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{1384}
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ref: -0 tags: NET probes SU-8 microfabrication sewing machine carbon fiber electrode insertion mice histology 2p date: 03-01-2017 23:20 gmt revision:0 [head]

Ultraflexible nanoelectronic probes form reliable, glial scar–free neural integration

  • SU-8 asymptotic H2O absorption is 3.3% in PBS -- quite a bit higher than I expected, and higher than PI.
  • Faced yield problems with contact litho at 2-3um trace/space.
  • Good recordings out to 4 months!
  • 3 minutes / probe insertion.
  • Fab:
    • Ni release layer, Su-8 2000.5. "excellent tensile strength" --
      • Tensile strength 60 MPa
      • Youngs modulus 2.0 GPa
      • Elongation at break 6.5%
      • Water absorption, per spec sheet, 0.65% (but not PBS)
    • 500nm dielectric; < 1% crosstalk; see figure S12.
    • Pt or Au rec sites, 10um x 20um or 30 x 30um.
    • FFC connector, with Si substrate remaining.
  • Used transgenic mice, YFP expressed in neurons.
  • CA glue used before metabond, followed by Kwik-sil silicone.
  • Neuron yield not so great -- they need to plate the electrodes down to acceptable impedance. (figure S5)
    • Measured impedance ~ 1M at 1khz.
  • Unclear if 50um x 1um is really that much worse than 10um x 1.5um.
  • Histology looks realyl great, (figure S10).
  • Manuscript did not mention (though the did at the poster) problems with electrode pull-out; they deal with it in the same way, application of ACSF.

{1286}
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ref: -0 tags: ovipositor wasp fig needle insertion SEM date: 05-29-2014 19:58 gmt revision:0 [head]

Biomechanics of substrate boring by fig wasps

  • Lakshminath Kundanati and Namrata Gundiah 2014

{1057}
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ref: Kozai-2009.11 tags: electrodes insertion Kozai flexible polymer momolayer date: 01-30-2013 04:45 gmt revision:10 [9] [8] [7] [6] [5] [4] [head]

PMID-19666051[0] Insertion shuttle with carboxyl terminated self-assembled monolayer coatings for implanting flexible polymer neural probes in the brain.

  • This study investigated the use of an electronegative (hydrophillic) self-assembled monolayer (SAM) as a coating on a stiff insertion shuttle to carry a polymer probe into the cerebral cortex, and then the detachment of the shuttle from the probe by altering the shuttle's hydrophobicity.
    • Used 11-mercaptoundecanoic acid. Details included.
    • SAM atrtacts water once inserted, causing the hydrophobic polymer to move away.
      • Why not make the polymer hydrophillic?
      • Is this just soap?
  • Used agarose brain model.
  • Good list of references for the justification of soft electrodes, and researched means for addressing this, mostly usnig polymer stiffeners.
    • "Computer models and experimental studies of the probe–tissue interface suggest that flexible and soft probes that approach the brain’s bulk material characteristics may help to minimize micromotion between the probe and surrounding tissue ({737}; {1203}; {1102}; {1200}; LaPlaca et al., 2005; {1216}; Neary et al., 2003 PMID-12657694; {1198})"
  • "However, polymer probes stick to metallic and silicon surfaces through hydrophobic interactions, causing the polymer probe to be carried out of the brain when the insertion shuttle is removed. The solution is to use a highly hydrophillic, electronegative, self-assembled monolayer coating on the shuttle.
  • Biran et al 2005 suggests that incremental damage due to stab wounds from the shuttle (needle) should be minor.
  • Probes: 12.5 um thick, 196 um wide, and 1.2cm long, polymide substrate and custom designed lithographed PDMS probes.
  • Polymer probes were inserted deep - 8.5 mm.
  • PDMS probes inserted with non-coated insertion shuttle resulted in explantation of the PDMS probe.

____References____

[0] Kozai TD, Kipke DR, Insertion shuttle with carboxyl terminated self-assembled monolayer coatings for implanting flexible polymer neural probes in the brain.J Neurosci Methods 184:2, 199-205 (2009 Nov 15)

{1177}
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ref: -0 tags: magnetic flexible insertion japan neural recording electrodes date: 01-28-2013 03:54 gmt revision:2 [1] [0] [head]

IEEE-1196780 (pdf) 3D flexible multichannel neural probe array

  • Shoji Takeuchi1, Takafumi Suzuki2, Kunihiko Mabuchi2 and Hiroyuki Fujita
  • wild -- they use a magnetic field to make the electrodes stand up!
  • Electrodes released with DRIE, as with Michigan probes.
  • As with many other electrodes, pretty high electrical impedance - 1.5M @ 1kHz.
    • 20x20um recording sites on 10um parylene.
  • Could push these into a rat and record extracellular APs, but nothing quantitative, no histology either.
  • Used a PEG coating to make them stiff enough to insert into the ctx (phantom in IEEE conference proceedings.)

