Emerging Tech

MIT’s Smart Sand Can ‘Build’ Whatever It Touches

Of late, people working in specialized fields such as industrial design, architecture and the medical and dental industries have been going gaga over 3D printing, a process in which three-dimensional solid objects are produced on a special printer using materials such as molten polymers.

However, this technology may be trumped by research on so-called self-sculpting sand being conducted at the Massachusetts Institute of Technology (MIT).

The material’s not really sand. Instead, it’s what you might want to consider pebbles — cubes measuring 10 mm to a side.

These cubes communicate with each other and can assume the shape of any object placed in a heap of such cubes.

“I think this work is very similar to some of the work done on ‘smart dust’ at U.C. Berkeley and MIT and the University of Michigan,” Carl Howe, a vice president at the Yankee Group, told TechNewsWorld.

The Smart Dust project at UC Berkeley, which ended in 2001, created sensors measuring one cubic inch that contained a bi-directional radio, a microprocessor controller and a battery and had a communication range of 20 meters.

The Shifting Sands at MIT

The objects used in the MIT experiment — let’s call them “pebbles” for want of a better word — have very rudimentary microprocessors that can store 32 kb of program code and have 2 kb of working memory.

They also have electropermanent magnets on the outside. Electropermanent magnets are devices whose external magnetic fields can be switched on and off by an electric pulse and retain their magnetic state whether or not the power is on, Ara Knaian wrote in his Ph.D. thesis at MIT in 2010.

Their switching energy scales with volume while their holding force scales with area, meaning the more magnets there are, the stronger their switching energy; and the more area these magnets cover, the stronger their holding force.

The idea is, when you put an object such as a small footstool into a box of MIT’s so-called smart sand, the pebbles will assume the shape of the object by subtraction, meaning that they will talk to each other and duplicate the object. Extraneous pebbles will fall away from the newly minted copy.

The object can be reused because returning it to the heap of so-called smart sand will see it fall apart into its constituent pebbles.

MIT’s smart sand project appears to be an extension of the Robot Pebbles idea Knaian proposed in his paper. MIT professor Daniela Rus, who is leading the smart sand project, was one of Knaian’s thesis supervisors, and team member Kyle Gilpin collaborated with Knaian on the Robot Pebbles project.

How the Smart Sand Works

“The easiest way to think about this project is one in which all the grains of sand or cubes act like nodes of a network,” the Yankee Group’s Howe said. “They discover their nearest neighbors and share what they know about other neighbors. Eventually all the nodes construct a model of how they are connected, which they share among themselves. That model represents the topology, or shape, of the object.”

The innovative idea in this project is that short-range communication is the key to smart sand, Howe remarked.

“All the nodes have to communicate simultaneously, and you don’t want them talking to other nodes that may be meters away from where they are because that won’t properly represent the shape,” Howe explained. Magnets are ideal for very short-range communication because magnetic fields decrease by the cube of the distance between the magnets, he said.

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