There are plenty of those gimmicky vocal stress level lie detectors out there, but as Robert De Niro made perfectly clear in Meet the Parents, nothing rattles the subject and amuses the proctor more than actually hooking someone up to the ol' poly. Unfortunately for amateur interrogators, CIA-quality lie detection equipment is expensive and hard-to-find, so LEGO-enthusiast Michael Gasperi's Mindstorms-based "Galvanic Skin Response Sensor" may be just the DIY option you need to liven up your next party. Basically a set of foil-lined velcro strips attached by 9V wire to an RCX control brick, Gasperi's lie detector works on the principal that people sweat more when they're fibbing, so his device measures the skin's electrical resistance of whomever's getting grilled. One word of caution if you decide to build one of these on your own: unless you want to end up under the hot lights of a real interrogation room, make sure to, like, keep your subject alive by powering your detector from batteries and not deadly AC.

[Via Make]

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