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[0] Porada I, Bondar I, Spatz WB, Kruger J, Rabbit and monkey visual cortex: more than a year of recording with up to 64 microelectrodes.J Neurosci Methods 95:1, 13-28 (2000 Jan 31)

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ref: -2001 tags: polyimide Kipke bioactive flexible electrode arrays date: 12-22-2017 01:16 gmt revision:2 [1] [0] [head]

PMID-11327505 Flexible polyimide-based intracortical electrode arrays with bioactive capability.

  • Appears to be the first or one of the first use of thin-film polyimide for intracortical recording; will have to cite.
  • Fab protocol: 500nm release thermal oxide, photo-paternable PI, Cr-Au metalization, O2 plasma de-scum for adhesion (ish?), <20um total thickness.
  • Conductive epoxy attachment to connector.

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ref: Ward-2009.07 tags: microelectrode arrays immune response recording MEA Purdue date: 01-28-2013 01:52 gmt revision:8 [7] [6] [5] [4] [3] [2] [head]

PMID-19486899[0] Toward a comparison of microelectrodes for acute and chronic recordings.

  • Good research, paper well written.
  • Results suggest significant variability within and between microelectrode types with no clearly superior array (from the abstract).
  • As Miguel mantains, "Much of the new technology, however, does not supersede traditional microwire technology in its ability to evade a host immune response".
  • Initial implantation wound initiates a cascade of immune responses which culminates in a sheath of microglia, astrocytes, various ectracellular matrix constituents, and macrophages.
    • Decent citation list -- many people have been working on MEAs.
  • Fibrous encapusulation of the electrode is much less conductive than healthy nervous tissue, hence impedance measurements can be used to track tissue response.
  • Used Osort to sort the recorded neurons.
  • "Despite differing implant locations, and thus potentially differing levels of background neural activity, and differing scarring responses, which relates to the level of thermal noise in the observed signal (Ludwig et al., 2006), no significant SNR differences were observed among the MEA types for the duration of the study."
  • SNR trends did not seem to relate to site impedance trends over the 31-day period, and by inference, the extent of tissue encapsulation and neuronal density loss.
    • SNR is likely controlled by background neural noise, not thermal noise (which would be linked to impedance).
  • Electrodes with lower impedance generally recorded units from more sites than arrays with higher impedance.

____References____

[0] Ward MP, Rajdev P, Ellison C, Irazoqui PP, Toward a comparison of microelectrodes for acute and chronic recordings.Brain Res 1282no Issue 183-200 (2009 Jul 28)

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ref: -0 tags: histology atryocytes immune response electrode arrays lund multiple exacerbate date: 01-24-2013 19:56 gmt revision:1 [0] [head]

PMID-23091629 Multiple implants do not aggravate the tissue reaction in rat brain.

  • After six weeks, the astrocytic scar surrounding the middle out of five implants was significantly smaller compared to the single contralateral implant, suggesting that an intrahemispheric interaction might be taking place, reducing the astrocytic response around the central implant.
  • Weak (?) staining for ED1 in this study?
  • -- after 6 weeks.
  • Thought: every paper has a different method for quantify immune response, GFAP staining in this case.

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ref: -0 tags: flexible micxrowire arrays electrode recording Georgia polymide date: 01-04-2013 00:13 gmt revision:1 [0] [head]

IEEE-906517 (pdf) Flexible microelectrode arrays with integrated insertion devices

  • 2001 MEMS Conference.
  • FMA = flexible microelectrode arrays.
  • Both for nerves (pass-through needle) and cortex (removeable needle).
    • Primarily tested in tissue proxies.
  • Anticipated the utility of photolithography for patterning the electrodes + rigid insertion devices.
  • The elastic modulus of polymers like polymide are two orders of magnitude less than metals, but still six orders of magnitude higher than brain tissue (46kPa).
  • Pass-through needle very similar to the threaded wire idea.
  • removable needle simply stops the thread & drives the needle a bit further to break the attachment site.
    • Did not test removable needle technique (?)
  • Defined electroplating with a thick photoresist mask, as Michel says.
  • Tested FMAs with movement and acceleration vs. rigid arrays. FMAs faired much better, of course!

____References____

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ref: Freire-2011.01 tags: Nicolelis BMI electrodes immune respones immunohistochemistry chronic arrays rats 2011 MEA histology date: 06-29-2012 01:20 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-22096594[0] Comprehensive analysis of tissue preservation and recording quality from chronic multielectrode implants.

