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{1381}
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ref: -0 tags: glassy carbon SU-8 pyrolysis CEC microelectrode stimulation stability platinum PEDOT date: 02-17-2017 00:05 gmt revision:2 [1] [0] [head]

A novel pattern transfer technique for mounting glassy carbon microelectrodes on polymeric flexible substrates

  • Use inert-atmosphere pyrolysis @ 900 - 1000 C of 20um SU-8 (which is aromatic) on a thermal oxide wafer.
  • Followed by spin & cure of PI.
  • Demonstrate strong carbonyl bonding of the glassy carbon with mechanical and FTIR testing.
  • Use of photosensitive PI allows through-vias to connect Cr/Au conductive traces.

PMID-28084398 Highly Stable Glassy Carbon Interfaces for Long-Term Neural Stimulation and Low-Noise Recording of Brain Activity

  • Use EIS to show superior charge-injection properties + stability of glassy carbon electrodes vs. Pt electrodes.
    • GC lasted > 5e6 pulses; Pt electrodes delaminated after 1e6 pulses.
    • Hydrogen bonding (above) clearly superior than neat PI-Pt interface
  • GC electrodes were, true to their name, glassy and much smoother than the platinum electrodes.
  • Further reduced impedance with PEDOT-PSS coating.
    • PEDOT-PSS coating on glassy carbon was, in their hands, far more stable than PEDOT-PSS on platinum.
  • All devices, GC, PEDOT:PSS, and Pt, had similar biocompatibility in their assay (figure 7)

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ref: -0 tags: polyimide platinum electrodes Spain longitudinal intrafasicular adhesion delamination date: 10-05-2013 22:24 gmt revision:4 [3] [2] [1] [0] [head]

PMID-17278585 Assessment of biocompatibility of chronically implanted polyimide and platinum intrafascicular electrodes. 2007

  • Designed platinum/polyimide longitudinal intrafasicular electrodes (LIFEs)
    • 25um PT/Ir, insulated to 60-75um diameter. PT/IR has a young's modulus of 202 Gpa.
      • Plated with platinum black under sonication, as this forms a tougher surface than without sonication.
      • See also: PMID-20485478 Improving impedance of implantable microwire multi-electrode arrays by ultrasonic electroplating of durable platinum black. Desai SA, Rolston JD, Guo L, Potter SM. 2010
    • Polyimide PI2611, 10um thick, 50mm long, 220um wide in the electrode segment.
  • Implanted into rat sciatic nerve for 3 months.
  • These electrodes have been tested in people for two days:
    • Electrical stimulation through the implanted electrodes elicited graded sensations of touch, joint movement, and position, referring to the missing limb. This suggested that peripheral nerve interfaces could be used to provide amputees with prosthetic limbs with sensory feedback and volitional control that is more natural than what is possible with current myoelectric and body-powered prostheses.
  • CMAPs = compound muscle action potentials.
  • CNAPs = compound nerve action potentials.
  • Platinum wire LIFE performed very similarly to the thin-film polyimide LIFE in most all tests, with slightly higher potentials recorded by the larger polyimide probe.
  • 'Higher encapsulation with the polyimide probes! Geometry?
  • However, the polyimide LIFEs induced less functional decline than the wire LIFEs.
  • Other polyimide studies [14] [16] [24] -- one of which they observed a 70% reduction of tensile strength after 11 months of implantation.
    • [14] F. J. Rodríguez, D. Ceballos, M. Schüttler, E. Valderrama, T. Stieglitz, and X. Navarro, “Polyimide cuff electrodes for peripheral nerve stimulation,” J. Neurosci. Meth., vol. 98, pp. 105–118, 2000.
    • [16] N. Lago, D. Ceballos, F. J. Rodríguez, T. Stieglitz, and X. Navarro, “Long term assessment of axonal regeneration through polyimide regenerative electrodes to interface the peripheral nerve,” Biomaterials, vol. 26, pp. 2021–2031, 2005.
    • [24] M. Schuettler, K. P. Koch, and T. Stieglitz, “Investigations on explanted micromachined nerve electrodes,” in Proc. 8th Annu. Int. Conf. Int. Functional Electrical Stimulation Soc., Maroochydore, Australia, 2003, pp. 306–310.
      • The technology of sandwiching a metallization layer between two layers of polyimide seems to be suitable, because no delamination of the polyimide layers was observed even after 11 months. The right choice of metals for building the electrical conductive elements of the microelectrodes is crucial. Ti/Au/Ti/Pt layers tend to flake off from polyimide while delamination of Ti/Pt layers was not observed. However, adhesion of Ti/Pt layers was investigated after 2.5 months of implantation while Ti/Au/Ti/Pt layers were exposed after 11 months to the biological system. In previous research projects, surgeons also reported on delamination of Ti/Au layers from polyimide substrate after three months. Unfortunately, we had no possibility of inspecting these microelectrodes in our laboratory.
      • See also {1250}

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ref: -0 tags: polyimide platinum nanowire recording electrode plating date: 06-28-2013 00:46 gmt revision:2 [1] [0] [head]

IEEE-5734597 (pdf) A novel platinum nanowire-coated neural electrode and its electrochemical and biological characterization

  • Young-Hyun Jin ; IMTEK, Univ. of Freiburg, Freiburg, Germany ; Daubinger, P. ; Fiebich, B.L. ; Stieglitz, T.
  • 10um thick RIE etched polyimide and platinum electrodes.
  • polyimide was spin coated onto wafers.
  • Used relatively simple wet chemistry to plate platinum onto electrodes:
    • 0.14 M-% chloroplatin acid hexahydrate (H2PtCl6·6H2O, Sigma-Aldrich) and 7.4 M-% formic acid (HCOOH, Sigma-Aldrich) were mixed in de-ionized (DI) water. The fabricated device was floated upside down on the solution.
  • Let this plate for 7 days & effective site was enlarged by 617 times!

{1009}
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ref: Thomas-1972.09 tags: MEA electrodes cell culture platinum black date: 01-04-2012 02:40 gmt revision:6 [5] [4] [3] [2] [1] [0] [head]

PMID-4672477[0] A miniature microelectrode array to monitor the bioelectric activity of cultured cells

  • Designed for heart cells.
  • 30-element muilt into the cluture chambers.
  • Utilizes PCB lithography technology. Indeed, the insulation is photoresist / 'photopolymer'.
  • platinum black

____References____

[0] Thomas CA Jr, Springer PA, Loeb GE, Berwald-Netter Y, Okun LM, A miniature microelectrode array to monitor the bioelectric activity of cultured cells.Exp Cell Res 74:1, 61-6 (1972 Sep)

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ref: GULD-1964.07 tags: platinum iridium microelectrode eltrolytic etching original date: 01-03-2012 19:05 gmt revision:2 [1] [0] [head]

PMID-14199966[0] A Glass-covered platinum microelectrode

  • Details the manufacture and testing of PT-IR (70/30) etched solder glass-coated microelectrodes.
  • Melt a bead of the glass on the top and gradually draw the bead downward, surrounded by the heater of a pipette drawing machine.

____References____

[0] GULD C, A GLASS-COVERED PLATINUM MICROELECTRODE.Med Electron Biol Eng 2no Issue 317-27 (1964 Jul)