I found a pretty cool arduino project that measures skin conductance and can be used as a makeshift lie detector.
Overview:
A polygraph contains among other devices a galvanic skin response device. A GSR device measures the conductance of your skin. When you are nervous, stressed or in pain you will perspire a bit and the GSR device will note the increased conductivity. This is the device we will create for this simple project.
Materials list:
-arduino
-aluminum foil
-velcro
-wire
-10k resistor
-breadboard
Step the first: Make the electrodes
What I did was take two wires and strip one end of each so some of the wiring was bare. I then took two 6x6 inch squares of tin foil and folded them up into two 1x6 in strips and placed the bare wire in the center of each strip. I placed a small piece of sticky backed velcro over the bare wires and placed a strip of velcro on the opposite side on the end. I also snipped off the side without velcro resulting in a 3 or four inch strip you can wrap around your fingers.
Your nodes should look something like this:
The step after the first step: wiring diagram
So the grey represent the electrodes and are made into an analog input. The resistor has a value of 10k ohms.
The last step: load the code
Use the example code "graph" that comes with the Arduino software. This program will that the values from the electrodes and sends them to be graphed over time. To actually view the graphing you need a program called "processing"
link. Read the comments in the code for the graph program for more instructions on using the processing application for graphing.
How to use
Once you have all this set up simply put the nodes onto your finders, interrogate and watch the graph. If the graph spikes there is a chance the subject is lying as the graph represents your skins conductivity.
Afterthoughts:
I would very much like to make an arduino heart rate monitor to go with the GSR device so if anyone has information on how to make that possible please post it.
