Inner workings: Roboclam.

Calla Cofield Science Writer Digging in the sand might seem like child’s play, but doing it efficiently has stumped many adult engineers. As is often the case, nature has revealed a superior solution: this time in the Atlantic razor clam, which can burrow into and out of sandy ocean bottoms more efficiently than man-made, mechanical anchors. In 2008, Amos Winter, a professor of mechanical engineering at the Massachusetts Institute of Technology, introduced roboclam: the razor clam’s laboratory doppelganger. Roboclam successfully replicated the horizontal in-and-out motion of the clam’s two shells. This briefly excites the sand, causing the grains to behave like a liquid and allowing the clam to slip through the material with minimal energy expense. Now, investors want to know if roboclam can perform outside the laboratory, and Winter is working on a bigger version of the bot. At the University of Maryland, postdoctoral researcher Kerstin Nordstrom is studying the behavior of the grains as roboclam moves through them, looking at how variables like the robot’s speed or the size of the grains change the optimal performance mode. Nordstrom and her colleagues use transparent grains and a water-like fluid with the same refractive index to create a totally transparent environment for roboclam to dig through. “That’s the magic we’re performing here. We can actually see inside stuff that is normally opaque,” says Nordstrom. Red laser light excites a fluorescent dye in the fluid but the grains remain dark, making them easily observable against the illuminated background. The researchers are able to record video of the nearby grains in 2D or compile 2D slices into a 3D image. These images reveal the area that is “liquefied” by roboclam’s motion. Roboclam could be used as a low-energy anchor for small submarines performing geologic or wildlife surveys or as a way to secure underwater internet cables.