A flexible three-dimensional electrode mesh: An enabling technology for wireless brain-computer interface prostheses.

Zhuolin Xiang,Jingquan Liu,Chengkuo Lee

doi:10.1038/micronano.2016.12

Abstract

The neural interface is a key component in wireless brain–computer prostheses. In this study, we demonstrate that a unique three-dimensional (3D) microneedle electrode on a flexible mesh substrate, which can be fabricated without complicated micromachining techniques, is conformal to the tissues with minimal invasiveness. Furthermore, we demonstrate that it can be applied to different functional layers in the nervous system without length limitation. The microneedle electrode is fabricated using drawing lithography technology from biocompatible materials. In this approach, the profile of a 3D microneedle electrode array is determined by the design of a two-dimensional (2D) pattern on the mask, which can be used to access different functional layers in different locations of the brain. Due to the sufficient stiffness of the electrode and the excellent flexibility of the mesh substrate, the electrode can penetrate into the tissue with its bottom layer fully conformal to the curved brain surface. Then, the exposed contact at the end of the microneedle electrode can successfully acquire neural signals from the brain.

Highlights

Brain–computer prostheses provide a bridge for humans to understand and communicate with the nervous system
Because a two-dimensional (2D) structure can be shaped precisely and most neural interfaces are fabricated into planar geometries, which are known as neural probes
The length of Utah Slanted Electrode Array (USEA) was restricted by the bulk silicon thickness and the etching process, while for the varying polymer microneedle array, the longest microneedles were fixed in the central area due to the droplet profile. These drawbacks limited their applications. Taking all these limitations into consideration, we demonstrate that a unique 3D microneedle electrode on a flexible substrate, which can be fabricated without complicated micromachining techniques, is conformal to tissues with minimal invasiveness; it can be applied to different functional layers in the nervous system without length limitations

Summary

Introduction

Brain–computer prostheses provide a bridge for humans to understand and communicate with the nervous system. Taking all these limitations into consideration, we demonstrate that a unique 3D microneedle electrode on a flexible substrate, which can be fabricated without complicated micromachining techniques, is conformal to tissues with minimal invasiveness; it can be applied to different functional layers in the nervous system without length limitations.

Results

Conclusion