An Eye-surface Conformable Retinal Prosthesis using Liquid Crystal Polymers

Abstract

 

Purpose:

 

A novel retinal prosthesis is developed based on the Liquid Crystal Polymer (LCP). The implantable system is designed to be conformable to the curvature of eyeballs for the stable attachment on the surface. This LCP-based monolithically encapsulated retinal implant system features three major advantages including: 1) a thin, flexible and eye-surface conformable structure, 2) a long-term reliability and 3) a simple fabrication process.

 

Methods:

 

For the LCP-based monolithic system, all the components including the electrodes array, the telemetric coil and the stimulator circuitries were integrated onto LCP substrates. The LCP-based planar coil was embedded into the package lid to minimize the size of the whole system and the 16-channel microelectrode array was also formed on the LCP substrate. Using thermo-forming process, the fabricated substrate was deformed into a domed shape to create the eye-surface conformable structure. The thermal pressing process was optimized to get rid of the adverse effects from the deformation such as line disconnections or the degradation of coil link performance. After assembling the ASIC stimulator chip and discrete components on the deformed LCP substrate, the whole system was finally encapsulated through the LCP fusion-bonding process.

 

Results:

 

The LCP-based retinal implant was successfully implemented and its maximum operating distance for the coil telemetry was 20 mm in the air. It was also confirmed that the spherical curvature did not adversely affect the interconnection or the capability of telemetric coil. The maximum thickness of the system was 1.5 mm and showed a streamlined shape when attached on the model eyeball.

 

Conclusions:

 

The LCP-based implantable system was developed for the next generation retinal implant which is thin, conformable, long-term reliable and simple to fabricate. To verify the effectiveness of the system, in vitro soak test as well as in vivo animal test is ongoing at this moment.  

 

Keywords: retina • age-related macular degeneration • retinitis