Name: open-source toolkit: benchtop carbon fiber microelectrode array for nerve recording
Uploaded: 2021-10-29T14:00:00
Description: Watch this Scientific Journal Video about Open-source Toolkit: Benchtop Carbon Fiber Microelectrode Array for Nerve Recording at JoVE.com

This work was financially supported by the National Institutes of Neurological Disorders and Stroke (UF1NS107659 and UF1NS115817) and the National Science Foundation (1707316). The authors acknowledge financial support from the University of Michigan College of Engineering and technical support from the Michigan Center for Materials Characterization and the Van Vlack Undergraduate Laboratory. The authors thank Dr. Khalil Najafi for the use of his Nd:YAG laser and the Lurie Nanofabrication Facility for the use of their Parylene C deposition machine. We would also like to thank Specialty Coating Systems (Indianapolis, IN) for their help in the commercial coating comparison study.

All animal procedures were approved by the University of Michigan Institutional Animal Care and Use Committee.
1. Choosing a carbon fiber array
<ol>
	<li>Choose a printed circuit board (PCB) from one of the three designs shown in Figure 1. 
	NOTE: For this protocol, Flex Arrays will be the focus.
	<ol>
		<li>Refer to PCB designs on the Chestek Lab website (https://chestekresearch.engin.umich.edu), free of charge and ready to be sent to and ...

<ol>
	<li>Szostak, K. M., Grand, L., Constandinou, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+interfaces+for+intracortical+recording:+Requirements,+fabrication+methods,+and+characteristics.">Neural interfaces for intracortical recording: Requirements, fabrication methods, and characteristics.</a> Frontiers in Neuroscience. 11, 665 (2017).</li><li>Cunningham, J. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+closed-loop+human+simulator+for+investigating+the+role+of+feedback+control+in+brain-machine+interfaces.">A closed-loop human simulator for investigating the role of feedback control in brain-machine interfaces.</a> Journal of Neurophysiology. 105 (4), 1932-1949 (2011).</li><li>Yoshida, K., Bertram, M. J., Hunter Cox, T. G., Riso, R. R., Horch, K., Kipke, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peripheral+nerve+recording+electrodes+and+techniques.">Peripheral nerve recording electrodes and techniques.</a> Neuroprosthetics: Theory and Practice. , 377-466 (2017).</li><li>Dweiri, Y. M., Stone, M. A., Tyler, D. J., McCallum, G. A., Durand, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+high+contact-density,+flat-interface+nerve+electrodes+for+recording+and+stimulation+applications.">Fabrication of high contact-density, flat-interface nerve electrodes for recording and stimulation applications.</a> Journal of Visualized Experiments: JoVE. (116), e54388 (2016).</li><li>Kim, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cuff+and+sieve+electrode+(CASE):+The+combination+of+neural+electrodes+for+bi-directional+peripheral+nerve+interfacing.">Cuff and sieve electrode (CASE): The combination of neural electrodes for bi-directional peripheral nerve interfacing.</a> Journal of Neuroscience Methods. 336, 108602 (2020).</li><li>Ciancio, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+prosthetic+hands+via+the+peripheral+nervous+system.">Control of prosthetic hands via the peripheral nervous system.</a> Frontiers in Neuroscience. 10, 116 (2016).</li><li>Jiman, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-channel+intraneural+vagus+nerve+recordings+with+a+novel+high-density+carbon+fiber+microelectrode+array.">Multi-channel intraneural vagus nerve recordings with a novel high-density carbon fiber microelectrode array.</a> Scientific Reports. 10 (1), 15501 (2020).</li><li>Welle, E. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sharpened+and+mechanically+robust+carbon+fiber+electrode+arrays+for+neural+interfacing.">Sharpened and mechanically robust carbon fiber electrode arrays for neural interfacing.</a> IEEE Transactions on Neural Systems and Rehabilitation Engineering. 29, 993-1003 (2021).