Japanese engineers are trying to get robots to imitate a uniquely human facial expression: smiling.
They created a face mask from human skin cells and attached it to the robot using a new technique that hides the connections and is flexible enough to frown or smile.
The effect is somewhere between the terrifying mask of Dr. Hannibal Lecter and a claymation Gumby.
But scientists say the prototype paves the way for more sophisticated robots that are resilient and durable enough to protect the machines, and have an outer layer that gives them a more human-like appearance.
In a study published June 25 in the journal Cell Reports Physical Science, the researchers said the product, which they called a “skin equivalent” and was made in a lab from living skin cells, is expressive, can be scratched and burned, and can heal itself.
“Human-like faces and expressions can improve communication and empathy in human-robot interactions, making robots more effective in medical, service and companion roles,” Shoji Takeuchi, a professor at the University of Tokyo and the study's lead researcher, said in an email.
The research comes as robots become increasingly prevalent on factory floors.
According to the International Federation of Robotics, there were 3.9 million industrial robots working on automotive and electronics assembly lines and other workplaces in 2022.
The whole robotics part includes so-called humanoids: two-armed, two-legged machines designed to work in environments made for human workers, such as factories, but also in hospitality, healthcare, education, and more.
Alliance spokesman Carsten Hehr said humanoid robots were an “exciting area of ​​development” but introducing them on the mass market could be complex and cost-constrained.
Nevertheless, in October 2023, the Chinese government announced a goal of mass-producing humanoids by 2025, predicting that this would significantly increase industrial productivity.
For decades, roboticists have experimented with materials, hoping to find one that would protect the complex mechanisms of their robots while also being soft and light enough for a wide range of applications.
The ability to self-repair is a “critical capability” for humanoid robots, as scratches or dents on the robot's surface can lead to mechanical failure, the researchers wrote in their paper.
Kevin Lynch, director of Northwestern University's Center for Robotics and Biosystems, said the new skin adhesion method advances the emerging field of “biohybrid” robotics, which combines mechanical engineering with genetic and tissue engineering.
“This work is an innovative contribution to the problem of anchoring artificial skin to base materials,” Professor Lynch said, adding that “living skin may help achieve the ultimate goal of self-healing skin for biohybrid robots.”
He added that the study did not address whether the robotic skin would heal on its own without outside assistance.
For these robots, the materials challenge extends to believability: finding ways to imbue machines with traits that make them look and behave more like humans, such as the ability to laugh.
Scientists, including Professor Takeuchi of the University of Tokyo and his colleagues, have been studying laboratory-grown human skin for years.
In 2022, a team of researchers developed a robotic finger covered in living skin, allowing the mechanical finger to bend like a human finger and giving it a sense of touch that allows it to perform more precise tasks.
Takeuchi's team tried to fasten the skin with tiny hooks, but they found that the skin tore when the robot moved, so they decided to mimic ligaments, the tiny, loose strings of tissue that connect bones.
Team members drilled small V-shaped holes in the robot and applied a collagen-containing gel to seal the holes and secure the artificial skin to the robot.
“This approach integrates soft biological skin onto a traditionally rigid robot, making it 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 biomimetic “soft robots.”
Skin bonding also gives bio-hybrid robots the potential for sentience, bringing science one step closer to sci-fi fantasy.
“This could create opportunities for robots to sense humans and interact with them safely,” Wang said.
The robotic face equipped with artificial skin in Professor Takeuchi's laboratory does not have the ability to sense external stimuli such as touch or temperature changes.
Professor Takeuchi said that this is his next research goal.
“By gradually building up essential components such as blood vessels, nerves, sweat glands, sebaceous glands and hair follicles, we aim to create skin that closely mimics the function of real skin,” he said.
Instead of a nervous system transmitting sensations in the human body, a robot's electronics would need to power the sensor signals, something Wang said would take more time and research to develop.