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[0] Sodagar AM, Wise KD, Najafi K, A fully integrated mixed-signal neural processor for implantable multichannel cortical recording.IEEE Trans Biomed Eng 54:6 Pt 1, 1075-88 (2007 Jun)

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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\alpha 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)

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ref: Hoogerwerf-1994.12 tags: Wise Michigan array MEA recording 3D date: 01-15-2012 07:12 gmt revision:4 [3] [2] [1] [0] [head]

IEEE-335862 (pdf) A three-dimensional microelectrode array for chronic neural recording.

  • see {995} for reasonable photos (they don't show up in the black and white IEEE scan).
  • 16-channel, 4 shanks.
  • 3D : 16 shanks, 64 channels, includes a 16:1 MNOS mux on the attached micromachined silicon platform.
  • Nickel plated lead stransfers (90 deg) see figure 6 electroplating current.
    • This was a point of difficulty, it seems.

____References____

Hoogerwerf, A.C. and Wise, K.D. A three-dimensional microelectrode array for chronic neural recording Biomedical Engineering, IEEE Transactions on 41 12 1136 -1146 (1994)

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ref: Olsson-2005.12 tags: recording Olsson Wise sorting date: 01-15-2012 06:04 gmt revision:3 [2] [1] [0] [head]

IEEE-1546254 (pdf) A three-dimensional neural recording microsystem with implantable data compression circuitry

  • quite a bit of engineering in this one!
  • 256 site
  • spike detection ASIC which transmits a parameterized version of the threshold crossings.
  • Only consumes 5.4mW total. wow.
  • outgoing bandwidth 2.5 Mb/sec.
  • Only allows spike detection on 32 of these sites
    • The mux is also limited to common groups to minimize consumed space.
  • 5 bit spike detection ADC.
  • 12.6uV RMS noise.
  • Unidirectional link -- sets threshold automatically.
  • 8:1 channel mux changes on both positive and negative clocks, which prevents clock transitions in the middle of the sampling window.
    • Measure crosstalk 6% or less -- really?
  • Vibert [16] evaluated neural spike separation baseed on eight parameters and concluded that using three parameters, Vmax (the maximum positive spike amplitude), Vmin (the minimum negative spike amplitude) and T (the time between Vmax and Vmin) not only adequately sorted spikes but was superior to separation using more parameters. Other parameters were found to be correlated with Vmax, Vmin, and T, whereas Vmax Vmin and T were uncorrelated.

____References____

Olsson, R.H., III and Wise, K.D. A three-dimensional neural recording microsystem with implantable data compression circuitry Solid-State Circuits, IEEE Journal of 40 12 2796 - 2804 (2005)

{995}
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ref: QingBai and Wise-2001.08 tags: Bai Wise buffered MEA recording electrodes Michigan date: 01-05-2012 04:53 gmt revision:5 [4] [3] [2] [1] [0] [head]

IEEE-936367 (pdf) Single-unit neural recording with active microelectrode arrays

  • Design neural probes with on-chip unity-gain amplifiers. Proven to not degrade recordings (indeed, it should help!)
  • 200ohm output impedance
  • 11uV RMS noise, 100Hz-10kHz.
  • Multiplexer adds 8uV rms noise. noise from clock transitions 2ppm.
  • Also built amplifiers with 40db voltage gain (100x).

____References____

Qing Bai and Wise, K.D. Single-unit neural recording with active microelectrode arrays Biomedical Engineering, IEEE Transactions on 48 8 911 -920 (2001)

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ref: Sodagar-2007.06 tags: neural recording telemetry Wise Najafi mulitichannel electrophysiology Michigan ASIC date: 01-03-2012 23:07 gmt revision:4 [3] [2] [1] [0] [head]

PMID-17554826[0] A fully integrated mixed-signal neural processor for implantable multichannel cortical recording.

  • document is rich in details! looks pretty well designed, too.
  • Michigan 3-d electrodes
  • inductively powered, 2Mbps output
  • 64 channels
  • 18b/spike for 64 channels in scan mode, continuous waveforms on 2 channels in monitor mode
  • programmable analog spike detection. resolution: 5 bits.
  • no timestamps - send them out as they come in, with a clock rate fast enough so that this does not matter.
    • temporary storage in SRAM
    • time compression and buffering is somewhat complex (?)
  • only transmit threshold crossings, positive, negative, and both.
    • they do not detail how the signal is telemetered - perhaps this is for another publication.
  • fabricated chip occupies 3.5 x 2.7 mm. 0.5um process.
  • fabricated chip has a power of 200uw @ 1.8V. that's 6.4mW altogether! I need to get down to this figure! (well..)

____References____

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ref: Wise-1970.07 tags: Wise MEA silicon gold lithography date: 01-03-2012 19:05 gmt revision:3 [2] [1] [0] [head]

IEEE-4502738 (pdf) An Integrated-Circuit Approach to Extracellular Microelectrodes

  • Used lithography techniques & to make SiO2 & Au electrodes.
  • 2um tips.
    • Back then, small tips were deemed good; nowadays, we want larger, lower-impedance tips (fad?)
  • Most previous work is glass insulated metal electrodes [1][2]
    • C. Guld, a glass-covered platinum microelectrode. {1014}
  • Probes cannot exceed more than 50um from the edge of the chip carrier without cracking, which limits how close one may get to a given cell.

____References____

Wise, Kensall D. and Angell, James B. and Starr, Arnold An Integrated-Circuit Approach to Extracellular Microelectrodes Biomedical Engineering, IEEE Transactions on BME-17 3 238 -247 (1970)