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Design and assembly considerations for an optical data and power link-based retinal implant

R. Fontaine1,3, W. Lemaire1,3, G. Martin-Hardy1,3, M. Besrour1,3, M. Benhouria1,3, K. Koua1,3, J. Lavoie1,3, W. Tong2, M. Stamp2, L.-P. Gauthier1,3, É. Laplante1,4, A. Ahnood2, M. Ibbotson2, K. Ganesan2, D. Garrett4, S. Prawer2, E. Plourde3, S. Roy1,3

1 Institute for interdisciplinary technological innovation (3IT), Université de Sherbrooke, Canada.
2University of Melbourne, Melbourne, Australia
3Department of electrical and computer engineering, Universitéde Sherbrooke, Canada.
4School of Engineering, RMIT University, Melbourne, Australia

The requirements to design a high acuity implantable retinal prosthesis include biocompatibility, size, power consumption, stimulation flexibility, high electrode density and ease of assembly.  Altogether, these requirements call  for highly integrated devices.
Most current retinal prostheses use an inductive link to transfer both the power and the data to the implant. The reliability of this method is well established but this approach requires wires crossing the eyeball, which leads to high postoperative complication risks, low reliability and patient discomfort. Another mechanism to transfer both the power and the data relies on the projection of an infrared image to a photodiode array to directly transform the optical signal into a stimulation current. Although this approach can overcome the safety and reliability limitations induced by the wires, it  restricts the flexibility regarding the stimulation patterns. In order to provide wireless operation while retaining the flexibility of an implanted digital stimulation controller, we designed a flexible, minimally invasive, intelligent stimulator based on an optical power and data link.
During this talk, I will present the ongoing efforts of the Australia-Canada vision collaboration to design and assemble a low power and flexible retinal prosthesis. The talk will focus on the design choices made for this first-generation retinal implant including the power management scheme, bidirectional data communication and the solution taken for delivering continuous stimulation despite the optical link interruptions caused by  blinking. Finally, the assembly method based on the pool of equipment accessible at the 3IT will be presented.
This work leads to a 3.8 × 4.7 × 1.0 mm3, 288-electrode retinal implant coupled to a 150 µm electrode pitch diamond interposer. A 2 Mbit/s upload link sustains a stimulation refresh rate of up to 500 kHz while a 1 Mbit/s download link monitors the implant status. The assembly method is based on regular electronic processes to improve manufacturability.

Financial disclosure: None

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