Unlike artificial skin commonly used to make robots, this skin is alive, said study lead author Shoji Takeuchi, a project professor in the Department of Mechanical and Biosystems at the Institute of Industrial Science at the University of Tokyo. “Living skin is the ultimate solution to give robots the look and feel of living creatures,” said Takeuchi. His research team chose a robotic finger for the experiment because this mechanism is well thought out and is a critical part of a robot, he said.
Building the skin
Human skin is made using the same building blocks as human skin, Takeuchi said. The robotic finger was first immersed in a solution of collagen, which is a fibrous protein, and human dermal fibroblasts, the two main components that make up human skin. Dermal fibroblasts are the main type of cells in the connective tissue of the skin. After the solution adhered around the finger, Takeuchi applied human epidermal keratinocytes outwards. Keratinocytes are the main type of cell that makes up the human skin, the outermost layer of the skin, he said. In the tests, the elastic human skin moved freely while the finger made different movements, Takeuchi said. His team put a collagen bandage on a part of his finger that had been inflicted with a wound to repair it and the robot was able to move freely after the protein repaired the skin. Collagen is a key component of human skin and has healing properties, according to a 2021 study. The skin could also repel water, which extended the work that the robot could perform. When the researchers used a robot with wet surface material, they stuck polystyrene foam beads to it, according to the study. These beads are commonly used as fillers in products such as bean bags and some stuffed animals. When the scientists performed the same experiment on water-repellent human skin, the robotic finger could remove the foam beads without sticking, the authors said.
Designing robots with our own image
Humans are robots that perform tasks that involve interacting with humans in environments such as medicine, nursing and the service industries, according to the study. “It’s important to have human robots when they’re in places that people usually frequent,” said Pulkit Agrawal, Steven and Renee Finn, a career development professor and assistant professor in the Department of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology in Cambridge. He did not participate in the study. “Humans are designing spaces around them, so having a robot that looks like a human is useful in these scenarios,” said Agrawal. For example, robots that may one day be in a household must be able to pick up items and move as a person does, he said. If a robot were made of metal, it would have to be extremely accurate to lift another hard object, such as a mug, Agrawal said. There would be little contact between the two objects as neither is flexible. If the hand were as soft as human skin, the robot could be less expensive, as it would cover more surface in the mug as the soft skin adapts to the handle, he said.
One step in the right direction
The discovery is important, Agrawal said, but the development of human skin still has a long way to go. The skin is a living organism, so it needs to be maintained by constantly nourishing while removing waste, Takeuchi said. Unfortunately, the skin that developed today does not have this ability built-in, so it can not be maintained, he said. Takeuchi is interested in adding a vascular system, the way blood circulates throughout our body, to help transport nutrients to and from the cells and keep the skin alive. He also wants to develop additional details for the skin, such as hair follicles, nails and sweat glands.
