Implantable Device Housing Temperature Estimation During Charging
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges in accurately measuring the temperature of external portions, particularly the housing, which is in contact with patient tissue, due to the difficulty in directly sensing temperatures and the potential for undesirable heat transfer during charging processes.
Innovation Solution
A system that uses temperature sensors disposed within the IMD to estimate the external temperature based on a dynamic transfer function operating in the time-domain, allowing for control of the charging process to maintain safe temperatures and prolong device longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are disposed within the internal portion of the device to enable temperature monitoring, then the reliability of temperature measurement is improved, but the measurement precision of external portion temperature deteriorates due to inability to directly sense external temperature
Solution Approach 1:
The patent uses an algorithm as an intermediary to estimate external temperature based on internal temperature measurements. The algorithm incorporates the sensed internal temperature and applies a dynamic transfer function to calculate the temperature difference between internal and external portions, thereby deriving the external temperature without direct sensing.
Solution Approach 2:
The patent replaces the physical temperature sensor on the external surface with a computational model. Instead of using a mechanical/physical sensing system on the external housing, the system uses mathematical algorithms and transfer functions to substitute for the direct measurement capability.
2Ease of operation
If wireless charging is performed via inductive coupling to enable convenient charging of the implanted device, then the ease of operation is improved, but the temperature of the external housing increases causing harmful heat transfer to patient tissue
Solution Approach 1:
The patent implements a feedback control system where the estimated external temperature is continuously monitored and used to adjust the charging process. When the estimated temperature approaches unsafe thresholds, the system automatically reduces or terminates charging power to prevent harmful heat transfer to patient tissue.
Solution Approach 2:
The patent performs preliminary temperature estimation before dangerous heat buildup occurs. By continuously estimating external temperature during charging and comparing it against predetermined thresholds, the system takes preventive action by adjusting charging parameters before harmful temperatures are reached.
3Productivity
If the external housing temperature is allowed to increase during charging to improve charging speed, then the productivity is improved, but the patient safety deteriorates due to potential tissue damage from excessive heat
Solution Approach 1:
The patent employs dynamic temperature thresholds and adaptive charging control. Rather than using fixed temperature limits, the system dynamically adjusts charging parameters based on real-time estimated temperature, allowing higher temperatures when safe and reducing temperatures when approaching safety thresholds, thereby optimizing both charging speed and patient safety.
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
Effectively estimates external temperatures of IMDs, preventing undesirable heat transfer and ensuring patient safety by dynamically adjusting the charging process based on internal temperature data, thereby extending the operational life of the device.
Implementation Method 1
determining, via at least one temperature sensor, a temperature of a first portion of a device
Implementation Method 2
the algorithm is representative of an estimated temperature difference between the first portion of the device and the second portion of the device
Implementation Method 3
A transcutaneous charging may be performed via an inductive coupling between a charging coil of the medical device and a corresponding charging coil of the external charging device
Data Source
AI summary
Techniques for estimating the temperature of an external portion of a medical device are described. In an example, processing circuitry may determine a temperature sensed by at least one temperature sensor of an internal portion of the device, and determine, based on an algorithm that incorporates the temperature of the internal portion of the device, an estimated temperature of a second portion of the device, wherein the algorithm is representative of an estimated temperature difference between the first portion of the device and the second portion of the device based at least in part on a dynamic transfer function that operates in a time-domain.