Tuesday, May 19, 2015

Octopus-inspired Robotic Arm Manipulates "Organs"

The strength and flexibility of an octopus arm has inspired Italian researchers from the Sant'Anna School of Advanced Studies to create a robotic tool that may assist in future keyhole surgeries.

An octopus-inspired robotic arm adapts to delicate objects in its environment.
Image courtesy of Tommaso Ranzani, The BioRobotics Group, Sant'Anna School of Advanced Studies

Much like the dexterous limb of an octopus, which can weave around corners and grasp objects, this prototype arm can perform multiple tasks at the same time, potentially reducing the number of tools needed in a surgery. By adjusting the stiffness in different parts of the same arm, the researchers hope to prevent damage to soft organs (represented by water balloons in their lab experiments).

"The human body represents a highly challenging and non-structured environment, where the capabilities of the octopus can provide several advantages with respect to traditional surgical tools," said lead author Tommaso Ranzani in an Institute of Physics press release.

These traditional surgical tools include single-purpose graspers, hook-like retractors, cameras, and pincer-like dissectors. With all of these tools, a single surgery can require larger or multiple incisions, with increased damage to the body.

"We believe our device is the first step to creating an instrument that is able to perform all of these tasks, as well as reach remote areas of the body and safely support organs around the target site," said Ranzani.

Wrapping and lifting an "organ" (water balloon) out of the way.
Image courtesy of Tommaso Ranzani, The BioRobotics Group, Sant'Anna School of Advanced Studies

In 2013 the team developed a basic robotic arm with one component that could move, bend, and stiffen. But the key to mimicking the flexibility of an octopus arm is a multi-component tool that can independently move and stiffen (or soften). Last Thursday, Ranzani and his colleagues presented their new two-component robotic arm in the journal Bioinspiration and Biomimetics.

This prototype arm is about 1.25 inches wide, 5.5 inches long, and covered in a gray silicon sheath, making it reminiscent of an elephant's trunk.

According to the team, this robotic arm may someday assist in surgeries by weaving through and supporting one organ out of the way, for example, and manipulating a second organ with the independent tip of the arm.

Coffee Jamming

These tasks are only possible if different sections of the arm can stiffen, bend, and stretch independently—a task that is powered by coffee grinds and air in this case.

In each section of the arm, coffee grinds fill a central, sealed pipe. To stiffen a particular section of the arm, air is sucked out of the pipe and the coffee grinds pack and lock tightly together in a transition known as jamming. To soften the section, air is simply allowed back in.

Jamming is observed in many types of granular materials, glasses, foams, and complex fluids and is similar to the phase transition between a fluid and a solid.

Each section of the arm can also bend up to 255 degrees away from straight and stretch up to 62 percent of its original size, thanks to three chambers spaced around the coffee core that inflate or deflate with air.

This video shows the arm in action, moving, twisting, and supporting various water balloons.

In the future, the team plan to link together many different sections into a much longer, more versatile arm. This octopus-inspired tool is part of a collaborative European Union project called Stiff-Flop.

By Tamela Maciel, also known as "pendulum"

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