Railing on 2, 5, 9, 12, and 14 - readings seem un-reliable

GeneralFoxGeneralFox
edited September 2017 in Cyton
Greetings,

I received my Cyton and V3 Daisy Module the other day.  I have designed my own headset using solid round steel wires, after having donned a swim cap to establish electrode positions and establishing where the wires needed to be run.  I covered the headset wiring with heat shrink tape and then secured sized wooden dowels to ensure that the electrodes are positioned correctly on the skull.  I have used Ten20 to help paste the electrodes to my head.  I have secured the ground wires to my ears using jewelry clamps (having soldered the wires directly to the clamps).  I am using the pins close to the board for the electrode connections.

For the first couple of minutes all seemed fine - but then it started to rail on 2, 5, 9, 12, and 14.  They appear to be firmly attached to skin, so I am unsure as to why they show like this.  As well, upon review in the OpenBCI application (running on Windows 10) - the readings show nothing more than straight lines that appear to be in sych with each other (patterns are the same).  If I disconnect the Daisy board it appears to work better. 

Upon investigation it appears that there is some sort of a flaw in the design of the Daisy boards that require pins 51 and 52 to be connected together?  This has not been done on mine - should it?  Is my board running a faulted software version?  Why is it not working as expected?

Any help is greatly appreciated!

Thanks,
Don
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Comments

  • wjcroftwjcroft Mount Shasta, CA
    Don, hi.

    (1) Using the Daisy requires that you make a Y-cable to connect the SRB2 reference signals together between the mainboard and the daisy. The output of that Y, then goes to your head reference (ear for example).

    https://www.google.com/search?as_q=daisy+y+cable&as_sitesearch=openbci.com

    (2) Steel is not generally used for EEG or other electrodes because it performs much more poorly than gold, silver, tin, or Ag-AgCl. Signal quality will be very erratic with steel. You can get the Ag-AgCl combs or cones easily from FRI, see the Electrodes Category in right column.


    Stainless is very occasionally used, but you are really better off with one of the other metals.

    William

  • GeneralFoxGeneralFox
    William,

    In reversing out which lead is connected to each of the head placements for each of the EEG leads for my custom headgear, I had already soldiered together the two white leads on SRB2 (bottom most pins) on both boards and connect them to my left ear.  I also have the two black leads connected to BIAS2 on both boards with the wires soldiered together and connected to my right ear.  So from what I understand, this should not be the problem, and should fully meet with the requirements.

    Regarding the ear clips, I had not realized that the metal chosen would play such a significant factor.  I soldiered the original ends back on, and now see the below when I use the device.  It still looks 'wrong' to me - opinions?

    Thanks,
    Don
  • GeneralFoxGeneralFox
    edited August 2017
    I can't paste the image, but all of the readings are essentially the same waveform - but I seem to have fixed the railing issue.
  • GeneralFoxGeneralFox
    edited August 2017
    I cut my hair very short, but still do have some hair trapped under the EEG connectors on my scalp.  I did use conditioner.  Could the conditioner be the issue?  Would I be better off using dry connectors?
  • wjcroftwjcroft Mount Shasta, CA
    If you are seeing "all of the readings [channels] are essentially the same waveform", this implies something odd about your reference connection, since that lead is in common with all channels.

    The Bias pins on both board are already linked, so a Y is not need there, but does no harm.

    You can upload a screenshot to Google Drive or other cloud storage, then place a link here.

    William
  • GeneralFoxGeneralFox
    edited August 2017
    Thanks for the help! 

    image

    Any ideas?  My soldering is good.  I'm using gold electrodes (the ones that ship).  I've not increased the length of the wires.  I'm using the pins closest to the board.

    Thanks!
  • GeneralFoxGeneralFox
    Here are some pics of my headset and wiring.

    Headset 1
    Headset 2
    Headset 3
    Board
    Ear Grounds
    Pins 1
    Pins 2

    Thanks!
  • wjcroftwjcroft Mount Shasta, CA
    Don, thanks.

