Researchers at Columbia University have conducted the first exhaustive study into kinetic energy harvesting — the harvesting of “free” energy from common human activities, such as walking, writing with a pencil, taking a book off a shelf, or opening a door. Surprisingly, except for those living the most sedentary lifestyles, we all move around enough that a kinetic energy harvester — such as a modified Fitbit or Nike FuelBand — could sustain a wireless network link with other devices, such as a laptop or smartphone.
Energy harvesting is expected to play a very important role in the future of wearable computing and the internet of things, where direct sources of power — such as batteries or solar power — are cumbersome, expensive, and unreliable. At its most basic, a kinetic/inertial energy harvester is a small box with a weight attached to a spring. When the spring moves, the mechanical energy is converted into electrical energy, usually by means of piezoelectrics or MEMS (microelectromechanical systems). If the spring moves with more force, or it bounces back and forth rapidly, more energy is produced.