Since I will be working at OpenBCI HQ during all the summer (which means that I can use everything that is among the four walls), I decided to write a blog post about how to make you EEG headset personable and comfortable.
But there was only one condition in our agreement: I would have to build my EEG headset accordingly to my research needs. I said yes immediately. I would be in the lab where they make all EEG headsets with all the material that I would need and professionals that could help me in critic moments. What could go wrong, right?
Select the components for my OpenBCI EEG headset
First of all, I chose all the components that I would need for studying the sensorimotor cortex area of my brain. I have already described my idyllic EEG headset in my last post. The components that I will use for my EEG headset are the following:
- Ultracortex Mark III “Supernova.”
- R&D Kit (16-channel) — 32bit, Daisy, & Accessories
- tDCS Shield for Direct Current Neurostimulation (Near future acquisition)
Build the EEG headset following the instructions
Ultracortex Mark III “Nova”
The assembly instructions from the GitHub are so well-explained that nobody can get lost in any of the steps.
- Remove residual support material & print flaws. The most important part of this process is that you thoroughly clean out the frames nodes where you will place your OCTANUT pieces.
- Glue the FRAME together. The best way to do this is to place both halves of the frame on a level surface and carefully bring them together. Be sure to be precise; it’s very hard to pull the pieces apart once you’ve put them together.
- Mount the OpenBCI BOARD_HOLDER. You might use a drill bit to expand the holes on the Ultracortex frame. Make sure that the orientation of the BOARD_HOLDER matches that of the pictures below.
- Assemble the Comfort Nodes. In order to fit the OCTANUT pieces into the frame, you will need the Comfort Nodes to securely glue the OCTANUTs in place. You just need to follow the instructions from the GitHub.
- Insert OCTANUT pieces (x21) into frame. At each node, you must line up the cut in the OCTANUT with the indentation on the frame as indicated in the GitHub picture. Most important, try over and over the optimum position of the OCTANUT to the frame that when the OCTABOLT is twisted into it, it is not a hard job. Once you find it, you can glue the OCTANUT to the frame like this.
- Embed OpenBCI into the Ultracortex. Connect your ~500 mAh lithium ion rechargeable battery to the back of your 32bit OpenBCI Board. Then fold the battery and its wires neatly behind the board before inserting the board into the BOARD_MOUNT. You can then use one of your #4 Drive Screws to secure the OpenBCI Board to the BOARD_MOUNT.
- Identify electrode locations. Before creating your electrode mounts, it’s a good idea to think about where you may want to place the electrodes on the Ultracortex FRAME. The placement of the electrode may affect how long you make the wire between the electrode and where the OpenBCI is mounted, at the back of the frame. The Ultracortex node locations are based on the 10-20 system, which is the internationally accepted standard for electrode placement in the context of EEG.The image below indicates the default 10-20 electrode locations that the OpenBCI Graphical User Interface expects (dark gray). This application is perfect for viewing/recording your EEG and can be found in our OpenBCI_Processing repo. The dark blue nodes indicate the 8 10-20 locations (channels 1-8) of the 32bit Board. The soft blue nodes indicate the 10-20 positions of channels 9-16 when using the OpenBCI 16-channel R&D Kit.For the remainder of this tutorial, the blue nodes on the 10-20 system diagram (channels 1-8 of the OpenBCI default settings) will be used. The channel to 10-20 system correlations are as follows:
- Connect wiring to OpenBCI. Before shortening any of your wires, connect the female header of each wire to the N pin of channels 1-8, as indicated in the GitHub image. The N pins are the ones closer to the OpenBCI Board. By default, the OpenBCI Board references these eight pins with the SRB 1 pin (the SRB bottom pin).
- Measure, cut, and strip wires. For each wire, measure the distance between where it is connected to the OpenBCI Board and the node that it will terminate at on the Ultracortex frame. Give yourself 2-3 inches of slack (extra length), because you’re going to strip the end of the wire, and you may want the extra slack to zip-tie/tape the wiring to the frame later on.
