Autonomous, entirely soft robot

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Powered by a chemical reaction, controlled by microfluidics, 3D-printed octobot has no electronics.

An octobot with fluorescently dyed fugitive inks (red, not auto-evacuated) and hyperelastic actuator layers (blue) fabricated by molding and EMB3D printing.
Photo credit: Lori Sanders/Harvard University

Harvard University researchers have demonstrated the first autonomous, untethered, entirely soft robot. This small, 3D-printed robot – nicknamed the octobot – could pave the way for a new generation of completely soft, autonomous machines.

Soft robotics could revolutionize how humans interact with machines. But researchers have struggled to build entirely compliant robots. Electric power and control systems – such as batteries and circuit boards – are rigid. Until now, soft-bodied robots have been either tethered to an off-board system or rigged with hard components.

Robert Wood, Charles River Professor of Engineering and Applied Sciences; and Jennifer A. Lewis, Hansjorg Wyss Professor of Biologically Inspired Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), led the research. Lewis and Wood are also core faculty members of the Wyss Institute for Biologically Inspired Engineering at Harvard University.

“The struggle has always been in replacing rigid components like batteries and electronic controls with analogous soft systems and then putting it all together,” Wood says. “This research demonstrates that we can manufacture the key components of an entirely soft robot, which lays the foundation for more complex designs.”

“Through our hybrid assembly approach, we were able to 3D print each of the functional components required within the soft robot body, including the fuel storage, power, and actuation, in a rapid manner,” Lewis says. “The octobot is a simple embodiment designed to demonstrate our integrated design and additive fabrication strategy for embedding autonomous functionality.”

Since octopuses can perform feats of strength and dexterity with no internal skeleton, they have been a source of inspiration in soft robotics.

Harvard’s pneumatic-based octobot is powered by gas under pressure. A reaction inside the bot transforms a small amount of liquid hydrogen peroxide into a large amount of gas, which 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,” states Michael Wehner, a postdoctoral fellow in the Wood lab and co-first author of the paper. “The 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.”

To control the reaction, the team used a microfluidic logic circuit based on work by co-author and chemist George Whitesides, the Woodford L. and Ann A. Flowers University Professor and core faculty member of the Wyss. The circuit, a soft analog of a simple electronic oscillator, controls when hydrogen peroxide decomposes to gas in the octobot.

“The entire system is simple to fabricate. By combining three fabrication methods – soft lithography, molding, and 3D printing – we can quickly manufacture these devices,” says Ryan Truby, a graduate student in the Lewis lab and co-first author of the paper.

The simplicity of the assembly process paves the way for more complex designs. Next, the Harvard team hopes to design an octobot that can crawl, swim, and interact with its environment.

The paper was co-authored by Daniel Fitzgerald of the Wyss Institute and Bobak Mosadegh of Cornell University. The research was supported by the National Science Foundation through the Materials Research Science and Engineering Center at Harvard and by the Wyss Institute.

Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS)

Wyss Institute for Biologically Inspired Engineering at Harvard University