Technology

How to See the Microscopic World Without a Microscope

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Photo Credits: All images courtesy of Micah Kimo Johnson

To see the world on the microscopic level, you usually need, well, microscopes. But with sensitive cameras and a gel that deforms around even the ink on a printed page, a team at MIT has developed a compact, portable equivalent. A device about the size of a soda can, it can register objects as small as two micrometers across.

A little pad of gel, coated on one side with metallic paint, is at the center of the device. When pressed against a finger, a dollar bill, or a Post-It, the paint on the gel gently bends to fit the form of the object. Cameras arrayed above the gel snap images of the pattern imprinted in the paint, and computer vision algorithms reconstruct the surface in 3D. The result is beautifully detailed imagesof such objects as the individual barbules of a feather, shown above.

Taking pictures of objects’ microscopic texture would be easier if their surfaces had the same reflective properties all over. Because human skin absorbs light and has the added complication of tiny hairs, it can be tricky to image clearly, but with the new device, called GelSight, pictures like the one above are easy to snap. Essentially, the thin layer of metallic paint provides a consistent surface for light to reflect from.

It’s like coating a person in silver Lycra: suddenly, every curve is clear.

In the cylinder of the handheld device (which you can see in action here), three colored lights at different angles shine on the impression left in the metallic paint. Then, cameras arrayed around the tube snap pictures of the impression and assemble a table of color values. Computer vision algorithms then extrapolate from the patterns of colored light on the surface to a 3D reconstruction. The device can capture depths as small as a fraction of a micrometer, allowing printed letters, like these ones, to show up as 3D.

The GelSight system isn’t a replacement for microscopes in the labs of biologists and others working with the truly tiny: While these pictures resemble images made by a scanning electron microscope, they have nowhere near the resolution (SEM images are orders of magnitude finer, on the nanometer rather than micrometer level). But anyone examining the surface of objects—materials scientists, for example, who study materials like concrete, plastic, and glass—it’s an exciting possible addition to their toolkit.

Here, the surface of the sticky part of a Post-It note shows both the fibers of the paper and the globules of glue.

GelSight might find its true home outside the lab, in providing quality control for manufacturers and perhaps helping forensic investigators, since the patterns left on bullet casings by guns, easily visible with the device, can help pinpoint what weapon was used in a crime. The scientists behind the device are already in talks with several industrial manufacturers and an aerospace company to help provide testing for their products.

For the rest of us, it’s another way to get a glimpse at the small beauties out there in the natural world, like the sand dollar’s spines, above.

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