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ref: Suner-2005.12 tags: MEA Utah reliability longevity SNR date: 01-25-2013 02:03 gmt revision:7 [6] [5] [4] [3] [2] [1] [head]

PMID-16425835[0] Reliability of signals from a chronically implanted, silicon-based electrode array

  • see {597}
  • Percutaneous connector used pressure-fitted pogo pins, as Gary was thinking of.
  • Utah array coated in parylene for this exp.
    • After implantation, array and cortex was covered in gore-tex (to prevent dura adhesion) -- they do not highlight this fact.
  • polyester insulated 25um gold wires as leads.
  • Reasonable SNR over 82, 172, 154 days.
  • One monkey had an array to 569 days -- 76 electrodes still provided good or fair waveforms.
  • ancilary (?) measure of tuning of the neurons. most neurons were not tuned.
  • SNR calculated as peak-peak of waveform divided by 2x standard deviation of signal.
  • A total of 36 implants in 16 other monkeys, which were not systematically evaluated for reliability here, provided successful recordings for up to 1264 days. Most of these studies ended because of headcap failure.
    • They no longer use dental acrylic -- only titanium bone screws.
  • 50-800K impedance
  • Improvement of the signal quality and increased yield, for which there was no clear trend in the three animals, may result from recovery produced by variations in the initial insertion injury.
  • The cortical capillary bed is densely packed, with spacing on the order of 40um in primate cortical tissue [27] ( vasculature ) -- they suppose that variance may be due to this.

____References____

[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)