Monday, July 8, 2013

Brain Computer Interfaces

Brain Computer Interfaces (BCIs) are trending communication technologies which are used to enhance Human Computer Interactions of people with severe motor disabilities. Brain–computer interfaces (BCIs) are applications that can translate brain activity into signals that control external devices [1]. A BCI has the ability to detect wave patterns caused in the brain because of neuron activities and to devise the intent of the user. These intents are then can be converted in to real world actions using number of output devices.

BCI devices work based on Neuro-signals: "‘neuro-signal’ refers to a signal related to the brain. A common approach to obtaining neuro-signal patterns is Electroencephalography (EEG). It measures and records neuro-signals using electrodes placed on the scalp [5]. Generally with help of a conductive gel. However, now it is possible to measure EEG without using a gel and by just placing electrodes on the scalp (dry electrodes). This method is obviously more convenient for the user as there is no hassle of wearing a sticky gel for a long time!

There are two (2) types of EEG montages in use: monopolar and bipolar. A monopolar montage is designed to collect signals at an active site of the brain and compares with a common reference electrode. However, it is difficult to find an ideal reference site with the monopolar setup while it can produce more accurate results because of the common reference. In addition, EMG and ECG artifacts which are caused of other organs which emanate similar signals may occur in the monopolar montage. Bipolar montage can compare signals from two active scalp sites. Here the difference of activity between sites are calculated after subtracting the common activity where some information can be lost because of this subtraction.

NeuroSky Inc. which is Silicon Valley based company has been able to produce few dry electrode based consumer BCIs. They have devised non-invasive (no need to pin the electrodes to scalp) and dry (without any liquid) EEG readers which can be used by a typical user [3]. Sensors made by NeuroSky use a monopolar montage where the active site is on the forehead and the reference site is the earlobe [4]. These devices are integrated with software to control diverse appliances in the real world. ThinkGear, MindWave, MindSet, and Necomimi are the most popular BCI tools by NeuroSky. While MindWave, MindSet and Necomimi are wearable devices ThinkGear AM is a chipset which acts as the backbone of all the tools. My next post will dive into the technical details and applicability of these tools!

Left to right: MindWave, MindSet and Necomimi by NeuroSky Inc. (Source:
[1] Cincotti, F., Mattia, D., Aloise, F., Bufalari, S., Schalk, G., Oriolo, G., Cherubini, A., et al. (2008). Non-invasive brain--computer interface system: Towards its application as assistive technology. Brain Research Bulletin, 75(6), 796–803.
[2] NeuroSky Inc. (2009). Brain wave signal (EEG) of NeuroSky, Inc. NeuroSky Inc. Retrieved from
[3] Crowley, K., Sliney, A., Pitt, I., & Murphy, D. (2010). Evaluating a Brain-Computer Interface to Categorise Human Emotional Response. 10th IEEE International Conference on Advanced Learning Technologies, 276–278. doi:10.1109/ICALT.2010.81
[4] NeuroSky Inc. (2012). Brainwave Technology. Retrieved July 9, 2013, from

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