As a researcher in the field of EEG, you might have already come across an Electrode Input Box (EIB). In the past, the main function of the EIB was to enable the use of touch-proof (1.5 mm DIN) electrodes with either BrainAmp or actiCHamp Plus systems. If your lab already has both actiCHamp Plus and BrainAmp equipment, you might find the new EIB64-DUO from EASYCAP particularly interesting for your passive electrode setup.
Let’s start with the basics. Just like its predecessor, the EIB64-DUO offers 64 inputs for single touch-proof electrodes and outputs for the BrainAmp amplifiers. In addition, it also has connectors for the actiCHamp Plus amplifier, hence the name, “DUO”. Consequently, the same box can be used as single touch-proof electrode input for either BrainAmp or actiCHamp Plus.
Left: EIB64-DUO; right: Touch-proof electrodes connected to actiCHamp Plus using EIB64-DUO
Needless to say, connecting 64 individual electrodes is tiresome. Therefore, the input box can serve as a Quick-Connect-Interface. Just leave the touch-proof electrodes in place and disconnect the amplifier cables between measurements.
All corresponding connectors of each channel are internally linked. This means that a lab, which has a wide variety of equipment, can use the EIB64-DUO creatively to mix and match caps and amplifiers. Let us show you a couple of examples.
Using BrainCaps with actiCHamp Plus
Thanks to the dual connectors, a traditional BrainCap or even an R-Net for BrainAmp can be interfaced to an actiCHamp Plus. Since these caps have a dedicated reference electrode, typically at the FCz position, while the actiCHamp Plus is a reference-free amplifier, one may wonder what happens with the signal coming from FCz?
The EIB64-DUO offers two choices here:
If the position of the reference electrode is not important, there is not much to do. The signal will be skipped and not forwarded to the actiCHamp Plus, similar to a 40-50pin adapter. This approach shall provide the highest data quality.
If the position of the reference electrode is needed for the experiment, one may decide to skip one signal position instead. Let’s assume for example, that we want to skip FT10 and use FCz as a reference electrode.
- Use a shortening cable to connect the touch-proof input of the reference to the single-channel input of the physical channel number of FT10.
- Make sure to update the BrainVision Recorder workspace: rename FT10 to FCz.
- Skip FT10 during cap preparation.
(simply do not fill it with gel if using the BrainCap or remove the sponge if using the R-Net)
- Validate the data quality. Technically, the empty electrode will act as an antenna to environmental noise and will contribute to the signal recorded at FCz channel. This contribution can be negligible, but this should still be verified first.
BrainCap connected to actiCHamp Plus via the EIB64-DUO.
Using actiCHamp caps with BrainAmp amplifiers
The opposite setup is also possible: A cap made for actiCHamp/actiCHamp Plus, can be interfaced to any BrainAmp amplifier using the EIB64-DUO. These caps do not have a dedicated reference electrode, but a reference is needed for the BrainAmp. Don’t worry! The EIB64-DUO can help here.
- Use a shortening cable to route the signal electrode of your choice to the reference connector.
The BrainAmp will use this electrode as a reference.
- Remember to modify the BrainVision Recorder workspace by deleting the signal electrode from the list.
Alternatively, one additional single electrode with a touch-proof connector – for example, a Multitrode – can be added to the setup. Certainly, this new electrode shall work as a reference and should be connected accordingly.
Using caps and touch-proof electrodes for concurrent EEG and peripheral physiology
It is worth also mentioning, that the two above approaches can be used simultaneously. A 32 channel passive cap and individual electrodes for EOG, EMG or ECG measurement can be connected to a 64 channel actiCHamp Plus.