- Assemble electrode mounts (x8 or x16). Repeat the steps shown in the figure above as many times as necessary, depending on your OpenBCI setup. In general, using more electrodes will distribute the downward scalp pressure, increasing comfort. Additionally, to improve comfort, you can create electrode units without electrodes and the wires to place at various nodes around the frame. This will also help to distribute pressure. Despite the instructions well explained in OpenBCI Learning Headwear page I’ve improved the way nodes can be assembled and adjusted to the scalp without twisting the cables. I reused jumpers from other cables to attached to the electrode. So, the cable from the electrode to the OpenBCI 32 bit board has completely angles of freedom.
- Insert electrode units into your Ultracortex. Once you’ve assembled all of your electrode units, twist them into their respective Ultracortex frame nodes. If the parts are tough to twist into place by hand, use the OCTATOOL that comes with your kit as shown in the picture below. Over time, the resistance between the OCTANUT and OCTABOLT will diminish, and the pieces will twist into place more easily.
- Reconnect wires to OpenBCI & connect ear clip electrodes (Reference & Ground). Now that all of your electrode units are connected to your Ultracortex frame reconnect the electrode wires to the OpenBCI board as detailed above. If you have some handy, you may want to use zip ties to secure the loose wiring to the Ultracortex frame.Next, connect two touch-proof adapter cables to SRB1 and bottom BIAS pin (white and black respectively in the image below). You can use the touch-proof adapter that comes with the OpenBCI 32bit Board or OpenBCI 16-channel R&D Kit. Then connect your ear clip electrodes to these touch-proof adapters. These ear-clip electrodes serve as the reference and bias (ground with common-mode noise rejection) for your EEG system.
- Fasten the BOARD_COVER. Now clip your board cover into place. If you’ve soldered any of the header rows onto your OpenBCI board, you’ll need to use the BOARD_COVER_ADVANCED, as seen in the picture below. Otherwise, you can use the BOARD_COVER_STANDARD with the OpenBCI logo.
- Adjust the Ultracortex for your head. Put the Ultracortex Mark 3 onto your head and gradually tighten the electrode units until the electrodes are snugly (but comfortably) against your scalp. If it ‘s hard to twist the OCTABOLT pieces by hand, you may need to use the OCTATOOL as seen in the gif below.Be careful not to strain the electrode wires when twisting the electrode unit with the OCTATOOL, or you may separate the wire from the electrode itself. Turn the OCTABOLT until the wire is nearly taught, then reposition the wire and tool and twist again, as demonstrated in the gif.
Ultracortex Mark III “Supernova”
If you have the “Supernova” you must follow the same instructions as the “Nova” before applying the following instructions:
- Stretch QUADSTAR over OCTARING.
- Zip Tie QUADSTAR onto frame. Using zip ties, tie down the corners of the QUADSTAR onto the frame of your ULTRACORTEX. You should be using four zip ties per QUADSTAR. For QUADSTARS that are next to each other, re-use the same zip tie to tie them both down to the frame.
NOTE: Tie the QUADSTARS down loosely at first in order to ensure that they are all centered while tied down to the frame. Once all of the QUADSTARS are tied loosely to the frame, tighten them to secure them to the frame.
- Cut Zip Ties. Turn the ULTRACORTEX over and snip off all of the loose ends of the zip ties.
- Insert Comfort Nodes. Next, screw a comfort node into each of the 8 QUADSTARS.
Supernova Assembly Complete!
Try the Ultracortex!
Place your UltraCortex on your head so that the back center node is roughly the same distance above your inion (bump on the back of your skull) as the front center node is above the bridge of your nose. As you place the UltraCortex on your head, the springs should adjust to the shape and size of your head.
Now that you have your Ultracortex assembled and comfortably adjusted to your head size and shape, it’s brain wave time!
First thing you shoul try is to see if I you are able to produce Alpha waves while your eyes are closed. Since you will not see the screen, you can eihter type “Ctrl + M” or press “Print Screen” to take a screenshot and have a look afterwards to the image.
For more information, please go to OpenBCI website.