    Without your headset and just using the gold cups and paste, what happens when you do the various sections of the tutorial (without the Daisy),


    Do you see the ECG, EMG, EEG, alpha, etc. As outlined there? Also you can try various combinations of channels to make sure all 8 of your channels work as expected.

    The gold cups are intended NOT to be pre-pasted as appears in your photos. But instead applied one at a time by hand with a small pea size glob of paste, then press down. There must be a solid and firm paste connection for the gold cups to work properly. That requires more paste as shown in this video,


    The other hunch I have is that there might be some capacitive or inductive coupling going on between the electrode wires, and the steel frame that they run along.

    Regards,

    William

  • GeneralFoxGeneralFox
    William,

    Ok.  I did not intend to need to put a lot of paste on - nor did I leave a lot of space to work with the paste after it is put on the skull. 

    I want to move to dry electrodes.  Rather than modify my current frame, I want to buy a Ultracortex IV.  I purchased the Cyton with wet electrodes, so I do not have an appropriate wire package to use.

    I have noticed that the large un-assembled are out of stock.  Does anyone know if I purchase a fully assembled one - will it come with the electrodes and wiring in place?  Will I only have to put in my Cyton board and connect the wires?  Or do I have to purchase the wires separately?  Is there an estimated time for the un-assembled large to become available?

    Thanks,
    Don
  • wjcroftwjcroft Mount Shasta, CA
    Don, send an email to contact at openbci.com, to ask about the time frames. The fully assembled UC's come with wiring in place.  I'll also mention @openbci, that sends to contact as well.

    William
  • GeneralFoxGeneralFox
    William,

    I just received my new Ultracortex - Professionally built.  I connected the wiring as per the document.  I have adjusted the dry spiky electrodes to be snug.  When I use it, I get the following:

    http://generalfox.com/EEG/Ultracortex.jpg

    Any suggestions? 

    Just as before, I notice that if I touch the daughter board, I get different results.  Sometimes channels 9 thru 16 show RAILED.  If I touch the board, then I will get some readings on a couple of them - then it stops.

    Is there something wrong with the unit?  I cannot seem to get this to work.

    Thanks,
    Don
  • wjcroftwjcroft Mount Shasta, CA
    Don, hi.

    This latest image shows tons of 60 hz noise. You can actually count the waveforms, about six per .1 second period. Whenever doing any type of EEG you need to be some feet away from any AC line cords, wall warts, etc. Even pay attention to where conduits run through your walls or floors. It's unclear why this is not showing up on the FFT plot, with this kind of noise one would expect a large spike at 60. You do seem to have the 60 hz notch filter on. But the mains noise may be so strong it's getting through that.

    I asked this previously, but will repeat again:

    ----

    Without your headset and just using the gold cups and paste, what happens when you do the various sections of the tutorial (without the Daisy),


    Do you see the ECG, EMG, EEG, alpha, etc. As outlined there? Also you can try various combinations of channels to make sure all 8 of your channels work as expected.
  • GeneralFoxGeneralFox
    Hi William,

    I connected the gold cups and paste to the Cyton.  I followed the instructions to extract EEG.  I also tried EKG on my wrist and also the muscle on my forearm. 

    When I connect to 2 and 7 I just get noise:  http://generalfox.com/EEG/No_signal.jpg
    I do not get anything on EKG or my wrist. 

    If I just turn it on, with no cables connected - no matter where I put it in the room - I get the following output - is this normal?
    http://generalfox.com/EEG/Nothing_connected_across_room_by_nothing_electrical.jpg

    I am color blind and had not noticed that the gold plating was removed from the connector when I cleaned them.  I had grabbed a toothbrush - not realizing that it had been used before.  Will the removal of the gold plating affect the readings?  If so, then I will need to order two new cables and try again.

