Engineers in Japan have made significant strides in the quest to create robots that can replicate human expressions, particularly the smile. They have successfully developed a face mask from human skin cells and attached it to robots using an innovative technique. This method not only conceals the bindings but is also flexible enough to form expressions ranging from a grimace to a squishy smile.

The result of this development is a face that is somewhat reminiscent of both Hannibal Lecter’s mask and the Claymation character Gumby. However, scientists believe that these prototypes are paving the way for more sophisticated humanoid bots. These robots will have an outer layer that is both elastic and durable, protecting the machine while making it appear more human.

Breakthrough in artificial skin technology

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Beyond expressiveness, the “skin equivalent” developed by researchers is made from living skin cells in a laboratory. This artificial skin can scar, burn, and even self-heal, according to a study published on June 25 in the journal Cell Reports Physical Science. “Human-like faces and expressions improve communication and empathy in human-robot interactions, making robots more effective in healthcare, service, and companionship roles,” explained Shoji Takeuchi, a professor at the University of Tokyo and the study’s lead researcher.

This research comes at a time when robots are becoming increasingly common in industrial settings. In 2022, there were approximately 3.9 million industrial robots working on auto and electronics assembly lines and other environments, according to the International Federation of Robotics.

The rise of humanoid robots

A subset of these robots includes humanoids, which are machines designed with two arms and two legs to operate in environments built for human workers. These humanoid robots are used in various fields, including hospitality, healthcare, and education. Carsten Heer, a spokesman for the federation, mentioned that humanoids represent an exciting area of development, although mass market adoption could be challenging due to cost constraints.

Despite these challenges, the Chinese government announced in October 2023 a goal to mass-produce humanoid robots by 2025. This move is expected to significantly boost industrial productivity in the country.

Innovative materials for robot protection

For decades, robotic engineers have been experimenting with various materials to find a solution that protects a robot’s complex machinery while being soft and light enough for diverse applications. If a robot’s surface is damaged, it can lead to machine malfunctions, making the capacity for self-repair a critical feature for humanoid robots.

The new method of attaching artificial skin advances the emerging field of biohybrid robotics, which combines mechanical engineering with genetic and tissue engineering. Kevin Lynch, director of the Center for Robotics and Biosystems at Northwestern University, praised the study as an innovative contribution to anchoring artificial skin to underlying materials. He noted that living skin might help achieve the goal of self-healing skins in biohybrid robots.

However, Lynch pointed out that the study does not address how the robots’ skin will self-heal without external support. The challenge for these robots extends to achieving verisimilitude—making the machine appear and behave more like a human, including the ability to smile.

Advancements in robotic skin technology

Scientists, including Professor Takeuchi and his team at the University of Tokyo, have been working with lab-made human skin for years. In 2022, they developed a robotic finger covered in living skin, allowing the digit to bend like a human finger and potentially perform more precise tasks. Initially, the team used mini-hooks to anchor the skin, but these caused tears as the machine moved. They then decided to mimic ligaments, the loose tissue ropes that connect bones, by drilling small V-shaped holes into the robot and applying a collagen gel. This method tethered the artificial skin to the machination effectively.

“This approach integrates traditional rigid robots with soft, biological skins, making them more ‘humanlike,'” said Yifan Wang, an assistant professor at Nanyang Technological University in Singapore, who researches soft robots that mimic biological creatures. The skin binding also gives biohybrid robots the potential for sensation, bringing science one step closer to sci-fi fantasies.

Future prospects in robot skin research

Currently, the faces of the robots in Professor Takeuchi’s lab do not have the capability to sense touch, temperature changes, or other external stimuli. However, this is the next research target for Takeuchi’s team. “We aim to create skin that closely mimics the functionality of real skin by gradually constructing essential components such as blood vessels, nerves, sweat glands, sebaceous glands, and hair follicles,” he said.

To achieve this, a robot’s electronics would need to power sensor signals, a development that Professor Wang noted would require much more time and research. Nonetheless, the findings published by the University of Tokyo researchers mark a significant step forward in the development of robots with real human faces, advancing the integration of living skin cells with robotic technology.