A group of Japanese engineers are trying to get robots to imitate a very human expression: a smile.
They created a face mask from human skin cells and placed it on the robots using a new technique that hides the joint and is flexible enough to turn into a grimace or smile.
The effect is something between a scary Hannibal Lecter mask and a plasticine Gumby doll.
But the researchers say the prototypes point toward more sophisticated robots with an outer shell flexible and durable enough to protect the machine while appearing more human.
In addition to expressiveness, the “skin equivalent,” as scientists call it, made in the lab from living skin cells, has healing and self-healing abilities and can sustain burns, according to a study published June 25 in the journal Cell Reports Physical Science.
“Humanoid faces and expressions improve communication and empathy in human-robot interactions, making robots more effective in healthcare, service and social roles,” Shoji Takeuchi, a professor at the University of Massachusetts who led the study, said in an email.
The research comes at a time when robots are becoming increasingly ubiquitous in factories.
According to the International Federation of Robotics, 3.9 million industrial robots will be working on automotive and electronics assembly lines and in other work environments in 2022.
A subset of all robots includes so-called humanoids, machines designed with two arms and two legs that allow them to work in environments designed for human workers, such as factories, but also in hospitality, healthcare and education.
Carsten Heer, a spokesman for the federation, said humanoids were an “exciting area of development” but mass market adoption would be difficult and could be cost-constrained.
However, in October 2023, the Chinese government announced a goal to mass-produce humanoids by 2025, which is predicted to greatly increase its industrial productivity.
For decades, robotics engineers have experimented with materials, hoping to find something that could protect a robot’s complex machinery while still being soft and light enough for a wide range of uses.
In the paper, the researchers explain that if the robot’s surface is bumped or torn, it can affect the machine’s operation, making self-healing a “critical feature” for humanoid robots.
According to Kevin Lynch, director of the Center for Robotics and Biosystems at Northwestern University, the new skin attachment method represents an advance in the emerging field of “biohybrid” robotics, which integrates mechanical engineering with genetic and tissue engineering.
“This study is a breakthrough contribution to the problem of anchoring artificial skin to a substrate material,” Lynch explained, adding that “living skin may help us achieve the ultimate goal of self-healing skin in biohybrid robots.”
He added that the study does not address how the robots’ skin will heal without external support.
For this type of robot, the problem of materials extends to believability; That is, finding a way for a machine to have features that make it look and act more like a human being, such as the ability to smile.
Scientists, including Takeuchi and his colleagues at the University of Tokyo, have been working with lab-made human skin for years.
In 2022, a research team developed a robotic finger covered in living skin that allowed it to bend like a human finger, giving it the sensitivity needed to perform more precise tasks.
Takeuchi’s team tried to secure the skin with tiny hooks, but they tore as the robot moved. So the team decided to mimic ligaments, the tiny strings of loose tissue that connect bones.
Team members drilled small V-shaped holes into the robot and applied collagen gel to seal the holes and secure the artificial skin to the robot.
“This strategy gives traditional rigid robots a soft biological skin, making them more ‘humanoid,'” said Yifan Wang, an associate professor in the School of Mechanical and Aerospace Engineering at Nanyang Technological University in Singapore, who researches “soft robots” that mimic biological creatures.
The skin bond also gives the bio-hybrid robot the ability to produce sensations, bringing science one step closer to sci-fi fantasy.
“This could create opportunities for the robot to feel and safely interact with humans,” Wang explained.
The artificial-skinned robot faces in Takeuchi’s lab cannot perceive touch, temperature changes, or other external stimuli.
Takeuchi noted that this was another goal of his research.
“We want to create skin that mimics the functionality of real skin by slowly building up basic components such as blood vessels, nerves, sweat glands, sebaceous glands and hair follicles,” he said.
Instead of the neural systems that transmit sensations in the human body, the robot’s electronics would have to feed the sensor signal, which Wang said would require much more time and research to develop.
An image by Shoji Takeuchi shows how a group of Japanese scientists used living skin cells to make a flexible 3D facial mold for a robot. (Shoji Takeuchi via The New York Times)
Shoji Takeuchi’s image shows how a Japanese research team managed to attach living skin to a moving robot. (Shoji Takeuchi via The New York Times)
