Electrodermal Activity

A project log for Aman :The low cost wireless stress monitoring sock

Quantify stress comfortably by measuring Electrodermal Activity(EDA) and Heart Rate along with contextual info like Humidity,Temp & Motion

Naveen SridharanNaveen Sridharan 09/28/2016 at 06:340 Comments

The core of the project revolved around development of an accurate and effective Electrodermal Acitivity sensor. EDA modulates the amount of sweat secretion from sweat glands. While sweat secretion is related to thermoregulation and sensory discrimination, changes in skin conductance in hand,foot regions are also triggered quite well by emotional stimulation. However both positive response (Joy) and (fear, sorrow) often illicit the same response. To this end after reading various research journals, I decided to use a conductive fabric based electrodermal sensor. The location I chose to measure was the arch of the foot to enable accurate sensing of dermal response and the lack of motion in that area made it ideal.

Using a bit of fabric glue to stick it to the inside lining of the sock I used conductive thread to stitch connection from the electrode to a snap.

The snaps enable the rest of the electronics to be disconnected.

The principle of electrodermal activity is relatively straightforward, Skin conductance is measured accurately. A low pass filter with a 0.1uF ceramic capacitor is used to give a clean signal.

I'm looking into a wheatstone bridge based sensor interface, Adding some active filtering is up on my list too.
I've gathered some data over serial for about 10 minutes and plotted it on excel