Autonomous and Fully Soft Robotic Octopus

The octopus is a fascinating creature. Without bones or any hard structures, it can accomplish amazing feats such as squeezing through spaces that are a fraction of their own size. Although soft robotics primarily is the engineering of robots with soft and compliant mechanisms and parts, the community has yet to see a robot that is like the octopus; completely soft, down to the means by which it is controlled. That is, until now. Robert Wood Ph.D. and Jennifer Lewis Sc.D. led research at the Harvard Wyss Institute that resulted in their paper, An integrated design and fabrication strategy for entirely soft, autonomous robots. The paper describes the process used to create an autonomous, untethered, entirely soft robot octopus, dubbed the Octobot.

Most autonomous and untethered pneumatic soft robots have been powered by electrical control systems that are composed of boards, pumps, valves, batteries, and more - all components that have hard elements. The Octobot is a pneumatic robot, yet uses none of these. The Octobot is controlled by a fluidic logic circuit that can alternate what parts of the robot are inflated based on the small fluid-based logic gates found in the robot's "head" (technically the mantle of an actual octopus). When the circuit switches, one of the fuel tanks at the back of the robot will let hydrogen peroxide pass through a platinum catalyst. The catalyst causes the hydrogen peroxide to break down rapidly, transforming into a gas and inflating certain tentacles. The tentacles are curled upwards by default, but bend downwards when inflated. Then the gas slowly deflates out of small vents in the front of the robot. When the circuit switches again, the other fuel cell powers a different set of tentacles in the same way. This cycle repeats itself until the fuel cells run out of hydrogen peroxide.

The Octobot is fabricated with three manufacturing techniques: soft lithography, casting, and 3D printing. First, a mold is made. Then the tentacles and fuel cell matrix are cast with a silicone material. The logic circuit is made with soft lithography and then placed inside of the mold. After that, the rest of the mold is cast. Then, an EMB3D 3D printing system prints all the traces and inflationary elements in a special ink. The mold (and everything in it) sits in an oven for four days, during which the ink has drains out of the robot, leaving empty space, and the silicone solidifies. Once demolded, the fuel chambers are filled through ports on the circuit and movement begins!

This research is quite valuable for a number of reasons. For example, autonomous soft robots can be used for applications like disaster relief and surgery. However, even a few hard parts can make such robots unusable for these high risk use-cases. With an entirely compliant robot, this problem is eliminated. I also see such robots being useful in applications such as hazardous material cleanup, in which electro-mechanical systems cannot be used due to the risk of a spark causing ignition. A robot entirely controlled by gas and liquid would have no such problem. Here at Super-Releaser, we find this kind of work extremely interesting and important, as topics such as untethered soft robots and new methods of pneumatic inflation can help advance the field of soft robotics tremendously.

-Aidan Leitch

Aidan Leitch