TOKYO: Japanese scientists have used human cells to develop an equivalent to living skin that can be attached to robotic surfaces to flash a realistic if creepy smile.

The University of Tokyo researchers published their findings this week along with a video of the gooey-looking pink material being stretched into an unsettling grin.

They used a `skin-forming cell-laden gel` to create a `robot covered with living skin`, their study in the journal Cell Reports Physical Science said.

The biohybrid robot specialists hope the technology will one day play a role in the invention of androids with human-like appearances and abilities.

`We also hope this will help shed better light on wrinkle formations and the physiology of facial expressions,` and help to develop transplant materials and cosmetics, the team led by profes-sor ShojiTakeuchisaid.

The new material could signal a departure from traditional humanoid robots covered with genuine-looking skin often made of silicone rubber, which cannot sweat or heal itself.

The scientists` goal is `to endow robots with the self-healing capabilities inherent in biological skin`, but they are not there yet. In previous studies they grafted collagen onto a cut on lab-grown skin covering a robotic finger to demonstrate how it could be repaired.

But they said conducting similar repair tests on their smiling robotic skin `is a future challenge`.

To create what they described as a `natural smile` that moves fluidly, they gelatinised the skin-like tissue and fixed it inside the robot`s holes, a method inspired by real human skin ligaments.-AFP