by Pierluigi Castellone
Sales Department Manager (Brain Products)
Brain Products presents the actiCAP Xpress, a dry electrode system with an innovative and unique design. Round shaped sensors, available in 4 different lengths, ensure high comfort and can be connected to the EEG cap even when the subject is already wearing it. A versatile solution for virtually any BCI application, provided in a bundle including a V-Amp 16 EEG recording system and the software OpenViBE™ for Brain Products at a price that fears no competition!
It is no secret that we have been working for some time on the development of a dry electrode system. We started with this project more than 5 years ago and have presented several prototypes at conferences and public events. The very first design of our dry electrode system was not much different from the multipin sensor approach that other manufacturers have been using. Nevertheless, and in spite of the enthusiastic feedback that we always received from those who tested our solution, we never felt fully satisfied with it.
We wanted something different. We were looking for something more flexible, comfortable and user friendly. In other words, we wanted something better for you, and we are confident we have found it now with our actiCAP Xpress!
Before I start talking about the features of our system, I would like to go one step back and recall why, for almost 100 years, the EEG signal has been recorded by using gel based electrodes.
The quality and amount of information you can record with the EEG is highly dependent on the contact impedance between the electrode and the skin. The higher the contact impedance, the lower is the signal quality and the narrower the frequency band over which it is possible to measure meaningful EEG data.
The conductive gel plays a crucial role in lowering the impedance because it:
(1) fills in the gap between the electrode and the skin
(2) improves the charge transfer from the scalp to the electrode
(3) helps to clean the skin of oils that typically increase the impedance value
(4) removes dead skin, thus offering a more direct contact with the underlying living skin tissues
In the light of the above, we would not expect a system that uses no conductive gel to produce the same data quality as a gel-based EEG system. A dry electrode system cannot represent the alternative to gel based electrode caps, except for some very specific applications in a limited frequency range. typically between 1 and 40 Hz!
You may be wondering why I am talking about such very basic concepts, but I think it is worth mentioning them, especially when presenting a dry electrode system. It would not be fair to talk only about how quick and cool it is to measure EEG signals without needing to apply gel, while “forgetting” to say what is really doable with such a system.
Anyway, now that we know the main issues faced with a dry electrode system, I can introduce to you the features that make our solution a “must-have”! First of all, you will have noticed that we didn’t choose a name that refers simply to a dry electrode system. This is because the actiCAP Xpress has not only been designed to work without gel. It was also conceived to speed up the preparation of the cap, resolving the problems that the majority of the existing products still confront you with.
A new design offering both comfort for your subjects and durability!
One of the main drawbacks of the multipin design, a widely used approach for the dry electrodes, is that they can be quite painful after a while. Some manufacturers solved this problem by designing electrodes made of a soft material. We designed a sensor that is comfortable and very robust at the same time.
Two kinds of dry electrode sensors can be connected to the 16 signal active electrodes, one reference electrode and one ground active electrode which are part of the actiCAP Xpress set. QuickBits T are T-shaped flat sensors to be used for frontopolar and hairless positions (e.g. to connect the reference and ground to the ear lobes). QuickBits are mushroom-headed sensors that are much more comfortable for the subject. The shape of these bits also ensures a stable contact with the scalp even if they are not completely perpendicular to the surface.
Both sensors are made of a robust gold plated material which makes it possible to reuse them for hundreds of measurements!
1..2..3…and the cap is already mounted!
The actiCAP Xpress set includes QuickBits with 4 different lengths. The lengths which should be used for your measurements depend on the growth of the hair and the head shape of the subject.
If a sensor of a different length is needed, with the actiCAP Xpress you will be able to change the QuickBits even if the subject is already wearing the cap. This is a unique feature of our solution that will considerably reduce the preparation time for your experiments.
Things are made even faster thanks to the very elastic electrode cap with large holes through which the electrodes are easily accessible. Moreover, since the QuickBits of different lengths are distinguishable by a colored ribbon, you can note down in the accompanying Configuration Sheet which length you have used for each electrode position for that particular subject. This will speed up the preparation step significantly if the subject returns to your lab for repeat experiments!
A versatile system for various applications at an unbeatable price
The 78 small holes available on the cap and the additional electrode holders provided with the set allow a very flexible channel layout, which can basically cover every position of the 10/20 system. With the actiCAP Xpress you can prepare your cap in advance and place the holders in the areas of interest for your various BCI applications. If needed, you will be able to move the electrodes from one position to another very quickly!
- The V-Amp is a very versatile amplifier, which can be used with passive, active and dry electrodes. It also supports the measurement of bipolar and auxiliary signals, thanks to its two AUX inputs.
- OpenViBE is a complete program for Brain-Computer Interface and neuroscience research developed initially by the INRIA research Institute in France. The OpenViBE™ for Brain Products includes specific developments for use with Brain Products GmbH EEG devices and provides three ready to use specific BCI applications: a P300 speller, a Motor Imagery experiment and an SSVEP task.
The actiCAP Xpress bundle, including the items mentioned above, will be available starting from € 6,500*. A really low price for the quality products that we are offering! actiCAP Xpress, a product leader for a successful research!
If you have questions about the actiCAP Xpress set and the actiCAP Xpress bundle, please don’t hesitate to write to firstname.lastname@example.org. We will be very happy to assist you!
* Market introduction price; valid only until 19.05.2015. Not including taxes and shipping costs.
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©Brain Products GmbH 2014