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I am currently interested in Transcranial Direct Current Stimulation (tDCS), and I have observed that most studies in the field utilize DC-Stimulation equipment from manufacturers like NeuroConn and RogueResolutions that appear to be embedded analog systems.

I am curious to know whether a similar application can be implemented using an Arduino or a BeagleBoard platform. It seems to me that using software to control the waveforms, and ramp-up and ramp-down ought to be a more robust and potentially safer approach than an embedded black box.

I am unfortunately rather uneducated in electronics, so I am looking for a remedial explanation and even some direction on what to read next.

In case it would help to provide context, here are two useful articles to describe the nature of the currents used in tDCS therapies:

Transcranial direct current stimulation: State of the art 2008

Electrical Brain Stimulation Improves Cognitive Performance by Modulating Functional Connectivity and Task-Specific Activation

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    \$\begingroup\$ Anyone "rather uneducated in electronics" shouldn't get near a circuit that will interface directly to the human body. This is not a rookie project, and there are serious dangers that even experienced EEs need to think about carefully. Work with a EE that knows what he is doing and learn from that process. \$\endgroup\$ – Olin Lathrop Mar 24 '12 at 18:08
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    \$\begingroup\$ If I could upvote your comment, I certainly would. Working with an EE is precisely what I am looking to do, and hence my post here at the ECE. My intent is not to build a widget from reading forum posts and attach it to my head. Rather, I am looking to better understand some basic principles so that I can be a more productive collaborator in a research endeavor. \$\endgroup\$ – Shaheeb Roshan Mar 24 '12 at 18:32
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    \$\begingroup\$ @Shaheeb - a basic principal is to make sure you don't kill somebody with electricity. Generally something like optical isolation between the part that plugs into the wall and the part that attaches to the person is used. That way if a major malfunction occurs in the control box the AC wall voltage wouldn't make it to the person. There are many more considerations as even a small signal could mess up a pacemaker and kill someone. This is why there are stringent safety requirements for medical devices. \$\endgroup\$ – JonnyBoats Mar 24 '12 at 19:00
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    \$\begingroup\$ @ShaheebRoshan - Please don't link to pirated content. \$\endgroup\$ – Kevin Vermeer Mar 24 '12 at 19:41
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    \$\begingroup\$ To eliminate coupling to the mains you can sometimes power your system with a battery. \$\endgroup\$ – russ_hensel Mar 24 '12 at 20:51
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No it cannot be done with an Arduino or similar board. This is a potentially extremely dangerous project if you don't know how to design circuits that interface with the human body. There is a reason why 'real' medical equipment is expensive.

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    \$\begingroup\$ The datasheet for Arduino's ATmega explicitly specify the following: "Atmel products are not intended, authorized, or warranted for use as components in applications intended to support or sustain life." \$\endgroup\$ – jippie Mar 24 '12 at 20:25
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OK, you need someone familiar with electronics to design your equipment. An electronics newbie (heck, even an experienced engineer!) shouldn't undertake something like that without a thorough understanding of the forces and risks involved.

The big, MASSIVE thing here is that the waveforms be adequately controlled and that appropriate isolation is in place.

Now, a micro-controller driven device might well be a VERY good idea for this kind of work, but the most important thing is patient safety!

Also, a quick look at neuroConn's website through the lens of Google Translate makes me think that their tDCS products ARE microprocessor based (their 16 channel product is PC programmable!), and in that way, they already do what you want, except that they are almost certainly very pricey.

The problem you face is that their prices are NOT because of their hardware, but because of their engineering ability, their having paid for appropriate testing and certifications, and because they carry a metric ton of liability insurance.

It is certain that a new product design could be made cheaper than an existing one (after all, components and such keep coming down in price!), but it'll take you a really long time to get it designed safely and appropriately certified. And that costs a lot of up-front money before you ever start attaching electrodes to human beings.

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  • \$\begingroup\$ Michael Kohne is quite right the best you can do is found an stimulator circuit, a current source with minimal current and then oscillate that current with your micro controller anything above 10khz (40hz recommended) will be safe, use batteries instead of home outlets. The trick here is your Current source reliability. Good luck. I'm now working on a neuro-stimulator design and tests. \$\endgroup\$ – Red Prado Oct 14 '13 at 16:49
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DC is "direct current". Imagine a graph. Up the Y axis label "VOLTS". Along the X axis label "TIME".

Imagine a 9 v battery, attached to a load. The line on the graph starts at 9 v, and then depending on the load, starts to curve down, drops to near 0 v. The battery is drained.

AC is "alternating current". Your X axis now has positive and negative. Now, draw a sine wave. The peaks are at +10 v and -10 v. One complete cycle (one whole positive peak and one whole negative peak) takes 10 mS. f=1/t, thus f=1/10ms, f=100 Hz.

You want a DC current. You want the current to be low, about 2 mA. Luckily, an Arduino or a Beagleboard are much too complicated for this.

Here's a link to a simple circuit.

http://flowstateengaged.com/img/kickstarter-images/public-schematic.pdf

As other people have said, you need to be careful. Too much current through your brain could cause significant harm.

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    \$\begingroup\$ Most. Useless. Schematic. Ever. \$\endgroup\$ – Federico Russo May 24 '12 at 5:34
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    \$\begingroup\$ Yeah, use the device on your head! Very clever. \$\endgroup\$ – Federico Russo May 24 '12 at 5:35
  • \$\begingroup\$ @FedericoRusso - tDCS is under a lot of development at the moment, including at some reputable universities. It's easy to say the diagram is hopeless, but perhaps you should explain the flaws with it. (It's not mine. They aim to raise enough money to build and sell units.) \$\endgroup\$ – DanBeale May 30 '12 at 22:54
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    \$\begingroup\$ That reaction was from the shock ;). It's upside down, the LED is placed wrong, and the 334's symbol is at least confusing; I've never seen anything like it. A proper circuit would have +12V at the top, ground at the bottom. Not that tiny loop between battery and LED (did I say the LED is reversed?). A circuit diagram should clearly show the flow of the different currents. (There seems to be at least one user who agrees) \$\endgroup\$ – Federico Russo May 31 '12 at 8:07
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    \$\begingroup\$ I really, really hope their plan fails. If not, they're probably going to wind up killing someone. Commodity components are NOT safe for that kind of connection to a person. They need to talk to the manufacturer of EVERY part they're hooking up to a person with wet-electrodes and get them to certify their design, and supply medical grade parts. They also need to talk to some real engineers about safe circuit design BEFORE producing prototypes, let alone retail hardware. \$\endgroup\$ – Connor Wolf Jun 10 '13 at 3:35

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