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[0] Suner S, Fellows MR, Vargas-Irwin C, Nakata GK, Donoghue JP, Reliability of signals from a chronically implanted, silicon-based electrode array in non-human primate primary motor cortex.IEEE Trans Neural Syst Rehabil Eng 13:4, 524-41 (2005 Dec)

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ref: Salcman-1973.07 tags: Salcman MEA microelectrodes chronic recording glass cyanocrylate date: 12-29-2017 04:33 gmt revision:7 [6] [5] [4] [3] [2] [1] [head]

PMID-4708761 Design, Fabrication, and In Vivo Behavior of Chronic Recording Intracortical Microelectrodes

  • Teflon-coated 25um Pt-Ir (90/10)
  • Heat fuse this with a glass micropipette & backfill with cyanoacrylate. {1011}
    • Isobutyl acrylate is hydrolysed more slowly and hence is less toxic to the surronding tissue
    • cyanoacrylate is apparently biodegradable.
  • Durable, stable: one electrode displayed a single cortical spike (though not necessarily the same one) for more than 90 consecutive days.
  • unacceptably low impedance = 100K or less
  • Unit activity was present only 10-24H after surgery.
  • formal review of even older microelectrode studies.
  • 10nA should be 100x too small to have any effect on a platinum tip [17]
  • A seperable cell with a SNR of 3:1 would become lost if the electrode tip moved 15um away from a 20um soma.
    • "It becomes clear that the problem of holding single units for prolonged periods in the unrestrained animal is not achieved without considerable difficulty". Yet they think they have solved it.

____References____

Salcman, Michael and Bak, Martin J. Design, Fabrication, and In Vivo Behavior of Chronic Recording Intracortical Microelectrodes Biomedical Engineering, IEEE Transactions on BME-20 4 253 -260 (1973)

{1352}
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ref: -0 tags: Charles Lieber syringe-injectable electronics SU-8 chronic flexible date: 10-14-2016 23:30 gmt revision:1 [0] [head]

PMID-27571550 Stable long-term chronic brain mapping at the single-neuron level.

  • Fu TM, Hong G1, Zhou T1, Schuhmann TG, Viveros RD2, Lieber CM.
  • 8 months with only 800nm of Su-8 (400nm of insulation!!). This is both surprising and very impressive; we have to step up our game!
  • In a mouse, too - their surgical technique must be very good. Mice only live ~ 2 years anyway.
  • Figure 3 -- stability -- incredible.
  • Recording sites were bare platinum, 20um diameter; stimulation sites were also bare Pt, 150um dia.
    • No plating or mircowire-fets, so far as I can see; electrode impedances were stable at 200 - 600k (supplementary figure 12).

{597}
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ref: Suner-2005.12 tags: Suner Utah probe electrophysiology reliability chronic electrode recording longevity histology MEA date: 01-31-2013 22:27 gmt revision:7 [6] [5] [4] [3] [2] [1] [head]

PMID-16425835Reliability of signals from a chronically implanted, silicon-based electrode array in non-human primate primary motor cortex

  • claim that they have done a logitudinal development series that included 39 array implants in 18 monkeys.
  • can get reliable recordings out to 3 months (only? probably the array was forced out of the brain?)
    • however, it seems that their recording quality did not decrease dramatically over those 3 months.
  • excellent methods section.
  • also {1027}

____References____

{946}
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ref: Salcman-1976.01 tags: Salcman electrodes recording chronic microelectrode array MEA original parylene date: 01-28-2013 22:18 gmt revision:8 [7] [6] [5] [4] [3] [2] [head]

PMID-1256090[0] A new chronic recording intracortical microelectrode

  • maintain that tethering is the rational way to go: it "re-establishes the normal biomechanics of the intact cranial vault". (Salcman 1972, 1973) {1010}
    • have model of electrode tip motion in response to brain-skull displacements (Goldstein and Salcman 1973) {1011}
      • Electrode would have a tip displacement of about 5um in response to a 1mm displacement of the electrode's point of entry into the skull.
      • Exponential dependence on recording amplitude and distance (Rall, 1962). Gradient: 7.5uv/um; movements of more than 1-2um can radically alter the recordnig shape.
      • Probably our electrodes work because the dura & gliosis becomes firmly attached to the electrode shafts.
    • not really an array so much as a number (10-12) of single-unit electrodes.
  • Details the process of parylene-C deposition, electrode microwelding, etc. Pretty cool stuff -- what has happened to this technology?
  • Each bubble is glued with cyanocrylate to the pia. (they too question the safety of this).
  • arrays can be manually inserted via forceps.
  • 25um iridium wire electroplated in 1-2um of gold
    • then electo-etched until the desired tip geometry is achieved, 1-3um diameter
    • and vacuum coated in 3um of parylene-C.
    • Impedance 1-2M with a 1kHz sine wave at 10nA. Impedance is inversely related to the frequency of the test current, phase angle of 70-80deg.
      • Ref Robinson, 1968.
    • We must emphasize the extreme sensitivity of electrode measurements to the test conditions. Measured values of Z e are usually increased 1-3M when the electrode has been stored away for a few days. Removing the electrode from the test bath for a few minutes in air can lead to equally large increases when the electrode is tested upon remersion. [...] might be oxide.
    • Pinholes are the usual failure mechanism (KD Wise 2004), {149}; parylene is 'pinhole-free'.
  • The connecting 25um Au lead is very flexible and imposes little stress on the iridium electrode.
    • Connecting wire coated in 12um of parylene C
    • Would prefer even finer wire, 12um.
  • Perspex window over the craniotomy; had a vent in this window which they could open.
  • Opening the vent would cause the brain to pulse, moving the electrodes through the cortex and changing neural activity.
  • Size of an electrode is limited by ability to introduce it into the brain.
    • Electrode must be introduced through the pia; as the pial vessels supply the cortex (or drain the cortex).
    • For their electrodes, P crit=0.9g ; the force necessary to penetrate the pia is 0.05 - 0.2g.
  • pure iridium is stiffer than Pt-Ir by a factor of 3 or so. (521 G N/m^2 = 521 GPa, higher than tungsten, which is 400 Gpa)
    • Pure iridium is apparently the stiffest metallic element ref
  • Interesting: "Once again we are impressed by the fact that passive recording electrodes exhibit drops in impedance in the living system which they never show on in vitro testing in protein solutions at 37C.
    • Between 40 and 50 days, a slow downward trend becomes noticeable; this trend continues for the life of the animal and asymptotically approaches values below 500k. Electrodes still record.
    • See {999}
    • Surmise that pure iridium electrodes have a different metal-electrolyte interface than more conventional metals (Pl and W).
  • Mention that the ultimate purpose is for a neural prosthesis.
    • Their then use was for recordings from M1 in monkeys and V1 from cats. (Schmidt, Bak, McIntosh 1974)
  • Ref Wise et al {1012}.

