Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

Shreya Mahajan; Jonah  A. Sharkins; Allen H. Hunter; Amir Avishai; Evon  S. Ereifej

doi:10.3791/60004

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Method Article

Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

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DOI:

10.3791/60004

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January 19th, 2020

Shreya Mahajan¹ , Jonah A. Sharkins²^,⁴ , Allen H. Hunter⁵ , Amir Avishai⁶ , Evon S. Ereifej²^,³^,⁴

¹Department of Electrical Engineering and Computer Science, University of Michigan, ²Veteran Affairs Ann Arbor Healthcare System, ³Department of Neurology, School of Medicine, University of Michigan, ⁴Department of Biomedical Engineering, University of Michigan, ⁵Michigan Center for Materials Characterization, University of Michigan, ⁶Carl Zeiss SMT, Inc.

Summary

We have shown that the etching of nano-architecture into intracortical microelectrode devices may reduce the inflammatory response and has the potential to improve electrophysiological recordings. The methods described herein outline an approach to etch nano-architectures into the surface of non-functional and functional single shank silicon intracortical microelectrodes.

Abstract

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of sophisticated microelectrodes with greater resolution and expanded capabilities. The progress in fabrication technology has supported the development of biomimetic electrodes, which aim to seamlessly integrate into the brain parenchyma, reduce the neuroinflammatory response observed after electrode insertion and improve the quality and longevity of electrophysiological recordings. Here we describe a protocol to employ a biomimetic approach recently classified as nano-architecture. The use of focused ion beam lithography (FIB) was utilized in this protocol to etch specific nano-architecture features into the surface of non-functional and functional single shank intracortical microelectrodes. Etching nano-architectures into the electrode surface indicated possible improvements of biocompatibility and functionality of the implanted device. One of the benefits of using FIB is the ability to etch on manufactured devices, as opposed to during the fabrication of the device, facilitating boundless possibilities to modify numerous medical devices post-manufacturing. The protocol presented herein can be optimized for various material types, nano-architecture features, and types of devices. Augmenting the surface of implanted medical devices can improve the device performance and integration into the tissue.

Introduction

Intracortical Microelectrodes (IME) are invasive electrodes which provide a means of direct interfacing between external devices and the neuronal populations inside the cerebral cortex¹^,². This technology is an invaluable tool for recording neural action potentials to improve scientists' ability to explore neuronal function, advance understanding of neurological diseases and develop potential therapies. Intracortical microelectrode, used as a part of Brain Machine Interface (BMI) systems, enables recording of action potentials from an individual or small groups of neurons to detect motor intentions that ca....