Scientists create nano solar cells

Two hundred billionths of a watt may not seem much, but at nanoscale it is enough to provide a steady output of electricity to run ultralow power electronics, including some that could be worn on -- or even inside -- the body.

It is also clean, highly efficient and renewable.

"An individual nanoelectonic device will indeed consume very little power, but to do something interesting will require many interconnected devices and thus the power requirement -- even for nanosystems -- can be a challenge," Lieber explained in an email.

Monitoring bioterrorism threats, for example, would require an entire array of nanosensors, nanoprocessors to analyse the signals received, and nanotransmitters to relay information to a centralised facility, he said.

Conventional sources, he added, are "bulky, non-renewable and expensive" by comparison.