Electrically conductive-resistive carbon fiber thread needed

[maniachalengineer]

I'm looking for a small diameter carbon fiber thread supplier or source that makes and sells a "sewing?" thread that is electrically conductive with considerable resistance. I've ordered a 1 lb spool of "carbon fiber graphite yarn tow" from Aircraft spruce and Specialties- this is typically used for winding and fabricating various carbon fiber structures/reinforcements and it measures about 12 Ohms per ft. I'm looking for something much smaller and thus with much higher electrical resistance, approx 500k Ohms per ft.
Ideally the "thread" material will be flexible and multi-stranded for reliability during flexing and build operations. I anticipate needing to coat or protect the carbon "conductors" using a dipped/sprayed conformal coating or polymer sheath- but maybe somebody already makes a small diameter "high resistance" wire? Spark plug wires are similar today- but the insulation diameter is huge and the spark plug wire is not always continuous to DC voltage but relies on "spark gap jumps" to work properly.
My application involves using the wires in RF fields where high DC resistance appears "invisible" and does not perturb the various RF fields. Definitely very low voltages and currents only. I've seen a bit of mention online about MRI catheter wires using carbon but no supplier, etc.. I'd like to find a cheap, high volume material/source for this application. Seems like I've seen what looked like tiny carbon/cotton/polyester "wires" used for microphones, telephones, and USB in the past- but I simply cannot find any current (domestic USA) suppliers after considerable searching. Any ideas out there?
I'd also consider a small 2D or "flat" carbon or vacuum deposited conductive tape if it is available and has similar properties.
Thanks in advance for your suggestions and comments!

 

[Demon3]

This jacket has been on the web for years but they never get around to commercializing it. It shocks attackers using a Taser connected to an elecrically conductive fiber called Aracon, developed by DuPont. Perhaps if you dig a bit you'll find more info.

http://www.wired.com/science/discoveries/news/2003/05/58914

http://www.no-contact.com/

Info on Aracon

http://www.micro-coax.com/pages/technicalinfo/ARACON/aracon_why.asp

http://www.glenair.com/composite/pdf/I-01.pdf

Chris DeArmitt

 

[Compositepro]

This company makes carbon fiber strings and cords.

http://www.fibraplex.com

But the resistance that you seek is very high. If you took one filament of carbon out of your 12,000 filament tow it would have about the right amount. That is 7 micron diameter and is virtually invisible.

By the way, if a single filament of carbon fiber gets into the composite used to make a composite aircraft radome, it can cause the whole dome to fail. The radar energy will vaporize the filament and the heat chars the resin, which then becomes conductive enough to continue charring.

 

[maniachalengineer]

To "Compositepro" and "Demon3"- Thanks for your suggestions and replies! I am investigating these for my application. I also have started making prototype resistive lines on flex substrates using thick film polymer paste materials- seems to work OK so far... I'm really interested in the electrical properties but not any mechanical strength (unlike most application for carbon fiber products that are exactly the opposite typically).
Thanks Again, "Maniachalengineer"

 

[Higgler]

Window film purchased for your car is approximately 25-35 ohms per square, and ultra cheap.
Long skinny lengths would be make a very resistive line and high overall impedance. i.e. 5 foot (60") x 0.1" would measure 25 ohm per square x 60/0.1 = 15,000 ohms. Attach it to monofilament fishing line for support.

The polarization of your RF field would affect your actual wave impedance.

Can you say how you plan to use it?

kch
PS: the resist material is a challenge to get at since there are protective layers on both sides of the resist. You can couple to it capacitively more easily.