Autonomous octobot is first 3D-printed entirely soft robot

Soft robotics could revolutionise how humans interact with machines, but researchers have long struggled to build entirely compliant robots.

Electric power and control systems such as batteries and circuit boards are rigid and until now soft-bodied robots have been either tethered to an off-board system or rigged with hard components.

"One long-standing 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 Harvard University’s Robert Wood who worked on the project.

“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."

Professor Jennifer A. Lewis, who was also involved in octobot’s development, said: "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."

"The octobot is a simple embodiment designed to demonstrate our integrated design and additive fabrication strategy for embedding autonomous functionality."

Octopuses have long been a source of inspiration in soft robotics due to their strength and dexterity, despite having no internal skeleton.

Harvard's octobot is pneumatic-based and is powered by gas under pressure. A reaction inside the bot transforms a small amount of liquid fuel (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," said Michael Wehner, co-first author of a paper on the device. "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."

To control the reaction, the team used a recently developed microfluidic logic circuit, which is a soft analogue of a simple electronic oscillator that controls when the hydrogen peroxide decomposes to gas in the octobot.

"The entire system is simple to fabricate. By combining three fabrication methods - soft lithography, moulding and 3D printing - we can quickly manufacture these devices," said Ryan Truby, a graduate student who worked on octobot.

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.

"This research is a proof of concept," Truby said. "We hope that our approach for creating autonomous soft robots inspires roboticists, material scientists and researchers focused on advanced manufacturing,"

In December 2015, E&T took a closer look at soft robots and what they could mean for the future of robotics.