Researchers at the University of Tokyo have developed an artificial biohybrid hand that utilizes “sushi-like” bundles of thin human skeletal muscle fibers to manipulate a soft robotic exoskeleton.
A study recently published in Science Robotics introduces the biohybrid’s multiple muscle tissue actuator (MuMuTA), which powers the device’s fingers to perform human-like movements. The breakthrough holds promising implications for the growing field of biohybrid robotics.
A Biohybrid Grip
The biohybrid hand’s fingers can manipulate objects and perform a “scissors” gesture—a significant improvement over the limited movements displayed by earlier biohybrid models. At approximately 18 cm in length, the MuMuTA-powered robot falls within the smaller range of a human male hand, making it a considerable step up from previous biohybrid robotic systems, which measured only a few centimeters. This increase in scale, combined with the ability to move individual fingers with precision, represents a major technological leap.
“One example of a previous device is small-scale biohybrid robots that used single muscle tissue actuators for simple contractions,” lead author Dr. Shoji Takeuchi of the University of Tokyo explained to The Debrief. “These devices were limited in movement complexity and scale. In contrast, the biohybrid hand developed in this research integrates multiple MuMuTAs, allowing for individual finger control and multi-jointed movements, making it significantly more functional and biomimetic.”
Building a Stronger, More Functional Hand
Enhancing the robotic hand’s strength, dexterity, and size required overcoming complex challenges beyond merely scaling up existing biohybrid concepts. While muscle strength is proportional to its cross-sectional area, supplying sufficient nutrients to thicker muscle tissues is a major obstacle—not only to maintain function but also to prevent necrosis. The “sushi” concept provides an innovative solution to these challenges.
“The muscle fibers are described as “sushi-like” because they are bundled together in a cylindrical shape, similar to how ingredients in a sushi roll are wrapped tightly,” Dr. Takeuchi explained. “This structure, called MuMuTA, is created by rolling thin muscle tissues, which helps optimize force generation while maintaining nutrient diffusion, preventing necrosis.”
The biohybrid hand also incorporates artificial components, including a soft exoskeleton, gold-plated electrodes to stimulate the muscle tissue, and tendon-like cable-driven mechanisms that convert muscle contractions into joint movements.
Advancing Biohybrid Robotics
The team’s advancements push biohybrid robotics closer to practical applications, and while challenges remain, Dr. Takeuchi envisions future uses such as soft robots with lifelike movements, biomimetic systems capable of safe human interaction, and improved insights into the mechanics of biological muscles. However, integrating biohybrid robotics with the human body is still a distant goal.
“While the concept of using biohybrid technology for prosthetics is intriguing, there are still major hurdles to overcome, such as ensuring long-term durability, control precision, and integration with the human nervous system. However, in the long term, this technology could contribute to biocompatible prosthetic limbs or regenerative medicine approaches,” Dr. Takeuchi commented.
The Next Phases of Biohybrid Research
Dr. Takeuchi has identified key challenges that must be addressed before biohybrid technology can be applied in real-world scenarios. Improving the longevity and durability of the cultured muscle tissues is a priority, as current models lasted only 175 days in laboratory testing. Additionally, researchers aim to refine the system for even more complex and coordinated motion, as well as explore alternative muscle stimulation methods, including neural control.
Eventually, future advances will allow for “scaling up the system further, potentially integrating more advanced soft robotics frameworks,” Dr. Takeuchi concluded.
The paper “Biohybrid Hand Actuated by Multiple Human Muscle Tissues” appeared on February 12, 2025 in Science Robotics.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.