When Dr. Homoud Aldahash started the three-hour process of removing a tumor about the size of a walnut from a patient's brain, it was an experience unlike any other in his 25 years as a neurosurgeon. It wasn't Aldahash's gloved hands slicing 68-year-old Mohammed Almutrafi's right frontal lobe, but surgical instruments attached to a set of robotic arms, which Aldahash controlled from a console where he sat three meters away.
Researchers at Zhejiang University in Hangzhou, China, figured out how to precisely control a knot's geometry and friction so that they could 'program' it to open when tugged on with a given force. This allows a surgeon - or a robot - stitching up a wound to pull a suture closed with just the right amount of force, simply by tugging the free end of the knotted thread and stopping when the knot unfurls.