Name: focused ion beam lithography to etch nano-architectures into microelectrodes
Uploaded: 2020-01-19T12:00:00
Description: Watch this Scientific Journal Video about Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes at JoVE.com

This study was supported by the United States (US) Department of Veterans Affairs Rehabilitation Research and Development Service awards: #RX001664-01A1 (CDA-1, Ereifej) and #RX002628-01A1 (CDA-2, Ereifej). The contents do not represent the views of the U.S. Department of Veterans Affairs or the United States Government. The authors would like to thank FEI Co. (Now part of Thermofisher Scientific) for staff assistance and use of instrumentation, which aided in developing the scripts used in this research.

NOTE: Do the following steps while wearing the proper personal protective equipment, such as a lab coat and gloves.
1. Mounting Non-functional Silicon Probe for Focused Ion Beam (FIB) Lithography
NOTE: For the complete procedure describing the fabrication of the SOI wafer with the 1,000 probes, please refer to Ereifej et al.39.
<ol>
	<li>Isolate a strip of 2-3 silicon probes from the silicon on insulator (SOI) wafer containing 1,000 probes....

The fabrication protocol outlined here utilizes focused ion beam lithography to effectively and reproducibly etch nano-architectures into the surface of non-functional and functional single shank silicon microelectrodes. Focused ion beam (FIB) lithography allows for the selective ablation of the substrate surface by using a finely-focused ion beam50,51. FIB is a direct-write technique that can produce various features with nanoscale resolution and high aspect rat...

