German researchers build robotic ear worm

Removing tumours from within the inner ear is a delicate process that typically requires the removal of the entire mastoid bone, the sponge like bone-structure which surrounds the inner and middle ear.

However, the creators of the tiny NiLiBoRo device (Non-linear Drilling Robot) claim their system, which is able to steer its way around sensitive tissues whilst it cuts a 5mm tunnel through the bone, could make the process far less invasive.

The system is being developed by researchers in the Mannheim Project Group for Automation in Medicine and Biotechnology, part of the Fraunhofer Institute for Production Technology and Automation IPA, in cooperation with the Technical University of Darmstadt, the University of Aachen, and the Düsseldorf University Clinic.

According to project group scientist Lennart Karstensen, whilst drilling machines capable of boring a tunnel through bone already exist, NiLiBoRo is the first one that can drill around corners as well.

Karstensen explained that the worm consists of a ‘head’ and a ‘tail’ section which are connected together by a flexible bellows mechanism, rather like an articulated passenger bus.

As it drills through the bone, a series of hydraulic lines enable the robot crawl forward in the right direction by first pumping hydraulic fluid into three bladders found in the rear section of the robot.

The bladders fill in the empty space between the worm and the bone and fix the rear section of the robot in place. The hydraulic fluid then travels into the bellows, causing the “accordion” to expand and pushing the head forward.

The worm stretches and presses its front section further into the bone and the drill attached to the head bores deeper inward.

Next, the bladders in the front section are pumped full of fluid to hold the front in place while the fluid in the rear bladders is evacuated. The rear section then retracts towards the head in a motion similar to that of a real worm.

As the robot drills its way forward, its path is precisely monitored by an electromagnetic tracking system, and its direction of travel is controlled by adjusting the bladders in the front section. “For instance, if we wanted to move left then we fill the left bladder with less fluid than the right, which will cause the robot to veer to the left,” explained Karstensen.

The team has already constructed an initial prototype, which is five times larger than the planned final version. They hope to have a miniature robot ready for testing by physicians in two years.