January 2, 2017
Scientist creates world’s smallest snowman out of silicon
The world’s smallest snowman has been produced by using a scanning electron microscope. The instrument’s operator at Western University in Canada said the 3-micrometer tall sculpture sets a new record.
In 2005, Todd Simpson from Western University produced the ‘snowman’ by chance. In an attempt to produce a matrix of isolated silica spheres, he placed a solution of them on a polymer film dotted with nanoscale holes. When the film was taken off the isolated spheres were left behind, sitting on a surface. A few of the holes were a little deeper than others and greater than one silica sphere had fallen in to develop a dimer, or one sphere on top of another. And in a few instances, a dimer was stacked on top of a different silica sphere to generate the three-sphered, albeit faceless, snowman.Recently, Simpson discovered the old specimen and used the focused ion beam of his lab’s electron microscope to create the snowman’s mouth and eyes. The ion beam is often used to put down tiny amounts of platinum and so Simpson was able to build arms and a nose for the Frosty-inspired sculpture. Each silicon sphere is 0.9 micrometers across making the snowman just short of 3 micrometers tall.
Miniscule silica spheres are good for more than just building snowman. In 2014, researchers used them to test out the possibility of bulletproof vests made from graphene, a very thin form of carbon just an atom or so thick.
In the study, researchers by fired silica spheres at sheets of the nearly-transparent form of carbon. They study team reported that graphene can be more resilient than steel when absorbing impact.
Created by arranging atoms in a honeycomb structure, graphene is thin, strong and flexible. It is also a very efficient conductor of heat and electricity. The researchers had to use lasers in order to observe the silica spheres as they hit sheets of graphene 10 to 100 layers thick. They then compared the kinetic energy of their “microbullets” both before and after piercing the graphene.
Electron microscope observations showed graphene dissipates the energy of projectiles by stretching into a cone shape and then cracking in random directions.