German scientists use DNA to construct the world’s smallest rotary motor


Nanotechnology’s stupendous growth in recent years has led us to something even more revolutionary: DNA origami. It refers to the highly-specialized technique of DNA folding, as a means to create two- and three-dimensional shapes in nanoscale. Using this technology, a team of scientists has developed what appears to be the smallest rotary engine in the entire world.

The new motor, which is even smaller than the microscopic HIV virus, is only 40 nanometers in height, and contains three distinct components that come together to form crude versions of a spinning crank lever and a miniature axle bearing. Resembling half a helicopter blade in shape, the contraption works very much like the flagella (or tiny whip-like propellers) used by microorganisms like bacteria. Speaking about the research, recently published in the Science Advances journal, Philip Ketterer, a physicist at the Technical University of Munich and the study’s leader, said:

It’s a step toward the long-term goal of artificial nano-robots. You could easily imagine a future where similar such motors are used for propelling nano-robots in our bodies, much in the same way that bacteria naturally move about.

According to the researchers, the rotational motion of the motor’s blade generates forward thrust that could in turn propel a variety of robotic devices. To construct the engine, the scientists relied on the process of DNA origami, in which strips of physical DNA material are used as scaffolds to form different structures and machines. The team is currently trying to create nano-sized versions of all the tools found in an engineer’s toolbox, such as clamps, hinges, bearing and others.

Claimed to be the “the most complex device made so far with this [DNA origami] technique”, the rotary motor is the smallest of its kind ever built by humans. As the scientists point out, choosing DNA molecules as the primary building material had nothing to do with its role in storage of genetic information. Their use in nanotechnology, however, is due to their incredible flexibility and the vast wealth of knowledge we possess about genetics. DNA, according to Ketterer, is:

… a great building material with some interesting physical properties. And, we use chemically synthesized DNA, which you can get loads of for cheap.

At present, the nano-sized device is not exactly a “motor”, since it is powered with the help of atomic collisions. The engine’s rotational motion is produced using energy harvested from the irregular collisions of surrounding molecules, a phenomenon which is also called Brownian motion. Consequently, the researchers do not have any control over the direction in which the rotors turn, nor can they actually switch the motor on or off.

The team is looking for ways to power the motor efficiently, while also being able to control its spin. One of the ideas they are currently working on involves the use of targeted laser light, in order to transfer tiny amounts of energy to the nanoscale rotary engine via waves. The project’s leader said:

It’s still a faraway goal when we have an [steady] energy source and can control the directional motion of these devices.

Source / Image Credit: Popular Mechanics

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