External Charger Adjustable Alignment Indicator
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Solution Overview
Problem
Existing methods for transcutaneously recharging implantable pulse generators, such as those used in spinal cord stimulation systems, face challenges in efficiently aligning the external charger with the implanted device, leading to sub-optimal charging rates and potential misalignment issues, particularly for deeply implanted devices.
Innovation Solution
The method involves transmitting electrical energy at multiple frequencies and measuring the magnitude of the current to determine the optimal frequency for alignment, adjusting the charge strength threshold based on the depth of the implant, and using a binary signal indicator to alert the user of alignment or misalignment, thereby ensuring efficient charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed charge strength threshold is used for alignment indication, then the alignment indicator can be simple to implement, but it generates unnecessary misalignment alerts for deeply implanted devices and fails to provide accurate alignment feedback for varying implant depths
Solution Approach 1:
The charge strength threshold is made dynamic rather than fixed. The system automatically adjusts the threshold based on the detected implant depth, allowing the alignment indicator to adapt to different implantation scenarios. This resolves the contradiction by making the threshold responsive to changing conditions (implant depth) while maintaining automatic operation without manual intervention.
Solution Approach 2:
The system performs self-adjustment of the charge strength threshold based on the detected implant depth. The processor automatically modifies the threshold value without requiring manual calibration or user input, enabling the system to serve itself in adapting to different implant depths. This eliminates the need for complex manual threshold adjustment mechanisms while maintaining high measurement precision.
2Measurement precision
If the external charger uses a single frequency for energy transmission, then the charging system is simpler to operate, but it cannot determine optimal alignment or account for varying implant depths
Solution Approach 1:
The system performs preliminary frequency sweeping before establishing the charging connection. By pre-detecting the optimal frequency range and determining implant depth characteristics during an initial detection phase, the system prepares the charging parameters in advance. This preliminary action enables accurate alignment detection without requiring complex real-time adjustments during charging, maintaining ease of operation.
Solution Approach 2:
The system uses feedback from measuring current magnitude at multiple frequencies to determine the optimal transmission frequency and implant depth. The processor analyzes the feedback signals and automatically adjusts charging parameters based on this information. This feedback mechanism enables precise alignment detection while the automatic adjustment keeps the user interface simple and easy to operate.
3Reliability
If the alignment indicator provides continuous feedback, then the user can maintain optimal alignment, but it may cause unnecessary anxiety or confusion with false alerts
Solution Approach 1:
The alignment indicator provides differentiated feedback based on the local condition of implant depth. Rather than using a uniform alert system for all scenarios, the system tailors the indication characteristics to the specific implant depth and alignment quality. This localized adaptation ensures reliable charging efficiency while avoiding false alerts that could cause user confusion or anxiety.
Solution Approach 2:
The system changes the parameters of the alignment indication based on the detected implant depth and alignment quality. By adjusting the threshold and feedback characteristics dynamically, the system maintains reliable charging efficiency while adapting the indication to avoid unnecessary alerts. This parameter adjustment ensures that alerts are meaningful and reduce user confusion.
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 approach allows for tailored alignment feedback, reducing the risk of sub-optimal charging and minimizing unnecessary misalignment alerts, ensuring efficient energy transfer and extended battery life for implantable devices.
Implementation Method 1
efficient power transmission through tissue from the external charger to the implanted pulse generator via inductive coupling requires constant close alignment between the two devices
Data Source
AI summary
Electrical energy is transcutaneously transmitted at a plurality of different frequencies to an implanted medical device. The magnitude of the transmitted electrical energy respectively measured at the plurality of frequencies. One of the frequencies is selected based on the measured magnitude of the electrical energy (e.g., the frequency at which the measured magnitude of the electrical energy is the greatest). A depth level at which the medical device is implanted within the patient is determined based on the selected frequency. For example, the depth level may be determined to be relatively shallow if the selected frequency is relatively high, and relatively deep if the selected frequency is relative low. A charge strength threshold at which a charge strength indicator generates a user-discernible signal can then be set based on the determined depth level.