Unwarranted grumpiness. Harvesting power from radio transmisssion is indeed not new. What they demonstrate, however, is transmission from the 'receiver' to add

Unwarranted grumpiness. Harvesting power from radio transmisssion is indeed not new. What they demonstrate, however, is transmission from the 'receiver' to additional devices by modulating how much power is absorbed or reflected. This is fundamentally different from just using the harvested power to run a second transmitter, because modulating backscatter is 'orders of magnitude' more efficient.