
Do-it-yourself EEG, EKG, and EMG - davidsmith8900
http://erkutlu.blogspot.com/2012/12/eeg-and-arduino-do-it-yourself-eeg-ekg.html
======
benbojangles
I have been working with EKG on and off for ten years. I helped with this
briefly:
[http://www.neozap.com/freeECG.htm](http://www.neozap.com/freeECG.htm) I would
love it if someone could produce a more 'rounded' piece of software.

I really love my 12-lead ECG machine I got for £10. It prints using thermal
paper, and has an audio output that I put into the laptop mic input. It's not
dangerous at all so you shouldn't be afraid. Sticky electrodes can be had for
very little on ebay.

Happy to help others with their experiments.

~~~
alphaoverlord
That's really cool. Where did you get your ECG machine? I'd be interested in
getting one if its that cheap.

~~~
benbojangles
good old ebay. It is a Nihon Kohden machine. comes in a brown briefcase. It's
old enough not to have an lcd screen, but with the output going into a laptop,
it is possible to record your ecg readout. sticky electrodes are by Ambu blue
(x50 for £5 on ebay).

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jonnii
There are some really good cheap prosumer level EEG devices on the market now,
for example the Avatar EEG ([http://avatareeg.com/](http://avatareeg.com/))
and a few of the Emotiv devices.

I've been working on a side project
([https://octopusmetrics.com](https://octopusmetrics.com)) that allows you to
connect these devices to your computer to record, visualize and analyze your
EEG data in the browser. I think it's great that there are people out there
thinking about how to do this more cheaply as it'll bring _real_ EEG devices
into the price range where it'll be more available to hobbyists.

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bayesianhorse
There are lots of useful applications which should prove at least harmless, if
not even beneficial.

For example with an EEG sensor you can do neurofeedback training to improve
attention, which has been shown to help with ADHD and even epilepsy, among
other things. For this purpose, the Neurosky Mindwave Mobile with its low
price tag and bluetooth interface is certainly a better choice than any
homegrown amplifier.

For EMG, besides controlling something, feedback training is also possible.
For example when EMG sensors are attached to your shoulder muscles you can
teach yourself to actually relax them. The computer can then alert you to
unconscious tension building up, during typing for example.

I don't know if ECG (I think that's the correct English spelling) has been
shown to be useful in biofeedback, but the trainability of heartrate is well
known.

~~~
charlemagne
Regarding EEG, that's what we're working on at Three Pound. We're providing
tools for mindfulness based stress reduction paired with consumer EEG devices
like the NeuroSky Mindwave Mobile
[http://threepound.com](http://threepound.com)

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david927
If you're interested in playing with EEG, you might want to also check out the
new Emotiv Insight headset:

[http://www.kickstarter.com/projects/tanttle/emotiv-
insight-o...](http://www.kickstarter.com/projects/tanttle/emotiv-insight-
optimize-your-brain-fitness-and-per)

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celso
Very interesting. You may also want to look into Bitalino
[http://www.bitalino.com](http://www.bitalino.com) it's an Arduino like
approach to playing/hacking with biomedical signals, at a fraction of the cost
this kind equipments usually has.

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saurik
I have been under the impression that doing this kind of thing is not that
difficult (as explained here) but somewhat "dangerous" in that if you get the
wiring at all wrong and accidentally apply even a small amount of current you
can confuse the heart and get it to damage itself. I do not see any paragraphs
here of "dire warning" or even any specific mentions of parts of this process
being dangerous, just a comment that "it seems to me almost impossible that
anybody could injure themselves", which I'm finding strange ;P.

Here is a much older article from 2003; it begins with a dire warning.

[http://www.eng.utah.edu/~jnguyen/ecg/ecg_index.html](http://www.eng.utah.edu/~jnguyen/ecg/ecg_index.html)

> This device requires you to strap electrodes across your chest. This is
> inherently dangerous. Both because of the pain caused by sticky tape pulling
> hairs out of a person's body and also because even small currents can kill.
> Do not attempt this experiment unless you fully understand the potential
> problems with this device.

Here is another article from 2007; again, it begins with a dire warning.

[http://web.archive.org/web/20070324054626/http://www.e-dsp.c...](http://web.archive.org/web/20070324054626/http://www.e-dsp.com/how-
to-build-your-own-heart-monitoring-device-a-simple-ecg/)

> Before I continue to explain what I did, I would like to WARN you! 500mA
> (miliAmps) on 220V will completely destroy your nervous system (so run it
> from battery supply), check everything twice and you are responsible for it
> on you own.

In this article from 2013, there is a rather extensive back/forth paragraph
;P.

[http://www.swharden.com/blog/2013-04-14-simple-diy-ecg-
pulse...](http://www.swharden.com/blog/2013-04-14-simple-diy-ecg-pulse-
oximeter-version-2/)

> If you’re worried about electrical shock, or unsure of your ability to make
> a safe device, don’t attempt to build an ECG machine. For an ECG to work,
> you have to make good electrical contact with your skin near your heart, and
> some people feel this is potentially dangerous. Actually, some people like
> to argue about how dangerous it actually is, as seen on Hack-A-Day comments
> and my previous post comments. Some people have suggested the danger is
> negligible and pointed-out that it’s similar to inserting ear-bud headphones
> into your ears. Others have suggested that it’s dangerous and pointed-out
> that milliamps can kill a person. Others contest that pulses of current are
> far more dangerous than a continuous applied current. Realists speculate
> that virtually no current would be delivered by this circuit if it is wired
> properly. Rational, cautionary people worried about it reduce risk of
> accidental current by applying bidirectional diodes at the level of the
> chest leads, which short any current (above 0.7V) similar to that shown
> here. Electrically-savvy folks would design an optically decoupled solution.
> Intelligent folks who abstain from arguing on the internet would probably
> consult the datasheets regarding ECG input protection. In all cases, don’t
> attach electrical devices to your body unless you are confident in their
> safety. As a catch-all, I present the ECG circuit for educational purposes
> only, and state that it may not be safe and should not be replicated There,
> will that cover me in court in case someone tapes wires to their chest and
> plugs them in the wall socket?

