Purchase this article with an account.
D. Rodger, W. Li, D. Guven, J. Weiland, M. Humayun, Y.C. Tai; Flexible Parylene Multielectrode System for the Intraocular Retinal Prosthesis . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1503.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To fabricate a retinal multielectrode prosthesis system using parylene C as the primary substrate. Methods: All animal experiments conformed to the ARVO guidelines for animal use. Unmodified parylene C was implanted in the vitreous cavity of two rabbits for 6 months, and histological analysis of the retina was performed post–mortem to examine its intraocular biocompatibility. Prototypes of the three components of the parylene–based intraocular system, including a 16X16 platinum multielectrode array, a chip–level high lead count package for direct integration of the application specific integrated circuit (ASIC) and discrete capacitors, and a radio–frequency (RF) inductively–coupled coil, were fabricated and tested. The electrode array consists of two parylene layers with sandwiched metal traces and with electrodes exposed by photoresist–masked oxygen plasma etching. The fabrication method for the high lead count packaging scheme places the prefabricated ASIC and other discrete components (e.g. capacitors) directly into the fabrication process of these electrodes, and can achieve 1000 photolithographically–defined interconnects. The heat–formable RF coil is covered by an external parylene coating and employs two discrete metal layers separated by a parylene layer, the device being fabricated in a method compatible with the ASIC packaging scheme. Results: Histological analysis of the retinas of the implanted right eyes of both rabbits showed no detectable difference from the left eyes which served as controls. 64 electrodes of the 12 µm thick 256 platinum multielectrode array were stable under continuous pulse–testing for 1 month, and soak tests in 80°C saline solution showed no observable delamination. The prototype of the scalable packaging system was electrically and mechanically robust, and saline soak tests are underway to determine its hermeticity. The two–layer RF coil was tested to have an inductance of approximately 1 µH at the target frequency. Conclusions: The results suggest that parylene C is a suitable material for a retinal prosthesis. Initial biocompatibility tests are positive. The component testing results suggest that a system comprising parylene–based microelectronic subunits (coil, electrodes, and packaged stimulator chip) is possible.
This PDF is available to Subscribers Only