"Our goal is to develop robots that are truly human-like,” said Shoji Takeuchi to IFLScience, who recently created a robot finger with living skin made from human cells. A Project Professor who specializes in biohybrid systems at The University of Tokyo, Takeuchi and colleagues' finger can bend and curl without breaking, and if it gets a boo-boo it can simply heal and reseal itself. 

“The silicone rubber covers that are commonly used [in robotics] today may look real from a distance or in photos or videos, but when you actually get up close, you realize that it is artificial,” said Takeuchi. “We think that the only way to achieve an appearance that can be mistaken for a human being is to cover it with the same material as a human being, i.e., living cells.”

The living skin, published in the journal Matter, was created by dipping the robotic finger into a solution containing collagen and human dermal fibroblasts, which are the two key connective ingredients in our flesh-colored organ covers. As they combined around the robotic appendage, the collagen and fibroblasts began to tighten, creating a fit that Takeuchi believes to be the success of the hyper-realistic finger.

Once the collagen-fibroblast foundation was set, it became a platform for human epidermal keratinocytes to adhere to, developing a top coat that represents 90 percent of the outermost layer of human skin. This adds a more life-like texture to the robot-human blend, even if it does look “slightly ‘sweaty’ straight out of the culture medium,” Takeuchi said in a statement.

The wet appendage comes together to create a finger that apparently looks very life-like indeed in person. That is, if you can ignore the mechanical whirring coming from inside.

Keratinocytes are also what make human skin waterproof, and they have the same effect on the robot finger meaning it can repel water, which is crucial for proper appearance and function. Perhaps most impressively of all, while the living skin is strong enough to survive bending, curling, and being plucked by tweezers, it can also heal itself if damaged.

To do so, the researchers placed a patch of collagen onto the robotic finger’s wound and left it to sit for seven days. During this time, the skin cells could migrate into the collagen patch and integrate it into the skin tissue, effectively resealing the injury.

However, as anyone who’s lived through teenage acne will be acutely aware, living skin has its downsides for humans. Is it possible these robots could ever be vulnerable to pathogens or infections in a similar way?

“The more human-like the skin, the more likely it is to be the same,” Takeuchi said to IFLScience. “But it might be possible to create highly resistant tissue by modifying cells.”

It’s perhaps too early, then, to launch your biohybrid blemish skincare range, but it seems more complex living skin (and the ability to feel pain) could well be on the cards for robots.

“One of the challenges is that there is no circulatory system built within the skin, so the skin cannot last long after being taken out from the culture medium,” Takeuchi concluded.

“We are conceiving strategies to build circulatory systems within the skin. Another challenge is to develop more sophisticated skin with skin-specific functions by reproducing various organs in the skin, such as sensory neurons, hair follicles, nails, and sweat glands. Also, scaling up our current method to cover larger structures would also be a challenging next step.”