~~~
neurotech1
No real danger for EEG if powered from an isolated laptop.

ECG can cause safety issues if there is a significant current across the
sensor leads, but even that is unlikely unless the completely wrong resister
values used and the person hypothetically has a heart condition.

Disclaimer: I'm not a physician, neurosurgeon or lawyer. I did however design
and repair EEG systems.

~~~
cybp
You are incorrect. This circuit can potentially apply unsafe currents across
the patient. A standard medical biopotential measurement circuit will have
single-point failure protection to prevent conditions like this. This is
required by standards like EC11, EC13, and 60601. Those systems are extremely
safe.

Most hobbyist designs, like the one in this article, do not have such
protection. Indeed, for this particular circuit, a simple static discharge, as
might happen when you're applying the electrodes after walking over carpet,
can fry the input amplifier, connecting it to the power rails. ESD (and,
indeed, defibrillation -- which is about a thousand times more energy than
ESD) protection would be present and required in any medical biopotential
amplifier, even unrelated to the single-point protection described above.

If the ESD failure happens to short out to power rails, your current will be
your power rails divided by your electrode impedance. This distribution is
described in EC11/EC13 (although electrode technology has improved since the
days when those tests were done, so impedance is even lower). Even with the
ancient electrodes in EC11/EC13, you would get unsafe currents some of the
time. With modern electrodes, you would get unsafe currents much of the time.

I've seen dozens of circuits for home EEG/ECG/EMG. Almost all of them,
including this one, are a deathtrap. They will work okay most of the time. At
some point, someone's going to kill themselves.

Disclaimer: I am not a physician, but I've designed ECG circuits all the way
through safe, successful human trials.

~~~
neurotech1
Your talking potentially "unsafe" vs somewhat likely hazard.

Most of the "danger" comes from poor isolation. The skin resistance is too
high for EEG to cause major problems. I realize the actual standards have
requirements that are detailed and somewhat strict.

The difference is that ECG has sensors that can directly put current through
the path to the heart so the risk is higher if there is a worse-case ESD
latchup. 5mA is enough to stop a heart in certain conditions.

EEG isn't ECG or EMG and have different characteristics even though they seem
vaguely similar.

PS. My contact info is in my profile.

~~~
cybp
Skin resistance is quite low. You are thinking skin-electrode impedance. That
is generally high enough to be safe, but with modern electrodes and luck, it
can get somewhat low too. 5v 1k 5mA would not be unreasonable.

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rrmm
Here's an article from analog devices (who make the AD620 used in the article)
[http://www.analog.com/library/analogdialogue/archives/37-11/...](http://www.analog.com/library/analogdialogue/archives/37-11/ecg.html)

It has some background as well as an example circuit with a discussion of
safety and isolation issues which is a bit more in-depth than the posted
article.

For the posted schematic: at least put some current limiting resistors on the
electrode leads.

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benbojangles
Could be good for practising meditation - learning to not be influenced by
auditory influences. I love my old jumble sale £10 ecg machine. I would love
it if someone made a more 'rounded' software. Something useful for medical
diagnostics.

Free ECG software:
[http://www.neozap.com/freeECG.htm](http://www.neozap.com/freeECG.htm)

Neuralfeedback training:
[http://vimeo.com/69318799](http://vimeo.com/69318799)

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kayoone
Thats really interesting and would add another dimension to these "self
monitoring" devices but i am skeptical as too much self monitoring can do more
harm than good.

DIY EEG/EMG can be used for alot of interesting applications though, if you
want to play around with "mind controlling" things ;)

