In the future vibrations from traffic on bridges, walking up and down stairs and machinery in factories will produce electricity. This is the goal for researchers at the University of Michigan creating tiny devices Parametric Frequency Increased Gernerators - PFIG, that harvest kinetic energy and convert it into usable power. Three prototypes have already been designed, the first two using electromagnetic induction to convert energy and the third utilizes a piezoeletric material that produces a charge when stressed.
The generators have demonstrated that they can produce up to 0.5 milliwatts (or 500 microwatts) from typical vibration amplitudes found on the human body. That's more than enough energy to run a wristwatch, which needs between one and 10 microwatts, or a pacemaker, which needs between 10 and 50. A milliwatt is 1,000 microwatts.
These generators could also power wireless sensors deployed in buildings to make them more energy efficient, or throughout large public spaces to monitor for toxins or pollutants.This is great news since the standard battery only lasts so long and hard to dispose of. With the PFIGs, devices can be smaller and run indefinitely, which is great news for pacemakers and other surgical implants.