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C. Koch, M. Goertz, W. Mokwa, H.-K. Trieu, EPI-RET-3 group; The EPIRET3 Wireless Intraocular Retina Implant System: Technical Features - Fabrication and Assembly Techniques. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1780. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
This contribution is related to the EPIRET3 Project, which aims at the development of a wireless intraocular retina implant system for patients suffering from Retinitis Pigmentosa. The specific purpose of the presented work is the development and fabrication of a flexible and wireless prosthesis completely implantable into the eye.
On 4" silicon wafers serving as carrier substrates a thin layer of polyimide is spin-coated and structured. In an electroplating step, a gold wiring layer is grown before a second polyimide film is deposited and patterned. A second gold electroplating step is performed to create a micro coil for energy and data transmission via RF-coupling and three dimensional hat-shaped electrodes with a height of 25µm. The gold surface of the stimulation electrodes is then covered with an iridium oxide thin film, deposited by reactive sputtering of iridium. Parylene-C coating is added using a CVD process, contact pads and active surface of the electrodes are opened by plasma etching. After removal from the wafer, required SMD components are attached and electrically connected to the implants. Receiver and stimulator chip are assembled by flip-chip technology.The implant was designed taking into account the physiology of the human eye and the surgery method.
The fabricated implants are electrically functional up to a distance of 35mm between transmitter and receiver. All 25 electrodes could be addressed correctly. Electroplated micro coil and flip-chip assembly of the thinned microchips result in a very thin, flexible and light implant, which allows to be completely implanted into the interior of the eye. The Iridium oxide covered stimulation electrodes were tested, showing excellent electrochemical properties.
A flexible wireless epiretinal implant has been developed and fabricated using wafer-level processes and advanced assembly techniques. In-vitro and in-vivo tests have shown that the implant functions well and is mechanically stable and biocompatible.
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