Working with Frank Chang at Caltech UCLA, the JPL boffin Adrian Tang is keen on ways to let devices with relatively low communications needs do without recharging.
As NASA explains here, their idea is to let a chip either reflect a signal back to a base station or access point (representing a binary 1), or absorb it (representing a binary 0). That way, the Wi-Fi device (be it a smart-watch or a a bio-sensor, for example), only needs enough energy for its own operations, instead of having to carry power for a full transceiver.
Not only that, but the device is fast. The NASA release says that at a short 2.5 metre distance, it can communicate at up to 330 Mbps, "using about a thousand times less power than a regular Wi-Fi link".'