Science

World's smallest gears measure mere nanometers to power molecular machines

World's smallest gears measure...
Researchers in Germany have developed the world's smallest working gears
Researchers in Germany have developed the world's smallest working gears
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Researchers in Germany have developed the world's smallest working gears
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Researchers in Germany have developed the world's smallest working gears
Left: an image representing how each component of the molecular photogear functions. Right: a molecular model of the two components of the gears, the propeller (gray) and plate (gold)
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Left: an image representing how each component of the molecular photogear functions. Right: a molecular model of the two components of the gears, the propeller (gray) and plate (gold)

In many fields of technology, smaller is better, and machinery is now getting so tiny it’s measured in mere atoms. Researchers at the University of Erlangen–Nuremberg (FAU) in Germany have now developed what they claim are the world’s smallest working gear wheels.

Molecular machines and nanorobots could be extremely useful in the coming decades, helping to construct electronic components, transport drugs through the body, or manipulate individual cells or molecules.

To that end, scientists have developed nanoscale versions of many machine parts, such as motors, pistons, pumps, wrenches and propellers.

Now, the FAU team has added another vital machine part to the list – gear wheels. The device is made up of two interlocking components, including a triptycene molecule with a structure like a propeller, and perpendicular to that sits a flat section of a thioindigo molecule that acts like a plate.

Left: an image representing how each component of the molecular photogear functions. Right: a molecular model of the two components of the gears, the propeller (gray) and plate (gold)
Left: an image representing how each component of the molecular photogear functions. Right: a molecular model of the two components of the gears, the propeller (gray) and plate (gold)

Together they work like a pair of gears, transmitting and stepping down motion. The pair has a transmission ratio of 2:3, so that when the plate rotates by 180 degrees the propeller has only rotated by 120 degrees. The entire device contains just 71 atoms and measures 1.6 nanometers long, which makes it the world’s smallest working gears according to the team.

The system can be switched on and off easily using light, earning it the name of a molecular “photogear.” This marks the first time molecular gears have allowed for this kind of direct control, rather than just passive movement.

The researchers say this new molecular photogear allows for more versatile molecular machinery, and should pave the way for new nanoscale gear systems that can transmit motion over longer distances, in different directions and at different speeds, much like their macroscale counterparts.

The research was published in the journal Nature Chemistry.

Source: FAU

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