{1356} revision 6 modified: 04-27-2017 01:42 gmt

PMID-27705958 Chronic in vivo stability assessment of carbon fiber microelectrode arrays.

  • showed excellent recording characteristics and nearly zero glial scarring.
  • 6.4um carbon fiber + 800nm parylene-C = 8.4um.
    • Cytec Thoronel T-650 CF, Youngs modulus = 255 GPa, tensile strength = 4.28 GPa, PAN-based.
  • Everything protected with our wonderful phenol epoxy 353NDT, heat-cure.
  • Used two coating solutions:
    • Solution of 0.01 M 3,4-ethylenedioxythiophene (483028, Sigma-Aldrich, St. Louis, MO): 0.1 M sodium p-toluenesulfonate (152536, Sigma-Aldrich, St. Louis, MO).
      • pTS is not that dissimilar from it's alkyl cousin, SPS, {1353}. Likely a soapy chemical due to the opposed methyl and sulfonic acid group; benzine will take up less room in the polymer c.f. SDS & may lower the oxidation potential of EDOT.
      • Tosylates have been explored as a EDOT counterion : PMID-22383043 Characterization of poly(3,4-ethylenedioxythiophene):tosylate conductive polymer microelectrodes for transmitter detection. and PEDOT-TMA
    • Solution was composed of 0.01 M 3,4-ethylene-dioxythiophene (483028, Sigma-Aldrich, St. Louis, MO):0.1 M polystyrene sulfonate (m.w. 70.000, 222271000, Acros, NJ).
    • For each solution the electrodeposition was carried out by applying 100 pA/channel for 600 s to form a layer of poly(3,4-ethylenedioxythiophene):sodium p-toluenesulfonate (PEDOT:pTS) or poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS).
      • Weird, would use voltage control here..
  • According to works by Green et al [45] and Hukins et al [46], equation (1) can be used to determine the aging time that
the fibers have undergone: t 37=t TQ10 T37)/10 where t 37 is the simulated aging time at 37 °C, t T is the amount of real time that the samples have been kept at the elevated temperature, T , and Q10 is an aging factor that is equal to 2, according to ASTM guidelines for polymer aging [47].
  • Show > 2MOhm impedance of the small-area electrodes. At the aging endpoint, PEDOT:pTS had about half the impedance of PEDOT:PSS.
    • 4M PSS, 7M pTS, both plated down to ~ 130k initial, went up to 2M pSS, 840k pTS.
  • Recording capability quite stellar
  • Likewise for the glial response.