Researchers from the University of Tokyo develop facial robot with 'living skin'

A research group led by Professor Shoji Takeuchi and Doctoral Student Michio Kawai (currently at Harvard University) of the Graduate School of Information Science and Technology at the University of Tokyo has developed a robotic face covered with cell-derived living skin using cultured skin produced from human skin cells. Inspired by the structure of human skin ligaments, they devised a method of attaching biological tissue to artificial structures and used this method to construct a robotic face with a dermis equivalent smoothly attached to the underlying structure. The technology developed to create cultured skin-covered robots is expected to be used in the development of humanoid robots with biological functions and in the fields of aesthetic and plastic medicine, such as understanding the mechanism of wrinkle formation. The work was published in Cell Reports Physical Science on June 26.

Until now, humanoid robots have been coated with silicone rubber to mimic the soft skin of humans. However, as long as silicone rubber is used, the surface structure does not have human-like capabilities such as self-repair, sensing, and heat release (perspiration). To address these issues, the research group has developed robotic fingers and other products that are covered with living skin tissue based on the approach of using cultured skin made from human skin cells as a robot skin material. However, to use skin tissue as a covering material for robots, a method for smoothly fixing the skin tissue to the robot is needed.

In humans, the skin is smoothly attached in a plane to the subcutaneous tissue, as evidenced by the fact that the human skin and muscle do not slide over each other. Previous studies have used protrusion anchors with a structure that hooks only the endpoints of the tissue to fix biological tissue to artificial materials; however, anchor structures protruding outward can compromise the smooth appearance of the robot and interfere with its movement. In the human body, a collagen-based mesh-like fiber structure called the skin ligament exists in the subcutaneous tissue and plays an important role in anchoring skin tissue to the subcutaneous tissue. This tissue also helps transmit muscle movement to the skin, particularly in the face, contributing to the formation of smooth facial expressions by the facial muscles.

In this study, the research group developed a "perforation-type anchor structure" inspired by this skin ligament structure, in which skin tissue is gelatinized and fixed inside V-shaped holes that penetrate the artificial object and used this anchor structure to construct a facial mold covered with living cultured skin. Moreover, they developed a robotic face exhibiting a smiling expression by transmitting motor power to the skin through perforation-type anchors and demonstrating power transmission to skin tissue through the anchor structure.

Journal Information
Publication: Cell reports Physical Science
Title: Perforation-type anchors inspired by skin ligament for robotic face covered with living skin
DOI: 10.1016/j.xcrp.2024.102066