</li><li>Moffitt, M. A., McIntyre, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Model-based+analysis+of+cortical+recording+with+silicon+microelectrodes.">Model-based analysis of cortical recording with silicon microelectrodes.</a> Clinical Neurophysiology. 116 (9), 2240-2250 (2005).</li><li>Nerve-cuff electrodes. Micro-Leads Neuro Available from: <a target="_blank" href="https://www.microleadsneuro.com/research-products/?jumpto=nerve-cuff">https://www.microleadsneuro.com/research-products/?jumpto=nerve-cuff</a> (2021)</li><li>Mortimer, J. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perspectives+on+new+electrode+technology+for+stimulating+peripheral+nerves+with+implantable+motor+prostheses.">Perspectives on new electrode technology for stimulating peripheral nerves with implantable motor prostheses.</a> IEEE Transactions on Rehabilitation Engineering. 3 (2), 145-154 (1995).</li><li>Boretius, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+transverse+intrafascicular+multichannel+electrode+(TIME)+to+interface+with+the+peripheral+nerve.">A transverse intrafascicular multichannel electrode (TIME) to interface with the peripheral nerve.</a> Biosensors &amp; Bioelectronics. 26 (1), 62-69 (2010).</li><li>Grill, W. M., Norman, S. E., Bellamkonda, R. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implanted+neural+interfaces+biochallenges+and+engineered+solutions.">Implanted neural interfaces biochallenges and engineered solutions.</a> Annual Review of Biomedical Engineering. 11, 1-24 (2009).</li><li>Larson, C. E., Meng, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+for+the+peripheral+nerve+interface+designer.">A review for the peripheral nerve interface designer.</a> Journal of Neuroscience Methods. 332, 108523 (2020).</li><li>Christensen, M. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+foreign+body+response+to+the+Utah+Slant+Electrode+Array+in+the+cat+sciatic+nerve.">The foreign body response to the Utah Slant Electrode Array in the cat sciatic nerve.</a> Acta Biomaterialia. 10 (11), 4650-4660 (2014).</li><li>Patel, P. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+in+vivo+stability+assessment+of+carbon+fiber+microelectrode+arrays.">Chronic in vivo stability assessment of carbon fiber microelectrode arrays.</a> Journal of Neural Engineering. 13 (6), 066002 (2016).</li><li>Yoshida Kozai, T. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasmall+implantable+composite+microelectrodes+with+bioactive+surfaces+for+chronic+neural+interfaces.">Ultrasmall implantable composite microelectrodes with bioactive surfaces for chronic neural interfaces.</a> Nature Materials. 11 (12), 1065-1073 (2012).</li><li>Saito, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+carbon+fibers+to+biomaterials:+A+new+era+of+nano-level+control+of+carbon+fibers+after+30-years+of+development.">Application of carbon fibers to biomaterials: A new era of nano-level control of carbon fibers after 30-years of development.</a> Chemical Society Reviews. 40 (7), 3824-3834 (2011).</li><li>Welle, E. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+characterization+of+a+carbon+fiber+peripheral+nerve+electrode+appropriate+for+chronic+recording.">Fabrication and characterization of a carbon fiber peripheral nerve electrode appropriate for chronic recording.</a> FASEB Journal. 34 (1), 1 (2020).</li><li>Guitchounts, G., Cox, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=64-Channel+carbon+fiber+electrode+arrays+for+chronic+electrophysiology.">64-Channel carbon fiber electrode arrays for chronic electrophysiology.</a> Scientific Reports. 10 (1), 3830 (2020).</li><li>Patel, P. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+density+carbon+fiber+arrays+for+chronic+electrophysiology,+fast+scan+cyclic+voltammetry,+and+correlative+anatomy.">High density carbon fiber arrays for chronic electrophysiology, fast scan cyclic voltammetry, and correlative anatomy.</a> Journal of Neural Engineering. 17 (5), 056029 (2020).</li><li>Massey, T. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Open-source+automated+system+for+assembling+a+high-density+microwire+neural+recording+array.">Open-source automated system for assembling a high-density microwire neural recording array.