Scientists in Singapore have reported a laser-ignited 1 nm thick graphene engine in the journal Nano Letters. Nanoengines are of course a major component in the development of nanomachines, but no one has yet developed one that works on the same internal combustion mechanism as traditional engines.
In this first fabrication of such an engine, the researchers used graphene layers with a molecule, ClF3, bound in between. When a laser was shone on the material, the ClF3 dissociated from the graphene and gassified leading to rapid expansion and the formation of a graphene "blister". The authors describe the expansion as akin to the explosion and motion of a piston in a traditional engine. The pressure obtained by this blistering procedure is close to 23 MPa or about 3336 psi.
Graphene wasn't chosen just because of its current popularity; it is an ideal material for this sort of engine design for a few reasons, all of which permit the high pressure between the graphene and the substrate below:
1. It has a high Young's modulus meaning it is very rigid.
2. It has a high gas impermeability so none of the gassified ClF3 can leak through when it expands.
3. It has a high adhesion energy allowing the formation of a localized high pressure blister as opposed to a delamination of the entire graphene sheet.
When the laser light is shut off, the highly reactive ClF3 molecules just re-bind to the graphene, allowing the process to be repeated many times. Impressively, the authors put the engine through 10,000 cycles without seeing any substantial loss in performance.
Clearly this is a very early study on this type of nano-engine, and no one is yet theorizing about its eventual applications of even how to incorporate it into some sort of nanomachine. However, I really enjoy these "first-of-its-kind" research papers as a reminder of how there is still so much room for brand new developments in nanotechnology.
You can check out the original paper, Nanometer Thick Elastic Graphene Engine, here.
Top image reprinted with permission from Nano Lett., Article ASAP, DOI: 10.1021/nl500568d. Copyright 2014 American Chemical Society.