(CN) — Humans are often fascinated by inhuman approximations of humanity, from Pygmalion’s Galatea to Frankenstein’s monster. Though biohybrid humanoid robotics remain the stuff of science fiction and fantasy, scientists at the University of Tokyo in Japan are inching us closer to robotic reality with a new method for apply a living skin to a robot.
A study published Thursday in the peer-reviewed materials science journal Matter details the experiment, in which researchers covered a robotic finger with an approximation of human skin. This skin equivalent not only replicates the texture and flexibility of human skin, but is even able to ‘self-heal’ when damaged.
Biohybrid robotics may sound fantastical, and the idea of robots with human skin may verge on horrific, but researchers anticipate that this technology will have a wide range of practical applications.
“The technology developed in this research to create cultured skin robots is expected to be utilized in the industries where its reparability and human-like qualities are important, in the development of cosmetics and pharmaceuticals for skin, lab-grown leather and in the field of regenerative medicine as transplantation materials,” says Shoji Takeuchi, professor at the Institute of Industrial Sciences at the University of Tokyo and an author of the study.
The project succeeded because the scientists could fabricate dermal and epidermal layers, modeled after our own skin, able to withstand movement upon a three-dimensional structure. Previous attempts at integrating a living skin with robotics typically involved sheets of the skin equivalent sewn or glued onto the robot like a glove.
“However, this tailoring method has difficulty reproducing the subtle unevenness on the surface of the object. It is difficult to cut, glue or suture the endpoints of skin equivalent without damaging the soft, fragile tissue,” the authors of the study contend. This new method allowed the skin to form directly, in one entire piece, onto the surface of the robot.
To create the dermis equivalent, they encased the robot finger in a collagen solution of human dermal fibroblasts that would shrink and conform to the finger. They prevented over-shrinkage by developing a system of hooks at the base of the finger to anchor the skin tightly to the surface of the robot.
To create the epidermal layer, the finger and the dermis equivalent were then coated with human epidermal keratinocytes, which are essential to creation of a barrier between the inside and outside of the skin. These keratinocytes adhered to the dermis layer to form the skin equivalent. This skin equivalent has the water retention and mechanical properties, complete with the look and texture, of human skin.
Since other methods of applying a living skin fell short of even coverage on mobile, three-dimensional surfaces, it was particularly important that this newly developed skin equivalent was able to move with the robot organically. Researchers tested the practical capabilities of this skin equivalent by manipulating the finger to flick a small polystyrene bead.
The skin equivalent was able to bend along the joints of the robotic finger without damage. While the bead would stick to the finger if only the dermal layer was applied, the addition of the epidermal layer of the skin was able to successfully send the bead flying.
With the help of a collagen sheet acting as a bandage, the skin-covered finger is even able to heal from wounds. Taking inspiration from skin grafts, like those used for burn injuries, the team applied the collagen sheet over a small cut on the dermal layer of the skin equivalent. Over time, the collagen bandage essentially fused to the dermal layer of the finger. Tests done after this process showed that the healed skin was able to stretch and move the way it did before the wound.
Takeuchi explains that their work is far from complete.
“We are conceiving strategies to build circulatory systems within the skin,” Takeuchi said. “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.”
The creation of these systems and organs is necessary if this method is to become sustainable on its own.
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