A team of researchers from the University of Toronto in Canada has created miniature magnet-powered tools for keyhole brain surgery that promises faster recovery, reduced pain and minimal scarring versus traditional methods.

According to its developers, the robotic tools, which measure just 0.1 inch in diameter, can grip, pull and cut tissue. The tools are tiny because they are powered not by motors but by external magnetic fields.

Source: Tyler IrvingSource: Tyler Irving

The team explained how current robotic surgical tools that replicate the human hand via cable-driven systems much like tendons that move fingers using muscles in the wrist, tend to break down at smaller length scales.

“The smaller you get, the harder you have to pull on the cables,” the researchers explained. “And at a certain point, you start to get problems with friction that lead to less reliable operation.”

Instead, the team’s new tools use magnetically responsive materials rather than cables and pulleys, which allows surgeons to guide them via external electromagnetic fields. The team explained that the system is composed of two parts: the tiny set of tools featuring a gripper, scalpel and forceps, and a coil table featuring built-in electromagnetic coils for controlling their movement.

“We can now replicate the wrist and hand movements of a surgeon on a centimeter scale, and these tools are widely used in surgeries that take place in the torso,” the team added. “But when it comes to neurosurgery, we are working with an even more restrictive space.”

The setup of the system involves the patient’s head placed over electromagnetic coils while the robotic tools enter the brain through a minimally invasive cut. The magnetic fields can be controlled by adjusting the level of electricity delivered to the coils, thereby encouraging the tools to grip, pull or cut tissue as desired.

To test the tools, the team built a life-sized brain model composed of silicone rubber that mimics the shape and structure of a real human brain. Small chunks of tofu and bits of raspberries were then used to replicate the mechanical properties of the brain tissue the tools are intended to operate on.

“The tofu is best for simulating cuts with the scalpel, because it has a consistency very similar to that of the corpus callosum, which is the part of the brain we were targeting,” the team added. “The raspberries were used for the gripping tasks, to see if we could remove them in the way that a surgeon would remove diseased tissue.”

The magnetic scalpel produced consistent, narrow cuts averaging 0.3 mm to 0.4 mm — which translates to greater precision than traditional hand tools that ranged from 0.6 mm to 2.1 mm. Further, the grippers achieved a 76% success rate in picking up the target.

The study, "Magnetically actuated dexterous tools for minimally invasive operation inside the brain," appears in the journal Science Robotics.

To contact the author of this article, email mdonlon@globalspec.com