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The robot that unfolds inside the abdomen

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The start-up company NISI (HK) Limited is currently developing a miniature surgical robot that can be inserted though natural openings in the body and unfolds inside the abdomen. To achieve this goal, the engineers are pushing components to their limits and beyond.

A pioneering robot for minimally invasive surgery

Astonishing new developments are shaking up the world of medtech. The surgical robot sector, in particular, is seeing some major changes. In summer 2018, the Hong Kong-based startup NISI announced that it had successfully performed a series of gynecological operations on live pigs. This may not sound like anything special at first, but the technique deployed was innovative indeed. The surgeons used a small robot that had been inserted rectally. This was a world’s first in medical history, according to the company.

NISI was founded in 2012 and works with the universities of Hong Kong and Cambridge to develop a robotic system that enables complex, minimally invasive surgeries in the abdominal and pelvic area without leaving visible scars. “We want to become the world’s leading expert in non-invasive surgical robotic technology,” said Dr. Corinna Ockenfeld at NISI. The successful surgeries in the summer of 2018 have given the start-up a lot of momentum. Initial surgeries on humans are planned for 2021.

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A high-tech surgical system

The idea behind NISI’s novel surgical system is as follows: The surgical robot is inserted through a natural orifice, usually the anus or the vagina. Only a small cut inside the body is necessary to get multiple robotic instruments inside the abdomen. Current systems require several incisions, one for each instrument. This new technology consequently has many benefits: less blood loss during surgery, fewer wound-related complications, shorter recovery time for the patient, and no visible scars.

The robot itself has two small arms that unfold inside the abdomen and can be controlled by the surgeon using a control panel. The two robotic arms are directly controlled by micromotors from maxon and have up to eight degrees of freedom. The system also has a high-resolution 2D and 3D camera and delivers haptic feedback, so that the surgeon is able to feel what is happening at the other end and can work with even higher precision.

Quality of the motorized components is a key element

Bringing surgical robots to the next level of technology requires more than outstanding technicians and engineers: Quality components are a key element too. NISI is therefore testing various concepts and combinations of components. “We want to push the boundaries of medical and robotic technology,” said Dr. Corinna Ockenfeld. With regard to the motors, this requires an extremely small size and extremely high power density. “We are working closely with maxon and have a weekly exchange of information. We really appreciate the support we’ve received over the past years. The collaboration with maxon is highly productive and extremely valuable for both sides.” 

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The prototypes of the NISI surgical robotic system currently use various brushless DC motors from the EC series, with diameters ranging from 4 to 8 millimeters, complemented by matching gearheads. Both partners are pushing the precision drives to their limits, sometimes running them outside the nominal specifications. However, the BLDC motors are customized for the application’s specific needs. They require high power density, and must fulfill extremely strict quality standards and be sealed against body fluids. In the future, the drives will also be biocompatible.

The next steps are to make the entire system even smaller, to make the motors even more dynamic, and to expand the working range of the robot. “We take care of every little detail and take innovative approaches to solving problems,” explained Dr. Corinna Ockenfeld. Step by step, NISI is coming closer in fulfilling its vision of making non-invasive surgery without scars a commonplace reality.

Author: maxon France

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