Series Resonant Tank Circuit for Implantable Stimulation Leakage Blocking
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Solution Overview
Problem
Existing medical devices, particularly implantable ones, face challenges in efficiently and safely transferring power and data wirelessly between external and internal components, leading to potential stimulation current loops and inefficiencies in power transfer.
Innovation Solution
The implementation of a series resonant tank circuit that capacitively couples stimulation assemblies to RF coils for wireless power transfer while galvanically isolating them, using low-capacitance capacitors and inductors to maintain voltage transfer ratios and prevent AC leakage, allowing for efficient power and data transfer with frequency isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If wireless power transfer is implemented between external and implanted devices, then power delivery capability is improved, but stimulation current loops and leakage currents are generated
Solution Approach 1:
A capacitive coupling circuit is introduced as an intermediary between the wireless power receiver and the stimulation electrodes. This capacitor couples the two components electrically while blocking direct current paths, thereby preventing stimulation current loops from forming while still allowing power transfer.
Solution Approach 2:
The electrical connection is segmented into separate AC and DC paths. The capacitive coupling allows AC power signals to pass while blocking DC stimulation currents, effectively separating the power transfer function from the stimulation function to prevent harmful current loops.
2Object-affected harmful factors
If capacitive coupling is used to block stimulation currents, then stimulation leakage is prevented, but power transfer efficiency decreases
Solution Approach 1:
The capacitance value is carefully selected and optimized to provide sufficient blocking of stimulation currents (typically <20kHz) while maintaining adequate coupling for power transfer frequencies (typically >60kHz). This parameter optimization ensures both safety and efficiency are achieved simultaneously.
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 effectively increases coil inductance, prevents stimulation current loops, and ensures efficient power transfer to implanted devices, enhancing the reliability and performance of implantable medical systems like cochlear implants and other prostheses.
Implementation Method 1
capacitively couple the second circuitry to the first circuitry while galvanically isolating the second circuitry from the first circuitry
Implementation Method 2
galvanically isolating the second circuitry from the first circuitry
Implementation Method 3
a magnetic induction coil configured to wirelessly receive power and/or data signals from a device external to the recipient's body
Implementation Method 4
at least a portion of the first circuitry and at least a portion of the third circuitry forming a series resonant tank circuit
Data Source
AI summary
An apparatus includes implantable first circuitry configured to wirelessly receive power from a device external to the recipient's body, implantable second circuitry configured to provide stimulation signals to a portion of the recipient's body, and implantable third circuitry, at least a portion of the first circuitry and at least a portion of the third circuitry forming a series resonant tank circuit configured to capacitively couple the second circuitry to the first circuitry while galvanically isolating the second circuitry from the first circuitry, such that at least a portion of the electric power is transferred from the first circuitry to the second circuitry through the third circuitry whilst preventing stimulation currents.