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ref: -0 tags: carbon fiber thread spinning Pasquali Kemere nanotube stimulation date: 02-09-2017 01:09 gmt revision:0 [head]

PMID-25803728 Neural stimulation and recording with bidirectional, soft carbon nanotube fiber microelectrodes.

  • Poulin et al. demonstrated that microelectrodes made solely of CNT fibers22 show remarkable electrochemical activity, sensitivity, and resistance to biofouling compared to conventional carbon fibers when used for bioanalyte detection in vitro.23-25
  • Fibers were insulated with 3 um of block copolymer polystyrene-polybutadiene (PS-b-PBD) (polybutadiene is sythetic rubber)
    • Selected for good properties of biocompatibility, flexibility, resistance to flextural fatigue.
    • Available from Sigma-Aldrich.
    • Custom continuous dip-coating process.
  • 18um diameter, 15 - 20 x lower impedance than equivalently size PtIr.
    • 2.5 - 6x lower than W.
    • In practice, 43um dia, 1450um^2, impedance of 11.2 k; 12.6um, 151k.
  • Charge storage capacity 327 mC / cm^2; PtIr = 1.2 mC/cm^2
  • Wide water window of -1.5V - 1.5V, consistent with noble electrochemical properties of C.
  • Lasts for over 97e6 pulsing cycles beyond the water window, vs 43e6 for PEDOT.
  • Tested via 6-OHDA model of PD disease vs. standard PtIr stimulating electrodes, implanted via 100um PI shuttled attached with PEG.
  • Yes, debatable...
  • Tested out to 3 weeks durability. Appear to function as well or better than metal electrodes.

PMID-23307737 Strong, light, multifunctional fibers of carbon nanotubes with ultrahigh conductivity.

  • Full process:
    1. Dissolve high-quality, 5um long CNT in chlorosulfonic acid (the only known solvent for CNTs)
    2. Filter to remove particles
    3. Extrude liquid crystal dope through a spinneret, 65 or 130um orifice
    4. Into a coagulant, acetone or water
    5. Onto a rotating drum to put tension on the thread & align the CNTs.
    6. Wash in water and dry at 115C.
  • Properties:
    • Tensile strength 1 GPa +- 0.2 GPa.
    • Tensile modulus 120 GPa +- 50, best value 200 GPa
      • Pt: 168 GPa ; Au: 79 GPa.
    • Elongation to break 1.4 %
    • Conductivity: 0.3 MS/m, Iodine doped 5 +- 0.5 MS/m (22 +- 4 microhm cm)
      • Cu: 59.6 MS/m ; Pt: 9.4 MS/m ; Au: 41 MS/m
      • Electrical conductivity drops after annealing @ 600C
      • But does not drop after kinking and repeated mechanical cycling.
  • Theoretical modulus of MWCNT ~ 350 GPa.
  • Fibers well-aligned at ~ 90% the density (measure 1.3 g/cc) of close-packed CNT.

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ref: -0 tags: ZeroMQ messaging sockets multithreading date: 05-03-2016 06:10 gmt revision:0 [head]

ZeroMQ -- much better sockets framework than native TCP/UDP sockets.

  • Bindings for Ocaml, too.
  • Supports Erlang-like concurrency.

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ref: -0 tags: carbon fiber electrode array parylene fire sharpening microthread date: 03-20-2014 19:57 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-23860226 A carbon-fiber electrode array for long-term neural recording.

  • Guitchounts G1, Markowitz JE, Liberti WA, Gardner TJ.
  • We describe an assembly method for a 16-channel electrode array consisting of carbon fibers (<5 µm diameter) individually insulated with Parylene-C and fire-sharpened. The diameter of the array is approximately 26 µm along the full extent of the implant.
  • Fibers from http://www.goodfellowusa.com/
    • young's modulus of 380GPa vs. tungsten 400GPa.
    • Data available from Toho Tenax
  • The absence of any report of single neuron isolation in HVC with a fixed chronic electrode implant underscores the difficulty of recording small cells (8-15um soma) with an implant whose damage length scale is large relative to the target neurons. (!!)

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ref: -0 tags: xmos microcontroller microporcessor threading date: 08-11-2009 16:15 gmt revision:0 [head]

http://www.xmos.com/

  • Looks nice! They even publish their board designs and schematics - makes sense given they want their chips to be incorporated into products.
  • Their processors are 'event-driven', which seems to mean that they have 8 sets of registers, one set per thread, with presumably rapid switching between the threads. I did not investigate how excatly their processor works, whether this means they don't need DMA, etc.
  • -- an example with dual LAN8700 ethernet interfaces.