In Japan, engineers are trying to make robots imitate a uniquely human expression: the smile.
They created a face mask from human skin cells and attached it to robots using a new technique that hides the bond and is flexible enough to transform into a grimace or a soft smile.
The effect is halfway between the terrifying Hannibal Lecter mask and the claymation figurine of Gumby.
But scientists say the prototypes pave the way for more sophisticated robots, with an outer layer that is elastic and strong enough to protect the machine while making it more humane.
The “skin equivalent,” as researchers call it, made from living skin cells in the lab can scar, burn, and even heal itself, according to a study published June 25 in the journal Cell Reports Physical Science.
“Human-like faces and expressions enhance communication and empathy in human-robot interactions, making robots more effective in healthcare, service, and companionship roles,” Shoji Takeuchi, a professor at the University of Tokyo and the study's lead researcher, said in an interview by email.
The research comes at a time when robots are becoming more ubiquitous in factories.
According to the International Federation of Robotics, as of 2022 there were 3.9 million industrial robots working on automotive and electronics assembly lines and other work environments.
A subset of the total robot fleet includes so-called humanoids, machines with two arms and two legs that allow them to work in environments designed for human workers, such as factories, but also in the hospitality, healthcare and manufacturing sectors. 'instruction.
Carsten Heer, a spokesperson for the federation, said humanoids were “an exciting area of development” but that mass adoption would be complex and could be limited by costs.
However, in October 2023, the Chinese government announced a goal of mass-producing humanoids by 2025, which it predicted would significantly increase its industrial productivity.
For decades, robotics engineers have experimented with different materials, hoping to find something that could protect a robot’s complex mechanisms but was also soft and lightweight enough for a wide range of uses.
If a robot's surface becomes dented or scratched, it can cause the machine to malfunction, making the ability to self-repair a “critical feature” for humanoid robots, the researchers said in the paper.
The new method of attachment to the skin advances the nascent field of “biohybrid” robotics, which integrates mechanical engineering with genetic and tissue engineering, said Kevin Lynch, director of the Center for Robotics and Biosystems at Northwestern University.
“This study is an innovative contribution to the problem of anchoring artificial skin to the underlying material,” Professor Lynch said, adding that “living skin could help us achieve the Holy Grail of self-healing skin in biohybrid robots.”
He added that the study does not address how the robots' skin self-heals without external support.
For these robots, the materials challenge extends to verisimilitude: finding ways to give the machine features that make it look and behave more like a human, such as the ability to smile.
Scientists, including Professor Takeuchi and his colleagues at the University of Tokyo, have been working with laboratory-created human skin for years.
In 2022, the research team developed a robotic finger covered in living skin, allowing the machine finger to bend like a human finger, giving it the tactility needed to potentially perform more precise tasks.
Professor Takeuchi's team had tried anchoring the skin with mini-hooks, but these caused tears as the robot moved. So the team decided to mimic ligaments, the small cords of loose tissue that connect bones.
Team members drilled small V-shaped holes in the robot and applied a collagen-containing gel, which plugged the holes and attached the artificial skin to the robot.
“This approach integrates traditional rigid robots with soft, biological skins, making them more 'human-like,'” said Yifan Wang, an assistant professor in the school of mechanical and aerospace engineering at Nanyang Technological University in Singapore who researches “robots soft” that imitate biological creatures.
Skin bonding also gives a biohybrid robot the potential to create sensations, taking science one step closer to sci-fi fantasy.
“This could create opportunities for the robot to safely perceive and interact with humans,” Professor Wang said.
The faces of the artificial-skinned robots in Professor Takeuchi's lab lack the ability to sense touch, temperature changes or other external stimuli.
Professor Takeuchi said this will be his next research focus.
“Our goal is to create skin that closely mimics the functionality of real skin, gradually building essential components such as blood vessels, nerves, sweat glands, sebaceous glands and hair follicles,” he said.
Instead of neural systems transmitting sensations in a human body, a robot's electronics would need to feed a sensor signal, a development that Professor Wang said would require much more time and research.