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Topic: Galvanic Vestibular Stimulation - AWESOME! (Read 22550 times) previous topic - next topic

PlastBox

May 16, 2010, 06:47 pm Last Edit: May 16, 2010, 06:49 pm by PlastBox Reason: 1
As the title suggests, I have spend a couple of hours today testing Galvanic Vestibular Stimulation (GVS). The theory is that a voltage applied to the mastoids (the small bone right behind each earlobe) will screw with your balance system, effectively creating a "pull" towards the anode.

Well, I made a couple of home-made electrodes by layering the stripped end of a wire between duct tape and aluminum foil (the kind found in any respectable kitchen), attached them to a DPDT-switch so I could reverse the polarity of the electrodes, and stuck them to the skin behind my ear. Balanced on one foot, flipped the switch...

...and very nearly fell flat on my behind! :o

The whole thing is so simple it's hard to believe we don't ever see people experimenting with it. A 9V battery, a couple of electrodes, and 1-1,5mA of current.

Try it out if you haven't already! It quite literally nearly floored me to experience this, the effect is quite pronounced!

As to practical applications.. The first thing that comes to mind is navigation systems. You could integrate this with your cellphones GPS and compass and have electrodes cleverly hidden in a pair of headphones gently "pull" you in the direction you need to go. You could experience something very similar to centripetal force when playing driving-simunator type games. There are probably other applications as well like, say, having fun with electronics. :D

amacmullen14

I tried this, and it works!  Though I didn't get the same falling effects you did.  Pretty weird still that I leaned forward involuntarily when I connected it to the battery.

PlastBox

I didn't really control or measure the current though, so my level of stimulation was probably too high. I read in a research paper (damn, why did I close that tab?) that the maximum level of vestibular stimulation occurs between 1 and 1,5mA and that a persons individual pain threshold lies just about 5mA above this.

When I said I almost fell, I was standing on one food with my eyes closed, no resistor in the circuit and moisturizing cream on the electrodes to decrease skin resistance. So yeah, the current was a bit above my pain (discomfort) threshold.

As described in the literature I have read the device creates a "pull" towards the side where anode of the battery is connected relative to the voltage(/current) applied.


Btw, do not try to put an electrode on your forehead thinking that current flowing "forward/backward" through your inner ear might tip your balance forwards or backwards. It didn't work and, in fact, made my entire field of vision "blink" (lacking a better word) each time I flipped the switch. That can't be good for ya! ::)

javagamer

I just tried the same thing.  It took me a little while to get it to work, turned out I needed to make my skin more conductive.  Mixing up some salt water and starch worked perfectly.

IMPORTANT WARNING BELOW:
BUT, I discovered that doing this without a resistor can certainly be risky.  It may have been a placement of my electrodes (I put them behind me ears then attached the battery as opposed to how I initially did it [connecting the battery then pressing the electrodes against my skull]) or the fact that I didn't have a resistor (I figured that my head had plenty of resistance already) but I ended up sending a spasm through my head.  As soon as I noticed it I disconnected it, but it really freaked me out.  This is about 15 minutes later and not noticing anything wrong, but I've decided to be a lot more careful from here on out.  However, if it looks safe enough I plan on continuing and hooking this up to an Arduino.

thoed

Haha, I'm not a big fan of sending any kind of current through my body :P

But this reminds me of a show I just watched on the Discovery channel, this guy created a helmet he calls "The God Helmet".   Lol basically he can make people feel like they're experiencing... something spiritual I guess, one girl said she felt like she was surrounded by "ghostly beings" and she felt like her head was gone and having an out of body experience.

Pretty weird stuff, lol now that I actually searched on Google, there's alot of stuff about it.
http://www.shaktitechnology.com/god_helmet.htm
http://en.wikipedia.org/wiki/God_helmet


javagamer

I've heard of that too, very similar idea only this seems slightly easy since it just involves electrodes as opposed to magnets.  Still, magnets feel a bit safer.  Yesterday I was actually wondering how hard this would be to replicate with magnets, that would also have the benefit of eliminating the need for any kind of conductive paste.

oscarcar

You can reduce the skin impedance by wiping away the oils with an alcohol swab. Abrading it also will help, like they do for EEG. You can use a Q-tip and some abrasive paste. Or you could use a small piece of lightly abrasive sandpaper.

I would suggest controlling the level of current before you do that tho.

Leon Heller

Attaching anything connected to a mains supply to yourself like that can be *very* dangerous. Use a battery to power the Arduino.
Leon Heller
G1HSM

javagamer

The fear of attaching something from a mains supply to myself is the reason I used a 9V battery as opposed to my power supply which I could current limit.  I'm now even more unsure as to how I managed to send a tremor through my head.  I just measured the resistance across my head using my homemade (and pretty terrible) electrodes and I found it to almost drop down to 5K Ohms at the lowest.  However, it varied quite a bit depending on how exactly I held them and what I did.  The 5K Ohms was received after wiping the site with alcohol, soaking in saline, dipping the electrodes in saline, and pushing my ear into it (so it touched both the skin behind my ear and my ear itself).  Even had the battery been brand new and outputting 10V (which it most definitely wasn't) that would mean the highest current I could achieve would be 2mA, which is lower than the pain threshold PlastBox cites and within the range of some journal articles iirc.  I will next be attempting to use an Arduino Duemilanove connected to my computer via USB w/ a 1K ohm resistor.  While there will obviously be significantly less current, I'm hopeful it will still be noticeable.  I think the next thing I should do if I continue experimenting with this is definitely get professional electrodes (and probably paste as well).

