It sounds very much like a science fiction film, but it could now become reality: humanoid robots with human skin. A Japanese research team is developing an artificial skin with human skin cells for a robot finger that can even heal itself in the event of wounds.
Robots with real skin have been in science fiction films for decades – now Japanese scientists have come a step closer to realizing them: They developed an artificial skin with human skin cells for a robot finger. The artificial skin is so stretchy that it does not tear when the finger moves, writes the group led by Shoji Takeuchi from the University of Tokyo in the specialist magazine “Matter”. In addition, she is capable of self-healing.
“To efficiently cover surfaces with skin cells, we developed a technique that sculpts skin tissue directly around the robot, resulting in seamless skin coverage on a robot finger,” Takeuchi said in a statement from his university. To do this, he and his colleagues placed the robotic finger in a mold and poured in a collagen solution containing human fibroblasts – i.e. connective tissue cells. As the cells thrive in a nutrient solution, they cause the collagen to shrink and cling tightly to the surface of the robotic finger.
This creates a kind of dermis, also known as the leather skin. The scientists also reproduced the outermost skin layer – the epidermis – by colonizing keratinocytes – horn-forming cells – on the dermis. This epidermis not only makes the finger look skin-like, but is also water-repellent and also does not let other substances from the environment through. It also has a higher electrical resistance than the dermis: while an electrically charged plastic bead sticks to the dermis when flicked, the bead is repelled from the epidermis.
The researchers also tested how best to cover the artificial dermis with horny cells. Accordingly, it was advantageous to have the dermis colonized from different directions. In addition, the artificial skin should be kept in a nutrient solution for two weeks. “Taken directly from the culture medium, the finger looks slightly sweaty,” reports Takeuchi. The authors emphasize that looking human is important for humanoid robots that come into contact with humans in the healthcare or service industries.
They also showed that the artificial skin they developed has the ability to heal itself. Inspired by the treatment of severe burns in humans, they used a flat piece of collagen that they placed on an artificially created wound. The collagen was gradually colonized by the connective tissue cells from the dermis. The healed area was then just as resilient as the seamless artificial skin.
“This work is just the first step towards creating robots covered in living skin,” says Takeuchi. The artificial skin that has been developed is still significantly weaker than natural skin and can currently only be used in a damp environment. Because without a constant supply of nutrients and waste disposal, the skin cells do not survive long. In the next step, the researchers therefore want to replicate other components of human skin, such as nerve cells, hair follicles, nails and sweat glands.
