# Development and Evaluation of Multi-Module Retinal Devices for Artificial Vision Applications

## TL;DR

This paper presents a new flexible retinal device designed to improve artificial vision by using a CMOS system and multiple modules for effective stimulation.

## Contribution

The novel contribution is the development of a parylene-based multi-module retinal device with a CMOS system for suprachoroidal transretinal stimulation.

## Key findings

- The device successfully generated expected current stimulation waveforms in vitro and in vivo.
- Optimized encapsulation and silane coupling improved fabrication reliability.
- The CMOS system reduced wiring complexity, enhancing the device's practicality.

## Abstract

Artificial retinal devices require a high-density electrode array and mechanical flexibility to effectively stimulate retinal cells. However, designing such devices presents significant challenges, including the need to conform to the curvature of the eyeball and cover a large area using a single platform. To address these issues, we developed a parylene-based multi-module retinal device (MMRD) integrating a complementary metal-oxide semiconductor (CMOS) system. The proposed device is designed for suprachoroidal transretinal stimulation, with each module comprising a parylene-C thin-film substrate, a CMOS chip, and a ceramic substrate housing seven platinum electrodes. The smart CMOS system significantly reduces wiring complexity, enhancing the device’s practicality. To improve fabrication reliability, we optimized the encapsulation process, introduced multiple silane coupling modifications, and utilized polyvinyl alcohol (PVA) for easier detachment in flip-chip bonding. This study demonstrates the fabrication and evaluation of the MMRD through in vitro and in vivo experiments. The device successfully generated the expected current stimulation waveforms in both settings, highlighting its potential as a promising candidate for future artificial vision applications.