We at MaterialDistrict tend to judge materials on what they are made of; are they plastic, stone, glass, etc.? With metamaterials, however, it is not that simple. These materials are defined by their engineered internal microstructures rather than what they are made of. Metamaterials can be made of anything, though the material should be elastic and able to withstand high forces without breaking. Researchers at the Hasso Plattner Institute in Potsdam, Germany, have used 3D printing to create metamaterial mechanisms out of a single piece of plastic.
The materials are made of a grid of silicone cells with different patterns, which creates various levels of rigidity. This grid is designed beforehand in a computer programme to determine how the cells will deform.
For the most part, the objects are made of rigid cells, which do not move. The shearing cell, however, is what makes movement possible. This cell is designed in such a way that it can deform and fold over in a controlled, multidirectional movement. In the example of the door handle they created: by rotating the handle, the shearing cells inside the object deform, pulling the latch towards the left and unlocking the door. This mechanism is much simpler than a usual door handle that consists of several parts.
Aside from the door handle, the researchers also designed pliers, a pantograph, a Jansen walker and a switch, which are all made from one piece. They are 3D printed with an Ultimaker 2 printer, using pink NinjaFlex filament. Some basic test mechanisms were laser cut from 3mm black rubber foam.
The advantages of these types of materials are obvious, as they do not need any assembly. A downside is that when it breaks, you need to replace the entire mechanism. By adding more cells, the stiffness of the object increases, so the metamaterial mechanisms are not suitable for mechanisms that should be operated with very small forces. The mechanisms are also not able to produce continuous rotation. In the case of the Jansen walker, they had to use a separate axle.
No matter the downsides, though, the metamaterial mechanisms are definitely impressive, as you can see below.
Photos via Dezeen