HANGZHOU, Nov. 29 (Xinhua) -- "Why not tie a slipknot?" A mechanical scientist proposed this simple idea to surgeons in a lab at east China's Zhejiang University.

That innovation, which seemed almost too straightforward, has now matured into a cover story this week in the journal Nature, titled "Knot Exactly," offering a potential solution to a persistent problem in robotic surgery: how to close a wound with exactly the right amount of force.

In robotic-assisted surgeries, surgeons tend to lose the tactile feedback, or the "feel" they rely on in traditional open surgery, to judge how tightly to pull a suture knot. A knot tied too loosely can lead to leaks; one tied too tightly can cut off the blood supply, causing tissue damage.

Instead of developing complex electronic sensors, an interdisciplinary team from Zhejiang University took inspiration from fundamental mechanics. Their solution, named "Sliputure," is a special suture with a pre-tied slipknot incorporated in it.

The principle is elegantly simple. The slipknot is designed to unravel at a specific, predetermined force. As a surgical robot pulls the suture tight, the slipknot holds until the precise optimal force is reached, at which point it releases.

The same action relays that specific force to the surgical permanent knot being tied nearby, so the robot halts with just the right amount of tension, according to the study.

"If a slipknot is tandem-linked to a dead knot on the same suture, they can share the tensile load," said Li Tiefeng, one of the study's corresponding authors.

The team prefabricated 500 slipknots, mined data from surgeons of every seniority level, across materials and styles, then modeled and spun hundreds of sutures, each carrying a unique knot that opens at a precise load. The slipknot mechanism demonstrated remarkable consistency, with a force-release precision of 95.4 percent across hundreds of tests.

In surgery, surgeons are allowed to choose the slipknot that best suits their case. The study shows that the invention has boosted novice surgeons' knot force accuracy by 121 percent, enabling them to tie knots indistinguishable from those of veterans.

In mouse bowel repairs, the device locked each knot at a shoelace-light 1.3 newtons, half the 2 to 3 newtons force of an unguided robot, sealing leaks without choking blood flow and accelerating healing.

In a rat colon injury model, the smart-suture group reached healthy healing 2 days earlier than controls and showed a richer blood supply. For surgical robotics, the team added vision-based detection: the moment the camera detects the slipknot release, the robotic arm stops itself -- automatically and without extra hardware.

The innovation is valuable for its simplicity and reliability. Unlike sensor-based systems, it requires no electricity, complex electronics, or computer algorithms, making it potentially cheaper, easier to sterilize, and usable in challenging environments, such as remote areas and even deep-sea or space missions.

The team also built a fully automated slip-knot line that churns out identical, shelf-ready sutures at scale. Enditem