</a> 2016 International Conference on Manipulation, Automation and Robotics at Small Scales (MARSS). , 1-7 (2016).</li><li>Schwerdt, H. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subcellular+probes+for+neurochemical+recording+from+multiple+brain+sites.">Subcellular probes for neurochemical recording from multiple brain sites.</a> Lab Chip. 17, 1104-1115 (2017).</li><li>Welle, E. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultra-small+carbon+fiber+electrode+recording+site+optimization+and+improved+in+vivo+chronic+recording+yield.">Ultra-small carbon fiber electrode recording site optimization and improved in vivo chronic recording yield.</a> Journal of Neural Engineering. 17 (2), 026037 (2020).</li><li>Guitchounts, G., Markowitz, J. E., Liberti, W. A., Gardner, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+carbon-fiber+electrode+array+for+long-term+neural+recording.">A carbon-fiber electrode array for long-term neural recording.</a> Journal of Neural Engineering. 10 (4), 046016 (2013).</li><li>Gillis, W. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+fiber+on+polyimide+ultra-microelectrodes.">Carbon fiber on polyimide ultra-microelectrodes.</a> Journal of Neural Engineering. 15 (1), 016010 (2018).</li><li>Dong, T., Chen, L., Shih, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+sharpening+of+carbon+fiber+microelectrode+arrays+for+brain+recording.">Laser sharpening of carbon fiber microelectrode arrays for brain recording.</a> Journal of Micro and Nano-Manufacturing. 8 (4), 041013 (2020).</li><li>Massey, T. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+high-density+carbon+fiber+neural+recording+array+technology.">A high-density carbon fiber neural recording array technology.</a> Journal of Neural Engineering. 16 (1), 016024 (2019).</li><li>Romeni, S., Valle, G., Mazzoni, A., Micera, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tutorial:+a+computational+framework+for+the+design+and+optimization+of+peripheral+neural+interfaces.">Tutorial: a computational framework for the design and optimization of peripheral neural interfaces.</a> Nature Protocols. 15 (10), 3129-3153 (2020).</li><li>Khani, H., Wipf, D. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+tip-protected+polymer-coated+carbon-fiber+ultramicroelectrodes+and+pH+ultramicroelectrodes.">Fabrication of tip-protected polymer-coated carbon-fiber ultramicroelectrodes and pH ultramicroelectrodes.</a> Journal of The Electrochemical Society. 166 (8), 673-679 (2019).</li><li>El-Giar, E. E. D. M., Wipf, D. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+tip-protected+poly(oxyphenylene)+coated+carbon-fiber+ultramicroelectrodes.">Preparation of tip-protected poly(oxyphenylene) coated carbon-fiber ultramicroelectrodes.</a> Electroanalysis. 18 (23), 2281-2289 (2006).</li><li>Venkatraman, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+and+in+vivo+evaluation+of+PEDOT+microelectrodes+for+neural+stimulation+and+recording.">In vitro and in vivo evaluation of PEDOT microelectrodes for neural stimulation and recording.</a> IEEE Transactions on Neural Systems and Rehabilitation Engineering. 19 (3), 307-316 (2011).</li><li>Petrossians, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrodeposition+and+Characterization+of+Thin-Film+Platinum-Iridium+Alloys+for+Biological+Interfaces.">Electrodeposition and Characterization of Thin-Film Platinum-Iridium Alloys for Biological Interfaces.</a> Journal of the Electrochemical Society. 158 (6), 269-276 (2011).</li><li>Lee, C. D., Hudak, E. M., Whalen, J. J., Petrossians, A., Weiland, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-impedance,+high+surface+area+Pt-Ir+electrodeposited+on+cochlear+implant+electrodes.">Low-impedance, high surface area Pt-Ir electrodeposited on cochlear implant electrodes.</a> Journal of The Electrochemical Society. 165 (12), 3015-3017 (2018).</li><li>Cassar, I. