Tdcs success and failure

Tonight I learned 2 things about tcds. Firstly our prototype works very well and is easy to mass produce.
Secondly, if you reverse the electrode by accident, you make yourself a weeeee bit really stupid.

We had the electrodes at f3 and the right shoulder but got them backwards by accident. Has this sort of thing happened to anyone else? If so, got any funny stories?
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  • I have been working on a tDCS that can be easily workshopped by amateur solderers and is very cost effective. However, I didn't research electrodes very well and instead of putting them on backwards I didn't failed to make a good path between the electrode and the skin. Since I didn't know what to expect I got some ugly, but not painful marks on my arm. My head is all right.
    image

    Are you planning to sell your devices or make them open source?
  • It's based loosely on some open source plans but we'll be selling them online shortly. Every test we've run so far turned out great (other than the temporary retardation). ours maxes out a little under 2.0ma so it can't hurt u if you try, and we've tried. it'll all be built into a rather stealthy tuque since we're in canada and it's cold as tits up hear and you've got wet saline sponges on your head XD may as well keep warm while you work. We're moving into mass production in the next week or so but are still working out price and waver and so on. It's a very basic setup so far but future model will have more functionality. the idea is to sell them to fund upgrades and equipment for the lab. what we may even do is anyone who buys the original models, every time we release an upgrade for the next few versions, they get sent an upgraded insert, so they have something to play with now and more to come later.
  • Also, ouch that looks like it hurt. my partner ended up with a bit of redness where the electrode contacted his shoulder but only because the electrode was drying up too fast and it was awkward for him to hold it there. we'd learned by the second run that a tight shirt could hold the thing in place without issue and to more thoroughly soak the electrode. 
  • Is this like Grindhouse Wetware's "thinking cap"?
  • little bit, but different internals. hats just make convenient housing and like i said, it's cold as tits up here so it's more an excuse to buy a ton of tuques 
  • Is the overal purpose the same?
  • sort of? the purpose of all tdcs is basically the same, which is to stimulate a part of your brain into being more active and another to be less. 
  • looking forward to getting my hand on one once orders open! Tdcs is something I've wanted to start exploring, but I haven't found an ideal starter unit. This sounds like it'll be the right balance between technical and quick to pick up.
  • i have yet to see a tdcs design that i'd recommend as safe. most designs i have seen suffer from serious design flaws which could very well kill you depending on the wrong circumstances.
  • which is why we'll be testing the hell out of these and holding off on release until we're comfortable with them so people can't kill themselves.we looked at the design you put forward originally when we were designing it but went in a different direction
  • edited October 2014
    Where does the 2mA come from? I thought I read that above 2mA there is simply no increased benefit. Is there a similar limit to voltage?

    @ThomasEgi, what do you want to see in a tDCS system to make it safe?
  • edited October 2014
    Ooh, I'd definitely be interested in buying when y'all are done.
  • @drjazz my design was a very minimalistic one, only suited for operating under well controlled conditions by people who know what the heck they are doing. if you let me look at the schematics i might be able to spot out sneaky and potentially lethal points of failure.
  • i'm still working on them but will pm you once theyre done. still working out any bugs i find
  • Um, how the hell did you do that to your arm? What did you use as an electrode? Also, I've been wanting to do a trial with tDCS along with EEG readings to look for changes both short term and long. If I remember correctly the DARPA study showed some long term changes with daily 20 minute intervals. I'll read it again. 

    If you think it would help I can send you a big box of EKG pads or something similar. I don't see why they wouldn't work. You can use them with a TENS unit no problem. 
  • I used a conductive rubber electrode with salt water on my arm. When I did that I didn't realize that conductive rubber electrodes are supposed to go inside an absorbent sleeve to hold the salt water.

    There was a pinching sensation the whole time but 9VDC at 2mA wasn't more than a mild irritation. As you can see there was tissue damage at the surface. So, lesson learned.

    Since then I have sewn sleeves for the electrodes and now when I use them there is no pinching sensation. Although I'm going to let my skin heal before I put the electrode there again.

    Thanks for the electrode offer and if my homemade sleeves don't work out I will gladly take you up on that offer.
  • I'm sure that'll work. What concentration was the salt water? Was it just table salt mix or buffered saline or what? Were these the type you used?

    http://www.1thebest.com/electrodes-conductive-rubber-3-diameter-red-2-pk-ZIM1084MM183.html?gclid=CjwKEAjwwdOhBRCG0fPrlfO1gGUSJAC1FmHXaJJjctNpoe6lFJegrAS2VzsA3c95ASQeUqvG_4minxoCx0fw_wcB
  • Good questions about the water. It was table salt but I'm not sure about the concentration. Any suggestions about mixing this stuff?
  • As far as I know, the conductivity of a solution increases proportional to the amount of ions... so wouldn't the best proportion be total saturation? I don't know really. I've succesfully used 0.9% normal saline. Whatever % you use, it's probably best to be consistent. Who knows... maybe you stumble on something crazy and then it's totally unrepeatable because you can never get that exact solution again. Ha.

    Also, I haven't used those types but I noticed that the first comment was someone complaining about the same thing. I'm not sure if that was your comment but I didn't think so based on the locations described. I'm wondering how hard it would be to make conductive gel or paste. I'll see if I can make up a cheap recipe. It performs way better than saline.
  • making a standard solution really isn't that hard if you have a good balance and measuring equipment and at that point the change in resistance doesn't matter much if it's by a fraction of a percent. oh also i looked over my circuit again, turns out i'd already accounted for the potential spikes. (i tend to design things in a bit of a trance so i forget that i've already fixed issues occasionally) it cuts the power if a capped amperage is exceeded so you don't fry someone. built right into the chip im using. the sense resistor sets the current and the load can't draw more than that. im gonna stress test it this weekend and make sure u can't spike it.
  • Yay update time. finished the first production level hat. Super quick video showing it off but much more to come. Gonna have more data and such to show shortly.

  • i'm still very interested in the schematics. Also the way you sealed the electronics.
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