"Rollbot" Needs No Power To Change Shape

Scientists from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Caltech Divison of Engineering and Applied Scientists have developed a new soft robot. The soft robot can move and change shape in response to external stimuli and paves the way for untethered soft robots of the future.

The team turned to origami to create multifunctional, soft robots using sequential folds. The origami is able to encode multiple shapes and functions in a single structure. The robots use liquid crystal elastomers that change shape when exposed to heat.

The team 3D printed two types of soft hinges that fold at different temperatures that can be programmed to fold in a specific order. That type of hinge makes it easier for the team to program robotic functions and control how the robot will change shape. A Grad student working on the project, Connor McMahan, says that using the tech you only need to program how a few small regions of the structure respond to changes in temperature.

The scientists built several soft devices, including a soft untethered robot called "Rollbot." Rollbot starts as a flat sheet about 8cm long and 4cm wide. When Rollbot is placed on a hot surface that is about 200 degrees Celsius, one set of hinges fold and the bot curls into a pentagonal wheel.

Another set of hinges is embedded in each of the five sides of the wheel. A hinge folds when in contact with a hot surface and propels the wheel to turn to the next side. When that happens, the next hinge folds. When the hinges are off the hot surface, they unfold and are ready for the next cycle. Another device folds when in a hot environment into a shape like a paper clip and unfolds when cooled.