{1217}
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ref: Bjornsson-2006.09 tags: micro vasculature histology insertion speed tissue shear date: 01-28-2013 03:38 gmt revision:3 [2] [1] [0] [head]

PMID-16921203[0] Effects of insertion conditions on tissue strain and vascular damage during neuroprosthetic device insertion.

  • We have developed an ex vivo preparation to capture real-time images of tissue deformation during device insertion using thick tissue slices from rat brains prepared with fluorescently labeled vasculature.
  • Direct damage to the vasculature included severing, rupturing and dragging, and was often observed several hundred micrometers from the insertion site. (yikes!)
  • Advocate faster insertion of sharp devices. (tatoo needle?).
  • Cortical surface features greatly affected insertion success; insertions attempted through pial blood vessels resulted in severe tissue compression.
    • Thus, avoiding vasculature is useful not only for avoiding hemorrhaging, but also to prevent excessive tissue compression.
  • High degree of variability
    • Indicates that this should be measured! Scientifically interesting!
  • Insertion speeds:
    • Fast 2 mm/sec
    • Medium 500 um/sec
    • Slow 125 um/sec
  • Perhaps there is no need to experiment with multiple insertion speeds?

____References____

[0] Bjornsson CS, Oh SJ, Al-Kofahi YA, Lim YJ, Smith KL, Turner JN, De S, Roysam B, Shain W, Kim SJ, Effects of insertion conditions on tissue strain and vascular damage during neuroprosthetic device insertion.J Neural Eng 3:3, 196-207 (2006 Sep)

{1205}
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ref: Rennaker-2005.03 tags: electrode recording longevity mechanical insertion Oklahoma MEA date: 01-25-2013 01:21 gmt revision:3 [2] [1] [0] [head]

PMID-15698656[0] A comparison of chronic multi-channel cortical implantation techniques: manual versus mechanical insertion.

  • Over 60% of the animals implanted with the mechanical insertion device had driven activity at week 6
    • whereas none of the animals with manually inserted arrays exhibited functional responses after 3 weeks.
      • Roughly identical responses immediately following surgery.
      • Could be that the manual inserter had horizontal movement / shear. (This is solveable with a stereotax).
      • Other research showed little difference in tissue response at 10um/s or 100um/s PMID-21896383[1]
  • Multi-wire electrodes.
  • Mechanical insertion device was capable of rapidly inserting the electrode without visible compression of the brain.
  • Response measured relative to auditory stimulus.
  • Their insertion device looks like a pen.

____References____

[0] Rennaker RL, Street S, Ruyle AM, Sloan AM, A comparison of chronic multi-channel cortical implantation techniques: manual versus mechanical insertion.J Neurosci Methods 142:2, 169-76 (2005 Mar 30)
[1] Welkenhuysen M, Andrei A, Ameye L, Eberle W, Nuttin B, Effect of insertion speed on tissue response and insertion mechanics of a chronically implanted silicon-based neural probe.IEEE Trans Biomed Eng 58:11, 3250-9 (2011 Nov)

{1116}
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ref: Snow-2006.02 tags: electrode insertion sharp recording tissue surrogate date: 02-10-2012 18:56 gmt revision:4 [3] [2] [1] [0] [head]

IEEE-1580838 (pdf) Microfabricated cylindrical multielectrodes for neural stimulation.

  • Used optical fiber as the substrate.
  • sharpened using a Dicing saw.
  • polymide insulatino removed by placing fiber tip next to a white-hot platinum filament.
  • cylindrical lithography system using a He-Cd laser.
  • tissue surrogate: two layers of 20um Saran Wrap over tofu. (!!!) -- see also {212}

____References____

Snow, S. and Jacobsen, S.C. and Wells, D.L. and Horch, K.W. Microfabricated cylindrical multielectrodes for neural stimulation Biomedical Engineering, IEEE Transactions on 53 2 320 -326 (2006)