Okay, this is pretty cool. Effectively lowering the EM noise floor in their vicinity by rectifying the energy is a neat trick. The catch has always been that the level of energy was such that the conversion circuitry for ambient noise was unable to process enough to both power itself and provide a bit extra (efficiency losses effectively prevented any net energy conversion). That they managed to do that is what I find so impressive.<p>The second thing is the low frequency stuff. Its taught in most EE programs that you can use an antenna that is tuned to a frequency to transfer energy wirelessly from xmitter to receiver (see NFC or RFID) but antennas that tune sub-MHz frequencies are typically quite long in order to have some level efficiency. That they do this by exploiting geometry of various conducive elements <i>and</i> get enough energy is super impressive too.<p>If you followed the old BEAM stuff[1] that Mark Tilden promoted, you could see some ideas about two-phase devices that live in a "collect" phase charging up an energy reservoir and then an "execute" phase where they dump that energy doing their thing. BEAM was focused on robotics and bug like behaviors but there is no reason you couldn't have a sensor that measures temperature and humidity and transmits that to a receiver somewhere. Or a passive "game" camera that, once it has collected enough energy, takes a snapshot when it detects motion and sends that along.<p>I'll be interested to see this stuff get commercialized and designed in. It does have shades of "Smart Dust"[2] though which is pretty ripe for abuse.<p>[1] <a href="https://en.wikipedia.org/wiki/BEAM_robotics" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/BEAM_robotics</a><p>[2] <a href="https://www.nanowerk.com/smartdust.php" rel="nofollow noreferrer">https://www.nanowerk.com/smartdust.php</a>