    Thanks,
    Don
  • wjcroftwjcroft Mount Shasta, CA
    Don, hi. Where are your reference and bias on the EEG test? The EMG test should produce huge signals, so surprised you are seeing nothing there.

    Colors of individual channel cables are not so important, it's the channel number that counts. So even if you have removed gold plating from one cup, you should have more in your set? See the tips on cleaning the cups without rubbing in the Electrodes category. Cups with chipped or removed gold can produce bad signals due to galvanic "battery like" effects. Because under the gold is another metal, hence the battery properties.

    A simple test for checking channels is to connect all three: channel, reference and bias together with clips or paste. This should produce close to 0 uV. When the channels have NO connection, results are unpredictable. 

    Has this Cyton ever worked with the tutorial steps when first purchased?

  • GeneralFoxGeneralFox
    William,

    Thanks again for all of your help with this.  I have not been having much luck with all of this. 

    To top it all off, my new headset shipped with two broken spikey units, and I am awaiting shipment on them.  I was told the headset should still work with the two broken units (some of the spikes broke off).

    But to answer your question - No - the unit has never worked right out of the box.  I have followed the tutorial originally but did not know what to expect from the wave forms, so when I seen some I figured it was working.  I then used the headset that I built.  When it did not produce the results I blamed it and purchased one from OpenBCI.  When I received the unit from OpenBCI I was disappointed to see that it still did not work correctly.  The unit either rails or shows the same signal across all channels. 

    It is my opinion that it is defective as it always seems to either show the same patterns across all or rails.  It seems to be getting worse.

    I really, really want this to work! 

    Don
  • wjcroftwjcroft Mount Shasta, CA
    Don, running out of suggestions here.

    I suggest you email contact at openbci.com, and inquire if there are some more tests you might try or if the board has indeed been damaged somehow prior to your receiving it. Mentioning @openbci.

    One statement you make above in response to my question about your first trials using the board with the tutorial: "No - the unit has never worked right out of the box.  I have followed the tutorial originally but did not know what to expect from the wave forms, so when I seen some I figured it was working."

    Is this true? The tutorial explains each connection, step, and resulting waveform carefully. What the ECG should look like, the EMG, the EEG. So none of those initial tests with gold cups and paste worked for you? And none are working now?

    Did you try the connecting a channel, reference and ground together to see if that produced close to 0 microvolts? Did you try that on multiple channels?

    You've also tried positioning yourself away from AC cords, conduits, wall warts, wifi, cell phones, etc.?

    Regards,


  • GeneralFoxGeneralFox
    Hi William,

    I will contact them immediately.  Thanks for all of your help.

    Truthfully, I did not do the EKG test when I first got the unit as I was not concerned about that.  I thought if the EEG portion worked, then I was golden.  Now when I look back at the original tests I see that it was simply showing the same waveform on the channels. 

    When I performed the tests the second time, I was concerned that the unit was defective - so I tested the EKG to find that it is not functioning correctly.  If you recall in one of our prior posts you mentioned that you were concerned that this was due to my having used a plastic covered metal wiring system, so I purchased the plastic headset.  To rule out any error on my part, I purchased the professionally crafted headset.  No difference.

    I just tested connecting channel 1 and 2 to SRB and BIAS.  I disabled 3 through 16.  I put it in the center of my living room.

    I sit in an apartment, 3 feet from a flat-screen monitor, with only my computer on.  I moved to the center of the living room when doing the test with - same result.  I can't believe I am immersed in that much EMF radiation?

    Thanks,
    Don
  • wjcroftwjcroft Mount Shasta, CA
    Don, thanks. FYI, the jpegs are not showing the waveforms, only the FFT.

    In terms of powering down the channels you're not using, does clicking on the channel number do that for you. Should not need to fiddle with the CHAN SET tab.
  • wjcroftwjcroft Mount Shasta, CA
    "so I tested the EKG to find that it is not functioning correctly.  If you recall in one of our prior posts you mentioned that you were concerned that this was due to my having used a plastic covered metal wiring system, so I purchased the plastic headset."

