{747} revision 13 modified: 02-23-2017 23:52 gmt

PMID-17517431[0] Neural probe design for reduced tissue encapsulation in CNS.

  • See conference proceedings too: PMID-17947102[1] Fabrication of polymer neural probes with sub-cellular features for reduced tissue encapsulation.
    • -- useful information.
  • They use SU8 - photoresist! - as a structural material. See also this.
    • They use silicon as a substrate for the fabrication, but ultimately remove it. Electrodes could be made of titanium, modulo low conductivity.
  • Did not / could not record from these devices. Only immunochemistry.
  • Polymer fibers smaller than 7um are basically invisible to the immune system. See [2]
  • Their peripheral recording site is 4 x 5um - but still not invisible to microglia. Perhaps this is because of residual insertion trauma, or movement trauma? They implanted the device flush with the cortical surface, so there should have been little cranial tethering.
  • Checked the animals 4 weeks after implantation.
  • Peripheral electrode site was better than shank location, but still not perfect. Well, any improvement is a good one...
  • No statistical difference between 4x5um lattice probes, 10x4um probes, 30x4um, and solid (100um) knife edge.
    • Think that this may be because of electrode micromotion -- the lateral edge sites are still relatively well connected to the thick, rigid shank.
  • Observed two classes of immune reactivity --
    • GFAP reactive hypertrophied astrocytes.
    • devoid of GFAP, neurofilament, and NEuN, but always OX-42 and often firbronectin and laminin positive as well.
    • Think that the second may be from meningeal cells pulled in with the stab wound.
  • Sensitivity is expected to increase with decreased surface area (but similar low impedance -- platinum black or oxidized iridium or PEDOT {1112} ).
  • Thoughts: it may be possible to put 'barbs' to relieve mechanical stress slightly after the probe location, preferably spikes that expand after implantation.
  • His thesis {1110}

____References____

[0] Seymour JP, Kipke DR, Neural probe design for reduced tissue encapsulation in CNS.Biomaterials 28:25, 3594-607 (2007 Sep)
[1] Seymour JP, Kipke DR, Fabrication of polymer neural probes with sub-cellular features for reduced tissue encapsulation.Conf Proc IEEE Eng Med Biol Soc 1no Issue 4606-9 (2006)
[2] Sanders JE, Stiles CE, Hayes CL, Tissue response to single-polymer fibers of varying diameters: evaluation of fibrous encapsulation and macrophage density.J Biomed Mater Res 52:1, 231-7 (2000 Oct)