During an experiment, water-filled balloons simulated organs inside human body

Octopus-inspired robot arm to revolutionise keyhole surgery

Italian researchers have created a flexible soft robotic arm inspired by the tentacles of an octopus that could improve safety of surgical operations.

Described in the latest issue of the Bioinspiration and Biomimetics journal, the device mimics the ability of an octopus tentacle to flex, twist and stretch throughout its length in order to smoothly adapt to the environment.

In the context of the human body, this ability would allow the doctors to navigate around organs without damaging them towards the area that requires intervention.

“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 Tommaso Ranzani, from the Sant’ Anna School of Advanced Studies in Pisa, Italy, the lead author of the study.

“Generally, the octopus has no rigid structures and can thus adapt the shape of its body to its environment.”

But surgical tools can’t be just soft and gentle. To remove an infected part or a tumour, sharp and rigid instruments are required. The research thus looked into another capability of the octopus – its ability to temporarily adjust the stiffness of its limbs.

“Traditional surgical tasks often require the use of multiple specialized instruments such as graspers, retractors, vision systems and dissectors, to carry out a single procedure,” Ranzani explained.

“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.”

The idea is that one part of the octopus-like arm could work in the soft mode, safely avoiding all organs in the way, while the other could switch into the rigid mode to perform the actual surgery.

This all-in-one approach would allow the surgeons to reduce the number of incisions required to get instruments inside the body, providing many tangible benefits to the patients including smaller scars.

To achieve this ability to switch from soft to rigid, the researchers made the device from two interconnecting modules. Each of the modules moves forward by inflating three cylindrical chambers, equally spaced inside. By alternating and combining the inflation of the three chambers, the module could be made to bend and stretch in various directions.

Inside the module is a flexible membrane that can be filled with fine granular material. When vacuum is applied to the membrane, its density increases and the whole membrane becomes rigid.

The researchers tested their device successfully in a series of experiments. Instead of a real body, though, they navigated around water filled balloons.

The tests showed the arm can bend to angles of up to 255° and stretch to up to 62 per cent of its initial length. The stiffening mechanism was able to provide stiffness increases from 60 to 200 per cent.

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