~~~
bobowzki
I'm a physician and I agree. Obtaining data is the easy part, interpreting the
data is the hard part. If you want solve interesting problems that's where you
should look.

~~~
alexchamberlain
But you _need_ the data first, where better to get it than yourself?

~~~
pygy_
In a larger sample, but it's usually more expensive. That being said, self
experimentation is fun. Very fun :-).

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mcculley
This reminds me of the AliveCor device, which excites and frustrates me. I'm
excited because I'm hopeful that when such monitoring becomes dirt cheap and
unobtrusive, people might find conditions earlier and have a better chance to
treat them. I'm frustrated because in the U.S. it currently requires a
prescription from a doctor to buy one. This feels like regulatory nonsense to
me. It seems like an obviously low risk that this could do any harm.

I'm a bit hopeful it will go on sale in some other country soon that doesn't
require a prescription and I can have one shipped to me.

~~~
alphaoverlord
I got one for free for a demo and while it was interesting, I can't think of a
good use case. A single lead ECG is not useful for much more than heart rate,
and there are already many interesting ways to get that ( light sensor on
phone ) that i dont know if it has much more utility from extra hardware.
Perhaps if you have lqts, it can flag it but otherwise very very few usecases.

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code_scrapping
Misinterpreted knowledge could be more harmful then ignorance (as any
hypochondriac would know), but that's not the case here - I'm really looking
forward to trying to build something like this.

It's nice to see DIY moving from blinking lights to really useful and serious
areas.

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flatline
Last time I had an EMG involved 45 minutes of a doctor poking needles into me
to measure current. Moderately uncomfortable, and does not seem feasible to do
on oneself. I assume this one just involves an electrode on the skin? Is that
even going to do anything?

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gwu78
Most difficult part of "personal EEG" going forward seems to be the pasting of
the electrodes to the front and back of the scalp and the chest. In hospital,
someone else does that for you.

~~~
aestra
EEG is an electroencephalography and measures electrical activity of the
brain. Why would you put the electrodes on your chest for that?

I've had a few EEGs and there was never any on the chest. Proper placement
would seem to be an issue.

~~~
gwu78
You are right. The proper acronym is ECG.

I guess you've never had a polysomnography. There are electrodes placed on the
scalp, chest and leg.

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lifeisstillgood
Dr House should be both delighted and worried by this. We are seeing the
flowering of an age where sophisticated medical diagnosis is just a (well
regulated and tested) app / dongle away. From on chip chemical analysis to
home brew EEG the things that say a child born today in Africa will see
connected to them will astound you and I.

I hope it it makes the difference between the infrastructure it has taken to
build to get care within our reach and the less infrastructure available /
needed in different corners of the world.

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aswanson
Projects like this suggest to me there is a combination of collusion and bs
from the FDA driving up the cost of medical equipment in this country, as well
as blocking innovation.

~~~
JunkDNA
Having worked in the pharma industry, I can attest that there is no shortage
of extreme risk aversion at the FDA. That being said, we just had an article
here where someone claimed to have created a spreadsheet in pure javascript
for some absurdly low number of lines of code. When you read through that
thread there are all sorts of people pointing out that this isn't a _real_
spreadsheet by any stretch. It merely looks like one, but is missing some
pretty complex and necessary stuff. I would submit that what you see here is
the medical device equivalent. There are no safety mechanisms, the system
doesn't monitor itself for failure, there's no characterization of the limits
of the system in various conditions, etc... That's fine because it's a
_hobbyist_ setup. But let's not kid ourselves about what it takes to have a
reliable device that works in a hospital setting under a multitude of
environmental conditions.

Things didn't end up the way they are by accident. The current situation is
the result of decades of medical devices and interventions killing people
because of faulty design. It's not unlike the situation with the FAA and
airlines.

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kimonos
Nice innovation! But I still prefer the physicians to do it in case I would
need to have an EEG, EKG or EMG in the future. Great info though!

