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Published on: October 20, 2021
High performance 3-coil wireless power transfer system for the 512-electrode epiretinal prosthesis
Yu Zhao1, Mandheerej Nandra, Chia-Chen Yu
1California Institute of Technology, Pasadena, CA 91125, USA.
Summary
This study introduces a novel 3-coil system for wireless power transfer in retinal prostheses, achieving 36% efficiency. This fully intraocular design bypasses problematic cables, reducing risks associated with chronic implantation.
Area of Science:
- Biomedical Engineering
- Medical Devices
- Ophthalmology
Background:
- Next-generation retinal prostheses require high-power (100 mW) wireless and efficient power delivery for chronic implantation.
- Current 2-coil inductive power links face challenges including trans-scleral cables causing hypotony and infection, or small intraocular coils suffering from drastic efficiency drops (e.g., 7% power transfer).
- Overheating and electromagnetic field exposure are concerns with inefficient power transfer systems.
Purpose of the Study:
- To develop a fully intraocular, highly efficient wireless power transfer system for retinal prostheses.
- To bypass the trans-sclera trans-choroid cable, mitigating risks of hypotony and infection.
- To improve power transfer efficiency and reduce heat dissipation and electromagnetic field exposure.
Main Methods:
- A 3-coil inductive coupling link was designed and implemented to create a fully intraocular power transfer system.
- The system was tested with a customized 512-electrode stimulator, simulating the equivalent load of a retinal prosthesis.
- Power transfer efficiency was measured at a 1-inch separation in saline, and the impact of eyeball rotation was evaluated.
Main Results:
- The 3-coil system achieved an overall power transfer efficiency of approximately 36% with a 1-inch separation in saline.
- Efficiency remained at 14.7% even with 30-degree left and right eyeball deflection during simulated use.
- The surgical implantation procedure for the intraocular coils was successfully demonstrated in a porcine eye model.
Conclusions:
- The developed 3-coil system offers a highly efficient and fully intraocular solution for powering advanced retinal prostheses.
- This approach effectively eliminates the need for trans-scleral cables, enhancing device safety and long-term reliability.
- The system's robust performance under simulated physiological conditions and eyeball movement indicates its potential for clinical application.
