Kids love games of exclusion. This usually manifests itself in games of ‘keep away,’ having someone ‘catch cooties,’ or the ever-popular ‘No Brian club.’ [Rob] wrote in to tell us about the digital cootie detector he built. The cootie detector operates on galvanic skin response. It’s actually very similar to an E-Meter, although instead of Thetans this device measures something that actually exists.
Galvanic skin response is a measure of the skin’s conductivity. Skin conductivity changes because sweat glands will be activated when someone is nervous. This is a measure of psychological arousal, making it a great detector for games of exclusion – a kid who doesn’t want cooties will ‘psych themself out’ and give themselves cooties.
The build is based around an ATtiny45 with just a few resistors and paperclips required for a complete build. The ‘Cootie Detection Algorithm’ starts off with a flashing light – a great way to make someone nervous. After the test is completed, a green light means they can enter the quarantined area, while a red light means they must be excluded. There’s also a “device tampered” result – alternating red and green lights – that will show up when a clever child tries to short the paperclip leads. Check out the demo below: