Galvanic Skin Response sensor

I promised Heidi some info about making a Galvanic Skin Response sensor, like the one I used to measure skin conductivity in the Greetometer Glove to test the sweatiness of the wearer’s hands.

I used the instructions and code on this blog post:
http://cwwang.com/2008/04/13/gsr-reader/
If you don’t want to use processing, you can just do a simple Serial.println() in the Arduino serial monitor.

And I made my own electrodes out of coins, like in the example:

In the final project I soldered crimping beads onto the coins.  They need to be polished now and then.

The cool thing about skin conductivity is that it indicates more than just humidity on the skin.  If you try the example in the link above and breathe in sharply (as if surprised) while testing, you’ll see a change in the readings.  Combined with other measurements (movements, heart-rate, etc) you can start to detect stress levels.

blinking LED without delay()

Andy’s step sequencer was coming along nicely until he added a delay to blink his LED to visualise the tempo.  The delay would slow down the whole main loop, meaning that all other readings (like push buttons) had to wait for the end of the delay before they were activated.

Here’s Andy’s lovely breadboard:

It just can’t be possible that Arduino has such a fundamental flaw, can it?  Well, kinda, but it turns out the problem can be solved.  In fact, the solution was right under our noses…

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