Implantable Charger Alignment Using 3D Magnetic Field Sensing
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Solution Overview
Problem
Existing systems for charging implantable medical devices (IMDs) face challenges in accurately aligning external wireless chargers with the IMDs under the skin, leading to inefficient charging, false detection, and heat generation due to improper positioning.
Innovation Solution
A system that includes an external charger device with a primary coil and a magnet, and a user device with a transceiver and magnetic field sensors, which communicate to determine the relative position of the charger in three dimensions and provide visual or audible feedback for alignment, ensuring efficient inductive coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If proximity sensors are used to detect whether the IMD and charger device are within a predetermined range, then the detection capability is improved, but the ability to determine positional relationship and alignment in two or three dimensions deteriorates
Solution Approach 1:
The system divides the detection task into multiple independent magnetic field sensors (e.g., three sensors along orthogonal axes) that each measure magnetic field strength in specific directions. By segmenting the detection function across multiple sensors, the system achieves comprehensive three-dimensional positioning capability while maintaining simple individual sensor operations.
Solution Approach 2:
A magnet is introduced as an intermediary element between the charger device and the IMD. This magnet serves as a reference object that generates a detectable magnetic field, enabling the IMD to determine the relative position and orientation of the charger device through magnetic field measurements without requiring complex direct sensing mechanisms.
2Reliability
If the external charger device is improperly positioned, then false detection and false charging occur, but determining proper alignment is difficult for the patient
Solution Approach 1:
The system implements feedback by having the IMD continuously measure magnetic field strength from the magnet and communicate this information to the charger device or user interface. This feedback enables real-time monitoring of alignment status and provides guidance for adjusting the charger device position to achieve optimal alignment, thereby improving both reliability and ease of operation.
Solution Approach 2:
The patent replaces mechanical alignment indicators or visual markers with a magnetic field-based detection system. The magnet generates a magnetic field that can be detected and measured electronically, substituting mechanical positioning methods with a more precise and easily measurable magnetic field approach that simplifies the alignment process for the user.
3Loss of energy
If improper positioning occurs, then charging power consumption increases and heat is generated on undesired metal surfaces
Solution Approach 1:
The system performs preliminary alignment verification by measuring magnetic field strength and determining relative position before initiating the charging process. This preliminary action ensures that the charger device is properly aligned with the IMD, preventing inefficient charging, excessive power consumption, and heat generation on undesired metal surfaces by establishing correct positioning in advance.
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 solution enables precise alignment of the charger device with the IMD, improving charging efficiency, reducing false detection and heat issues, and ensuring reliable power transfer.
Implementation Method 1
at least one magnet having a static magnetic field, wherein the at least one magnet is positioned in proximity to the primary coil
Implementation Method 2
an inductive coil that enables power to be wirelessly transferred, through the patient's skin, from the charger device to an inductive coil in the IMD
Data Source
AI summary
A magnetic field sensor is positioned in proximity to a charging coil in an implantable medical device (IMD). An external device for charging the IMD includes a primary coil and a magnet positioned in proximity to the primary coil. The magnetic field sensor in the IMD detects a static magnetic field of the magnet and provides measurements proportional to the static magnetic field along three axes. These measurements of the static magnetic field are used to determine whether the external device is aligned with the IMD for charging. These measurements of the static magnetic field may also be processed to determine a position of the charger device relative to the IMD in three dimensions. When misaligned, a direction may be generated for a user to reposition the charger device to improve alignment.