I'm rather late reporting on this, but it's such an important development, that it cannot go unnoted. Scientists have developed a way to power nanodevices off ambient vibrations. The device consists of zinc oxide nanowires whose movement generates a tiny electrical current via the piezoelectric effect.
The salutary uses are the most obvious, and of course the ones touted by the inventor:
But Wang believes the nano-generator could be ideal for powering tiny devices, including those that may be implanted inside the human body. "Imagine self-powered force-sensors implanted in blood vessel walls, taking your blood pressure. Or generators in your shoes that can charge devices while you walk," he says.
Almost any device that could use a wireless, mobile power source could potentially use the nanogenerator, Wang says: "I have full confidence that within three years we will have something that is useful commercially." (New Scientist)
Whether or not Wang's prediction proves true, the fact of this technology marks a decisive change in the possibilities for the kind of technology we can implant in the human body. No longer will machines in vivo be limited to bulky external power supplies or the chemical dangers of miniature batteries.
But imagine the harm that could be done if someone designed a malicious device that could be implanted in your body. Perhaps a self-replicating nanomachine—essentially a human-made micro-organism. As always, technological development expands the possibility not only for good, but also for unparalleled mischief.
Kevin Bullis, "Nano-generator could power tiny devices," Technology Review (April 27, 2006).
Michael Reilly, "Free Electricity from Nano Generators," New Scientist (05 April 2007).