Method Article

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

DOI:

10.3791/63099

⸱

October 29th, 2021

 ,  ,  ,  ,  ,  , 
1Department of Biomedical Engineering, University of Michigan, Ann Arbor, 2Department of Mechanical Engineering, University of Michigan, Ann Arbor, 3Department of Mechanical Engineering, University of Massachusetts Lowell, 4Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, 5Neuroscience Graduate Program, University of Michigan, Ann Arbor, 6Robotics Graduate Program, University of Michigan, Ann Arbor

In This Article

Summary

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

Abstract

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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.

Introduction

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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 ma....

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Protocol

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All animal procedures were approved by the University of Michigan Institutional Animal Care and Use Committee.

1. Choosing a carbon fiber array

  1. 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.
    1. Refer to PCB designs on the Chestek Lab website (https://chestekresearch.engin.umich.edu), free of charge and ready to be sent to and ordered for printing through a PCB printing house.
    2. See Table 1 for a summary of connectors for each board and their specif....

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Results

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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 wer.......

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Discussion

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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.......

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Disclosures

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The authors declare that they have no competing financial interests.

Acknowledgements

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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 compari....

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
3 prong clams05-769-6QFisherQty: 2
Unit Cost (USD): 20
3,4-ethylenedioxythiophene (25 g)
(PEDOT)		96618Sigma-AldrichQty: 1
Unit Cost (USD): 102
353ND-T Epoxy (8oz)++
(ZIF and Wide Board Only)		353ND-T/8OZEpoxy TechnologyQty: 1
Unit Cost (USD): 48
Ag/AgCl (3M NaCl) Reference Electrode (pack of 3)50-854-570FisherQty: 1
Unit Cost (USD): 100
AutolabPGSTAT12Metrohm
Blowtorch1WG61GraingerQty: 1
Unit Cost (USD): 36
Carbon FibersT-650/35 3KCytec ThornelQty: 1
Unit Cost (USD): n/a
Carbon tapeNC1784521FisherQty: 1
Unit Cost (USD): 27
Cotton Tipped ApplicatorWOD1002MediChoiceQty: 1
Unit Cost (USD): 0.57
Delayed Set Epoxy++1FBG8GraingerQty: 1
Unit Cost (USD): 3
DI Watern/an/aQty: n/a
Unit Cost (USD): n/a
Dumont Tweezers #550-822-409FisherQty: 1
Unit Cost (USD): 73
Flex Array**n/aMicroConnexQty: 1
Unit Cost (USD): 68
FluxSMD291ST8CCDigiKeyQty: 1
Unit Cost (USD): 13
Glass Capillaries (pack of 350)50-821-986FisherQty: 1
Unit Cost (USD): 60
Glass Dishn/an/aQty: 1
Unit Cost (USD): n/a
Hirose Connector
(ZIF Only)		H3859CT-NDDigiKeyQty: 2
Unit Cost (USD): 2
Light-resistant Glass Bottlen/aFisherQty: 1
Unit Cost (USD): n/a
Micropipette Heating FilimentFB315BSutter Instrument CoQty: 1
Unit Cost (USD): n/a
Micropipette PullerP-97Sutter Instrument CoQty: 1
Unit Cost (USD): n/a
Nitrile Gloves (pack of 200)19-041-171CFisherQty: 1
Unit Cost (USD): 47
Offline Sorter softwaren/aPlexonQty: 1
Unit Cost (USD): n/a
Omnetics Connector*
(Flex Array Only)		A79025-001Omnetics IncQty: 1
Unit Cost (USD): 35
Omnetics Connector*
(Flex Array Only)		A79024-001Omnetics IncQty: 1
Unit Cost (USD): 35
Omnetics to ZIF connectorZCA-OMN16Tucker-Davis TechnologiesQty: 1
Unit Cost (USD): n/a
Pin Terminal Connector
(Wide Board Only)		ED11523-NDDigiKeyQty: 16
Unit Cost (USD): 10
Probe storage boxG2085MelmatQty: 1
Unit Cost (USD): 2
Razor Blade4A807GraingerQty: 1
Unit Cost (USD): 2
SEM post16327lnfQty: 1
Unit Cost (USD): 3
Silver Epoxy (1oz)++H20E/1OZEpoxy TechnologyQty: 1
Unit Cost (USD): 125
Silver GND REF wires50-822-122FisherQty: 1
Unit Cost (USD): 423.2
Sodium p-toulenesulphonate(pTS)- 100g152536Sigma-AldrichQty: 1
Unit Cost (USD): 59
Solder24-6337-9703DigiKeyQty: 1
Unit Cost (USD): 60
Soldering Iron TipT0054449899N-NDDigikeyQty: 1
Unit Cost (USD): 13
Soldering StationWD1002N-NDDigikeyQty: 1
Unit Cost (USD): 374
SpotCure-B UV LED Cure Systemn/aFusionNet LLCQty: 1
Unit Cost (USD): 895
Stainless steel rodn/an/aQty: 1
Unit Cost (USD): n/a
Stir Platen/aFisherQty: 1
Unit Cost (USD): n/a
Surgical Scissors08-953-1BFisherQty: 1
Unit Cost (USD): 100
TDT Shroud
(ZIF Only)		Z3_ZC16SHRD_RSNTDTQty: 1
Unit Cost (USD): 3.5
Teflon Tweezers50-380-043FisherQty: 1
Unit Cost (USD): 47
UV & Visible Light Safety Glassees92522LoctiteQty: 1
Unit Cost (USD): 45
UV Epoxy (8oz)++
(Flex Array Only)		OG142-87/8OZEpoxy TechnologyQty: 1
Unit Cost (USD): 83
UV Lasern/aWERQty: 1
Unit Cost (USD): 30
Weigh boat
(pack of 500)		08-732-112FisherQty: 1
Unit Cost (USD): 58
Wide Board+n/aAdvanced CircuitsQty: 1
Unit Cost (USD): 3
ZIF Active HeadstageZC16Tucker-Davis TechnologiesQty: 1
Unit Cost (USD): 925
ZIF Passive HeadstageZC16-PTucker-Davis TechnologiesQty: 1
Unit Cost (USD): 625
ZIF*n/aCoast to Coast CircuitsQty: 1
Unit Cost (USD): 9

References

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  1. Szostak, K. M., Grand, L., Constandinou, T. G. Neural interfaces for intracortical recording: Requirements, fabrication methods, and characteristics. Frontiers in Neuroscience. 11, 665(2017).
  2. Cunningham, J. P., et al.

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Tags

Carbon Fiber ElectrodesMicroelectrode ArrayNerve RecordingBenchtop FabricationTip OptimizationUV Laser CuttingBlowtorch ElectrodeParylene C DepositionElectrophysiological RecordingPeripheral Nerve Probe

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