Researchers at the University of Tokyo have built a robotic finger covered in live human skin. This is a major step in the eventual goal of creating robots that resemble real people. According to biohybrid engineer Shoji Takeuchi, human-like robots can work more seamlessly in medical care and service industries than in inhuman-looking versions. Still, this research may raise alarms for people who enjoy sci-fi dystopian fiction. It also raises the question: How humanoid do we want robots to be?
Human Skin on a Robotic Finger
Takeuchi and his colleagues accomplished this feat by submerging the robotic finger into a mixture of collagen and dermal fibroblasts, a kind of human skin cells. The mixture settled into a base skin layer. Then the team poured a liquid with human keratinocyte cells onto the digit, creating epidermis, a layer of outer skin. After two weeks of setting, the skin was a few millimeters thick, similar to the thickness of regular human skin.
The lab-made skin is durable and elastic enough to suit the three-joint finger’s movements. And like regular skin, it could heal. The researchers carefully cut the finger and covered the wound with a collagen bandage. Within a week, the skin cells merged with bandage, healing the cut.
“Our skin model is a complex three-dimensional matrix that is grown in situ on the finger itself,” explains Takeuchi. “It is not grown separately then cut to size and adhered to the device; our method provides a more complete covering and is more strongly anchored too.” 
Three-dimensional skin models have already existed and been used for researching and testing cosmetics and drugs. For instance, treating severe burns using skin grafts inspired this research. However, this technology has never been applied to a robotic finger before, let alone grown on a robot before. That element was particularly challenging and required special structures to anchor the synthetic skin. 
“Our creation is not only soft like real skin but can repair itself if cut or damaged in some way. So we imagine it could be useful in industries where in situ repairability is important as are humanlike qualities, such as dexterity and a light touch,” said Takeuchi. “In the future, we will develop more advanced versions by reproducing some of the organs found in skin, such as sensory cells, hair follicles and sweat glands. Also, we would like to try to coat larger structures.”
The Future of Engineering and Robotics
This technology also presents potential in industries like pharmaceuticals, cosmetics, and regenerative medicine, where it may reduce the need for animal testing and well as reduce costs, time, and complications during research.
“This is very interesting work and an important step forward in the field,” says Ritu Raman, an MIT engineer who also builds machines with living components. “Biological materials are appealing because they can dynamically sense and adapt to their environments.” She added that it would be interesting to have nerve cells in future versions of manufactured skin so robots can sense touch and textures. 
However, according to Raman, robots won’t wear human-like skin any time soon. The noteworthy robotic finger needs to spend most of the time bathing in ingredients such as sugar and amino acids to nourish the skin cells. In the meantime, Takeuchi continues to explore and intersect robotics and bioengineering. His research involves lab-grown meat, artificial muscles, synthetic odor receptors, and more.
Do We Want Our Robots to Look Like Humans?
Nevertheless, this new advancement sparks a debate on the future of artificial intelligence. How much do we want them to resemble humans? One study from the Georgia Institue of Technology discovered that the majority of college-aged adults preferred robots to look like machines while older adults preferred them to look more humanoid. But this may also depend on the function of the robots. For example, the participants preferred house-cleaner robots to look like robots but prefer a more human look for those who communicate with people. Robots are likely to take over certain tasks in the future and their appearance can greatly impact how the public receives them.
One potential issue is defining the “uncanny valley”. When non-humanoids look too human, their subtle inhuman features may feel eerie and disturbing for people who notice that something is off. Human-like skin on a robot may already seem unsettling for this reason, but researchers need to strike the balance of robots seeming human enough to seamlessly fulfill their roles while not appearing “too human.”
“If you have machines that are too similar to us, you start to have this blurring of human identity and people can be threatened by that,” says Maria Paola Paladino, who has studied human attitudes towards robots at the University of Trento, Italy. “If they are as human as I am, then what does it mean to be human?” She added that people’s relationships and views of robots may change and evolve over time.
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- “A robotic finger with living skin tissue points to future manufacturing methods.” Science Daily. University of Tokyo. June 9, 2022
- “Living skin on a robot.” Matter. Michio Kawai, Minghao Nie, Haruka Oda, Yuya Morimoto, Shoji Takeuchi. June 9, 2022
- “Scientists grew living human skin around a robotic finger.” Science News. Maria Temming. July 9, 2022
- “How Humanlike Do We Really Want Robots to Be?” Smithsonian Magazine. Biran Handwek. June 10, 2022