Do androids dream of wearing human skin?

When you think of a robot, it’s likely you’d picture something hard and rigid, probably made out of metal or plastic. Something that’s clearly not human and isn’t trying to look like one (beware the uncanny valley).

Soft androids made from flesh-like materials – like Data from Star Trek: The Next Generation or Ash in Alien – are just a thing of sci-fi… aren’t they?

Actually, making robots look more human is a top priority when designing them to interact with people in healthcare and service industries, since a human-like appearance can improve communication and evoke likability (apparently).

Now, biohybrid robots – made of both living and artificial materials – are one step closer to walking among us, with scientists from Japan designing living human skin on a robot according to a new study in Matter.

By combining robotics with tissue engineering, the team have given a robotic finger a skin-like look and texture, as well as water repellent and self-healing capabilities that will be particularly helpful when they go Terminator on us.

Researchers at the University of Tokyo developed a method to cover a robotic finger with living human cells. Credit: Matter/Kawai et al

“The finger looks slightly ‘sweaty’ straight out of the culture medium,” says first author Shoji Takeuchi, a professor in the Department of Mechanical and Biofunctional Systems at the University of Tokyo, Japan. “Since the finger is driven by an electric motor, it is also interesting to hear the clicking sounds of the motor in harmony with a finger that looks just like a real one.”


Soft, seamless skin coverage

The silicone currently used to cover robots can mimic the appearance of human skin to some extent, but up close the illusion falls apart when it comes to textures like wrinkles.

But previous attempts to fabricate living human skin sheets for humanoid robots have had limited success, since conforming sheets to moveable, three-dimensional objects (with uneven surfaces) poses a major technical challenge.

“With that method, you have to have the hands of a skilled artisan who can cut and tailor the skin sheets,” says Takeuchi. “To efficiently cover surfaces with skin cells, we established a tissue moulding method to directly mould skin tissue around the robot, which resulted in a seamless skin coverage on a robotic finger.”

Top – A robotic finger covered with the epidermis has water-repellent properties but without the epidermis – Bottom – the bead sticks. Credit: Matter/Kawai et al

So how did they manage it?

The robotic finger was slowly submerged into a cylinder filled with a solution of collagen and human dermal fibroblasts – the two main components that make up the skin’s connective tissues.

The mixture shrank and tightly conformed to the finger, forming the first dermis layer that acted as the foundation for a second layer of cells – human epidermal keratinocytes – to stick to.

These cells made up 90% of the outermost layer of skin, giving the robot a skin-like texture and moisture-retaining barrier properties.

A robotics finger covered with human living skin self heals in culture medium after researchers covered its wound with a collagen sheet
In the culture medium a robotic finger covered with human living skin self heals after researchers covered its wound with a collagen sheet. Credit: Shoji Takeuchi

It’s also self-healing!

The skin was thick enough to be lifted with tweezers, had enough strength and elasticity to remain in tact as the robot finger curled and stretched, and could repel water.

Particularly useful for when the robots eventually gain sentience and rise up against human civilisation in the coming robot-human war, the skin can be healed by grafting a collagen hydrogel patch onto its wounds. “This resembles the process of skin graft surgery of human beings,” the authors say.

“We are surprised by how well the skin tissue conforms to the robot’s surface,” adds Takeuchi. “But this work is just the first step toward creating robots covered with living skin.

“I think living skin is the ultimate solution to give robots the look and touch of living creatures since it is exactly the same material that covers animal bodies.”

Perhaps one day we won’t even be able to tell them apart from ourselves.

Close up of the robotic finger skin. Credit: ©2022 Takeuchi et al.

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