Nano-submarines powered by light may not be much use in warfare – think nano-sized torpedoes vs a typical aircraft carrier – but there’s certainly hope in other areas for these miniature marvels designed by researchers at Rice University in Texas. It’s thought that the nano-subs might one day carry cargo for medical purposes.

These single-molecule, 244-atom nano-submarines have motors that are powered by ultraviolet light. Each full revolution of the motor’s tail-like propeller moves the nano-submarine 18 nanometres (25,4 millimetres per second). Yes, 18 nanometres might not sound like much, but chemist James Tour says it’s a breakneck speed: “These are the fastest-moving molecules ever seen in solution.”

The motors operate like a bacterium’s whip-like flagellum, and complete each revolution in four steps. When the motor is exposed to UV light, the double bond that holds the motor’s rotor to the body becomes a single bond. This allows it to rotate a quarter step. When the motor wants to return to a lower energy state, it jumps adjacent atoms for another quarter turn. This process keeps the nano-submarine moving as long as the light is on.

“These motors are well-known and used for different things,” said lead author and Rice graduate student Victor García-López. “But we were the first ones to propose they can be used to propel nano-cars and now submersibles.”

Source: Rice University

Illustration credit: Loïc Samuel/Rice University