A Miniaturized, Eye-Conformable, and Long-Term Reliable Retinal Prosthesis Using Monolithic Fabrication of Liquid Crystal Polymer (LCP)

Abstract

A novel retinal prosthetic device was developed using biocompatible liquid crystal polymer (LCP) to address the problems associated with conventional metal- and polymer-based devices: the hermetic metal package is bulky, heavy, and labor-intensive, whereas a thin, flexible, and MEMS-compatible polymer-based system is not durable enough for chronic implantation. Exploiting the advantageous properties of LCP such as a low moisture absorption rate, thermobonding, and thermoforming, we fabricate a small, light-weight, long-term reliable retinal prosthesis that can be conformally attached on the eye-surface. A LCP fabrication process using monolithic integration and conformal deformation was established enabling miniaturization and a batch manufacturing process as well as eliminating the need for feed-through technology. The functionality of the fabricated device was tested through wireless operation in saline solution. Its efficacy and implantation stability were verified through in vivo animal tests by measuring the cortical potential and monitoring implanted dummy devices for more than a year, respectively.

Silicon-Integrated High-Density Electrocortical Interfaces

“…They are superior over metal, glass, and ceramic hard seals in miniaturization, flexibility, and compatibility with the semiconductor process [185]. However, polymers are susceptible to degradation and are not long-term impermeable to body fluids.…”

“…While polymer encapsulation has been used for relatively simple and short-term (less than 1-2 years) implants, substantial improvements are needed for viable solutions to long-term hermetic encapsulation [182], [186]. Recent next-generation advances in miniaturized hermetic sealing of silicon integrated circuits, such as multilayer multimaterial coating [187], and encapsulation using liquid crystal polymers (LCPs) [185], are promising developments toward highly miniaturized implantable electronics for chronic clinical use. Furthermore, recent advances in dissolvable flexible electronics [188], [189] offer alternatives to hermetic encapsulation for acute applications without the need for post-use surgical extraction.…”

Implantable electrical stimulation bioreactor with liquid crystal polymer based electrodes for enhanced bone regeneration at mandibular large defects in rabbit

“…The timing and duration of ES and BMP-2 treatment is an important aspect of experimental design for the 21 optimal results. The effect of the ES in bone cells is different in different stages of cell maturation [10].…”

“…Because of the similarity in the mechanical strength and a good fixation-to-bone property [26], this material is considered adequate for orthopedic applications. Furthermore, it is chemically inert, allows hermetic sealing, and is compatible with MEMS microfabrication process with multilayer integration [15,21,40,51]. LCP-based packaging of a neural prosthetic device was studied [31,47,49].…”

The Synthesis and Characterization of Spacer-Free Liquid Crystal Polyrotaxane by Virtue of the Mobility of Threaded α-Cyclodextrins

“…Liquid crystalline polymers (LCPs) have been subjected to extensive attention in recent years, owing to their fascinating potential functional applications, such as biomedical materials, photoelectric materials, switches, smart, and stimuliresponsive materials . However, the LCPs always suffered from so‐called “matrix effect,” which restricted the movement of mesogen moieties resulting in the weakening and disappearing of liquid crystalline phase.…”