WHY THIS MATTERS IN BRIEF

Our ability to turn almost any material, seemingly, into a robotic device, including crystals,  will help us open the door to new drug delivery and healthcare applications as well as ones we haven’t discovered yet.

All of a sudden I’m seeing a new glut of robots of all shapes, sizes and types, from bio-hybrid robots, co-bots and softbots to DNA robots and molecular robots, and that’s before I mention regular robots, like ATLAS or these fruit picking or brain surgeon robots, or this self-evolving robot, and their brethren, but now researchers have demonstrated that tiny micro-meter sized crystals, that are just barely visible to the naked eye, can also “walk” inchworm style across the slide of a microscope, and that other crystals are also capable of different modes of locomotion such as rolling, flipping, bending, twisting, and jumping. And in the future these moving crystals may open the doors to the development of an entirely new type of robots – Crystal Robots. Yep, robotics is starting to get weird(er).

The research team which was led by Hideko Koshima at Waseda University in Japan published their paper on walking and rolling crystal robots in a recent issue of Nature Communications.

“We believe that these findings open the door to a new field of crystal robotics,” said Koshima, “currently, robots made from metals are rigid and heavy, making them unsuitable for daily interaction with humans. Our goal is to make symbiotic soft robots using mechanical crystals.”

Watch them go!

In their work the researchers investigated asymmetric crystals derived from Chiral Azobenzene and in experiments they showed that exposing the crystals to alternating hot and cold temperatures, between 120° and 160°C over the course of approximately 2 minutes, caused changes in the crystals’ shapes and behaviours. Depending on their dimensions, some of the crystals repeatedly bent and straightened, and over repeated heating and cooling cycles, these shape changes translated into the mechanical motion of inchworm like walking.

Meanwhile, crystals with other dimensions exhibited bending and flipping under temperature changes, and in experiments repeated heating and cooling cycles caused these crystals to quickly roll across a surface, attaining speeds of 16 mm/second. This was approximately 20,000 times faster than the walking crystals, which crawled along at just 3 mm/hour.

As the researchers explain in their paper the asymmetrical shapes of the crystals is the driving force of both types of locomotion. In particular, the walking crystals have a thickness gradient while the rolling crystals have a width gradient. Both varieties of crystal experience a phase transition at a critical temperature, and due to the asymmetry, this results in a shape change that is more pronounced at one end of the crystal than at the other.

The new research suggest that crystals appear to be promising candidates for robotics, and more generally materials that respond to external stimuli, such as temperature changes, have potential applications as sensors, switches, as well as in a wide variety of other areas, so I expect to hear more about the advances in “crystal robotics” over the coming years.