Westcotec has developed an application for traffic signs using an energy harvesting switch from ZF Friedrichshafen.
Westcotec's traffic warning sign to help horse riders to cross busy rural roads. The riders have handheld battery-free energy harvesting switch transmitters that trigger the traffic signs on when approaching the road to warn car drivers of horses crossing. These switches work completely battery-free and wireless. Only the mechanical actuation of the switch generates enough electrical energy to transmit an RF signal to the traffic sign and activate it. The lights then flash for 60 seconds and can be activated multiple times where groups of horses are crossing the road.
The same idea was implemented to herd animals across a road. When moving the animals the twin amber flashing beacons are triggered by the farmer with a push button on a hand held unit containing the energy harvesting switch.