Battery-free short-range wireless communication between devices | KurzweilAI

Researchers demonstrate how one payment card can transfer funds to another card by reflecting energy from ambient RF signals acting as both power source and communication medium.

Ambient backscatter: communication between two battery-free devices. One such device, Alice, can backscatter ambient signals that can be decoded by Bob and other ambient backscatter devices. To legacy receivers, this signal is simply an additional source of multipath, and they can still decode the original transmission.