Metallic Flagella

Bradley Nelson

The control of metallic flagella with magnetic fields is the subject of a recent paper by Li Zhang and Bradley Nelson.^[NanoLett] The synthetic approach is a top-down process, and an image of a pre-released flagellum is shown below.

Although typical bacteria like E. Coli are 1-2 μm long, this system is still a fascinatingly model of the motion of objects at low Reynolds numbers. The head of the artificial bacterium is composed of thin films of chromium, nickel, and gold. While the helical body is a composite of layers of indium gallium arsenide, gallium arsenide, and chromium. Motion is controlled by using three orthogonal electromagnetic coil pairs at 1-2 mT and a frequency of 5-35 Hz. A video of two of their flagella in action is shown below.

A couple of other videos showing the ability of the authors to steer the flagella are provided here: 1 flagellum, 3 flagella.

This system is a fascinating example of precise control of small devices that do not require outside chemical or photo sources. These systems have enormous promise and will likely comprise the type of motion the first nanorobots will utilize. One should couple this system to Gracias’ current generation of microgrippers for even more awesomeness.

Link to the article is here: Characterizing the Swimming Properties of Artificial Bacterial Flagella

Mitch

Subscribe to the comments for this post