  • Says what might be expected: tungsten microelectrode arrays work, though the quality gradually declines over 6 months.
  • Histological markers correlated well with recording performance.
  • Shows persistent glial activation around electrode sites + cell body hypertropy.
    • Suggest that loss in recording quality may be due to glial encapsulation.
  • References
    • Szarowski et al 2003 {1028}
    • Ward et al 2009
  • Histology:
    • NADPH-d: nicotinamide adenine dinucleotide phosphate-diaphorase, via beta-NADP
    • CO: cytochrome oxidase, via diamnibenzidine DAB, cytochrome c and catalase.
      • both good for staining cortical layers; applied in a standard buffered solution and monitored to prevent overstaining.
  • Immunohistochemistry:
    • Activated microglia with ED-1 antibody.
    • Astrocytes labeled with glial fibrillary acid protein.
    • IEG with an antibody against EGR-1, 'a well-known marker of calcium dependent neuronal activity'
    • Neurofilament revealed using a monoclonal NF-M antibody.
    • Caspace-3 with the associated antibody
    • Details the steps for immunostaining -- wash, blocknig buffer, addition of the antibody in diluted blocking solution (skim milk) overnight, wash again, incubate in biotinylated secondary antibody, wash again, incubate in avidin-biotin-peroxidase solution.
    • Flourescent immunohistochemistry had biotynlation replaced with alexa Fluor 488-conjugated horse anti-mouse and Alexa Fluor 594-conjugated goat anti-rabbit overnight.

____References____

[0] Freire MA, Morya E, Faber J, Santos JR, Guimaraes JS, Lemos NA, Sameshima K, Pereira A, Ribeiro S, Nicolelis MA, Comprehensive analysis of tissue preservation and recording quality from chronic multielectrode implants.PLoS One 6:11, e27554 (2011)

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ref: Porada-2000.01 tags: electrodes recording oblique inverted MEA arrays Kruger date: 01-05-2012 23:07 gmt revision:3 [2] [1] [0] [head]

PMID-10776811[0] More than a year of recording with up to 64 microelectrodes

  • for more than a year action potentials of good quality were obtained from most electrodes!
  • used 60mm-long, 12.5um Ni-Cr-Al (Isaohm) wire, polyimide insulated, soldered to microconnectors. Tips purely ('primitively') cut after bonding them to a piece of photographic film substrate.
  • implanted in the rabbit and marmoset V1 cortex from afar.
  • with the 8 rabbits they used a magnetic release to prevent excessive force from removing the implant.
  • used small sections of thicker wire to individually label the electrodes for x-ray; thusly could reconstruct the electrode positions. electrodes in the white matter were silent mais or menos.
  • the autocorrelation functions of the neurons generally look good; some of them do not have a refractory period though.
  • in GFAP-stained sections a single electrode track appeared as a hole of about 28 um wide. The outer diameter of the wire insulation as 18um. electrode tracts were not visible in cresyl violet tracts. the neurones near the electrode tips appeared normal.
  • we recorded signals for up to 711 days, during which time the recording quality did not degrade. nice, nice!
  • they think that the large length of free wire, running about 5mm through the brain provides a sufficient degree of friction so that locally the tissue is prevented from moving relative to the electrodes. They did not need to use microstimulation to improve recording quality.

____References____

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ref: Verloop-1984.08 tags: recording electrode arrays MEA epoxy teflon simple mold slice cultures date: 01-03-2012 00:57 gmt revision:2 [1] [0] [head]

PMID-6492861[0] A simple method for the construction of electrode arrays.

  • It is simple!
  • of note: "Therefore arrays of equidistant electrodes have been developed for superficial and depth recording. During the last decade the construction of many of these multiple electrodes for in vivo and in vitro measurements is based o n thin film techniques (Wise a n d Angell, 1975; Pickard, 1979; Pochay et al., 1979; Prohaska et al., 1979; Kuperstein and Whittington, 1981).
    • Have to go back and check these thin-film attempts.
  • See also: PMID-7248818[1] A flexible high density multi-channel electrode array for long-term chronic implantation. (surface recording).

____References____

[0] Verloop AJ, Holsheimer J, A simple method for the construction of electrode arrays.J Neurosci Methods 11:3, 173-8 (1984 Aug)
[1] Weissman AD, Schwartz EL, A flexible high density multi-channel electrode array for long-term chronic implantation.Brain Res Bull 6:6, 543-6 (1981 Jun)