Why bother with risky battery-changing surgical operations when your own cardiovascular system can provide all the power your heart-shocking pacemaker will ever need? Engineers at Switzerland's University of Bern have been working on tiny turbines; turbines small enough, in fact, to fit inside a human artery. Working like a blood powered hydroelectric generator, a working prototype -- tested in a simulated artery -- has been able to produce 800 microwatts of electricity. That's roughly eighty times the power required to power the average pacemaker; such a device could provide independent, sustainable power to neurostimulato
