Magnetic tentacle robot navigates smallest bronchial tubes

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A magnetic tentacle robot could one day take tissue samples or deliver targeted cancer therapy to the smallest bronchial tubes in the lungs. 

This is the claim of engineers, scientists and clinicians at the STORM Lab at Leeds University who have developed the proof-of-concept robot that measures 2mm in diameter.

The team is pioneering the use of robotic systems to assist in endoscopy and catheter procedures and their current findings have been published in Soft Robotics.

The proof of concept was based on laboratory tests involving a 3D replica of a bronchial tree modelled from anatomical data. The next phase of the research will investigate the effectiveness of the device in navigating lungs taken from a cadaver.

Currently, doctors use a bronchoscope to carry out an examination of the lungs and air passages. The procedure involves passing a flexible tube-like instrument measuring around 3.5 to 4mm in diameter through the nose or mouth and into the bronchial passages.

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Because of its size, the bronchoscope can only travel as far as the upper levels of the bronchial tree. From there, a catheter measuring about 2mm in diameter is passed through the bronchoscope and then into the smaller tubes of the lungs.

Doctors are limited in how they can move a bronchoscope, making it difficult to navigate the instrument and the catheter to where they are needed.

According to Leeds University, the magnetic tentacle robot has been developed to be much more manoeuvrable and uses a robotic guidance system that is personalised for each procedure.

In a statement, Professor Pietro Valdastri, director of the STORM Lab who supervised the research, said: “A magnetic tentacle robot or catheter that measures 2mm and whose shape can be magnetically controlled to conform to the bronchial tree anatomy can reach most areas of the lung, and would be an important clinical tool in the investigation and treatment of possible lung cancer and other lung diseases.

“Our system uses an autonomous magnetic guidance system which does away for the need for patients to be X-rayed while the procedure is carried out.”

To develop the robotic system, the research team had to make a device that was small, flexible and able to navigate the the anatomy of the bronchial tree. They then needed an autonomous system to guide the magnetic tentacle robot into place.

Magnetic tentacle robot
The image shows a life-size model of part of a bronchial tree built from anatomical data. A section of the magnetic tentacle robot is seen on the right (Image: Leeds University)

To reduce the size of the robot while retaining controllability of motion, the researchers manufactured it from a series of interlinked cylindrical segments, each 2mm in diameter and around 80mm in length. The segments were made of a soft elastomeric material impregnated with magnetic particles.

Because of the presence of the magnetic particles, the interlinked segments can move somewhat independently under the effect of an external magnetic field. The result is a magnetic tentacle robot which is highly flexible, able to shape shift and small enough to avoid catching on anatomical structures in the lungs.

Magnets mounted on robotic arms on the outside of the patient would be used to guide the device into the lungs in a process that would be suitable for each procedure.

The route through the bronchial tree is planned from pre-operative scans of a patient’s lungs and programmed into the robotic system. As the magnets outside of the patient move, they develop forces on the magnetic particles in the segments of the catheter, causing them to change shape or direction - enabling the robot to be manoeuvred through the lungs and to a site of a suspicious lesion.

Once at the target location, the robot is used to take a tissue sample or deliver treatment.

The team caution that the magnetic tentacle robot may be several years from being rolled out in hospitals.