Skin Conductance Sensor (SCS), also known as Galvanic Skin Response (GSR), is a method of measuring the electrical conductance of the skin, which varies with its moisture level. This is of interest because the sweat glands are controlled by the sympathetic and parasympathetic nervous systems, so skin conductance is used as an indication of psychological or physiological arousal.
This device measures the electrical conductance (which is the inverse of the electrical resistance) between 2 points, and is essentially a type ofohmmeter. The two paths for current are along the surface of the skin and through the body. Active measuring involves sending a small amount of current through the body. Due to the response of the skin and muscle tissue to external and internal stimuli, the conductance can vary by several microsiemens.

When correctly calibrated, the (SCS) can measure these subtle differences. There is a relationship between sympathetic activity and emotional arousal, although one cannot identify which specific emotion is being elicited. The SCS is highly sensitive to emotions in some people. Fear, anger, startle response, orienting response and sexual feelings are all among the reactions which may produce similar skin conductance responses. SCS is used in scientific research of emotional or physiological arousal – how activated, conscient or attent the person is. High levels of arousal tend to accompany significant and attention-getting events. Arousal could depends on the skill level and the challenge level a person is exposed [1][2].

This sensor represents different values of voltage and conductance. This is a method of measuring the electrical resistance of the skin. There has been a long history of electro dermal activity research. Here is a relationship between sympathetic activity and emotional arousal, although one cannot identify the specific emotion being elicited.
Mental states Mental state in terms of challenge level and skill level, according to Csikszentmihalyi [2].
Hardware

This details about the construction of the device are described in this file.
Software

In order to use this hardware and get the information from it, our team developed a console application for Windows written in Java.

It is important to mention that this same application works for four different hardware: Skin Conductance Sensor, Posture Chair Sensor, Pressure Mouse Sensor and Pressure Guitar Sensor.
Installation
  1. Download the application.
  2. Unzip the file, and copy all the files into a new folder called "sensors".
  3. And you are done!
Using the system
  1. Before using the application, you need to physically connect all sensors to the computer, and find out in which port (COMM) it is connected.
  2. Open a Command window.
  3. Change to the "sensors" folder.
  4. Type CommonSensorsJ2E <output_file_name>. Where output_file_name is the name of the file where all data will be stored. This file will be stored on the "sensors" folder.
  5. The application prompt you to specify in which port is connected each sensor. In this case we need to find the port where the SCS is connected. When it shows up in the screen type "skin", if there is listed a port where none sensor is connected just type "none".
  6. To stop recording data just press Ctrl + C.
  7. The output file will be in the same folder as the application is.
Description of the output file

The output file could be opened as CSV file, so it can be readed as plain text file or using some spreadsheet application such as Excel. If you run the programm just with the SCS your file will have the following fields:

Field Description Values
Timestamp It is the timestamp (date and time) of the computer running the system. It could be used to synchronize the data with other inputs. The value is a combination of the date and time on the computer, with the following format "yymmddhhmmssSSS" (y - year, m - month, d - day, h - hour, m - minutes, s - seconds, S - milliseconds).
Battery voltage This value shows the level of the battery voltage. This value is between 0 to 3 volts.
Conductance This value shows the level of the arousal. This value is between 0 to 3 volts.
Details about time rates
The information generated for these sensors is about one value every 500 millisec, in otther words 2 values per second.
References
[2] Csikszentmihalyi, M., Finding Flow, 1997.