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrodeposited+platinum-iridium+coating+improves+in+vivo+recording+performance+of+chronically+implanted+microelectrode+arrays.">Electrodeposited platinum-iridium coating improves in vivo recording performance of chronically implanted microelectrode arrays.</a> Biomaterials. 205, 120-132 (2019).</li><li>Taylor, I. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+dopamine+detection+sensitivity+by+PEDOT/graphene+oxide+coating+on+in+vivo+carbon+fiber+electrodes.">Enhanced dopamine detection sensitivity by PEDOT/graphene oxide coating on in vivo carbon fiber electrodes.</a> Biosensors and Bioelectronics. 89, 400-410 (2017).</li><li>Mohanaraj, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold+nanoparticle+modified+carbon+fiber+microelectrodes+for+enhanced+neurochemical+detection.">Gold nanoparticle modified carbon fiber microelectrodes for enhanced neurochemical detection.</a> Journal of Visualized Experiments: JoVE. (147), e59552 (2019).</li><li>Pusch, J., Wohlmann, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+2+-+Carbon+fibers.">Chapter 2 - Carbon fibers.</a> Inorganic and composite fibers. Production, properties, and applications. , 31-51 (2019).</li><li>Budai, D., Hern&#225;di, I., M&#233;sz&#225;ros, B., Bali, Z. K., Gulya, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+responses+of+carbon+fiber+microelectrodes+to+dopamine+in+vitro+and+in+vivo.">Electrochemical responses of carbon fiber microelectrodes to dopamine in vitro and in vivo.</a> Acta Biologica Szegediensis. 54 (2), 155-160 (2010).</li></ol>

Material substitutions 
While all materials used are summarized in the Table of Materials, very few of the materials are required to come from specific vendors. The Flex Array board must come from the listed vendor as they are the only company that can print the flexible board. The Flex Array connector must also be ordered from the vendor listed as it is a proprietary connector. Parylene C is highly recommended as the insulation material for the fibers as it provides a conformal coa...

Much of neuroscience research relies upon recording neural signals using electrophysiology (ePhys). These neural signals are crucial to understanding the functions of neural networks and novel medical treatments such as brain machine and peripheral nerve interfaces1,2,3,4,5,6. Research surrounding peripheral nerves requires custom-made or commercially available neural recording electrodes. Neural recording electrodes-unique tools with micron-scale dimensions and fragile materials-require a specialized set of skills and equipment to fabricate. A variety of specialized probes have been developed for specific end uses; however, this implies that experiments must be designed around currently available commercial probes, or a laboratory must invest in the development of a specialized probe, which is a lengthy process. Due to the wide variety of neural research in peripheral nerve, there is high demand for a versatile ePhys probe4,7,8. An ideal ePhys probe would feature a small recording site, low impedance9, and a financially realistic price point for implementation in a system3.
Current commercial electrodes tend to either be extraneural or cuff electrodes (Neural Cuff10, MicroProbes Nerve Cuff Electrode11), which sit outside the nerve, or intrafascicular, which penetrate the nerve and sit within the fascicle of interest. However, as cuff electrodes sit further away from the fibers, they pick up more noise from nearby muscles and other fascicles that may not be the target. These probes also tend to constrict the nerve, which can lead to biofouling-a build-up of glial cells and scar tissue-at the electrode interface while the tissue heals. Intrafascicular electrodes (such as LIFE12, TIME13, and Utah Arrays14) add the benefit of fascicle selectivity and have good signal-to-noise ratios, which is important in discriminating signals for machine interfacing. However, these probes do have issues with biocompatibility, with nerves becoming deformed over time3,15,16. When bought commercially, both these probes have static designs with no option for experiment-specific customization and are costly for newer laboratories.
