Octopus tentacles inspire new robotic arm for surgery

Octopus tentacles have inspired the creation of a flexible robotic arm for surgeons that can access hard-to-reach regions of the body.

The mechanical arm is designed to bend, stretch and squeeze its way past obstacles and manipulate soft organs without damaging them.

Scientists believe the Italian-made device could make operations less invasive by reducing the number of instruments and entry incisions needed.

A key advantage is its ability to switch quickly from being bendy and flexible to stiff and rigid - a trait shared with the octopus.

The cephalopod has eight arms, or tentacles, with no rigid skeletal support that can adapt to any surrounding environment by twisting, bending and changing length.

But at the same time, the octopus can vary the stiffness of its arms, temporarily making parts of them rigid in order to move and interact with objects.

The artificial “tentacle” uses a system that involves selectively inflating cylindrical chambers to make it bend and stretch in different directions.

Stiffness is controlled by filling a flexible membrane with a granular material. When a vacuum is applied, its density increases and the membrane becomes rigid.

‘Octopus capabilities’

Lead researcher Dr Tommaso Ranzani, from the Sant'Anna School of Advanced Studies in Pisa, said: "'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.

“Generally, the octopus has no rigid structures and can thus adapt the shape of its body to its environment. Taking advantage of the lack of rigid skeletal support, the eight highly flexible and long arms can twist, change their length, or bend in any direction at any point along the arm.”

In tests the robot arm could be bent to angles of up to 255 degrees and stretch by up to 62 per cent of its original length.

Stiffness increases of between 60 per cent and 200 per cent were also achieved.

The ability of the robotic arm to manipulate internal body parts was successfully demonstrated in simulated scenarios, with water-filled balloons representing organs.

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

“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 research is reported in the Institute of Physics journal, Bioinspiration and Biomimetics.