Skin for the robot
Anastasia Gorshkova, PCR.news
We are still a long way from living side by side with humanoid robots, but scientists from the University of Tokyo have brought their creation one step closer by developing a method of covering robots with living human skin. The robotic finger, clad in a seamless analogue of the skin, feels like a real one and can recover from injuries.
Robots created in the likeness of human appearance or other characteristics are called androids. It is they who are predicted to succeed in social interaction with people, since a humanoid appearance increases the effectiveness of communication and causes sympathy. Usually such robots are covered with silicone skin, but it is not able to accurately reproduce the textures of real skin, for example, wrinkles, has no skin-specific functions and differs from it tactilely.
The authors of the new work covered a three-jointed robotic analogue of a human index finger with artificial skin. Tissue cultivation consisted of two stages: first it was necessary to create the equivalent of the dermis, forming deep layers of skin, and then the epidermis, covering the dermis. To do this, scientists immersed a robotic finger in a bioreactor containing collagen and human dermal fibroblasts (the dermal layer of the skin mainly consists of these two components). They built a special case, repeating the shape of the finger, so that the suspension of cells evenly surrounded the object covered with skin from all sides. The success of the study consisted in the natural ability of fibroblasts to fit snugly to the object in suitable conditions. The next step was to fix human keratinocytes forming the epidermis on the surface of the dermis. These cells just give the robotic finger the usual skin texture, as well as retain moisture and perform a barrier function. The scientists tested various protocols for growing the epidermal layer and realized that it is possible to cover more than 80% of the finger surface with cells with a gradual supply of cells from both sides for 14 days.
Next, they performed a histological analysis, which showed that the grown skin does not contain stitches or tears. In the tests, which consisted of flexion and extension of the finger, the skin proved to be strong and elastic enough to withstand movement. "The finger looks slightly sweaty because of the cultural environment," says the first author of the article Shoji Takeuchi, a professor at the University of Tokyo. "Since it is driven by an electric motor, it was interesting to notice that the clicking sounds of the motor are in harmony with the movements of the joints of the finger, which looks just like a real one."
The damage on the artificial skin was restored after the application of collagen hydrogel, which is usually used to treat people. After 14 days, the "patch" has grown into the skin. Previously, the damaged area withstood the stress from the movements of the robotic finger.
The authors note that, despite the success of the new method, there is still room for improvement. Thus, the tensile strength of reactor-grown skin is much lower than that of natural skin. In addition, artificial leather cannot exist outside the environment for a long time and requires a constant supply of nutrients. In the future, the team plans to solve these problems and introduce more complex functional structures into the skin, such as sensitive neurons, hair follicles, nails and sweat glands. "I think grown leather is the perfect solution for giving robots the appearance of a human, since it is exactly the same material as the one that covers the bodies of animals," says Shoji Takeuchi.
A video recording of the flexion of a robotic finger covered with skin is available at the link.
Article by Kawai et al. Living skin on a robot is published in the Matter magazine.
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