Could taking a stroll in these shoes create actual power?
German researchers have answered this question with a resounding "yes". They've built shoe-sized devices that harvest power from simply putting one foot in front of the other. The technology could be used to power wearable electronic sensors without the need for batteries.
Two separate devices come together in this new invention. One, a "shock harvester", generates power when the heel strikes the ground. The other is called a "swing harvester" and produces power when the foot is swinging back and forth.
The swing harvester was developed with the intention of making a self tying shoe for the elderly that would lace itself up.
The energy these harvesters generate is still relatively small and doesn't provide enough power to charge a smartphone. But it is enough to power small sensors and transmitters, opening up a range of new applications.
Klevis Ylli from HSG-IMIT, a research centre in Villingen-Schwenningen, Germany said there are other ways this shoe could be groundbreaking.
"From the data from these sensors, you could calculate how far you have traveled and in which direction. So imagine a rescue unit walking into a building they don't know. They could then track which way they went on their handheld device."