power when safe and reduce power when temperature thresholds are approached, optimizing both charging speed and safety.
3Measurement precision
If temperature sensors are thermally coupled directly to the housing, then accurate housing temperature measurement is achieved, but the sensors may interfere with housing structure or require additional mounting components
Solution Approach 1:
The thermal coupling structure serves as a mediator that simplifies sensor installation by providing a dedicated mounting interface. This intermediary component eliminates the need for complex sensor-to-housing attachment methods and facilitates easier assembly during manufacturing.
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
Enables accurate temperature monitoring and control of IMD housings during charging, ensuring patient safety and reducing charging duration by allowing higher power levels for extended periods while preventing tissue damage.
Implementation Method 1
sensing, by a temperature sensor, a temperature of an internal portion of an implantable medical device
Implementation Method 2
determining, by processing circuitry and based on the sensed temperature of the internal portion of the implantable medical device and an algorithm, a temperature of a housing
Implementation Method 3
the process of inductive coupling may generate heat within the IMD, for example, by electrical current flowing within electrical components within the IMD as part of the charging process
Implementation Method 4
transcutaneous charging may be performed via inductive coupling between a primary coil in the charging device and a secondary coil in the IMD
Implementation Method 5
Other sources of heating of the IMD, such as eddy currents generated in the external case forming a housing of the IMD
Data Source
AI summary
Devices, systems, and techniques for monitoring the temperature of a device used to charge a rechargeable power source are disclosed. Implantable medical devices may include a rechargeable power source that can be transcutaneously charged. The temperature of an external charging device and/or an implantable medical device may be monitored to control the temperature exposure to patient tissue during a charging session used to recharge the rechargeable power source. In one example, a temperature sensor may sense a temperature of an internal portion of a device, wherein the housing of the device is not directly thermally coupled to the temperature sensor. A temperature for the housing of the device may then be estimated based on the sensed temperature provided by the non-thermally coupled temperature sensor. A processor may then control charging of the rechargeable power source based on the determined temperature for the housing.