In response to the high cost and biocompatibility issues presented by other probes, carbon fiber electrodes may offer an avenue for neuroscience laboratories to build their own probes without the need for specialized equipment. Carbon fibers are an alternative recording material with a small form factor that allows for low damage insertion. Carbon fibers provide better biocompatibility and considerably lower scar response than silicon17,18,19 without the intensive cleanroom processing5,13,14. Carbon fibers are flexible, durable, easily integrated with other biomaterials19, and can penetrate and record from nerve7,20. Despite the many advantages of carbon fibers, many laboratories find the manual fabrication of these arrays arduous. Some groups21 combine carbon fibers into bundles that collectively result in a larger (~200 &#181;m) diameter; however, to our knowledge, these bundles have not been verified in nerve. Others have fabricated individuated carbon fiber electrode arrays, although their methods require cleanroom-fabricated carbon fiber guides22,23,24 and equipment to populate their arrays17,23,24. To address this, we propose a method of fabricating a carbon fiber array that can be performed at the laboratory benchtop that allows for impromptu modifications. The resulting array maintains individuated electrode tips without specialized fiber populating tools. Additionally, multiple geometries are presented to match the needs of the research experiment. Building from previous work8,17,22,25, this paper provides detailed methodologies to build and modify several styles of arrays manually with minimal cleanroom training time needed.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>3 prong clams</td>
			<td>05-769-6Q</td>
			<td>Fisher</td>
			<td>Qty: 2 
			Unit Cost (USD): 20</td>
		</tr>
		<tr>
			<td>3,4-ethylenedioxythiophene (25 g) 
			(PEDOT)</td>
			<td>96618</td>
			<td>Sigma-Aldrich</td>
			<td>Qty: 1 
			Unit Cost (USD): 102</td>
		</tr>
		<tr>
			<td>353ND-T Epoxy (8oz)++ 
			(ZIF and Wide Board Only)</td>
			<td>353ND-T/8OZ</td>
			<td>Epoxy Technology</td>
			<td>Qty: 1 
			Unit Cost (USD): 48</td>
		</tr>
		<tr>
			<td>Ag/AgCl (3M NaCl) Reference Electrode (pack of 3)</td>
			<td>50-854-570</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 100</td>
		</tr>
		<tr>
			<td>Autolab</td>
			<td>PGSTAT12</td>
			<td>Metrohm</td>
			<td></td>
		</tr>
		<tr>
			<td>Blowtorch</td>
			<td>1WG61</td>
			<td>Grainger</td>
			<td>Qty: 1 
			Unit Cost (USD): 36</td>
		</tr>
		<tr>
			<td>Carbon Fibers</td>
			<td>T-650/35 3K</td>
			<td>Cytec Thornel</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Carbon tape</td>
			<td>NC1784521</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 27</td>
		</tr>
		<tr>
			<td>Cotton Tipped Applicator</td>
			<td>WOD1002</td>
			<td>MediChoice</td>
			<td>Qty: 1 
			Unit Cost (USD): 0.57</td>
		</tr>
		<tr>
			<td>Delayed Set Epoxy++</td>
			<td>1FBG8</td>
			<td>Grainger</td>
			<td>Qty: 1 
			Unit Cost (USD): 3</td>
		</tr>
		<tr>
			<td>DI Water</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Qty: n/a 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Dumont Tweezers #5</td>
			<td>50-822-409</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 73</td>
		</tr>
		<tr>
			<td>Flex Array**</td>
			<td>n/a</td>
			<td>MicroConnex</td>
			<td>Qty: 1 
			Unit Cost (USD): 68</td>
		</tr>
		<tr>
			<td>Flux</td>
			<td>SMD291ST8CC</td>
			<td>DigiKey</td>
			<td>Qty: 1 
			Unit Cost (USD): 13</td>
		</tr>
		<tr>
			<td>Glass Capillaries (pack of 350)</td>
			<td>50-821-986</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 60</td>
