A hybrid robotic hand made from plastic bones and muscle cultured from human cells has been developed. Experts evaluated this as a significant step toward developing advanced robots that can replace not only prosthetics for disabled individuals but also human arms and legs in the long term.
A research team from the University of Tokyo and Waseda University announced on the 12th (local time) that they have created a robotic hand that moves using muscle made from human cells, as published in the international academic journal Science Robotics. The robotic hand developed this time is the largest among robotic hands made using human muscles.
In the past decade, attempts to build robots using the muscles of humans or animals have steadily spread worldwide. The international journal Science reported that since the concept of a "bio-hybrid robot" operated by animal muscle cells was first proposed in 2012, the sophistication of machines has greatly improved.
The research team decided to use muscle tissue to mimic the precise movements of human hands. They cultured human skeletal muscle cells and created elongated muscle (tendon) shapes measuring 3 cm long. To precisely control the robotic hand, which is composed of five fingers, the team developed a unique device called a multi-muscle tissue actuator (MuMuTA). They rolled the fine muscle tissue grown in the culture chamber like a sushi roll to secure contraction force and sufficient length. The research team likened this process in their press release, stating it was made like Japan's "sushi roll."
The research team connected the actuator to a mold shaped like a finger, slightly larger than the average adult male hand at 18 cm. This robotic hand mold, which was 3D printed, functions like a human hand and finger. When an electrical stimulus is applied, the connected fingers bend and then straighten. The team explained that the thumb, ring finger, and little finger can bend to create a scissors gesture for playing rock-paper-scissors. Additionally, they can use only a few fingers to grip a test tube with precision.
In fact, there have been limitations in making actuators from human cells large enough to replace arms and legs. Large muscles are needed to fit into hands or limbs. One solution is to use longer and more muscle fibers to provide higher contraction force. However, the thick muscle tissue necessary for moving larger arms and legs tends to undergo necrosis, making it difficult to culture in the laboratory. Nutrients and oxygen have trouble penetrating thick muscle tissue, leading to cell death. However, the actuator used in the robotic hand has successfully operated, opening the possibility for application in larger areas.
There is still a perception that using muscle as a driving mechanism for robots is inferior to motors or mechanical actuators. When individuals exercise for extended periods, they experience fatigue due to a lack of oxygen and blood flow along with a buildup of lactic acid. The robotic hand that uses human muscle also exhibits similar phenomena in muscle cells after prolonged use. However, scientists are focusing on the remarkable resilience of humans and animals. The research team confirmed that the robotic hand using cultured muscle displays recovery responses after resting for about an hour. They noted plans to develop a hand that can move freely in the air, moving away from previous experiments that were conducted stably in liquid.
The multi-muscle tissue actuator plays a crucial role in the long-term development of bio-hybrid arms and legs. Experts share the common view that hybrid robots possess great market potential due to their ability to closely mimic bodily functions.
Shoji Takeuchi, a professor at the University of Tokyo leading the development, stated, "The development of the multi-muscle tissue actuator is an important milestone for developing bio-hybrid robots," and added that "once basic obstacles are resolved, it can be used in advanced prosthetics, and it could also serve as a tool for understanding how muscle tissue functions in biological systems or testing surgical procedures or drugs targeting muscle tissue."
China recently unveiled that it has developed a robotic hand capable of performing a variety of movements at the highest global level. Researchers from the University of Science and Technology of China (USTC) introduced on the 13th that they have developed a lightweight artificial hand with more than 19 degrees of freedom (DF) in the international journal Nature Communications. In robotics, the degree of freedom refers to the minimum number of independent variables needed to describe the state of an object, serving as a measure of how complex and sophisticated the movements can be.
The artificial hand unveiled by the Chinese team is nearly on par with the Dextrous Hand, which was developed by the private company Shadow Hand last year and possesses the world’s highest level of 20 degrees of freedom. The Chinese researchers used shape memory alloy (SMA) as artificial muscle instead of muscle tissue.
The Chinese researchers explained that "a separate pathway for force transmission and 23 sensor devices were integrated into the fingers and wrist to achieve precise joint control." This artificial hand weighs only 0.37 kg and possesses the dexterity to perform everyday tasks like styling hair, writing, shaking hands, exchanging business cards, and playing chess. They also added that it can perform complex sign language using scissors or a smartphone.
References
Science Robotics (2025), DOI: https://doi.org/10.1126/scirobotics.adr5512
Nature Communications (2025), DOI: https://doi.org/10.1038/s41467-025-56352-5
Science (2024), DOI: https://doi.org/10.1126/scirobotics.adr9299