The first robot was developed in 1956 and today it is hard to imagine our lives without them. Whether industrial robots on the factory floor or service robots in the living room, such as roombas, they make many things easier for us. However, so far, robots have shown little resemblance to humans. This could soon change thanks to new advances in tissue research and with the help of 3D printing.
At the University of Tokyo, under the direction of Professor Shoji Takeuchi, artificially cultivated skin tissue was attached to robotic faces using 3D-printed perforation anchors. The cultivated skin, inspired by human skin bands, consists of living cells and has the ability to heal itself. To attach the skin to the surface, a perforation-like, V-shaped anchor was integrated into the robot head, providing both high strength and flexibility. The small perforations make it easier to attach the skin to the surface.
3D printing and applying the living skin to the 3D robotic face (photo credits: Takeuchi et al)
The V-shaped holes and the robot head were produced using the AGLISTA-3100 3D printer from Keyence, a Japanese company. The printer used material jetting technology, in which UV light-sensitive resin hardens and eventually forms the 3D object. This technology was chosen because it enables precise and reliable printing.
Thanks to the perforations, it was easier to spread collagen gel on the surface to keep the skin firmly attached to the 3D printed robot head. The collagen gel, which is normally tough and therefore difficult to insert into the small holes, underwent a plasma treatment. This allowed the collagen to slide into the perforations, allowing the skin to remain attached to the surface.
With previous methods, movements damaged the applied skin and the conventional materials did not allow for the creation of a human appearance. This is now changing thanks to the anchors connected to the base, which allow the smile to move and the skin to stretch.
Takeuchi explains: “In this study, we managed to replicate human appearance to some extent by creating a face with the same surface material and structure as humans. Additionally, through this research, we identified new challenges, such as the necessity for surface wrinkles and a thicker epidermis to achieve a more humanlike appearance. We believe that creating a thicker and more realistic skin can be achieved by incorporating sweat glands, sebaceous glands, pores, blood vessels, fat and nerves. Of course, movement is also a crucial factor, not just the material, so another important challenge is creating humanlike expressions by integrating sophisticated actuators, or muscles, inside the robot. Creating robots that can heal themselves, sense their environment more accurately and perform tasks with humanlike dexterity is incredibly motivating.”
The application of collagen gel, which leads to the attachment of living skin (photo credits: Takeuchi et al.)
To produce the skin, the researchers purchased normal human dermal fibroblasts and epidermal keratinocytes from anonymous human donors. To maintain the skin cells, they were treated with a special growth medium and antibiotics, while the nutrient supply was regularly replenished. “Manipulating soft, wet biological tissues during the development process is much harder than people outside the field might think. For instance, if sterility is not maintained, bacteria can enter and the tissue will die,” emphasized Takeuchi.
Research opens up many possibilities: Skin could be used for product testing in the cosmetics industry, potentially leading to the reduction of animal testing. The skin would also be a great advantage for training plastic surgeons to familiarize themselves with surgical procedures. Human-robot communication could be transformed by human-like robots, as they would be able to convey emotions through different facial expressions. In robotics, the innovation is beneficial because it leads to increased mobility, improved sensor functions and a humanoid appearance. The self-healing skin helps to extend the lifespan of the robots, reducing the cost of potential repairs.
The research report concludes: “One significant next step in this research is to leverage this model to enhance our understanding of the mechanisms underlying wrinkle formation. Moreover, applying this knowledge to recreate such expressions on a chip could find applications in the cosmetics industry and the orthopedic surgery industry.” Read more about the progress HERE.
The V-shaped anchor contorts the flat robot face with the living skin into a smile. The skin then returns to its original shape (photo credits: Takeuchi et al.)
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*Cover Photo Credits: ©2024 Takeuchi et al. CC-BY-ND