additional channels, higher sampling rates
FarukEroglu2048
Turkey
Hi,
I am a 20-year-old biology major and I have been using my DIY ADS1299 based EEG until now for research. However signal quality was not great especially because of me using a breadboard instead of a proper circuit board, as I am really bad at soldering.
I have a budget of around 5000-7000 USD and I have been looking for a research-grade EEG, but I was unable to find one for my budget. Hence I am planning to get OpenBCI Cyton+Daisy along with Greentek's dry EEG cap. However I have encountered a few issues: It seems like Cyton+Daisy out of the box does not meet neither my sampling rate requirements (at least 250 Hz, with 500 Hz or even 1 kHz being preferred) nor my channel requirements (at least 32 channels)
I think using OpenBCI hardware would still be possible by stacking multiple Daisy boards and modifying the OpenBCI software. For the hardware side of things, do you sell more than 1 Daisy module per person, as I will need 3 to accomplish 32 channels? If so, is it possible for you to do a small modification to the Daisy modules (soldering long female headers to make stacking possible) as I am really bad at soldering? For the software part, is there a way to modify OpenBCI GUI software (along with other software / libraries that use OpenBCI, including OpenViBE and LSL) to keep using OpenBCI software and libraries? For transmitting data, I am familiar with Arduino programming and I believe an HC-06 can handle 32 channels @ 500 Hz using 1M baud rate. While I believe modifying the OpenBCI board firmware to simultaneusly send 32 channels @ 500 Hz would be trivial, I have no idea on adjusting OpenBCI GUI and other receiving software to expect that. Do you have any information on that?
I also used to have a DIY Cyton board with a DIY WiFi Shield, however the signal was extremely unstable with constant cyclical noise patterns. It seems like it is also an issue with the original WiFi Shield (https://github.com/OpenBCI/OpenBCI_GUI/issues/231), so using WiFi Shield is not an option for me. Either case, WiFi Shield seems to be out of stock, so I have no other chance either.
Lastly, do you have any information on specifications of OpenBCI Cyton+Daisy? I especially would like to know about CMRR and RMS noise of the board. I know that the ADS1299 is quite good on that regard, but I am curious about the performance of the Cyton+Daisy board itself, which can be affected by other components on the board. If you don't have official specifications for CMRR and RMS, do you at least have an average value to be expected based on customer feedback?
Thanks in advance and sorry for the long post, I am quite lost.
Comments
Hi Faruk,
re: stacking multiple Daisy boards. This is not possible nor supported.
re: Wifi Shield. This will eventually be available in the shop, with corrected operation. Priorities on the Galea project are limiting resources.
re: performance benchmark. See this paper by Jeremy Frey.
https://arxiv.org/abs/1606.02438
Regards, William
Emotiv is also an option for more affordable (than research grade) hardware
https://www.emotiv.com/product/epoc-flex-gel-sensor-kit/
Hi,
Thank you so much for your response. I am aware that such a configuration is not supported by default. However what I want to do is to use existing OpenBCI hardware to make a custom EEG - while I have the skills needed for software and circuit design, I simply do not have the skills to design and build a PCB, so I am limited to pre-built hardware. I also have realized that posting this thread in "Build-it-yourself" section would have been a better idea to prevent confusion, I am really sorry for that.
In short, I am unable to design and build my own PCB, therefore I want to make a custom EEG based on existing OpenBCI hardware. While still haven't decided on how to do that, I have a few ideas: I believe Daisy modules can be used as ADS1299 breakout boards, so I can connect them to a microcontroller. Another idea is using a Cyton as a microcontroller board and then stacking Daisy modules on top of it.
Do you have any recommendations on that? I mainly plan to accomplish at least 250 Hz sampling rate with at least 32 channels. Thanks in advance.
Faruk, hi.
Sorry, but the Daisy boards are not sold separately. They are only sold as part of a 16 channel package. Or, if a previous 8 channel Cyton owner wants to upgrade to 16 channels.
William
Hi,
I see, thank you so much for the help and sorry for the inconvenience. Do you know of another way to get an ADS1299 breakout board? I was thinking of using TI's evaluation board, but I have concerns about its safety.
Thanks in advance.