Innovative wireless light switch could cut house wiring costs in half

https://techxplore.com/news/2023-11-wireless-house-wiring.html

"transmitter on the switch and a receiver near a light fixture or other appliance—have been around for many years, but required batteries... switch costs <$1 and runs without batteries, harvesting energy from ambient sources such as RF (1 or 2 RF sources per floor)... seamlessly automated sensors and systems for temperature, humidity and occupancy... turn lights and heating vents on and off as occupants move from room to room"