Model-informed design of a biohybrid OstraBot. Credit: Nature Communications (2026). DOI: 10.1038/s41467-026-70259-9
NUS
researchers have developed a platform that lets lab-grown muscle tissues train
themselves to record-breaking strength, with no external stimulation required.
By mechanically coupling two muscle tissues so they continuously pull against
each other, their own natural contractions become a round-the-clock workout.
The resulting muscles powered OstraBot, an ostraciiform (a type of fish
locomotion) swimming robot that reached 467 millimeters per minute—the fastest
speed reported for any skeletal muscle-driven biohybrid robot.
The advance removes a long-standing
bottleneck in
biohybrid robotics—machines driven by living cells rather than conventional
motors. Because muscle-based actuators are soft, quiet and efficient at small
scales, stronger versions could unlock minimally invasive biomedical tools,
soft environmental sensors and fully biodegradable robots that safely degrade
after completing their task.
"For years, researchers have been
interested in building robots powered by living muscle because biological
actuation is soft, adaptive and energy-efficient at small scales. However, the
performance of these systems has been limited by the low force output of
cultured skeletal muscle. If the actuator is weak, the robot cannot move fast,
generate meaningful thrust, or perform useful tasks," said Assistant
Professor Tan Yu Jun from the Department of Mechanical Engineering in the
College of Design and Engineering at NUS, who led the research.
"The purpose of this study was not
just to build a faster robot, but to remove a fundamental bottleneck in the
field and open the door to high-performance biohybrid systems designed with
sustainability in mind," Asst Prof Tan added.
The study was published in Nature Communications on March 18, 2026. In December 2025, the first author of the paper, Dr. Chen Pengyu, won the Best Poster Award based on this study at the Materials Research Society (MRS) Fall Meeting 2025, one of the largest international conferences for materials science research.
Credit: National University of Singapore
Two muscles in an arm-wrestling match
The key insight came from a
behavior that biologists have long observed but rarely exploited: the
spontaneous contractions that young skeletal muscle cells produce as they
mature. Starting around day three of differentiation, engineered tissues begin
twitching on their own, peaking by day five before fading as the cells reach
full maturity. Although most researchers had treated this as a biological
curiosity, the NUS team
treated it as a training resource.
They designed a platform in which
two muscle tissues are coupled through a sliding block, so that when one
contracts, it stretches the other, which then contracts back. The result is
continuous cycles of shortening and lengthening that run autonomously throughout
the week of early maturation, with no external power source, control unit or
manual intervention.
"As the cells mature, they
naturally begin to contract spontaneously. Because the two tissues are
connected, they continuously pull against each other, effectively exercising
without any external control," explained Asst Prof Tan.
The self-trained muscles generated
a maximum force of 7.05 millinewtons and a stress of 8.51 millinewtons per
square millimeter—the highest values recorded for this cell line in biohybrid
robotics, and more than an order of magnitude above many previously reported
figures. The method uses a commercially available muscle cell line found in
labs worldwide, making it far more reproducible and cheaper than conventional
approaches.
Optimizing OstraBot to achieve personal bests
The team developed a physiology-based model tracing the full chain from electrical
stimulation through calcium signaling and muscle activation to force output,
then used it to guide OstraBot's design. Inspired by the boxfish, which keeps
its body rigid and propels itself entirely by oscillating its tail, OstraBot
pairs this model-informed structure with a single trained muscle that drives
two flexible tails. At optimal stiffness and 3 Hz stimulation, it swam more
than three times faster than an identical robot powered by conventionally cultured
muscle.
Beyond speed, the robot
demonstrated something equally significant: precise controllability. Its speed
could be tuned continuously by adjusting electrical field strength, and a
sound-triggered system let it start and stop in response to clapping signals.
"The clap shows that the robot
is not just alive—it is controllable. In the past, muscle-powered robots either
moved constantly without clear control or were too weak to respond visibly. Our
strengthened skeletal muscle allows the robot to react clearly to an external
signal, similar to how nerves control muscles in the body," said Asst Prof
Tan. "This demonstrates that biohybrid robots can combine strength with
precise regulation, which is essential for real-world applications."
Robots with a vanishing act
The NUS team is now pursuing
systems in which all structural materials are biodegradable—robots that perform their
function and then safely break down. Possible applications include
environmental monitoring devices deployed in sensitive ecosystems such as
wetlands or coral reefs, as well as temporary implantable tools that perform a
clinical task before dissolving inside the body, eliminating the need for
surgical retrieval.
"Strength is one important
milestone, but long-term stability, energy efficiency and lifecycle design are
equally important," said Asst Prof Tan. "Ultimately, we aim to
develop biohybrid machines that are not only high-performance but also
environmentally responsible by design."
The team's next steps include
integrating biodegradable structural materials, refining control strategies and
improving the durability and efficiency of muscle-powered robotic systems.
Provided by National University of Singapore
Source: Swimming robot propelled by lab-grown muscle hits record speed
No comments:
Post a Comment