Simulation on Junctionless Silicon Nanowire Devices for Implementation of Photodetection Circuit in Retinal Prosthesis

Sangmin Lee

doi:10.18494/sam.2019.2286

Abstract

Simulation on Junctionless Silicon Nanowire Devices for Implementation of Photodetection Circuit in Retinal Prosthesis

Highlights

In the human eye, photoreceptor cells sense light and convert it into electrical signals that stimulate optic nerves in the brain
In the current driver, where the silicon-nanowire field-effect transistors (FETs) and microelectrodes are connected in series, the current stimulus pulses can be delivered to the microelectrode by the amplitude-modulated driving current, which is proportional to the external light intensity
By applying the extracted electrical parameters of siliconnanowire-based devices, the proposed photodetection circuit is simulated for implementation in a photosensitive retinal prosthetic device

Summary

Introduction

Photoreceptor cells sense light and convert it into electrical signals that stimulate optic nerves in the brain. Several research groups worldwide have attempted to use electrical signals modulated by visual data obtained from external image acquisition devices.[6,7,8] For other approaches, integrating a solid-state photodiode into a microelectrode array (MEA) has been proposed.[9] For those devices, photodiodes are integrated with signal amplification circuits to increase and control the magnitudes of stimulation current at low light intensities. We have proposed light-responsive silicon-nanowire photodetectors (PDs) on a flexible substrate, which can convert visible light into electrical signals.[10] In the report, the devices using a topdown fabrication method have shown excellent potential for applications in retinal prosthetic systems with high photosensitivity, photoresponsivity, and mechanical flexibility. The proposed method consists of a voltage divider and a current driver, and is implemented using silicon-nanowire PDs, siliconnanowire field-effect transistors (FETs), and a microelectrode on a flexible substrate. In the current driver, where the silicon-nanowire FET and microelectrodes are connected in series, the current stimulus pulses can be delivered to the microelectrode by the amplitude-modulated driving current, which is proportional to the external light intensity

Methods

Results

Conclusion