"...a reliable and cost-effective energy harvesting power source for autonomous sensors and electronics,"
Using humans as some kind of battery?
Where have I heard that before?
This sounds like something straight out of the Matrix.
A group of Scottish engineers claim to have come up with a new way to harvest the electricity wasted by everyday human movement: electrically conductive foam. The team from the University of West Scotland reported their findings in a recently published paper detailing the addition of three-dimensional graphene (3DG) foam to …
You're probably thinking of Pavegen, a British company that's been banging on about generating electricity from footsteps for ages. The last time I looked at them they stated that each footfall generated 7 joules of energy. Even at a military double time pace, which most people do not walk at, that's only 21 watts from a tile, or 2 days continuous footfall to generate one unit of electricity. Electricity prices may have gone up lately, but not that much.
When I did the calculations, given Pavegen's estimate of how long the tiles would last, by the time the tiles wore out the most you would have recouped would be ~25% of the tile cost(*) if you were getting retail prices for your power. As you'd only get wholesale prices in reality you'd lose most of your money. At best this is an attraction generating gimmick, it's certainly no way to generate meaningful amounts of power. Adding graphene for the latest woo doesn't change things, and as remarked you're laying yourself open for all sorts of litigation for accidents and possibly breach of privacy.
(*) And that's ignoring cost of installing them.