External Coil Assembly for Retinal Prosthesis Telemetry
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Solution Overview
Problem
In inductively powered retinal prostheses, retrieving low-level feedback signals is challenging due to strong magnetic fields from the power carrier, especially when the implant coil is mechanically linked to the eyeball, leading to compromised coupling conditions and reduced telemetry reliability.
Innovation Solution
An external coil assembly with a transmitting coil and two receiving coils, where the coupling coefficients between the transmitting coil and each receiving coil are made substantially identical, allowing for improved back telemetry signal retrieval by reducing the influence of the power carrier signal, without increasing receiver complexity or altering the mechanical configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single receiving coil is used in the external coil assembly, then the device complexity is low, but the back telemetry signal retrieval is compromised due to strong magnetic field interference from the power carrier
Solution Approach 1:
The external coil assembly is segmented into multiple receiving coils (first receiving coil and second receiving coil) with different orientations. Each coil receives the back telemetry signal with different coupling to the power carrier magnetic field, allowing differential processing to reject the common-mode interference while preserving the telemetry signal
Solution Approach 2:
The patent introduces an intermediary processing stage that differentially combines the outputs of multiple receiving coils. This intermediary differential combination acts as a mediator that separates the desired telemetry signal from the interfering power carrier signal, improving retrieval reliability without requiring complex filtering at the source
2Stability of the object's composition
If the implant coil is mechanically linked to the eyeball for stable positioning, then the implant stability is improved, but the coupling condition between external and implant coils deteriorates due to eyeball movement
Solution Approach 1:
The patent transitions from a static single-coil coupling system to a dynamic multi-coil system where the external assembly includes multiple receiving coils oriented in different directions. This dynamic configuration can adapt to varying coupling conditions caused by eyeball movement, maintaining reliable telemetry as the eye moves while the implant remains mechanically stable
3Productivity
If the back telemetry signal frequency is close to the power carrier frequency, then the signal transmission is efficient, but the signal retrieval is compromised due to strong magnetic field interference
Solution Approach 1:
The patent converts the harmful effect of the strong power carrier magnetic field into a beneficial common-mode signal that can be rejected through differential processing. By using multiple receiving coils that all pick up the power carrier interference similarly, the system transforms the interference into a cancelable common-mode component while preserving the differential telemetry signal
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 configuration enhances the reliability of back telemetry signals in the presence of strong magnetic fields, improving the signal-to-carrier noise ratio and maintaining mechanical stability, thus aiding visually impaired individuals by providing more effective communication with the implant.
Implementation Method 1
In inductively powered retinal prostheses, coils are used to transmit and receive RF power in both external and implant ends
Implementation Method 2
a first receiving coil, adapted to receive signals from the implant, the first receiving coil exhibiting a first coupling coefficient with the transmitting coil
Data Source
AI summary
Methods and devices for inductively coupled implants on the human or animal body are disclosed. An external coil assembly to be used with the implant has a transmitting coil and one or more receiving coils. The number of the receiving coils, their distance from the transmitting coil and their shape is chosen to reduce the influence of a noise signal received by the external coil assembly.