		</tr>
		<tr>
			<td>Glass Dish</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Hirose Connector 
			(ZIF Only)</td>
			<td>H3859CT-ND</td>
			<td>DigiKey</td>
			<td>Qty: 2 
			Unit Cost (USD): 2</td>
		</tr>
		<tr>
			<td>Light-resistant Glass Bottle</td>
			<td>n/a</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Micropipette Heating Filiment</td>
			<td>FB315B</td>
			<td>Sutter Instrument Co</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Micropipette Puller</td>
			<td>P-97</td>
			<td>Sutter Instrument Co</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Nitrile Gloves (pack of 200)</td>
			<td>19-041-171C</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 47</td>
		</tr>
		<tr>
			<td>Offline Sorter software</td>
			<td>n/a</td>
			<td>Plexon</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Omnetics Connector* 
			(Flex Array Only)</td>
			<td>A79025-001</td>
			<td>Omnetics Inc</td>
			<td>Qty: 1 
			Unit Cost (USD): 35</td>
		</tr>
		<tr>
			<td>Omnetics Connector* 
			(Flex Array Only)</td>
			<td>A79024-001</td>
			<td>Omnetics Inc</td>
			<td>Qty: 1 
			Unit Cost (USD): 35</td>
		</tr>
		<tr>
			<td>Omnetics to ZIF connector</td>
			<td>ZCA-OMN16</td>
			<td>Tucker-Davis Technologies</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Pin Terminal Connector 
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			<td>ED11523-ND</td>
			<td>DigiKey</td>
			<td>Qty: 16 
			Unit Cost (USD): 10</td>
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		<tr>
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			Unit Cost (USD): 2</td>
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			<td>Grainger</td>
			<td>Qty: 1 
			Unit Cost (USD): 2</td>
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			<td>lnf</td>
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			Unit Cost (USD): 3</td>
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		<tr>
			<td>Silver Epoxy (1oz)++</td>
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			<td>Epoxy Technology</td>
			<td>Qty: 1 
			Unit Cost (USD): 125</td>
		</tr>
		<tr>
			<td>Silver GND REF wires</td>
			<td>50-822-122</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 423.2</td>
		</tr>
		<tr>
			<td>Sodium p-toulenesulphonate(pTS)- 100g</td>
			<td>152536</td>
			<td>Sigma-Aldrich</td>
			<td>Qty: 1 
			Unit Cost (USD): 59</td>
		</tr>
		<tr>
			<td>Solder</td>
			<td>24-6337-9703</td>
			<td>DigiKey</td>
			<td>Qty: 1 
			Unit Cost (USD): 60</td>
		</tr>
		<tr>
			<td>Soldering Iron Tip</td>
			<td>T0054449899N-ND</td>
			<td>Digikey</td>
			<td>Qty: 1 
			Unit Cost (USD): 13</td>
		</tr>
		<tr>
			<td>Soldering Station</td>
			<td>WD1002N-ND</td>
			<td>Digikey</td>
			<td>Qty: 1 
			Unit Cost (USD): 374</td>
		</tr>
		<tr>
			<td>SpotCure-B UV LED Cure System</td>
			<td>n/a</td>
			<td>FusionNet LLC</td>
			<td>Qty: 1 
			Unit Cost (USD): 895</td>
		</tr>
		<tr>
			<td>Stainless steel rod</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Stir Plate</td>
			<td>n/a</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): n/a</td>
		</tr>
		<tr>
			<td>Surgical Scissors</td>
			<td>08-953-1B</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 100</td>
		</tr>
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			<td>TDT Shroud 
			(ZIF Only)</td>
			<td>Z3_ZC16SHRD_RSN</td>
			<td>TDT</td>
			<td>Qty: 1 
			Unit Cost (USD): 3.5</td>
		</tr>
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			<td>50-380-043</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 47</td>
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			<td>Loctite</td>
