Because conventional lie detector test (the polygraph) is not really a hundred percent reliable, alternative lie detectors have been developed over time. EEGs and fMRIs can measure brain activity and seem to have good potential. However, EEGs provide low resolution images and fMRIs are extremely expensive. Scott Bunce from the Drexel University's College of Medicine in Philadelphia turned to infrared rays and thought it a better alternative to the polygraph test.

Bunce's model is to emit near-infrared light through the skull into the brain using a special headband designed just for the purpose. The aim is to measure brain activity by monitoring how much light is reflected back. According to NewScientist, the light than bounces back depends upon the blood oxygen levels, which are indicative of brain activity. Unfortunately, it's not even known yet whether brain activity could be a measure of deception, so this gadget might not even be of use at all, if ever.

Check out the infrared lie detector headband patent application