News-Letter

Robots flexible enough to squeeze through tiny cracks, and metals that can fix their own bends or dents are both on the horizon, according to recent research studies and proposals.

Both technologies rely on metallic compounds with "memory" for past shapes. These metals may be as strong and flexible as other alloys, but display the unique ability to flip back to their original form given a stimulus such as electric current.

Self-repairing metals are already a reality, at least in the laboratory. Researchers at the University of Illinois describe a method for producing these specialized substances in the online edition of the journal Science.

Most industrially produced metals consist of many microscopic crystals of metal atoms. The trick to making flexible and form-changing metals is to create a mix of small and large crystals.

The researchers developed a process for synthesizing aluminum and gold sheets with exceedingly small crystal sizes: 100 nanometers, or a tenth of a percent of the width of a human hair.

Because of the tiny crystalline size, these metals are able to snap back to their original shape if they are deformed; all that is required is the application of heat.

In principle, this technique should be applicable to a wide variety of industrially-useful metals and metal alloys. Self-repairing metals could be useful in any number of consumer products and scientific applications.

Liquid robots are more of a brainstorm at the moment: the Defense Advanced Research Projects Agency (DARPA) has just released a request for proposals for designing and building them. The request would provide federal funding for researchers to develop "ChemBots."

DARPA envisions tiny robots that are able to perform some function, such as delivering nano-scale payloads, through miniscule holes and cracks. To do this, the robot would need a great degree of flexibility -- in effect, it would need to act almost as a droplet of liquid.

These ChemBots could conceivably find use in a wide variety of situations, from military applications to medical treatments. Any practical use for ChemBots is likely to be years in the future.

The DARPA request does not specify one particular way to design the ChemBots. Flexible metals, such as those developed by the University of Illinois team, are one possibility.

If a robot were made out of a flexible but strong material, it could squeeze through a tiny space and then revert to its original form once on the other side.

Many small animals, such as octopi and insects, are able to fit themselves through such narrow openings.

Other means of achieving the same goal include substances that are able to exhibit both solid and gel-like properties, robots that can fold up into significantly smaller volumes, and devices that can disintegrate and subsequently reassemble themselves into the same form.

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