External Charger With Three-Axis Magnetic Sensor for IMD Positioning
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Solution Overview
Problem
Existing external chargers for implantable medical devices lack the ability to accurately discern the relative position of the device in three-dimensional space, leading to inefficient charging due to misalignment or deep implantation, which affects coupling and charging efficiency.
Innovation Solution
An improved external charger equipped with a three-axis magnetic field sensor and control circuitry that determines the position of the implantable medical device in three-dimensional space using measurements from the sensor, allowing for real-time adjustments to ensure optimal alignment and power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional external chargers without position sensing are used, then the device structure remains simple, but charging efficiency deteriorates due to misalignment or deep implantation
Solution Approach 1:
The patent replaces mechanical alignment methods with magnetic field-based sensing. A three-axis magnetic field sensor detects the magnetic field generated by the implantable device to determine its position in three-dimensional space, eliminating the need for mechanical alignment mechanisms while improving charging efficiency.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the external charger and the implantable device. The magnetic field sensor detects the device's position through the magnetic field it generates, enabling indirect position detection without direct contact or complex mechanical interfaces.
2Measurement precision
If magnetic field sensing is added to determine device position, then positioning precision is improved, but device complexity increases due to additional sensors and control circuitry
Solution Approach 1:
The implantable device itself generates the magnetic field that serves as the sensing signal. The external charger's magnetic field sensor detects this self-generated field to determine position, eliminating the need for separate signaling mechanisms and reducing overall system complexity.
Solution Approach 2:
The magnetic field generated by the implantable device serves multiple functions: it enables wireless power transfer and simultaneously provides positioning information for alignment. This multi-functionality reduces the need for separate systems and minimizes overall complexity.
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 solution enables precise positioning and alignment of the charger relative to the implantable medical device, enhancing charging efficiency by ensuring adequate power transfer and indicating misalignment or deep implantation, thereby improving the overall charging process.
Implementation Method 1
a three-axis magnetic field sensor within the charging coil... determine a position of the IMD in three-dimensional space using measurements provided by the three-axis magnetic field sensor
Implementation Method 2
a charging coil configured when excited to provide a magnetic charging field
Data Source
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AI summary
An external charger for an implantable medical device (IMD) is disclosed including a three- axis magnetic field sensor at the center of a primary charging coil. The sensor first senses a magnetic charging field produced by the coil with no IMD present (vector A). The sensor then senses the field in useful operation when such field is being provided to the IMD (vector B). From these vectors, a vector C is calculated representing the magnetic field reflected from the IMD. Vector C can be used to determine a vector D, representing the position of the IMD in physical space relative to the external charger. Information comprising one or more volumes can be stored in the external charger, and compared with vector D to determine whether charger-to-IMD positioning will provide an adequate amount of power to the IMD, and/or to provide an indication of charger-to-IMD alignment.