From Popular Mechanics
Researchers carved the tiniest gingerbread house ever made with a gallium ion beam and an electron microscope.
It sits on the head of a microscopic snowman, and the entire thing is just one human hair’s width high.
Ion beams have myriad applications, from medical imaging to spectral analysis.
A new microscopic gingerbread house is actually made of silicon, but it’s still thought to be the smallest such structure ever made. McMaster University research associate Travis Casagrande carved the tiny house using a focused ion beam shooting gallium ions at the silicon surface.
Casagrande belongs to the Canadian Center for Electron Microscopy (CCEM), where the Brockhouse Institute for Materials Research has assembled a collection that scientists from all over can use for their research. The Center has 10 electron microscopes (both transmission and and scanning), Auger electron spectroscopy, atom probe tomography, and the ion beam Casagrande used to carve his tiny house.
The gingerbread house is both a curiosity and a showcase—its roof is labeled with “CCEM” and “McMaster University,” and its welcome mat is a Canadian flag—for the kind of work the CCEM is enabling. The house is positioned on the flattened top of a snowman made of other micromaterials, and the height of the entire assemblage is about the diameter of a human hair.
Instead of building the house by adding materials, Casagrande cut silicon away, more like sculpting from a block of marble or using a 3D router. The level of detail is mindboggling, and Casagrande used the ion beam to carve letters and building textures into just the surface of the silicon. This must be the world’s tiniest bas relief.
Charged ion beams are part of the overall field of spectroscopy, which includes electron microscope technology, chemical spectral analysis, and MRI machines. The same extremely tiny detail in Casagrande’s carved gingerbread house is how the focused electron beams in an electron microscope illuminate the tiniest details so we can see them.
Traditional ways to carve, using tools, just aren’t possible on the micro scale. By the time you’ve manufactured microscopic tools, you might as well have used the same methods to directly carve the item—it all goes back to beams rather than physical implements. In this way, a potentially programmable ion beam offers similar appeal to a 3D printer: It removes not just human error but the need for more intermediary technology. One complete and programmable micro-level tool takes the place of a whole box of regular-size tools.
In Casagrande’s case, he carved the microscopic house using careful, good old fashioned human motor skills in operation of the ion beam. His details, textures, and overall composition are more artistic than scientific, and the record-setting tiny house is more than just an achievement in microscopic fabrication.
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