Sandwich structure
The drone's resilience comes from a unique combination of stiff and elastic layers. An elastomer membrane is stretched and then sandwiched between rigid plates. When the system is at rest, the plates hold together and give the structure its stiffness. But when enough force is applied, the plates draw apart and the structure can bend.
"When we make a drone, we can give it specific mechanical properties," says Stefano Mintchev, the study's lead author. "This includes, for example, defining the moment at which the structure switches from stiff to flexible." And because the drone builds up elastic potential energy when it is folded up, it can unfold automatically when so instructed.
Structures that are stiff and flexible at the same time have a range of other potential applications, as well. As they were developing their drone, the researchers used the same technology to create a soft-touch gripper. The gripper softens once it reaches a certain level of pressure so as not to break the object that it is picking up. This also means it cannot pick up a load that exceeds its capacity.