It’s easy enough to put an always-on camera somewhere it can live off solar power or the grid, but deep in nature, underground, or in other unusual circumstances every drop of power is precious. Luckily, a new type of sensor developed for DARPA[1] uses none at all until the thing it’s built to detect happens to show up. That means it can sit for years without so much as a battery top-up.
The idea is that you could put a few of these things in, say, the miles of tunnels underneath a decommissioned nuclear power plant or a mining complex, but not have to wire them all for electricity. But as soon as something appears, it’s seen and transmitted immediately. The power requirements would have to be almost nil, of course, which is why DARPA called the program Near Zero Power RF and Sensor Operation[2].
A difficult proposition, but engineers at Northeastern University were up to the task. They call their work a “plasmonically-enhanced micromechanical photoswitch,” which pretty much sums it up. I could end the article right here. But for those of you who slept in class the day we covered that topic, I guess I can explain.The sensor is built to detect infrared light waves, invisible to our eyes but still abundant from heat sources like people, cars, fires, and so on. But as long as none are present, it is completely powered off.
But when a ray does appear, it strikes a surface is covered in tiny patches that magnify its effect. Plasmons are a sort of special behavior of conducting material, which in this case respond to the IR waves by heating up.
Here you can see the actual...