UMBERTO BACCHI IN a move that will give chills to fans of the dystopian movie "The Matrix", scientists have developed a wearable device that could use the human body to replace batteries. Echoing world-domineering robots' use of enslaved humans in the 1999 cyberpunk movie, U.S. researchers at the University of Colorado Boulder have created an environmentally-friendly gadget that harvests body heat and converts it into energy. Tech-lovers could power their own watches or fitness trackers by wearing a stretchy ring or bracelet containing thermoelectric chips that convert heat into electrical energy, according to research published in the journal Science Advances.…