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GOING TO NEW DEPTHS
At the University of Colorado Boulder, researchers have created biohybrid robotic jellyfish to aid in deep-sea research that could provide new insights into the causes of climate change.
Written by Claudia Hoffacker
RESEARCHERS AT THE UNIVERSITY OF COLORADO (CU) BOULDER are using moon jellyfish to improve aquatic research. They’ve created a robotic system—similar to a pacemaker—that attaches to a live jellyfish to control its swimming and reach previously unreachable parts of the ocean.
“Our motivation is to understand more about the ocean and how we can track markers of climate change,” said Nicole Xu, assistant professor in the Paul M. Rady Department of Mechanical Engineering, Robotics Program, Biomedical Engineering Program, and the BioFrontiers Institute at CU Boulder. “To do this, we need more tools and technologies to measure the ocean at relevant times and locations. The ocean is so vast that this is a difficult challenge, so we need all the help we can get.”
But why jellyfish? Because they are the most energy-efficient animal in the world, and they’re found in a variety of environments in the ocean. This makes them an ideal model organism to build robots from, explained Xu, who is the lead researcher on the project.
“In my lab, we focus on taking inspiration from nature to create more energy-efficient underwater vehicles,” Xu said. “But instead of looking at jellyfish as just inspiration, we thought, why not use the animal itself to simplify the engineering design?”
The microelectronic device Xu attaches to the jellyfish activates key swimming muscles and turns the animals into biohybrid robotic jellies. The device allows the research team to control the swimming frequency and speed of the jellyfish, causing them to swim three to four times faster than usual.
Nicole Xu reaches her hand into the tank and touches one of the moon jellyfish. Photo: Glenn Asakawa/University of Colorado Boulder
Xu said it took years to develop the robotic system. “The first step was to figure out what electrical signals can stimulate jellyfish muscles to contract,” she explained. “Once we determined a reliable signal, I then found small, lightweight, off-the-shelf components: A microcontroller, battery, electrodes, waterproof housing, and pin to attach to the animal.”
The idea of a “cyborg” in robotics is fairly new. Most biohybrid robots that incorporate cyborg methods have involved terrestrial or flying insects such as cockroaches and beetles, rather than underwater applications. This is the first example of using a jellyfish as an underwater vehicle that can potentially sense the environment and provide information about processes in the ocean in areas that couldn’t be accessed before.
“In my lab, we focus on taking inspiration from nature to create more energy-efficient underwater vehicles.”
—Nicole Xu, Assistant Professor in the Paul M. Rady Department of Mechanical Engineering, Robotics Program, Biomedical Engineering Program, and the BioFrontiers Institute at the University of Colorado Boulder
The researchers’ previous work focused on straight swimming. Now, they’re working on ways to make the jellyfish turn and go in different directions. The goal is to be able to remotely control them, so they can collect data in areas of interest.
The challenge is that jellyfish are neutrally buoyant with their surrounding environments, and when the device is attached to the animal, it tends to ballast the system and cause the animal to swim in one direction.
“We are working on an active system that uses a mass transformer to turn the jellyfish in certain directions, so that we can incorporate remote control and eventually steer the animals through an obstacle course,” Xu said.
Another part of the research is to visualize the flow around the animal to show structures that a jellyfish leaves in its wake. This is typically done by seeding the water with small particles and illuminating them with a laser light sheet. But the particle tracers researchers usually use are very expensive and can be harmful to the jellyfish and the surrounding environment. They recently found a safer way of doing this.
“Usually, we use silver-coated glass beads that cost hundreds of dollars for a small vial, and we wear N95 masks to mix these dry particles into the water,” Xu said. But the researchers discovered that instead, they can use a $3 bag of cornstarch to do the same series of experiments and get the same level of precision. Xu and her colleagues explained this in a paper published earlier this year.
From left: Nicole Xu and graduate students Marshall Graybill and Charlie Fraga stand next to the main jellyfish tank in Xu's lab. Photo: Glenn Asakawa/University of Colorado Boulder
The researchers were excited to find inexpensive, safe, and easily accessible materials to use for flow visualization with jellyfish, as well as other underwater systems, so they can conduct their research in a more ethical way.
“In doing this work, we have to consider the ethics of working with live animals and translating this work into the field,” Xu said. “We’re trying to create a dialogue and ethical framework to be responsible engineers.”
Xu’s team will continue to be responsible, even as work expands with these cyborg jellyfish. Eventually, the researchers plan to add sensors to the biohybrid robots to gather critical data on temperature, pH and other environmental characteristics. They also want to go into more remote areas of the ocean, including the Mariana Trench, which sits about 36,000 feet beneath the western Pacific Ocean’s surface at its deepest point.
In October, Xu received a 2025 Packard Fellowship for Science and Engineering, worth $875,000 over five years, to continue this research.
“One goal is to harden the microelectronic system—which is simpler than hardening an entire robot—so that we can send these biohybrid jellyfish into the Mariana Trench for ocean exploration and observations of natural animal behavior,” Xu said. “Using these biohybrid robotic jellyfish can hopefully open a whole host of opportunities to understand more about our oceans and how we can be responsible stewards of the natural world.”
Claudia Hoffacker is an independent writer in Minneapolis.
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