Design of the electrode and the system package for the retina prosthesis based on liquid crystal polymer

Abstract

Purpose: To develop a retina prosthesis which can be implanted in the orbit, the stimulator and the electrode were integrated into one system. Whole system was fabricated with liquid crystal polymer (LCP) in multi-layered structure, and their shape and the size were investigated.

Methods: The 16-channel current stimulator integrated circuit and multi-layered coil were implemented onto the LCP film by semiconductor fabrication technology, and stacked to form a tiny package. A semi-flat, ovoid LCP capsule was designed and applied onto the system to establish the hermetic sealing. The electrode was directly connected to the stimulator package to make an integrated system. Whole system was implanted into the rabbit eye, and the the shape, size, and the topological relationship between the electrode and the stimulator package were evaluated.

Results: The electrode with the maximum diameter of 3 mm could be safely implanted into the subretinal or suprachoroidal space through scleral tunnel.Meticulous hemostasis of the choroid with high-frequency electrocauterization increased the success rate of the operation. Sharp angulation between the stimulator package and the electrode shaft could help stabilizing the electrode tip under the retina during surgery. The size of the system package was the major issue for the stable and safe implantation of the whole system. The flexibility of the LCP electrode and the leverage effect of the electrode shaft affected the surgical outcome.

Conclusions: The flexibility and the edge sharpness of the electrode were important for decreasing the tissue damage during implant surgery. The size and the weight of the external part also affected the stability of the electode by leverage effect. Optimized design according to the size and the shape of the eyeball is necessary for the successful implantation of the mololithic retina prosthesis.

Keywords: 688 retina • 741 transplantation