Walking Small: The First Bipedal Molecule

Different views of the molecule striding along, as visualized in a computer simulation. Credit: Ludwig Bartels, UC Riverside

Scientists have created a molecule that walks on two feet when it feels hot or when lured by the tip of scanning tunneling microscope.

The molecule, called 9,10-dithioanthracene (DTA), walks in such way that only one "foot" rests on a surface at any one time. When heated, the body of the DTA molecule pivots forward, causing one leg to lift up and the other to plop down.

In this hot-potato fashion, it plods along in a straight line without veering off course or stumbling.

Bipedalism like this is, of course, the preferred mode of natural movement for humans, but it's not easy to accomplish even in the realm of human-sized robots.

DTA can also be lured by the tip of a scanning tunneling microscope serving as a sort of carrot. In tests on a standard copper surface, DTA took 10,000 steps without faltering once.

Ludwig Bartels, lead researcher of the project at the University of California, Riverside, said the tiny walker could one day be used to guide the movements of molecule-based information storage or even computation.

The bipedal molecule joins a growing list of recently manufactured oddities at the molecular level:

• The World's Smallest Car
• The World's Smallest Motor
• The World’s Smallest Robot
• The World's Smallest Refrigerator
• The World’s Smallest Fountain Pen