Much has been said in recent months about fMRI (functional magnetic resonance imaging) as a potential tool for lie detection. See, e.g., here and here. This article emphasizes some other techniques, including thermal facial imaging (reporting 84% accuracy in laboratory simulations) :
What makes this method ideal for detecting deception is that unlike a pulse or respiration rate, subjects can't manipulate their response, Levine says. "You can double your respiration rate or make it zero by holding your breath. But no one I know of knows how to change the heating of minute areas of the face by choice."
It also discusses a technique which focuses on irregular eye movements:
Cohen found that people move their eyes over fewer areas when viewing familiar scenes, and gravitate to any areas of previously viewed scenes that have been modified. The following year, he showed that the same was true even in people with amnesia. The studies were published in the Journal of Experimental Psychology and Psychological Science. "We think these responses are automatic and obligatory," he says. "And it happens very early. We think it might, in fact, happen before you're even aware of it."
This means even practised liars will find it tough to beat the eye-tracker. It is easy to see when people don't follow the instructions, Cohen warns. "If you're not looking at the image or you're blinking, we'll know. If you stay fixated on one point and don't move your eyes, we'll know. Or, if you look too little at a particular region, we will know, because that's exactly what we're measuring."