How Pine Cones Inspired Making Of These New Micro Robots

Short Bytes: Researchers at Seoul National University have been inspired by the adaptation of pine cones to change in humidity into the making of tiny robots, powered solely through changes in humidity.

What is the first thing that comes to your mind when you come across a pine tree on a winter morning? Most of us would probably admire the beauty of it.

However, a group of researchers at Seoul National University is greatly fascinated by their adaptation to change in humidity and studying it to find huge application in robotics as well. The reason being that plants follows a comparatively simpler mechanism over animals.

So how is the future of Robotics inspired from plants or pine trees in particular?

At the 68th Annual Meeting of the Division of Fluid Dynamics, of the American Physical Society held on Nov 22-24, 2015, in Boston, they explained how plant mechanism enabled them to develop tiny robots powered solely through changes in humidity.

Awns are composed of two layers of tissue, one that swells with humidity – active, and the other that is insensitive to humidity changes – inactive. If the humidity in environment tends to increase, the bilayer bends from changes in lengths swelling. Depending on the periodic humidity changes, the bilayer tends to bend and unbend repeatedly, thus ensuring that changes in environmental humidity could be converted to mechanical work.  This led to the realization that if the bilayer structure could be imitated in making an actuator, then it was possible to generate motion on utilizing environmental humidity changes.

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Building up a robot:

Plants tend to move slowly. Perhaps, so slowly that one cycle of bending and unbending could take a whole day. Hence, the increase in response speed of bilayer demands the development of a new way of fabricating the active layer. The response speed tends to increase with the surface-area-to-volume ratio of the layer since humidity is absorbed quickly and so active nanoscale fibers are deposited onto an inactive layer. The development of a robot demanded repeated bending as well as unbending without producing net locomotion.

Kim states:

“This motion of cycle needs to be converted into directional motion in order to create a robot which moves.”

On this, Kim said:

“Making a bilayer for the robots isn’t difficult, but making a fast one requires technical expertise. Generally, it tends to be drier during the day and more humid at night — the periodic humidity change cycle that enables seeds to bury themselves in the ground. Humidity changes occur even when we breathe, because humid air is exhaled.”

The group had also created a mathematical model to discover the optimum design for the robot in achieving the fastest speed for any given robot size. After this, researchers are optimistic of exploring the potential of human skin, which is more humid than the atmosphere.

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