Batteries used to be the only way to power implantable gadgets, but additional surgeries are needed to replace the power packs once their juice runs out -- a less-than-ideal solution for patients. Recent discoveries, however, have such medgadgets being powered by photons, hip hop and now high-frequency radio waves. Electrical engineers at Stanford built a cardiac device that uses a combination of inductive and radiative transmission of power, at about 1.7 billion cycles per second, to its coiled receiving antenna.
Previous prevailing opinion held that the high frequencies needed for wireless power delivery couldn't penetrate the human body deep enough, and the lower frequencies that would do the trick require antennas too large to work as implants. That conundrum was solved by getting the high-frequency signals to penetrate deeper using alternating waves of electric and magnetic fields. That allowed a 10x increase in power delivery -- up to 50 microwatts to a millimeter radius antenna coil -- to an implant five centimeters below the skin. That antenna also was also designed to pull power regardless of its orientation, making it ideal for applications inside always-moving human bodies. Of course, the implant's really just a proof-of-concept at this stage, but hopefully it won't be long before battery powered implants go the way of the