Developed in 2013, by the Science and Technology department of the Directorate Department (S&T) and the Jet Propulsion Laboratory (JPL) of NASA, the device uses microwave-radar technology to track signs of human heartbeat. According to NASA, it is possible to track people buried under 30ft of rubble, 20ft of solid concrete, from a distance of 100ft in open spaces, significantly enhancing rescue teams' work. The device's latest feature sends a confirmation sign to rescue crews each time a heartbeat is received, and depending on the type of the rubble provides the approximate location of the victim within a 5 feet radius. The involved radar technology allows rescuers to tell the difference between the human heartbeat and that of other living creatures, and also determine whether the victim is conscious or not, planning their rescue approach accordingly.
Two FINDER devices were used in search-and-rescue missions after the disastrous Nepal quake, leading to the successful rescue of four men buried under 10ft of rubble in the village of Chautara. This was the first application of the device under real conditions, and according to Dr. D. Miller, NASA's chief technologist at NASA Headquarters in Washington, "FINDER solidifies NASA's role in exploration and improving-even saving- the live of people on earth". FINDER's transition to the commercial level has also been announced by NASA, setting the ground for the widespread use of the device in similar rescue missions worldwide.
The picture below, presents a simple diagram on how the radar works!