Implantable Device Load Modulation Equalization
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Solution Overview
Problem
Existing wireless power/data transfer systems for implantable medical devices 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
The system equalizes the modulation levels of communication links by measuring Received Signal Strength Indicators (RSSI) and adjusting the modulation indices of sensor devices to ensure uniform amplitude modulations, allowing for simpler demodulation and maintaining high data transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same load resistance change is used for load modulating uplink data from multiple implanted medical devices, then the data transmission process is simple, but the voltage amplitudes induced on the primary coil will be different due to different coupling coefficients, complicating the demodulator circuitry
Solution Approach 1:
The patent changes the parameter of load resistance change amount for each implanted medical device based on its coupling coefficient. Specifically, devices with lower coupling coefficients use larger load resistance changes, while devices with higher coupling coefficients use smaller load resistance changes. This parameter adjustment equalizes the voltage amplitudes induced on the primary coil, allowing for simplified demodulator circuitry with a single threshold level.
Solution Approach 2:
The system measures the received signal strength indicator (RSSI) for each implanted medical device and uses this feedback information to determine the appropriate load resistance change amount. The measured RSSI values are used to adjust the modulation parameters, creating a closed-loop system that optimizes signal uniformity across multiple devices.
2Device complexity
If the data transmission rate is reduced, then the demodulation process becomes simpler, but the productivity of the system decreases
Solution Approach 1:
Instead of reducing the data transmission rate, the patent changes the modulation parameters (load resistance change amounts) to achieve signal equalization. This allows the system to maintain high data transmission rates while simplifying the demodulation process through uniform signal amplitudes from all implanted devices.
3Measurement precision
If different threshold levels are used for demodulating uplink data from different implanted medical devices, then accurate demodulation is achieved, but the demodulator design becomes more complex
Solution Approach 1:
The patent adjusts the modulation parameters (load resistance change amounts) for each device to compensate for different coupling coefficients. This parameter adjustment ensures that all devices produce voltage amplitudes within a predictable range, allowing the use of a single threshold level for demodulation while maintaining accurate data recovery.
Solution Approach 2:
The system equalizes the signal amplitudes from different implanted devices by adjusting their respective load resistance changes. This creates an equipotential condition where all devices operate at comparable signal levels, enabling the use of a unified demodulation threshold and simplifying the overall demodulator design.
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 reliable and efficient demodulation of uplink data from multiple implantable medical devices without reducing data transmission rates, by ensuring uniform RSSI across all communication links, thus simplifying the demodulation process and maintaining data integrity.
Implementation Method 1
Power transfer and data communication between the external control unit and implanted medical device(s) are provided via an inductive link. A primary coil Lp located inside the TC inductively couples and powers secondary coils Ls(y), Ls(z) respectively inside the implanted medical devices 14(y), 14(z).
Implementation Method 2
Due to the inductive coupling between the primary coil Lp and the corresponding secondary coil Ls, a voltage amplitude change on the primary coil Lp according to the uplink data is obtained.
Data Source
Figure 1
Figure 2~3A
Figure 3B~3C
AI summary
A medical system and method of communicating between a telemetry controller and a plurality of medical devices implanted within a patient is provided. Communication links are respectively established between the telemetry controller and the implanted medical devices. The communication links are respectively amplitude modulated by the implanted medical devices at modulation levels using load modulation. Received signal strength indicators (RSSIs) of the amplitude modulated communication links for the implanted medical devices are measured. A variation of the RSSIs is decreased by modifying, based on the measured RSSIs, at least one modulation level at which the respective at least one communication link is amplitude modulated by the respective implanted medical device(s).