3D Printing Materials Sense Their Own Movements

MIT researchers innovated a method for 3D printing materials with tunable mechanical properties, which can sense how they are moving and interacting with the environment. They create the sensing structures using one material and a single run on a 3D printer.

They began with 3D-printed lattice materials and incorporated networks of air-filled channels during the printing process. They measure pressure changes within the channels when they squeezed, bent, or stretched the structure, giving engineers feedback on how the material moves.

Changing the size or shape of the cells alters the material’s mechanical properties, such as its stiffness or hardness. This may enable flexible soft robots with embedded sensors that allow the robots to understand their posture and movements. We might also use such structures to produce wearable smart devices that provide feedback on how a person moves or interacts with their environment. Since the “fluidic sensors” are incorporated into the material, they are more accurate than sensors on the outside of a structure.

The researchers incorporate channels into the structure using digital light processing 3D printing. The form is drawn out of a pool of resin and hardened into a precise shape using projected light. An image is projected onto the wet resin, and areas struck by the light are cured.

The researchers had to work quickly to remove excess resin before it was cured, using a mix of pressurized air, vacuum, and intricate cleaning. They created several lattice structures and demonstrated how the air-filled channels generated clear feedback when the forms were squeezed and bent. They also incorporated sensors into a new class of materials developed for motorized soft robots known as handed shearing auxetics or HSAs that can be twisted and stretched simultaneously, which enables them to be used as effective soft robotic actuators.