A team of engineers and scientists based at the STORM Lab at the University of Leeds has developed a proof of concept for a robot that can reach some of the smallest bronchial tubes in the lungs in order to take tissue samples or deliver cancer therapy. Known as a magnetic tentacle robot, it measures just two millimetres in diameter and will be guided into place from outside the patient using magnets.
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 ability of the device to navigate through lungs taken from a cadaver.
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Currently, doctors use an instrument called a bronchoscope – a flexible tube-like instrument, about 3.5–4 millimetres in diameter that’s passed through the nose or mouth – to examine the lungs and air passages. However, the instrument’s size limits its use to the upper levels of the bronchial tree.
Delving deeper requires passing a catheter measuring about two millimetres in diameter through the bronchoscope and then into the smaller tubes of the lungs. Here again doctors are limited in how they can move the bronchoscope, making it difficult to place the instrument and the catheter where they’re needed. It’s also often necessary to expose the patient to x-rays in order to determine the placement of the bronchoscope. The new magnetic tentacle robot is much more manoeuvrable and uses a robotic guidance system that’s personalised for each procedure.
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‘A magnetic tentacle robot or catheter that measures two millimetres 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,’ said Professor Pietro Valdastri, director of the STORM Lab, who supervised the research. ‘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.’
The robotic system had to be made small, flexible and able to navigate the twists and turns of the anatomy of the bronchial tree while also featuring an autonomous system to guide the robot into place. The researchers manufactured the robot from a series of interlinked cylindrical segments, each of which were two millimetres in diameter and around 80 millimetres in length. The segments were made of a soft elastomeric or rubber-like material that had been impregnated with tiny magnetic particles. These particles enable the interlinked segments to move somewhat independently under the effect of an external magnetic field, resulting in a highly flexible shape-shifting robot that is small enough to avoid snagging itself on structures within the lungs.
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Magnets mounted on robotic arms on the outside of the patient would be used to guide the device. The route through the bronchial tree would be planned based on pre-operative scans of the patient’s lungs and then programmed into the robotic system.Moving the magnets outside the patient would cause the catheter to change shape or direction, so the robot could be manoeuvred through the lungs. Once at the target location, the robot could be used to take a tissue sample or deliver treatment.
According to the researchers, it may be several years before the technology is available in a hospital setting.
The research has been published in Soft Robotics.