    No, my earlier comment was specifically about the metal framework of your steel rod headset possibly interfering with the EEG. 
  • GeneralFoxGeneralFox
    Hi William,

    Sorry for not being clear in my prior email.  I meant to say that I purchased the plastic headset so as to ensure that it was not causing the issues with the Cyton. 

    Thank you for pointing out that I published the wrong link to the waveforms above.  Please find it here.  You can kind of see the wave forms behind the settings in the other screen shot.  I did that as I found the output a little strange, considering what was selected. 

    I have contacted support for help.  I mentioned that I had a discussion on-going regarding this.  They have shipped me two replacement spikey units.  I really, really hope to get this all working soon.

    Thanks,
    Don


  • wjcroftwjcroft Mount Shasta, CA
    Don, you should actually TURN OFF the unused channels (following the tutorial instruction) by clicking the channel number. That will cause the channel number colored circle to go dark. This turns off the channel completely. You do not (and should not) try to turn off the unused channels with the detailed Hardware Settings (previously called CHAN SET tab on earlier GUIs) page, as you have done.
  • GeneralFoxGeneralFox
    edited July 2018
    William,

    Thank you for pointing that out.  When I was not seeing the results I wanted to see, I thought it because I needed to adjust the settings as found in 4 d) of the Cyton tutorial.

    Thanks,
    Don
  • wjcroftwjcroft Mount Shasta, CA
    Try rerunning your 0 uV and other tests by powering down the unused channels. Do NOT fiddle with the Hardware Settings panel unless instructed by the tutorial specifically.

  • pushtheworldpushtheworld
    @GeneralFox

    Sounds like you are running into classic EEG problems. The high gain of the ADS1299 causes channels to rail especially when the metals are different for electrodes and reference, i.e. everything should be Ag/AgCl. 

    you can try reducing the gain for your problem channels to 12 instead of 24. Railing is at the hardware level. My understanding is that your DC offset for the railing channels is too high/different from reference and the ADC becomes saturated and rails. If i had a nickle for every time my EEG channels railed I'd be a millionaire. 

    Some of the electrode positions on the Ultracortex don't work on my head shape, try changing those electrodes to different positions and watch how the signal doesnt rail anymore. 

    Lastly you should look into FRI electrodes for your dry electrode needs. They just made 5mm long spike electrodes that should get through hair!
  • GeneralFoxGeneralFox
    Hi Pushtheworld,  Thanks for the input!

    I would hope that the headgear provided by OpenBCI would conform with the specifications you offered.  I purchased the pre-assembled Ultracortex Mark IV headset direct from OpenBCI.

    Perhaps OpenBCI themselves can comment as to whether I need to adjust the gains down?  Or someone else knowledgeable with their products?  Or can you advise me?  I would've thought they'd sell units using compatible electrodes / spikey's?

    Not sure about why the electrode positions would not work in some spots
    on your head?  The electrodes seem very 'adjustable'?  How were you able
    to distinguish that they were not able to work on those spots?

    Thank you for the detailed explanation about railing - I was wondering as to what was happening.  I had assumed it was hardware driven, but was only advised to stop using conditioner, and cut my hair shorter (which I have done). My unit seems to work for a bit (upwards of 10 to 20 minutes), then it starts to rail and won't stop until it is turned off for a while.  I mentioned maybe it was due to heat, but was sharply advised this was impossible - so then don't know - maybe a cold solder joint?

    According to my tracking information, OpenBCI received my old unit this past Friday, and although I've been regularly sending them emails requesting a status update I have yet to hear back from them about whether they sent me my old unit.  As well it would be great if they would respond to me about whether they received my old unit yet.

    Hopefully some day, somebody from OpenBCI gets back to me.

    Thanks,
    Don
  • pushtheworldpushtheworld
    edited October 2017
    I guess my head is not normal? Im not sure why i couldn't record data with it on certain spots.