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&#39; 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 can be used to produce functional outputs3. In fact, BMI systems have successfully been used for prosthetic and therapeutic purposes, such as acquired sensorimotor rhythm control to operate a computer cursor in patients with amyotrophic lateral sclerosis (ALS)4 and spinal cord injuries5 and restoring the movement in people suffering from chronic tetraplegia6.
Unfortunately, IMEs often fail to record consistently over time due to several failure modes that include mechanical, biological and material factors7,8. The neuroinflammatory response occurring after the electrode implantation is thought to be a considerable challenge contributing to electrode failure9,10,11,12,13,14. The neuroinflammatory response is initiated during the initial insertion of the IME which severs the blood brain barrier, damages the local brain parenchyma and disrupts glial and neuronal networks15,16. This acute response is characterized by the activation of glial cells (microglia/macrophages and astrocytes), which release pro-inflammatory and neurotoxic molecules around the implant site17,18,19,20. The chronic activation of glial cells results in a foreign body reaction characterized by the formation of a glial scar isolating the electrode from healthy brain tissue7,9,12,13,17,21,22. Ultimately, hindering the electrode&#39;s ability to record neuronal action potentials, due to the physical barrier between the electrode and the neurons and the degeneration and death of neurons23,24,25.
The early failure of intracortical microelectrodes has brought about considerable research in the development of next generation electrodes, with emphasis on biomimetic strategies26,27,28,29,30. Of particular interest to the protocol described here, is the use of nano-architecture as a class of biomimetic surface alterations for IMEs31. It has been established that surfaces mimicking the architecture of the natural in vivo environment have an improved biocompatible response32,33,34,35,36. Thus, the hypothesis compelling this protocol is that the discontinuity between the rough architecture of the brain tissue and smooth architecture of the intracortical microelectrodes may contribute to the neuroinflammatory and chronic foreign body response to implanted IMEs (for a full review refer to Kim et al.31). We have previously shown that the utilization of nano-architecture features similar to the brain&#39;s extracellular matrix architecture reduces astrocyte inflammatory markers from cells cultured on nano-architectured substrates, compared to flat control surfaces in both in vitro and ex vivo models of neuroinflammation37,38. Furthermore, we have shown the application of focused ion beam (FIB) lithography to etch nano-architectures directly onto silicon probes resulted in significantly increased neuronal viability and lower expression of pro-inflammatory genes from animals implanted with the nano-architecture probes compared to the smooth control group26. Therefore, the purpose of the protocol presented here is to describe the use of FIB lithography to etch nano-architectures on manufactured intracortical microelectrode devices. This protocol was designed to etch nano-architecture sized features into silicon surfaces of intracortical microelectrode shanks utilizing both automated and manual processes. These methods are uncomplicated, reproducible, and can certainly be optimized for various device materials and desired feature sizes.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>16-Channel ZIF-Clip Headstage</td>
			<td>Tucker Davis Technologies</td>
			<td>ZC16</td>
			<td>The headstage and headstage holder may need to be changed, depending on the electrode used. <a href="https://www.tdt.com/zif-clip-digital-headstages.html" target="_blank">https://www.tdt.com/zif-clip-digital-headstages.html</a></td>
		</tr>
		<tr>
			<td>1-meter cable, ALL spring wrapped</td>
			<td>Thomas Scientific</td>
			<td>1213F04</td>
			<td>Any non treated petri dish will suffice. <a href="https://www.thomassci.com/Laboratory-Supplies/Cell-Culture-Dishes/_/Non-Treated-Petri-Dishes?q=petri%20dish%20cell%20culture" target="_blank">https://www.thomassci.com/Laboratory-Supplies/Cell-Culture-Dishes/_/Non-Treated-Petri-Dishes?q=petri%20dish%20cell%20culture</a></td>
		</tr>
		<tr>
			<td>32-Channel ZIF-Clip Headstage Holder</td>
			<td>Tucker Davis Technologies</td>
			<td>Z-ROD32</td>
			<td>The headstage and headstage holder may need to be changed, depending on the electrode used. <a href="https://www.tdt.com/zif-clip-digital-headstages.html" target="_blank">https://www.tdt.com/zif-clip-digital-headstages.html</a></td>
		</tr>
		<tr>
			<td>Acetone, Thinner/Extender/Cleaner, 30ml</td>
			<td>Ted Pella</td>
			<td>16023</td>
			<td><a href="https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062" target="_blank">https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062</a></td>
		</tr>
		<tr>
			<td>Baby-Mixter Hemostat</td>
			<td>Fine Science Tools</td>
			<td>13013-14</td>
			<td>Any curved hemostat will suffice. <a href="https://www.finescience.com/en-US/Products/Forceps-Hemostats/Hemostats/Baby-Mixter-Hemostat" target="_blank">https://www.finescience.com/en-US/Products/Forceps-Hemostats/Hemostats/Baby-Mixter-Hemostat</a></td>
		</tr>
		<tr>
			<td>Carbon Conductive Tape, Double Coated</td>
			<td>Ted Pella</td>
			<td>16084-7</td>
			<td>The protocol suggested three options for mounting the functional electrode to the aluminum stub (copper or carbon conductive tape or a low profile clip. We utilized the carbon conductive tape in our study. <a href="https://www.tedpella.com/semmisc_html/semadhes.htm" target="_blank">https://www.tedpella.com/semmisc_html/semadhes.htm</a></td>
		</tr>
		<tr>
			<td>Corning Costar Not Treated Multiple Well Plates - 6 well</td>
			<td>Sigma Aldrich</td>
			<td>CLS3736-100EA</td>
			<td>Any non-treated 6 well plate will suffice. <a href="https://www.sigmaaldrich.com/catalog/substance/corningcostarnottreatedmultiplewellplates1234598765" target="_blank">https://www.sigmaaldrich.com/catalog/substance/</a></td>