Also, the flashes PlastBox mentions are known as phosphenes and I experienced some as well with the electrodes behind my ears.  They've been mentioned in research with electrostimulation before and don't appear to be harmful on their own.  I noticed the occipital lobe (responsible for visual processing) is somewhat near where I had my electrodes, so that could explain it.

modat7

This is the starting point of CES (which I use for stress management for my chronic sleep disorder):

http://en.wikipedia.org/wiki/Cranial_electrotherapy_stimulation

I built my own since I researched the designs of others and considered them to be mediocre for the price. Someday I want to use an arduino connected to a computer with the OpenEEG project and have this dynamically controlled while I sleep.

I also figure an H-Bridge could turn that into a TENS unit.

One warning that is very important: people with epilepsy or a history of epilepsy in the family should be very careful to what they hook up to their heads. Needless to say, it could create a very bad situation. On the flip side, I have a theory that a CES unit could also control "uncontrollable" epilepsy if implemented correctly.

cr0sh

Back in the late 1990s a company (which has since fell victim to late-runner .COM death) existed which created prototype vestibular stimulation devices for the purpose of enhancing in-game simulation effects (both for immersive and non-immersive systems). They were offering a helmet and API for Windows to developers for something like $350.00 or so. The idea being developers could ready their software for the system in exchange for being early testers.

I think it was demonstrated at CES. I remember the electrodes being behind the ears as well as two up front on the forehead or nearby. Supposedly, it allowed one to experience not only left/right motion cues, but  also frontal/posterior, and falling/weightlessness (to a degree); enough of a stimulation to enhance games using it.

I don't know if they got any takers, or if anything beyond some demonstration software was ever created, but the company went out of business fairly rapidly. The form of vestibular stimulation used wasn't DC current only; instead, a low-current AC signal was used, and the shape of the wave and the frequency affected how the effect was perceived by the user.

A form of such a system is used medically, but not with anywhere near any form of control (probably closer to what PlastBox experienced).

:)
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

javagamer

Cool to see other people interested in this too :D
I've been reading about all sorts of electrostimulation and I've come across CES in addition to some other interesting things such as TENS and electroanesthesia.

cr0sh I came across that as well, but I heard that no one wanted to be the first to delve into this.  I found a paper which does a great job detailing how this can used to stimulate movement on multiple axises, but I've not had time to fully digest it.  You can find the paper for free at http://jap.physiology.org/cgi/content/full/96/6/2301 .

Speaking of commercial uses for this technology, Nippon is apparently looking into commercializing it.  They have one of the most dramatic demonstrations with a remote controlled person http://www.youtube.com/watch?v=OlXYqfQHNuA .  They also displayed this at SIGGRAPH with a paper called Shaking The World: Galvanic Vestibular Stimulation As A Novel Sensation Interface.

I've found a slightly better electrode setup using saline soaked cotton balls held in place with an elastic band.  I also believe I previously placed the electrodes a bit higher than I needed too which may have been the cause of the phosphenes.  Hooking my setup without a resistor to my multimeter I determined I was running just over 2.5mA through my skull which while being on the high side isn't as alarming as I worried when I managed to send a tremor through my head (I'm blaming it on bad electrode placement atm).

sdraisey

there are quite a few scientific groups out there experimenting with using a controlled version of this - mostly US, Japan, UK, Australia and Germany.  Some for medical (for memory, sleep, motion sickness, rehabilitation), some for navigation, some for virtual reality.  NTT produces a wireless unit, which they don't sell commercially.  We have one we sell, but there's not a lot of customers, so the cost is high.  The researchers all have to get ethics reviews from their organizations, before they're allowed to do experiments on human subjects.

Its apparently easy to 'excite' one degree of freedom, but the other 2 are much more difficult (if even possible at all).

ArduinoGVS

I Have been trying to build such a device you described here but unfortunately unsuccessfully. I don't know whether it's my circuit or the electrode connection to my head but it just doesn't work. Could anyone please send me the schematics of the circuit or perhaps some pics.
It would be really helpful.
Thanks A lot!!!

dosman

Nice to find people experimenting with GVS and other things :). I have two Arduino's hooked up using those SparkFun 315MHz RX/TX boards and an RF driver library I came across. Using one as a remote control I can send a pulse left or right to the receiver and through the wearers head. The problem is that I'm not getting the expected "fall left" or "fall right" as all the videos show. Sending a zero-crossing pulse (left and right quickly - CES) has a very strong sensation so I know I'm getting plenty of current, although I have not measured it. I've done quite a bit of experimentation with CES, honestly I would be afraid to connect a 9v battery up with no current limiting at all. I've read a couple different papers on GVS so far and they seem to agree that a 1-2Hz pulse with 2mA max is required to get the strongest sensation. The jury is still out on this one for me.

Also, with regard to the Koren Helmet. The Wikipedia article pretty well sums up the problems with the testing methodology used in the original experiments. As far as the Shatki device, while I've not tried it I strongly suspect it's bogus. Why? They are clearly using magnetic pickup coils that suction to old desk phones for recording conversations (Radio Shack used to sell them). They even admit as much on their site. These coils are pretty weak. I'd be strongly surprised to learn they do any more than heat up and burn out.

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