30. Picowatt Power

Solar cells 200 hundred times smaller than human hair have been developed.

Capable of powering ultra-microscopic gadgetry to be developed in about a decade, these cells have an output of about 200 picowatts.

Two hundred billionths of a watt is not much, but at nanoscale can power up ultra-low power electronics.

The nanowire is made of silicon with 3 different types of conductivity in layered shells.

The incoming light generates electrons in the outer shell which are then swept into the second layer and inner core along micropores.

These 'holes' carry equal and opposite charge as electrons.

The outer and inner core thus function as positive and negative terminals of a battery.

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