WASHINGTON: Airplanes might soon have flexible wings like birds and robots could change shape as they please thanks to research under way on mimosa plants, researchers said. The shrub's leaves, which can retract at the slightest of touches, could inspire a new class of structures that can twist, bend, harden and even repair themselves, explained University of Michigan professor of mechanical engineering Kon-Well Wang. “This and several other characteristics of plant cells and cell walls have inspired us to initiate ideas that could concurrently realize many of the features that we want to achieve for adaptive structures,” he said Saturday at an annual meeting of the American Association for the Advancement of Science. “The phenomenon is made possible by osmosis, the flow of water in and out of plants' cells. Triggers such as touch cause water to leave certain plant cells, collapsing them. Water enters other cells, expanding them. These microscopic shifts allow the plants to move and change shape on a larger scale,” he said. The mimosa is a type of plant able to move itself in a way that is visible to the naked eye in real time. The plant's “hydraulic system” makes that “nastic motion” possible. “Triggers such as touch cause water to leave certain plant cells, collapsing them. Water enters other cells, expanding them. These microscopic shifts allow the plants to move and change shape on a larger scale,” the researcher explained. Observing the process can be a gateway to designing cells with special mechanical properties, he believes. “This and several other characteristics of plant cells and cell walls have inspired us to initiate ideas that could concurrently realize many of the features that we want to achieve for adaptive structures,” Wang said. “We can design those cells according to our needs. We can put those cells into structure, control them in different sequences,” he explained. “Currently we are looking at basic research only, but there are some applications that we have in mind,” Wang said. He mentioned the notions for example of planes able to change the shape of their wings while in flight as birds do; and other machines that change their shape perhaps to go under a bridge.
