Product Review: tDCS-Kit.Com tDCS Devices

Introduction

If you are new to  transcranial direct current stimulation (tDCS) and unfamiliar with it, may I suggest you click on the tDCS link above and read some of my other posts. This post assumes that you are at least somewhat familiar with tDCS and are curious about the device offering from tDCS-Kit.com.

The Products

tDCS-Kit.com offers two very interesting and potentially useful tDCS devices, one powered by a 9 volt battery (pretty common setup in the world of tDCS) and another more unique (and perhaps riskier) powered from a USB port. According to tDCS-Kit.com, both use an LM-334 regulator to produce a maximum current of about 2 mA, depending on electrodes and other factors (more below).


(tDCS-Kit.com tDCS Device powered by 9 volt Battery. Pic from the web)


(tDCS-Kit.com tDCS Device powered by USB. Pic from the web)

What really sets the products from tDCS-kit.com apart from other tDCS offerings is simplicity and price.  $39.95? Are you kidding? You could hardly build a device yourself for less money.

What’s Included?

You get a “cable” that connects to the power source (9v or USB) – it has the regulator circuitry in a small housing about mid-cable.  At the end are anode and cathode pin-style connectors for electrodes. tDCS-Kit includes a small starter selection of electrodes to get you going and a small carry-bag, but you will need more electrodes very quickly. See my suggestion below.


(Small kit of electrodes supplied. Pic from the web)

Operation

It’s about as simple as it gets.

  • You decide upon electrode placement (by carefully researching on your own). tDCS-Kit does not supply montage information.  An assortment of links at tDCS-kit.com get you started on your research.
  • After placing your electrodes, you connect the cable to the appropriate power source and off you go.

Limitations

  1. tDCS-Kit devices do not ramp the current up or down as a session begins and ends, so you are likely to see a phosphene. You may also feel pronounced, even uncomfortable, tingling as current begins to flow. The devices do not include any form of timer – that is left up to you.  Finally, the devices do not report actual current delivered in any way. You are left to guess how much current is actually flowing – from 0 to 2 mA.
  2. You may have difficulty reaching an effective treatment current level with the supplied stick-on, gel electrodes (or those that you might buy). Gel electrodes always have some “built in” coupling resistance by nature. The resistance level is highly variable by brand/model of electrode – from hundreds to thousands of ohms! This can be a problem because the source voltage is only 5 or 9 volts (USB or 9 volt battery model.)  Professional model tDCS devices overcome this resistance by automatically raising delivery voltage via a “buck converter” or similar circuit – some as high as 80 volts! The tDCS-kit devices cannot do this. BTW Saline wetted sponges are typically much closer to zero ohms due to salt-water contact with the skin.
  3. I’m very concerned about the USB model of the tDCS-Kit device. Yes – I err on the safety side in saying this, but it’s possible that sooner or later someone will be hurt by connecting the USB device to an electrical outlet source. An unlikely and unusual failure might get them hurt – or killed. I have a strong stand that for the DIY tDCS world at least, no tDCS device should be directly or indirectly connected to a wall electrical outlet. It’s not worth the risk and is certainly not necessary.

DSCN0294
(
Never, ever, do this!)

4.  It’s my experience that some people cannot handle tDCS at 2 mA due to skin sensitivity or other issues. I haven’t seen any problems with 1 mA treatments and very few at 1.5 mA.      Perhaps tDCS-Kit should offer some lower current alternatives with 1.5 mA being a good middle ground.

Suggestions

If you are planning purchase of a tDCS-Kit device, may I suggest:

  1. Buy the 9 volt battery device and avoid the temptations of USB that could really get you hurt.
  2. If you must buy the USB device, get a low current reserve “USB Battery” – about $10 on Amazon – and only connect the device to that battery. Make sure you get one with a full-size USB socket. Never connect to a USB power adapter! I would not even connect to a laptop or tablet. tDCS-Kit indicates their devices are fuse protected. But why take the risk?

    (USB Battery. Pic from Amazon.com)
  3. Use some method to measure delivered current (DVM for example).  Otherwise how do you have any idea if you are properly following a treatment montage?
  4. My tests show that you will have trouble reaching desirable current level (reliably) using gel electrodes.  You might consider sponge electrodes instead (the Amrex 2” are very popular and available from a number of sources – including Amazon.) You will need to make or buy an adapter for the Amrex electrodes – they use a banana style plug. A simple adapter can be made with an alligator-clip lead. Cut off one end and attach a banana plug. The other alligator clip can connect to the tDCS-Kit pin-plug.

DSCN0295

Wrap-Up

The tDCS-Kit devices represent a bare-bones, low-cost way to get a tDCS device. This is not an ActivaDose or foc.us headset. The build quality seems very good, but you must recognize and understand the feature limitations of the devices and buy only if you are prepared to deal with them.  Remember it is DIY. As with everything DIY tDCS, it is up to you to do your homework, be well informed, and make sure your priority is safety.

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3 comments on “Product Review: tDCS-Kit.Com tDCS Devices

  1. Hi, Nice review! I also bought this device and can confirm that it’s a bit harsh. However, considering that currently it is by far the cheapest “out of the box” working solution you cannot expect much. For me perhaps the only drawback is that it lacks a voltage regulation. As you described in follow-up article it wouldn’t be complicated or expensive to attach a simple potentiometer. This would ameliorate flashes and skin burning sensations that occur uppon connecting and disconnecting 9V battery.
    Do you think that soaking the sponges with a saline solution that wasn’t prepared accurately (i.e. much higher salt concentration in tap water) can add significat resistance?

    • Thank you for your comments.

      Higher salt concentration would reduce resistance. Getting it too high though can lead to skin irritation and excessive corrosion of electrode parts.

      Brent

  2. Thanks, I read somewhere that too high salt concetration can make it actually less conductive. Anyway I guess there’s no need to worry too much about that.

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