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			Unit Cost (USD): 45</td>
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			<td>UV Epoxy (8oz)++ 
			(Flex Array Only)</td>
			<td>OG142-87/8OZ</td>
			<td>Epoxy Technology</td>
			<td>Qty: 1 
			Unit Cost (USD): 83</td>
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			<td>n/a</td>
			<td>WER</td>
			<td>Qty: 1 
			Unit Cost (USD): 30</td>
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			<td>Weigh boat 
			(pack of 500)</td>
			<td>08-732-112</td>
			<td>Fisher</td>
			<td>Qty: 1 
			Unit Cost (USD): 58</td>
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			<td>Wide Board+</td>
			<td>n/a</td>
			<td>Advanced Circuits</td>
			<td>Qty: 1 
			Unit Cost (USD): 3</td>
		</tr>
		<tr>
			<td>ZIF Active Headstage</td>
			<td>ZC16</td>
			<td>Tucker-Davis Technologies</td>
			<td>Qty: 1 
			Unit Cost (USD): 925</td>
		</tr>
		<tr>
			<td>ZIF Passive Headstage</td>
			<td>ZC16-P</td>
			<td>Tucker-Davis Technologies</td>
			<td>Qty: 1 
			Unit Cost (USD): 625</td>
		</tr>
		<tr>
			<td>ZIF*</td>
			<td>n/a</td>
			<td>Coast to Coast Circuits</td>
			<td>Qty: 1 
			Unit Cost (USD): 9</td>
		</tr>
	</tbody>
</table>

open-source toolkit: benchtop carbon fiber microelectrode array for nerve recording

Conventional peripheral nerve probes are primarily fabricated in a cleanroom, requiring the use of multiple expensive and highly specialized tools. This paper presents a cleanroom "light" fabrication process of carbon fiber neural electrode arrays that can be learned quickly by an inexperienced cleanroom user. This carbon fiber electrode array fabrication process requires just one cleanroom tool, a Parylene C deposition machine, that can be learned quickly or outsourced to a commercial processing facility at marginal cost. This fabrication process also includes hand-populating printed circuit boards, insulation, and tip optimization. 
The three different tip optimizations explored here (Nd:YAG laser, blowtorch, and UV laser) result in a range of tip geometries and 1 kHz impedances, with blowtorched fibers resulting in the lowest impedance. While previous experiments have proven laser and blowtorch electrode efficacy, this paper also shows that UV laser-cut fibers can record neural signals in vivo. Existing carbon fiber arrays either do not have individuated electrodes in favor of bundles or require cleanroom fabricated guides for population and insulation. The proposed arrays use only tools that can be used at a benchtop for fiber population. This carbon fiber electrode array fabrication process allows for quick customization of bulk array fabrication at a reduced price compared to commercially available probes.

Tip validation: SEM images 
Previous work20 showed that scissor cutting resulted in unreliable impedances as Parylene C folded across the recording site. Scissor cutting is used here only to cut fibers to the desired length before processing with an additional finish cutting method. SEM images of the tips were used to determine the exposed carbon length and tip geometry (Figure 8).
Scissor and Nd:YAG laser-cut fibers w...

Watch this Scientific Journal Video about Open-source Toolkit: Benchtop Carbon Fiber Microelectrode Array for Nerve Recording at JoVE.com

Open-source Toolkit: Benchtop Carbon Fiber Microelectrode Array for Nerve Recording

Here, we describe fabrication methodology for customizable carbon fiber electrode arrays for recording in vivo in nerve and brain.

Conventional peripheral nerve probes are primarily fabricated in a cleanroom, requiring the use of multiple expensive and highly specialized tools. This ...