		</tr>
		<tr>
			<td>Dumont #5 Fine Forceps</td>
			<td>Fine Science Tools</td>
			<td>11251-30</td>
			<td>Either this fine forceps or the vacuum pump will suffice. <a href="https://www.finescience.com/en-US/Products/Forceps-Hemostats/Dumont-Forceps/Dumont-5-Forceps/11251-30" target="_blank">https://www.finescience.com/en-US/Products/Forceps-Hemostats/Dumont-Forceps/Dumont-5-Forceps/11251-30</a></td>
		</tr>
		<tr>
			<td>Ethanol, 190 proof (95%), USP, Decon Labs</td>
			<td>Fisher Scientific</td>
			<td>22-032-600</td>
			<td>Any 95% ethanol will suffice. <a href="https://www.fishersci.com/shop/products/ethanol-190-proof-95-usp-decon-labs-10/22032600" target="_blank">https://www.fishersci.com/shop/products/ethanol-190-proof-95-usp-decon-labs-10/22032600</a></td>
		</tr>
		<tr>
			<td>Falcon Cell Strainer</td>
			<td>Fisher Scientific</td>
			<td>08-771-1</td>
			<td><a href="https://www.fishersci.com/shop/products/falcon-cell-strainers-4/087711" target="_blank">https://www.fishersci.com/shop/products/falcon-cell-strainers-4/087711</a></td>
		</tr>
		<tr>
			<td>FEI, Tescan, Zeiss (also for Philips, Leo, Cambridge, Leica, CamScan), aluminum, grooved edge, &#216;32mm</td>
			<td>Ted Pella</td>
			<td>16148</td>
			<td>Depending on the SEM machine used, you may need a different size stub. <a href="https://www.tedpella.com/SEM_html/SEMpinmount.htm#_16180" target="_blank">https://www.tedpella.com/SEM_html/SEMpinmount.htm#_16180</a></td>
		</tr>
		<tr>
			<td>Fisherbrand Aluminum Foil, Standard-gauge roll</td>
			<td>Fisher Scientific</td>
			<td>01-213-101</td>
			<td>Any aluminum foil will suffice. <a href="https://www.fishersci.com/shop/products/fisherbrand-aluminum-foil-7/p-306250" target="_blank">https://www.fishersci.com/shop/products/fisherbrand-aluminum-foil-7/p-306250</a></td>
		</tr>
		<tr>
			<td>Fisherbrand Low- and Tall-Form PTFE Evaporating Dishes</td>
			<td>Fisher Scientific</td>
			<td>02-617-149</td>
			<td>Any Teflon plate will suffice, this is used to dry the probes after washing on a surface they will not stick onto. <a href="https://www.fishersci.com/shop/products/fisherbrand-low-tall-form-ptfe-evaporating-dishes-12/p-88552" target="_blank">https://www.fishersci.com/shop/products/fisherbrand-low-tall-form-ptfe-evaporating-dishes-12/p-88552</a></td>
		</tr>
		<tr>
			<td>Michigan-style silicon functional electrode</td>
			<td>NeuroNexus</td>
			<td>A1x16-3mm-100-177</td>
			<td><a href="http://neuronexus.com/electrode-array/a1x16-3mm-100-177/" target="_blank">http://neuronexus.com/electrode-array/a1x16-3mm-100-177/</a></td>
		</tr>
		<tr>
			<td>Model 1772 Universal holder</td>
			<td>KOPF</td>
			<td>Model 1772</td>
			<td>Other stereotaxic frames and accessories will suffice. <a href="http://kopfinstruments.com/product/model-1772-universal-holder/" target="_blank">http://kopfinstruments.com/product/model-1772-universal-holder/</a></td>
		</tr>
		<tr>
			<td>Model 900-U Small Animal Stereotaxic Instrument</td>
			<td>KOPF</td>
			<td>Model 900-U</td>
			<td>Other stereotaxic frames and accessories will suffice. <a href="http://kopfinstruments.com/product/model-900-small-animal-stereotaxic-instrument1/" target="_blank">http://kopfinstruments.com/product/model-900-small-animal-stereotaxic-instrument1/</a></td>
		</tr>
		<tr>
			<td>Model 960 Electrode Manipulator with AP Slide Assembly</td>
			<td>KOPF</td>
			<td>Model 960</td>
			<td>Other stereotaxic frames and accessories will suffice. <a href="http://kopfinstruments.com/product/model-1772-universal-holder/" target="_blank">http://kopfinstruments.com/product/model-1772-universal-holder/</a></td>
		</tr>
		<tr>
			<td>Parafilm M 10cm x 76.2m (4&#34; x 250&#39;)</td>
			<td>Ted Pella</td>
			<td>807-5</td>
			<td><a href="https://www.tedpella.com/grids_html/807-2.htm" target="_blank">https://www.tedpella.com/grids_html/807-2.htm</a></td>
		</tr>
		<tr>
			<td>PELCO Vacuum Pick-Up System, 220V</td>
			<td>Ted Pella</td>
			<td>520-1-220</td>
			<td>Either this vacuum pump or the fine forceps will suffice. <a href="http://www.tedpella.com/grids_html/Vacuum-Pick-Up-Systems.htm#anchor-520" target="_blank">http://www.tedpella.com/grids_html/Vacuum-Pick-Up-Systems.htm#anchor-520</a></td>
		</tr>
		<tr>
			<td>PELCO Conductive Silver Paint</td>
			<td>Ted Pella</td>
			<td>16062</td>
			<td><a href="https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062" target="_blank">https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062</a></td>
		</tr>
		<tr>
			<td>SEM FIB FEI Helios 650 Nanolab</td>
			<td>Thermo Fisher Scientific</td>
			<td>Helios G2 650</td>
			<td>This is the specific focused ion beam and scanning electron microscope used in the protocol. The Nanobuilder software is what it comes with. If a different FIB instrument is used, it may not be completely compatible with the protocol, specifically the steps requiring the Nanobuilder software. <a href="https://www.fei.com/products/dualbeam/helios-nanolab/" target="_blank">https://www.fei.com/products/dualbeam/helios-nanolab/</a></td>
		</tr>
	</tbody>
</table>

focused ion beam lithography to etch nano-architectures into microelectrodes

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.

FIB Etched Nano-architecture on the Surfaces of Single Shank Intracortical Probes 
Utilizing the methods described here, intracortical probes were etched with specific nano-architectures following established protocols39. Dimensions and shape of the nano-architecture design described in these methods were implemented from previous in vitro results depicting a decrease in glial cell reactivity when cultured with the nano-architecture design described here37</...

Watch this Scientific Journal Video about Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes at JoVE.com

Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

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.

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of ...

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