Flexdrive- connect the electrode to the EIB

[Qiaosheng Zhang]

Hi,

I am trying to make the flexdrive for the first time. Now, it is the step for connecting electrode wire to the EIB. I try to connect the electrode to the EIB using gold pins. Since the wire has the insulation, the question is how I know the electrode connect with EIB well enough. In fact, the wire is easy to broken when I push the gold pin tightly. If the gold pin is loose, I don't know whether the wire connected with EIB or not.   

Best,

Qiaosheng

[Jakob Voigts]

Hi,

by pushing the gold pins in enough to secure them, the insulation is stripped off and contact is made.
If you break the wires, you are likely using too much force.

Whether you made good contact will be evident when you plate and impedance check the electrodes - see here for details on general drive building,
http://www.jove.com/video/1094/micro-drive-array-for-chronic-in-vivo-recording-drive-fabrication
and here for plating:
http://www.jove.com/video/1098/micro-drive-array-for-chronic-in-vivo-recording-tetrode-assembly

Of course the flexdrive wiki has basic instructions as well: https://open-ephys.atlassian.net/wiki/display/OEW/flexDrive+Building+instructions
but i dont think we covered the tetrode gold pin method there.

best,
jakob

[Jakob Voigts]

also, i just saw that youre using the small pins, for these i usually use just medium fine forceps, not pliers to push them in. If youre using pliers you're definitely going to have trouble because they'll push the pins in too hard.
Basically as long as they dont fall out they're usually ok. You should always add a layer of epoxy to the gold pins after plating the trodes, so mechanical stability is not a big concern.

[Qiaosheng Zhang]

Hi Jakob,

Thank you very much. Your suggestions are very helpful. I am wondering have you ever been solder the gold pin with the EIB board?

By the way, what kind of gold pins do you use? I appreciate your help.

Best,

Qiaosheng

在 2015年11月19日星期四 UTC-5下午2:05:35，Jakob Voigts写道：

[Jakob Voigts]

Hi,
i think some people do solder the pins, but i never really saw the point:
- you'd need tinned vias, so that wouldnt work for the small gold pins because it would likely mess up the hols size tolerances.
- you should still just epoxy the pins, so mechanical stability is not an issue.
- adding epoxy has a ~0 chance of messing up a good connection, and will not change the impedance etc. soldering requires you to touch the pins, which seems a bit riskier to me.
- epoxied eibs can be easily re-used a few times, (just let the whole thing sit in ethanol for a few days, and then just pull the epoxy off - it becomes pretty rubbery, then clean everything and re-epoxy the omnetics) soldered can technically be salvaged but it sounds like it would be a massive pain.

For the EIB that you use, and all EIBs with that hole size, i just go with the small neuralynx pins ( http://neuralynx.com/products/eib/eib_pins ) in small.

best,
Jakob

[Arne Meyer]

Hi Qiaosheng,

In case you're worried about the electrical connectivity you might try to put a tiny little bit of conductive silver paint into the hole after inserting the pin. Use a 30G needle because otherwise you might mess up the EIB. Ideally, you remove some of the insulation of the electrode wire before doing that, e.g., by holding it over an oil lamp for < 1 second (too long will make the wire brittle). Then add some epoxy on top as described by Jakob. This way you'll get a nice mechanical and electrical connection.

Best,
Arne

[Karel Jezek]

Hi,

cutting often comes when we use a brand new EIB. The reason is the edge of the hole is too sharp and acts as a razor. We soften it by pushing there a pin without the wire first (or an instrument shaped as the pin at the end). This shapes the hole into bit conical and helps a lot. After that you can usually push the pin enough to be stable without loosing the connection.

Karel 

 

Dne čtvrtek 19. listopadu 2015 17:31:01 UTC+1 Qiaosheng Zhang napsal(a):

[Qiaosheng Zhang]

Hi Arne,

Thank you very much. You suggestions are very valuable for me. Could you please tell me what kinds of conductive silver paint and oil lamp do you use? Thanks again.

Qiaosheng

在 2015年12月8日星期二 UTC-5下午3:44:51，Arne Meyer写道：

[Qiaosheng Zhang]

Hi Karel,

Thanks for your suggestion. That's a great idea. I'll try your method. Thanks a lot.

Qiaosheng

在 2015年12月11日星期五 UTC-5上午6:24:15，Karel Jezek写道：

[Jakob Voigts]

thats a great idea, could you add this consideration to the wiki? Just so people can easily find this information in the future.
https://open-ephys.atlassian.net/wiki/display/OEW/5+-+Electrode+loading

also, it would be great if you could add an 'issue' and post the solution here:
https://github.com/open-ephys/flexDrive/issues?q=is%3Aissue+is%3Aclosed