Technology

MAKE subscriber Rob Miles of Tacoma, WA, made a cootie detector for his kids out of an ATtiny45 with a paper clip for the biometric sensor.

Kids love games of exclusion. “You’re a zombie!”, “You’ve got cooties!”, “You can’t come in my room because….”. I must hear this 500 times a week around the house. Well, after some exhausting research we have discovered that zombification and cooties have a similar galvanometric effect on the victim’s skin. Sooo….

This device will provide the following feedback depending on your skin’s resistance:
“CLEAR” = Green light after test sequence.
“INFECTED” = Red flashing light and then solid red after test sequence.
“DEVICE TAMPERED” = Alternating red and green lights (as seen when I shorted it with the screwdriver).

6 thoughts on “Pocket Biometric Cootie Detector

  1. I used an Arduino on the circuit for a bit to send the output of the voltage divider (analog input) to my serial port. Your results will certainly vary but mine were:
    Scale of 1 to 1000.
    Right around the middle of the range is where it would detect the presence of a finger. So >500 it just runs waiting on an input. At <500 it starts an analog reading.
    At about 150 to 200 is where I would start noticing differences between people's fingers and differences in my own finger depending on activity, etc.
    At about 20 I call it a short and show a fault.

  2. I used an Arduino on the circuit for a bit to send the output of the voltage divider (analog input) to my serial port. Your results will certainly vary but mine were:
    Scale of 1 to 1000.
    Right around the middle of the range is where it would detect the presence of a finger. So >500 it just runs waiting on an input. At <500 it starts an analog reading.
    At about 150 to 200 is where I would start noticing differences between people's fingers and differences in my own finger depending on activity, etc.
    At about 20 I call it a short and show a fault.

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My interests include writing, electronics, RPGs, scifi, hackers & hackerspaces, 3D printing, building sets & toys. @johnbaichtal nerdage.net

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