Carbon fiber electrodes, are smaller than neurons and do minimal damage. In addition, they can be manufactured with minimal specialized equipment on the bench top. The main advantage of this technique is in its simplicity.It allows users to build and customize neural arrays, with no cleanroom experience. Manipulating the carbon fibers and placing the silver epoxy is tricky and critical. These two parts take a lot of practice and fine motor control.The first day is always the worst, but with practice, after about a week, you will build a functional neural array. To begin, set a soldering iron to 315 degrees Celsius. Apply flux to all soldering pads.Form small mounds of solder on the back pads of the flex array, then solder the pins on either side of the connector. Once secure, gently push the soldering iron tip, between the front pins, to solder the remaining connections in the back. Apply an additional flux layer, if soldering takes a long time, then solder the front row of pins to the board.Clean away excess flux with 100%isopropyl alcohol, and a short bristle brush. Next, slowly push the laid set epoxy with a syringe, placed bevel side down on the pins, to encapsulate the soldered connection. Lay a small line of the epoxy across the board's backside, and pull it onto the connector's edges to secure it.Make capillaries with a glass puller and filament. Cut a pulled glass capillary, so that its tip fits between the traces of the array. Then, scoop approximately a one to one ratio of silver epoxy into a plastic dish, with the wooden ends of two cotton tipped applicators and mix it.Discard the applicators after mixing. Cut two to four millimeters, from the end of a carbon fiber bundle, onto a printer paper with a razor blade. Pull a laminated paper, gently, over the top of the bundle to separate the fibers and the bundle.Next, take a little epoxy onto the pulled capillary's end. And gently apply it between every other trace, on the end of the board, filling the gap. Place one carbon fiber in each epoxy trace, with teflon coated tweezers.Then, adjust the carbon fibers with a clean pulled capillary, to make perpendicular to the end of the flex array board and bury them beneath the epoxy. Place the arrays on a wooden block, with fibered ends overhanging the edge of the block. Bake the wooden block and arrays at 140 degrees Celsius for 20 minutes, to cure the silver epoxy and lock the fibers into place.If silver epoxy shorts two or more of the fibers together, it can be removed using a clean glass capillary, and gently scraping it off the board. Store the finished boards in a box with a raised platform, to suspend the fibered ends of the board, to prevent fiber breakage. Apply a tiny droplet of UV epoxy on the exposed traces with a clean capillary, and continue adding droplets, until the traces are completely covered.Cure the UV epoxy under a UV pen for two minutes and repeat it for the other side of the board. Cut the fibers to one millimeter with a stereoscope reticle and surgical scissors. To check electrical connections, set the potentiostat to zero volts, for five seconds, and stabilize the recorded signal.Run a one kilohertz impedance scan for each fiber with a potentiostat. Record the measurements via the potentiostat associated software. Then dip the fibers in deionized water in a beaker, three times, to rinse them.Gently scrape away Parylene C from the ground, and reference wires on the board with tweezers. Next, cut two five centimeter lengths of insulated silver wire with a razor blade. De-insulate two to three millimeters of wire, from one end and around 10 millimeters from the opposite end.Next, heat the soldering iron to 315 degrees Celsius, and apply a small flux to the wires. Insert two to three millimeters of one wire, into each electrophysiology wire on the board, and apply solder to the top of the wires. After allowing the probe to cool, flip it over to apply a little solder to the backside of the wire.Snip off any exposed wire sticking out of the back solder mound. Place the arrays in the storage box, bending the wires back, away from the fiber and secure the wires on the adhesive tape, to prevent potential fiber wire interactions. SEM images of the tips were used to determine the exposed carbon length and tip geometry.Scissor cut fibers have inconsistent tip geometries, with Parylene C folding over the end. The NDYAG laser cut fibers remain consistent, in the recording site area, shape and impedance. Blow torched fibers lead to the largest electrode size, and shape variability and a sharpened tip.On average, 140 micrometers of carbon were re-exposed. UV laser cut fibers were similar to blow torched fibers, showing 120 micro meters of carbon, exposed from the tip. The resulting impedances were within range, for electrophysiological recording.NDYAG laser cut fibers had the smallest surface area but the highest impedances. Followed by blow torched and UV laser cut fibers. However, in all cases, the PEDOT:pTS coated fibers, fell under the 110 kilo ohm threshold.Acute recordings from four UV laser treatment fibers, of two millimeter length, simultaneously implanted in rat motor cortex, showed three units across all fibers, suggesting that the treatment of the fibers with the inexpensive UV laser, is similar to other cutting methods. When attempting this protocol, give yourself a large, clean space when populating carbon fibers. It is easy to accidentally sweep all of your fibers off the table, because there's not enough maneuvering room.These arrays are now suitable for signal unit recordings from the brain. These building techniques allowed Dr.Barnes'group, at the University of Michigan, to report and Dr.Chiel's group at Case Western Reserve University, to report intracellular

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