Scientists have made a robotic face smile with real human skin in a breakthrough that could lead to grafts onto humanoids.

Researchers at the University of Tokyo discovered how to bind lab-grown skin to mechanical faces allowing the robots to make human-like facial expressions.

They said the breakthrough will pave the way for creating more convincing humanoid robots – bringing increased mobility and embedded sensing capabilities.

The engineering feat also holds promise for the cosmetics industry and for the training of plastic surgeons, scientists said.

According to the scientists, the skin is not only soft but can repair itself if damaged, by copying human skin ligaments.

The team had previously attempted to use mini hooks as anchors but they ripped the experimental skin when the robot moved.

To recreate the stretchy ligaments in human skin, they drilled small holes into the robot’s face and used a collagen gel to secure the lab-engineered skin on top.

Prof Shoji Takeuchi, the lead researcher, said: “By mimicking human skin-ligament structures and by using specially made V-shaped perforations in solid materials, we found a way to bind skin to complex structures.

“The natural flexibility of the skin and the strong method of adhesion mean the skin can move with the mechanical components of the robot without tearing or peeling away.”

Prof Takeuchi, a pioneering researcher in the field of biohybrid robotics, hopes to improve the realness and thickness of the skin by adding sweat glands, pores, blood vessels, fat and nerves.

Another important challenge, he explained, will be “creating humanlike expressions by integrating sophisticated actuators, or muscles, inside the robot.”

His lab has already created robots capable of walking using biological muscle tissue, 3D lab-grown meat and self-healing artificial skin.

Earlier this month, EXROBOTS, a Chinese company, revealed their hyper-realistic humanoid robot heads that can mimic facial expressions and emotions.

Complete with smiles, beards, and the ability to stick out their tongues, their creators say the £162,600 humanoids are among the most advanced in the world.