EPFL engineers have created an agile, compact swimming robot that skillfully maneuvers through cluttered water surfaces. Taking cues from marine flatworms, this novel device opens up new avenues for environmental monitoring and ecological research.
Robots that swim are key tools for tracking pollution, investigating aquatic ecosystems, and assessing water quality in fragile regions like coral reefs or lake shores. Traditional devices often depend on noisy propellers that may disturb or damage wildlife. Moreover, the natural obstacles found in these settings—such as vegetation, animals, and debris—present additional hurdles.
A team from EPFL’s Soft Transducers Lab and the Unsteady Flow Diagnostics Laboratory, together with researchers from the Max Planck Institute for Intelligent Systems, have developed a highly maneuverable robot that can navigate tight spaces and carry payloads much larger than its own weight. Measuring smaller than a credit card and weighing only 6 grams, this nimble swimmer is ideal for confined areas like rice fields or for inspecting waterborne machinery. Their findings were recently published in Science Robotics.
“In 2020, our team showcased autonomous crawling robots at the insect scale, but designing untethered, ultra-thin robots for water presented a completely new challenge,” explains Herbert Shea, head of EPFL’s Soft Transducers Lab. “We had to build from the ground up, creating more powerful soft actuators, novel undulating motion strategies, and compact high-voltage electronics.”
This design not only mimics nature but also surpasses the capabilities of natural organisms.
Florian Hartmann, now leading a research group at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany, elaborates: Unlike conventional propeller-driven systems, the EPFL robot employs quietly undulating fins—modeled after marine flatworms—for propulsion. Its lightweight design allows it to rest on the water’s surface and integrate effortlessly into natural settings.
By moving its fins up to 10 times faster than actual marine flatworms, the robot can achieve speeds of 12 centimeters per second, equivalent to 2.6 of its own body lengths per second. It also demonstrates remarkable agility by using four artificial muscles to control the fins, enabling it to swim forward, turn, and even move backward or sideways.
The researchers equipped the robot with a compact electronic control system that supplies up to 500 volts to the actuators while consuming only 500 milliwatts—just a quarter of the power used by an electric toothbrush. Despite the high voltage, the low current and well-shielded circuitry ensure the robot is completely safe for its surroundings. Simple light sensors allow it to autonomously detect and follow light sources.
Looking ahead, the team envisions this robot playing a significant role in ecological research, pollution monitoring, and precision agriculture, among other applications. Future work will focus on developing a more durable platform for field testing, extending its operating time, and increasing its autonomy. Hartmann concludes, “The core insights from this project will not only push the boundaries of bioinspired robotics but also lay the groundwork for practical, nature-compatible robotic systems.”
