Now a team of Harvard University researchers specializing in 3-D printing, mechanical engineering and microfluidics has developed the first-ever autonomous, untethered, entirely soft robot. The small, 3-D-printed robot, which the team calls “octobot,” paves the way for a new generation of entirely soft, autonomous machines with the potential to change the way humans interact with machines.
“One longstanding vision for the field of soft robotics has been to create robots that are entirely soft, but the struggle has always been in replacing rigid components like batteries and electronic controls with analogous soft systems and then putting it all together,” said Robert Wood, the Charles River Professor of Engineering and Applied Sciences. “This research demonstrates that we can easily manufacture the key components of a simple, entirely soft robot, which lays the foundation for more complex designs.”
According to Jennifer A. Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences, the team was able to 3-D print each of the functional components that were needed within the robot’s body, which included fuel storage and power parts.
“The octobot is a simple embodiment designed to demonstrate our integrated design and additive fabrication strategy for embedding autonomous functionality,” said Lewis.
So how is it powered?
Octopuses are a popular inspiration in the soft robotics field due to their strength and dexterous abilities, all without an internal skeleton.
The octobot is powered by gas under pressure. Inside of the bot, a transformation occurs in which a small amount of liquid fuel—in this case hydrogen peroxide—is converted into a large amount of gas that then flows into the octobot’s arms and inflates them like a balloon.
“Fuel sources for soft robots have always relied on some type of rigid components,” said Michael Wehner, a postdoctoral fellow in the Wood lab and co-first author of the paper. “The wonderful thing about hydrogen peroxide is that a simple reaction between the chemical and a catalyst—in this case platinum—allows us to replace rigid power sources.”
Once the team figured out how to power the bot with no components, it needed to determine how it would control the reaction. The researchers opted for a microfluidic logic circuit that possessed a soft analog of a simple electronic oscillator. This is what controls the time at which hydrogen peroxide decomposes to gas in the octobot.
“The entire system is simple to fabricate; by combining three fabrication methods—soft lithography, molding and 3-D printing—we can quickly manufacture these devices,” said Ryan Truby, a graduate student in the Lewis lab and co-first author of the paper.
Now that the researchers have discovered such a simple solution, they plan to upgrade the robot by providing it with new skills, such as crawling, swimming and interacting.
“This research is a proof of concept,” said Truby. “We hope that our approach for creating autonomous soft robots inspires roboticists, material scientists and researchers focused on advanced manufacturing.”