Recently, Japanese scientists made a "face" for the robot, which can smile and move with wrinkles.
Many netizens thought of "Terminator" after seeing it, after all, the smile in the picture is indeed very similar to Schwarzenegger's performance in "Terminator".
This is not actually a science fiction movie, but a "robot face" created by Professor Shoji Takeuchi and Michio Kawai of the University of Tokyo, Japan, using living human skin cells.
And this face, most likely, will be used on people first.
How to put on a robot "human skin"
For more than a decade, robotics researchers have been experimenting with a variety of materials in the hope of finding a material that would protect the robot's complex machinery while being soft and lightweight enough, but progress has been slow.
Although the silicone skin of the robot can imitate human skin to a certain extent, it is still not enough in the details, not only is it difficult to achieve proper adhesion to the machine, but once the surface is scratched, it often affects the operation of the machine, which can easily lead to the "uncanny valley effect".
A robot that makes people look scared, how can it serve people?
The uncanny valley effect – when humanoid robots or simulated images become very realistic but not complete, people feel intense unease and disgust
而日本科学家竹内昌治在其论文《穿孔型锚，灵感来自皮肤韧带，用于覆盖活体皮肤的机器人面部（Perforation-type anchors inspired by skin ligament for robotic face covered with living skin）》中描述的这个方法，由于其生成的皮肤是由人类皮肤细胞培养而成的混合物，所以在视觉触感上与人类皮肤很像，而且在很大程度上解决了机器人皮肤固定的问题。
In humans, there is a vast network of ligaments that hold the skin to the underlying muscles and tissues, and the researchers designed a V-shaped perforated structure along the lines of thought, according to Professor Takeuchi:
By mimicking the structure of human skin ligaments and using a specially crafted V-shaped perforation in a solid material, we have discovered a way to combine artificial skin with mechanical structures. The design of the V-shaped piercing mimics the structure of human skin ligaments, allowing the skin to move with the robot's mechanical parts without tearing or peeling.
Left: Human face structure Right: Robot face structure
The researchers also tested and evaluated the ability of this perforated anchor to fix skin tissue through a series of experiments:
First, to demonstrate the versatility of perforated anchors on 3D objects covered with complex contours, the researchers fabricated 3D facial devices covered with skin equivalents.
By pouring in the gel dermal solution and incubating for 7 days, a dermal equivalent fixed to the anchor is formed. In order to mimic the structure of the human face, they also set up small holes in the robot's face, filled with a large amount of gel containing elastic material.
The dermis is then inoculated with artificial epidermal keratinocytes and cultured for 17 days, resulting in robotic skin with dermal and epidermal layers.
The study noted that an even thickness of the collagen injection space was essential to achieve even coverage and found that the thickness of the skin equivalent varied in different contour areas.
Experiments have also shown that the use of perforated anchor points is essential to fix skin equivalents, otherwise the tissue will be separated by contractile forces.
Tissue without an anchor shrinks during culture and does not retain its shape
To verify the effect of perforated anchors in inhibiting skin contraction, the researchers fabricated devices with perforated anchors of different diameters (1mm, 3mm, and 5mm) into which a collagen gel containing human normal skin fibroblasts was injected to form a dermal equivalent, and the contraction of the dermal equivalent was observed over a 7-day period.
The results showed:
- The sample without anchorage shrank by 84.5% over 7 days, while the sample with anchoring shrank was greatly reduced.
- A 1mm diameter anchor can limit shrinkage to 33.6%.
- A 3mm diameter anchor can further limit shrinkage to 26.3%.
- At 5mm, the degree of shrinkage increased by 32.2%.
This may be because larger anchors occupy more surface area, making the tissue shrink more far toward the center.
Effect of different anchor points on inhibition of skin contraction
The researchers also evaluated the effect of the number of anchor points on anchor performance using the finite element method (using computer simulation techniques to evaluate and analyze the effect of the number of anchor points on anchor performance), and the results showed:
- The higher the number of anchors, the more resistant the skin is to tensile forces.
- When the anchor bolt is far away from the stress point, the skin will be significantly displaced under a small force.
That is, areas with lower anchor density allow for greater deformation, but tend to cause concentrated loads on a single anchor. Conversely, a higher anchor density provides stronger adhesion and lower deformation.
