Using the principles of origami, along with smart material actuators, engineers at the University of Michigan have developed microbots that are faster, more agile, and more responsive than ever before. No more than a centimeter in size, the bots are able to form one shape, complete a task, then reconfigure for each additional task. Based on new methods of design, fabrication, and actuation, the machines have the potential for a broader range of applications in fields as diverse as medical equipment and infrastructure sensing.
The behavioral rules that underpin the Japanese art of folding provide a simple approach to fabricating a wide range of robot morphologies. The multistable characteristics of origami structures form a natural basis for programming unique, reconfigurable features. Most microbots have traditionally limited movements, which limits the applications for which they are useful. The ability to fold at large angles dramatically increases the range of motion and enables more complex shapes, and the University of Michigan team’s microbots are able to fold as far as 90 degrees. Manipulating both material properties and geometric parameters of their materials, the machines have a built-in crease structure that has the potential to exhibit many soft body properties, effectively allowing them to fold into complex geometries.
The design and fabrication processes exploit top-down, parallel transformation approaches rather than a bottom-up assembly. Though past designs for such origami-based microbots often required an outside stimulus like heat or a magnetic field to activate, these bots include a layer of gold and a layer of polymer that acts as an onboard actuator. While currently controlled by a tether, eventually, the microbots have an onboard battery and microcontroller as well. As current passes through the gold layer, it creates the heat that is used to control the motions of the machine. The bot heats to fold overheats to achieve plastic folding and static geometry, and unfolds as it cools down. And fulfilling the promise of faster than ever before, it is able to complete its full range of motion up to 80 times per second.
The integration of origami principles within traditional microfabrication methods produces morphing microscale metamaterials and 3D systems suitable for a much wider range of applications than slower microrobots or those with a more limited range of motion. Origami principles have enabled researchers to unlock the potential of these centimeter-small bots and opened the way for more unique designs and enhancements.