Developed for the Defense Advanced Research Projects Agency (DARPA), these novel sensors are simultaneously dormant and always awake, becoming alert only when in the presence of a so-called signal of interest. DARPA believes this could enhance situational awareness for war-fighters.
Adding to the Internet of Things (IoT), the novel sensors are capable of sleeping for years in between active periods. They are still able to detect events despite "using virtually zero standby power" and not needing a battery top-up thanks to DARPA's Near Zero Power RF and Sensor Operation. Northwestern engineers worked on the sensors and referred to them as "a plasmonically-enhanced micromechanical photoswitch." The technology behind the tiny sensors was published recently in a Nature Nanotechnology paper.