This demonstrates the potential utility of perforated anchors for the selective drive of facial skin, just like human facial muscles. In other words, the different anchor densities on the skin will become the key to the "expression" design on the skin.
In the expression of human emotion, the facial skin is often driven to form expressions through the contraction of mimic muscles. On this skin, the researchers also controlled the skin thickness, anchor density, anchor length and other factors to make the skin selectively deform, and reproduce a smile similar to a human face.
Simulate robot facial drives
Why "skin" is so important
In fact, Professor Takeuchi has been advocating the combination of human biological tissues and mechanical materials to create robots with more anthropomorphic characteristics. He argues:
Living skin is the ultimate solution for giving robotic creatures the look and feel they need.
In 2022, he and his team used collagen and dermal fibroblasts to make human-like dermal fingers.
The artificial "skin" created not only has good elasticity, but also wrinkles and stretches with the movement of the fingers, which is very close to the feeling of real fingers.
And the skin also has some repairability. The researcher cut a small incision in the "finger", used a collagen dressing to wrap it, and after sitting in a petri dish for a week, the collagen can repair the skin to a certain extent.
After this experiment, Professor Takeuchi said:
We were amazed at how well the skin tissue fits into the robot's surface.
In January of this year, he also proposed to imitate human muscles to make robot legs, creating a mechanical structure biological hybrid robot with machinery as bone and human tissue as skin and flesh.
Although today's artificial skin is still a bit "scary", in fact, making robots more and more human-like is one of the important goals of humanoid robots.
This is mainly due to the fact that humanoid robots can provide a more natural and intimate interaction experience by mimicking humans through their appearance, expressions, and movements. This similarity makes humans feel more comfortable interacting with robots and are more receptive to and trusting them. Masaharu Takeuchi said:
Human-like faces and expressions improve communication and empathy in human-computer interaction, making robots more effective in healthcare, service, and companionship.
For example, in many science fiction movies, realistic human skin has become the standard configuration of humanoid robots, and even in "Liao Zhai", the beautiful "painted skin" is also an inevitable choice for ghosts to get close to humans.
Clearly, humans are naturally more susceptible to emotional connections to similar faces and behavioural patterns, providing emotional support and companionship. By mimicking human expressions, voices, and body language, humanoid robots can more smoothly integrate into the human work environment, use the same tools and equipment as humans, and even excel in roles as actors, models, or art creators.
Wang Yifan, an assistant professor at Nanyang Technological University's School of Mechanical and Aerospace Engineering in Singapore, said this skin-to-skin bond gives biohybrid robotic sensation the potential:
This can create opportunities for robots to perceive humans and interact with them safely.
A humanoid robot from the movie "Ex Machina".
However, despite the success of the experiment, there is still a long way to go before it can be used on the robot, Professor Takeuchi said:
First of all, we need to improve the durability and longevity of cultured skin when applied to robots, especially to solve the problems related to nutrition and water supply. This may involve the development of integrated vascular or other perfusion systems within the skin. Second, it is crucial to increase the mechanical strength of the skin to match the strength of natural human skin. This requires optimizing the collagen structure and concentration within the cultured skin.
He also pointed out that to be truly functional, artificial skin must eventually be able to convey sensory information such as temperature and touch like the robot that wears it, which is the next goal of Professor Takeuchi's research, he said:
Our goal is to create skin that is closely related to real skin function by gradually building basic components such as blood vessels, nerves, sweat glands, sebaceous glands, and hair follicles.
Shoji Takeuchi
It is worth mentioning that if the research on artificial skin is successful, it can be used not only in robot manufacturing, but also in other fields, such as the design and production of prosthetics, the treatment of burns, the sequelae of plastic surgery, facial paralysis, etc., said Michio Kawai.
With the development of AI technology and several others, making robots take on more roles, the functional needs of robot skins are also changing.
In some experiments, researchers have found that when the robot's skin remains in a single shape for a long time, it is able to replicate the process of wrinkle formation:
A skin model that reproduces the formation of wrinkles and has the potential to be used in tests of cosmetics and skin care products aimed at preventing, delaying, or improving the formation of wrinkles.
And this is undoubtedly a very huge role in researching and testing new cosmetics and skin care products.
This "skin" created specifically for robots is most likely to be used on humans first.
Obviously, there is still some controversy about whether this technology can help robots become more human-like, but it may be "unintentionally inserted into the willows" in areas other than robots.
Isn't that another success?
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