Looking for extremely flexible hookup wire.

[AlessandroAU]

Hi everyone,

I've got a project where I am measuring the dynamic behaviour of a beam with some sensors bonded to its surface. The beams are very small and light so wires used to connect to the sensors have a significant affect on the vibration characteristics of the beam. 

These are very low level differential signals so current capacity is not a concern. Can anyone with experience tell me what type hookup wire is the most pliable? PVC insulation is fairly stiff, does PTFE fair much better?

edit:spelling

[mtdoc]

I think silicone insulation would be the best. It is very pliable.

HobbyKing is a good source. Look HERE

[dom0]

How about enameled wire (road runner or something similar)? Standard diameter is 0.2 mm iirc, so it's very thin. Alternatively one might consider single wires from a stranded cable w/o any insulation - ensure insulation by mechanical means, i.e. bent the wires so, that they won't touch.

[MrAl]

Hi,

I dont know what kind of current you are dealing with, but Litz wire is sometimes used for flexibility.  It is made from many strands of very thin gauge wire.  They use this sometimes in high quality PC mice, with silicone insulation around all the individual Litz wires that form the mouse cable.

[Pjotr]

If current is not of a concern simply use the thinnest enamelled wire, 35um or 50um. But it is very fragile. An other source are the diy phono guys. This one has very fine flexible silicone isolated litz wire in short lengths: https://www.kabusa.com/frameset.htm?/superflex.htm

[ConKbot]

Strain gages? A fairly standard technique is to have a short jumper of the super fine enameled wire running from the gage back to a terminal strip, bonded on like the gage is, in a less sensitive area and then heavier wire running from the strip to the signal conditioner. See http://www.vishaypg.com/micro-measurements/list/product-11022/ for an example. 

If you have 3 wires (or 4)  hooked to a 2 terminal gage for temperature compensation, ( www.vishaypg.com/doc?11092 ) make that the final junction is at the gage not the terminal strip.

[T3sl4co1l]

Agree, silicone -- or neoprene.  Also look for extremely fine stranding.

Example: a #0 welding cable is more flexible than THHN #6, despite being over twice as thick, because it's made from a great number of fine strands, and a flexible rubber jacket.  It is more expensive -- not that that'll be so big a problem for your purpose, as you probably won't be measuring your wires by the pound!

There are also unusual constructions, that look like metal tinsel woven with fiber, used for small signal, high flex applications such as internal speaker connections, telephones, headphones, microphones and so on.

Depending on your setup, you may also be better off using relatively springy wire, which is self-supporting and relatively free from fatigue.  The downside is, the spring force must be factored into your mechanical design, and arranged to bear in such a way that it does not disturb the measurement.  In electrical terms, this is analogous to using a radio-frequency coil instead of a transformer (a high inductance) to convert voltages; the component's characteristics can't be ignored, but once factored out (in the case of the RF coil, by resonating it at some frequency), it works just fine.

Tim

[IanB]

My suggestions are:

(a) Use thin enamelled wire coiled into a spiral. The thinness and the coiling will provide mechanical isolation between each end.
(b) Use thin strips of aluminium foil curved into an arch. This will only work if you can make a good electrical connection to the aluminium.

Unless you need enormous currents, don't try to use plastic insulated hookup wire. It would be like trying to use a back-hoe as a trowel to plant a daffodil.