Adjustable Load Modulation for Multi-Implant Telemetry
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Solution Overview
Problem
Existing wireless power/data transfer systems for medical implants face challenges in demodulating uplink data due to varying coupling coefficients between primary and secondary coils, leading to different signal amplitudes and requiring complex demodulator designs or reduced data transmission rates.
Innovation Solution
A medical system with a telemetry controller, primary coil, and implantable devices featuring secondary coils, amplitude detectors, and modulators that adjust modulation magnitudes inversely with coupling coefficients to ensure uniform amplitude modulation of the primary carrier signal, allowing for simpler demodulation and maintaining high data transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If load modulation is used for uplink data transmission from multiple implants, then data communication is enabled, but signal amplitude variations occur due to different coupling coefficients requiring complex demodulation
Solution Approach 1:
The system performs preliminary measurement of the secondary carrier signal amplitude at each implant before data transmission. Based on this pre-measured amplitude information, the modulation magnitude is pre-adjusted to compensate for coupling coefficient variations, ensuring uniform modulated signal amplitudes are induced on the primary coil without requiring complex demodulation circuitry
Solution Approach 2:
The system uses feedback from the amplitude detector that measures the secondary carrier signal amplitude to dynamically adjust the modulation magnitude. This feedback mechanism allows each implant to automatically adapt its transmission strength based on its specific coupling conditions, simplifying the demodulator design at the external device
2Ease of manufacture
If uniform load resistance change is used for load modulation, then implementation is simplified, but received signal amplitudes vary due to different coupling coefficients
Solution Approach 1:
The system transitions from a static fixed load resistance approach to a dynamic adjustable modulation magnitude approach. The modulation magnitude is dynamically adjusted based on the measured secondary carrier signal amplitude, allowing the system to adapt to varying coupling conditions while maintaining reliable and consistent received signal amplitudes across multiple implants with different coupling coefficients
3Device complexity
If threshold-based demodulation is used, then demodulation is simplified, but accurate data recovery requires precise threshold setting amidst amplitude variations
Solution Approach 1:
The system performs preliminary measurement of the secondary carrier signal amplitude to determine the appropriate modulation magnitude before data transmission. This pre-adjustment ensures that the modulated signal amplitudes induced on the primary coil are substantially uniform, allowing simple threshold-based demodulation to accurately recover data without requiring complex adaptive thresholding mechanisms
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 enables efficient and reliable demodulation of uplink data from multiple medical implants with varying coupling coefficients, ensuring consistent signal amplitudes and maintaining high data transmission rates without the need for complex demodulator designs.
Implementation Method 1
A primary coil Lp located inside the TC 12 inductively couples and powers secondary coils Ls(y), Ls(z) respectively inside the implanted medical devices 14(y), 14(z). Power is delivered to the implanted medical devices 14 by applying an alternating current (AC) current on the primary coil Lp at a selected transmission frequency Ft.
Implementation Method 2
A primary coil Lp located inside the TC 12 inductively couples and powers secondary coils Ls(y), Ls(z) respectively inside the implanted medical devices 14(y), 14(z).
Data Source
AI summary
A medical system and method of communicating between a telemetry controller and medical devices is provided. Coupling coefficients between a primary coil of the telemetry controller and secondary coils of the medical devices differ from each other. A primary carrier signal is applied to the primary coil, thereby respectively inducing secondary carrier signals on the secondary coils. An amplitude of the secondary carrier signal is measured on each of the secondary coils. The envelope of each secondary carrier signal is modulated in accordance with data, thereby inducing modulation of the envelope of the primary carrier signal for the implanted medical devices. The secondary carrier signal envelopes are modulated based on the measured amplitudes of the respective secondary carrier signals.