Res, a matter.

The XS is a free and open project started by individuals and kept evolving by a worldwide community. You can build your own Xth Sense biophysical sensors from scratch.
Building the wearable sensor is very easy (you need to solder literally 4 components) so it requires only a basic knowledge of soldering.
The schematic, the parts list, and a tutorial are available below. Building an XS sensor by hand takes between 1 or 4 hours, depending on your skill and your tools. Try to work with the right tools; it is usually very easy to find them in an electronics shop in your town.

Xth Sense, biophysical, wearable sensor.
Copyright (C) 2011 Marco Donnarumma

The Xth Sense Wearable Sensor (“The work”) is provided under the terms of this Creative (“CCPL” OR “LICENSE”). The work is protected by copyright and/or other applicable law. Any use of the work other than as authorized under this license or copyright law is prohibited.

You are free (and encouraged) to use, modify, extend the Xth Sense Wearable Sensor; however, if you wish to distribute the result of your modification, or any other hardware that depends on the Xth Sense Wearable Sensor you have to distribute it under the same license, and to include the mention of the original copyright. See the Creative Commons Public License for more details.