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ref: -0 tags: electrode area review impedance date: 04-28-2017 17:55 gmt revision:9 [8] [7] [6] [5] [4] [3] [head]

Quick review of electrode area / impedance within m8ta:

  • {895} 500um^2
  • {311} 490um^2 nominal; 900k
  • {1040} 108um^2, plated from 5M to 1M.
  • Neuronexus: 177, 413um, 700um, and 1250um.
    • Suggest 177um for SUA, 413um for MUA.
    • Community consensus seems to be that these electrodes don't last as long, though.
    • Electroplating 177um^2 sites with PEDOT:PSS reduces impedance to 23k {1388}
  • {823} 122um^2 nominal
  • {736} 500um^2
  • {1027} (Utah) 1600um^2
    • Impedance: ~ 220K +-91K (in vivo -- large variance)
    • Blackrock site lists impedance @ 400k
  • SIrOF Utah array -- 3100um^2 (3.1e-5cm^2) -- large!
    • Impedance ~50K according to [www.blackrockmicro.com/userfiles/file/Microelectrode%20Arrays.pdf Blackrock product brochure].
  • PMID-20124668 (Utah again) 2000um^2, 125k Pt, 6k SIROF.
  • Neuropixel: 144um^2 acid-etched TiN
  • Carbon fiber: ~38 um^2, PEDOT:PSS or PEDOT:pTS started ~ 4M, plated down to ~ 130k initial, went up to 2M pSS, 840k pTS.

{1196}
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ref: Skousen-2011.01 tags: electrodes immune response Tresco Wise Michigan histology GFAP atrocyte surface area foreign body response date: 01-25-2013 01:44 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-21867802[0] Reducing surface area while maintaining implant penetrating profile lowers the brain foreign body response to chronically implanted planar silicon microelectrode arrays.

  • We studied the chronic brain foreign body response to planar solid silicon microelectrode arrays and planar lattice arrays with identical penetrating profiles but with reduced surface area in rats after an 8-week indwelling period.
  • Using quantitative immunohistochemistry, we found that presenting less surface area after equivalent iatrogenic injury is accompanied by significantly less
    • persistent macrophage activation,
    • decreased blood brain barrier leakiness,
    • and reduced neuronal cell loss.
  • Could be a factor of micromotion, too -- the lattice array has more anchoring points (?)
  • They propose it's a factor of TNF- α concentration around the implants. This, and other proinflammatory and cytoxic cytokines, is released by macrophages.
  • "Recent studies from our lab have described disruption of BBB integrity, indicated by the presence of autologous IgG in the brain parenchyma, surrounding both microwire and planar silicon recording devices ([1][2]. Under normal conditions, autologous IgG is excluded from the brain parenchyma (Azzi et al., 1990; Seitz et al., 1985) but has been observed following BBB disruption (Aihara et al., 1994).
    • E.g. the presence of IgG proves that the BBB was compromised.
      • Less so with the lattice implants.
  • Previous work from our lab using single microwires and single shaft, planar silicon microelectrode arrays indicated that the spatial distribution of GFAP does not increase with time over the indwelling period and did not support the “increase in astrogliosis over time hypothesis” as a dominant or general biologically related failure mechanism for this type of microelectrode recording device {1197}.

____References____

[0] Skousen JL, Merriam SM, Srivannavit O, Perlin G, Wise KD, Tresco PA, Reducing surface area while maintaining implant penetrating profile lowers the brain foreign body response to chronically implanted planar silicon microelectrode arrays.Prog Brain Res 194no Issue 167-80 (2011)
[1] Winslow BD, Christensen MB, Yang WK, Solzbacher F, Tresco PA, A comparison of the tissue response to chronically implanted Parylene-C-coated and uncoated planar silicon microelectrode arrays in rat cortex.Biomaterials 31:35, 9163-72 (2010 Dec)
[2] Winslow BD, Tresco PA, Quantitative analysis of the tissue response to chronically implanted microwire electrodes in rat cortex.Biomaterials 31:7, 1558-67 (2010 Mar)

{407}
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ref: bookmark-0 tags: tab textarea javascript date: 08-02-2007 23:11 gmt revision:0 [head]

http://www.baconbutty.com/blog-entry.php?id=13

how to make a text area where tab key inserts 'tab' into the text (like here - for tables!) "

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