The Cyton will definitely give you the flexibility to collect EEG, EKG and EMG all at once, and it supports the active electrodes. The Ganglion will also be able to support variations of your EEG pro

On which I recommended the EmotiBit as a possible aid that will collect SPO2, heart rate, HRV, GSR/EDA, etc.

You are right about multi-modal approach, We did a prototype with GSR and some research to integrate the PPG or HRV signals in our solution as well which seems to be crucial.

https://de.wikipedia.org/wiki/Elektrochemische_Spannungsreihe

I don't have experience with specific GSR devices, but there are some on the market that connect for example with usb. Other search results will show you ways to achieve GSR with simple Arduino setups

I have considered both HRV and GSR before. I thought that maybe EEG would be much more accurate and more efficient. I have practically no idea about EEG. During this week i am doing research on it and

I would agree with Billh, there are probably easier was to gauge stress level with GSR (skin conductance) and heart measures (pulse rate or HRV).

 I would like to know if it is possible to measurate both the EEG and GSR (Galvanic Skin Condutance) in the same ganglion, because I want to measurate the stress level of someone and to train a neural

I was able to receive data from a GSR sensor on A5 (D11) using OpenBCI_GUI 3.3.0 and the BLE dongle. One thing I noticed is that Turn Analog Read On disables the Accelerometer, and vice versa. I think

Another way to go about it is to use the analog input pins of the PIC32, and build a simple voltage divider to measure GSR.

The Empatica device, impressive! Wonder how well the wrist works versus the fingers. Yes one of the Empatica founders (Rosalind Picard) is author on the GSR paper.

GSR measurements on the forehead will probably interfere with eeg

GSR is best measured on skin areas that have more sweat gland activity. Such as finger tips, palms, etc. Ears 'might' work, but less typical and could be less effective.

Can GSR be measured using the ear clips or something?

@wjcroft look! http://wiki.seeed.cc/Grove-GSR_Sensor/

Awesome info William, thanks so much. I would love to throw down on an open source GSR circuit. I'm surprised adafruit or sparkfun doesnt have a I2C/SPI module already for this!

This EDN article shows the circuit and algorithms used by the Maxim dev kit GSR developer eval module. It is using AC drive.

Lots of HOW TO pages on simple Arduino GSR using DC,

pins. A side benefit is the ability to measure GSR. If this has not yet been done it's because nobody has paid any attention to it.

And... if the GSR measurement is just short term and precision or polarization artifacts are not a concern, then there a many other circuits shown online for measuring GSR with Arduino style microcont