Smithsonian: Sensor-studded clothing, a Band-Aid-sized electrocardiogram machine, and computer screens in contact lenses—such miniature embedded electronics may one day be possible, provided the right power supply can be developed. As Michael Belfiore explains in the August issue of Smithsonian magazine, current batteries are too bulky for those applications. Researchers at MIT are therefore working to harvest thermal and kinetic energy from the human body, which they hope can be converted into electricity and stored in a capacitor on a millimeter-sized chip. So, in future, just walking or nodding your head could power, say, a cell phone implanted in your tooth.