Looking as similar as possible to humans is one of the top priorities for robots that are used in healthcare or service industries, since a human-like appearance can improve communication efficiency and evoke likeability. While current silicone skin made for robots can mimic to a certain degree human appearance, it nevertheless lacks skin-specific functions and falls short when it comes to delicate textures such as wrinkles. However, a team of researchers led by the University of Tokyo has now managed to craft living human skin on a robotic finger. Besides looking real, this skin has also self-healing functions and is water-repellent.
“The finger looks slightly ‘sweaty’ straight out of the culture medium,” said study first author Shoji Takeuchi, an expert in Biohybrid Systems at the University of Tokyo. “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.”
To craft the skin, Professor Takeuchi and his colleagues submerged the robotic finger in a cylinder filled with a solution of collagen and human dermal fibroblasts, the main components of human skin’s connective tissues. This layer provided a uniform foundation for the next coat of cells – human epidermal keratinocytes – to stick to. These cells make up 90 percent of the outermost skin layer, giving the robot finger a skin-like texture and moisture-retaining barrier properties.
This skin had sufficient strength and elasticity to bear the dynamic movements as the robotic finger curled and stretched, while the outermost layer could repel water. Moreover, the crafted skin could even heal itself with the help of a collagen bandage that gradually morphed into the skin and withstood repeated movements.
However, this skin is weaker than natural skin and cannot survive for long without constant nutrient supply and waste removal. In future research, Professor Takeuchi and his team are planning to incorporate more sophisticated functional structures within the skin, including sensory neurons, hair follicles, nails, and sweat glands.
“We are surprised by how well the skin tissue conforms to the robot’s surface,” said Professor 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,” he concluded.
The study is published in the journal Matter.