'RFind' Battery-Free, Wireless Stickers Help Locate Objects

Researchers from MIT Media Lab  introduce "RFind," a technology that transforms low-cost, wireless stickers into powerful radars. Placing one of these battery-free stickers on an object allows it to be located with extreme accuracy. The technology operates by measuring the time it takes the signal to travel from the wireless sticker to an access point. By taking into account the speed of propagation of light, the MIT researchers can then map the time to an exact location (with sub-centimeter precision) in 3D space. Their key innovation is a new technique called two-frequency excitation. The technique uses one frequency to power up the battery-free sticker and uses the other frequency for pinpointing the exact location.