Atomic force microscopes are the tool of choice to see the tiniest atomic structures, right down to hydrogen bonds. The drawback with current models is that they're too slow to create anything but static images, making them useless for processes like chemical reactions. However, MIT researchers have created a prototype model that's 2,000 times faster than any commercial product, making it feasible for video (below). "People can see, for example, condensation, nucleation, dissolution or deposition of material in real-time -- things [they've] never seen before," says MIT professor Kamal Youcef-Toumi.
In a demonstration, the team dissolved a 70-by-70 micron calcite sample with acid, showing the layer-by-layer stripping of crystals over several seconds. By contrast, current commercial atomic force microscopes simply drag a tiny needle over a structure to trace its topography, meaning it takes up to 10 minutes to scan an entire image. Smaller scanners have been tried, but "it's like if you were landing somewhere in the United States and have no clue where you're landing, [but] you're only allowed to look a few blocks around," says inventor Soltani Bozchalooi.
Bozchalooi's new model incorporates two scanners: a smaller, rapid scanner and a larger one, which together can trace a relatively wide 3D area in seconds. "Our controller can move the little scanner in a way that it doesn't excite the big scanner, because we know what sort of motion triggers this scanner, and vice versa," he says. "In the end, they're working [together], so from the perspective of the scientist, it looks like a single, high-speed, large-range scanner." As a result, the instrument can scan at 4,000 lines per second, yielding about an 8-10 fps frame rate.
The device could help researchers visualize chemical reactions and trigger breakthroughs in fields like battery research, medicine and material science. For now, the team is just working on speeding it up a bit, though. "We want to go to real video, which is at least 30 frames per second, Youcef-Toumi says.