____References____

[0] Salcman M, Bak MJ, A new chronic recording intracortical microelectrode.Med Biol Eng 14:1, 42-50 (1976 Jan)

{1190}
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ref: Biran-2005.09 tags: Tresco histology chronic implantation astrocytes microglia date: 01-04-2013 02:28 gmt revision:3 [2] [1] [0] [head]

PMID-16045910[0] Neuronal cell loss accompanies the brain tissue response to chronically implanted silicon microelectrode arrays.

  • We observed persistent ED1 immunoreactivity around implanted silicon microelectrode arrays implanted in adult rat cortex that was accompanied by a significant reduction in nerve fiber density and nerve cell bodies in the tissue immediately surrounding the implanted silicon microelectrode arrays.
  • We found that explanted electrodes were covered with ED1/MAC-1 immunoreactive cells and that the cells released MCP-1 and TNF-a under serum-free conditions in vitro.
  • See also [1] and [2]
  • Electrodes: Michigan type, 5mm long, 200um wide tapering to 30um, 15um thick at the shank tapering to 2um.
    • Show that the chronic response is markedly different than acute stab wounds.
    • "Stab wounds resulted in comparatively minimal neurofilament loss at 2 weeks (A) and no apparent loss by 4 weeks".
    • "The number of neuronal bodies is reduced in the area adjacent to microelectrodes (B, D) but appears unaltered surrounding stab wound lesions (A, C; lesion site in center of each image)."
  • Includes details of immunostaining, which could be useful.

____References____

[0] Biran R, Martin DC, Tresco PA, Neuronal cell loss accompanies the brain tissue response to chronically implanted silicon microelectrode arrays.Exp Neurol 195:1, 115-26 (2005 Sep)
[1] Szarowski DH, Andersen MD, Retterer S, Spence AJ, Isaacson M, Craighead HG, Turner JN, Shain W, Brain responses to micro-machined silicon devices.Brain Res 983:1-2, 23-35 (2003 Sep 5)
[2] Gilletti A, Muthuswamy J, Brain micromotion around implants in the rodent somatosensory cortex.J Neural Eng 3:3, 189-95 (2006 Sep)

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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)

{1018}
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ref: Rouse-2011.06 tags: BMI chronic DBS bidirectional stimulator Washington Medtronic ASIC translational date: 03-05-2012 23:56 gmt revision:3 [2] [1] [0] [head]

PMID-21543839[0] A chronic generalized bi-directional brain-machine interface.

  • Using a commercial neurostimulator package & battery etc.
  • "A key goal of this research prototype is to help broaden the clinical scope and acceptance of NI techniques, particularly real-time brain state detection" Good purpose! good work!
  • Augments the stimulator with 4 channels of ECoG/LFP + accelerometer + wireless telemetry.
    • Can be used to detect parkinsons state or pre-epileptiform behavior.
      • Much of this has been though of before, it just took the technology to catch up & a group to make it.
    • Chronic data is needed from humans -- animal models are often inadequate.
  • Tested in a primate for brain control of a cursor: 1D control using ECoG.
    • Good Left/right ROC, actually.
    • A large cost is simply the clinical testing; hence they piggy-back on an existing design.
    • There should be more research-industry collaborations like this.
  • impressive specs.
  • SVM classification algorithm (only consumed 10uW!) for data compression.
  • short-time Fourier transform for extracting the power over a given band. This using a modified chopper-amplification scheme. Output data has a bandwidth of less than 5Hz, which greatly reduces processing requirements.
  • Lots of processing on the BASIC chip, much like here.
  • Also see the press release

____References____

[0] Rouse AG, Stanslaski SR, Cong P, Jensen RM, Afshar P, Ullestad D, Gupta R, Molnar GF, Moran DW, Denison TJ, A chronic generalized bi-directional brain-machine interface.J Neural Eng 8:3, 036018 (2011 Jun)