    I think the electrodes are something you need to need routine maintenance on. Don't expect the electrodes that came with the ultra cortex go last for ever. Dry electrodes are harder to use for sure!

    I think you should use a strap under your chin to apply a downward pressure to ensure your channels don't rail after 20 minutes. Sounds like that would solve these problems too.
  • GeneralFoxGeneralFox
    Thanks PushTheWorld!

    Thankfully the unit is brand new - although when shipped it came with two broken spikey's.  They were replaced - the unit seemed to work better. 

    Do you know what the duty cycle is on the spikey's? 

    I will try the chin strap.

    Thanks!
  • GeneralFoxGeneralFox
    edited July 2018
    @pushtheworld

    I received my replacement Cyton and daughterboard.  It worked for 20 minutes when I first connected it back up - but then it started to rail again.  I noticed the following: 
    - if I pull on the wire to pull the electrode away from the skull, and then let go it will sometimes work again.
    - other times, I have to tighten them.
    - if they are all the way in, then I have to screw them back out, and then back in again.
    - once they rail, they don't work for very long before they rail again.
    - I also notice that if I take the ear clips on/off it might fix some that are railing, but then others might start to rail. 
    - if I squeeze the ear clip then they will stop railing immediately.
    - in trying to emulate using a chin strap, if I put my fingers on the bottom of the headset and pull down then there is no change.  But if I do this harder and then let go they will sometimes all stop railing.

     My hair is now only 1/4" long all over.  I use no conditioner, and my hair is fully dry. The apartment is not hot, so I am not sweaty.  Brand new batteries in use.  My head is 58.5cm - so I had to purchase the largest headset.
    So to speed things along, I reduced the gain.  This has helped a little - I was 20 minutes again before it railed on 9.  What causes the DC Offset to be too high / different from the reference - just at that node?

    I would rather have the gain as high as possible, thus acquiring as much signal as is possible.

    I guess to get by for now I can pull the unit down and let go from time to time while running it with a lesser gain until this can be figured out.  But these are in tight enough to hurt my head - is this really the requirement?

    Thanks,
    Don
  • wjcroftwjcroft Mount Shasta, CA
    Don, your comment about "if I squeeze the ear clip, then they will stop railing immediately" -- inclines me to think there may be something amiss with your ear clip connection. By squeezing, you are lowering the resistance between your skin and the silver chloride electrode. Can you clarify, when you do this, everything becomes ok for a moment until you release?

    Can you try swapping the Reference and Bias ear clip leads, one may be better than the other.

    Another experiment you could try is something used in "saline" based electrodes. Get a thin strip of cloth and make a dilute solution of saline solution. DON'T use sea salt, as this contains many various metallic ions that can increase corrosion. Just use plain salt. Or you could even go to the drug store and pickup a small bottle of saline used for eye care or contact wetting.

    Wet the thin strip of cloth, and place between your ear lobe and the ear clip silver chloride surface. That will increase conductivity.

    ----

    So you say the new Cyton is acting just like the old one? In that case this is clearly not an issue with the Cyton, but rather with the electrodes, wiring, ear clips, etc. Mentioning @openbci.

    William

  • GeneralFoxGeneralFox
    edited October 2017
    William,

    I tried tightening the ear clips, but today noticed no difference.  It continued to rail.

    No, I think this unit is better.  It takes longer to rail, and now seems to rail on different electrodes.  It does not always rail on 9 non-stop.

    In fact, today I took out all of the comfort plugs and screwed the top electrodes out almost as far as they would go, effectively lowering my headset by 2 cm.  The unit is working WAY better.  It's been on for 15 minutes now, and has only been showing Near Railed on 2 electrodes, running at full gain.  Not once has it railed, and the waveform patterns are all looking great.  See HERE.

    I'll keep you posted.  This is more like what I expected!  Mentioning @openbci.

    Thanks,
    Don
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