Bacteria build pyramids

By Aimee Whitcroft 26/03/2010 1


Giza pyramid

And true.  Not the ones with which we’re all familiar, of course (and by these I am referring to the Giza structures).

[Interesting sidenote: bacteria are capable of building structures with sand, which they turn into sandstone, and there’s a fascinating TED talk which looks at how this ability could be used to build human habitats in the desert.]

Back to the post at hand, though: scientists at the Nanorobotics Laboratories – a name of which I was immediately enamoured – of the École Polytechnique de Montréal have found a way to control bacteria using computers.  And they can get the bacteria to do things.  In this case, they managed to marshall thousands of bacteria to actually assemble a tiny little pyramid.

I’m not going to try rephrase the article which IEEE Spectrum has written.  That wouldn’t be fair.  Nope, mainly I wanted to draw everyone’s attention to this remarkable development.  You can watch the embedded video, below, to see how it happens.

But how do the scientists actually do this?  Well, these types of bacteria contain magnetosomes: little organelles which are sensitive to magnetic fields and act as a sort of compass.  To quote the IEEE article:

In the presence of a magnetic field, the magnetosomes induce a torque on the bacteria, making them swim according to the direction of the field. Place a magnetic field pointing right and the bacteria will move right. Switch the field to point left and the bacteria will follow suit.

Yes, the effect of each bacterium is tiny, but one of the great things about bacteria is their propensity to hang out in really big crowds.  At which point all those tiny little forces add up to one rather less tiny force.

And what actual use could something like this have?  Building nanoscale architectural monuments is fun, but hardly useful, after all.  Well, having thought it out, the scientists realised that rather than trying to build tiny robots which mimic the behaviour of bacteria, and use said robots for functions such as drug delivery, organ repair and disease detection, it might be easier to use the tiny little robots nature has been so kind as to design already.

Clever stuff, this…

The paper detailing the advance can be found here, and is entitled “A Robotic Micro-Assembly Process Inspired By the Construction of the Ancient Pyramids and Relying on Several Thousands of Flagellated Bacteria Acting as Workers”.  The structures involved may be tiny, but the titles apparently aren’t…

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