The standard definition of a robot is an electromechanical device that works automatically. But an artificial jellyfish created by Harvard and Caltech researchers goes a lot further than biomimicry using electromechanical means. It's more like an android: It looks like a real creature, moves like one, and incorporates living cardiac muscle cells.
The artificial jellyfish, dubbed "Medusoid," has cultured rat heart muscle cells that produce the pumping action that propels the artificial creature's silicone muscle structure through water.
Made of silicone and rat heart cells, the Medusoid engineered jellyfish's muscles contract like a real jellyfish when placed in liquid and shocked. (Source: California Institute of Technology/Harvard University)
"As engineers, we are very comfortable with building things out of steel, copper, concrete," said co-researcher Kevin Kit Parker, professor of bioengineering and applied physics at Harvard's School of Engineering and Applied Sciences, in a Harvard Gazette article describing the project. "I think of cells as another kind of building substrate, but we need rigorous quantitative design specs to move tissue engineering to a reproducible type of engineering."
Although this graceful, squishy, robot jellyfish's movements aren't nearly as elegant as those of Festo's AirJelly, they make the action of the silicone robot we reported on that mimics its surrounding look crude in comparison.
Parker, an authority on cell- and tissue-powered actuators, collaborated with Janna Nawroth, a Caltech doctoral student in biology, to reverse engineer the movements of a natural Medusa jellyfish. Nawroth’s adviser, John Dabiri, a professor of aeronautics and bioengineering at Caltech, was consulted for his expertise in biological propulsion. The researchers published their work in an article in Nature Biotechnology (subscription or payment required).
The researchers say that a major goal of creating Medusoid was to advance biological tissue engineering. To date, many of these efforts have focused on copying a tissue or organ without considering the relationship between the components and their function, or analyzing which materials would best suit that function.
Since jellyfish use their muscles to pump their way through the water, and their basic structure is similar to that of a beating human heart, the researchers decided to reverse-engineer that function to advance heart tissue research.
After mapping the alignment of subcellular protein networks in the Medusa jellyfish's muscle cells, they studied the propulsion system's electrophysiological triggering and the propulsive stroke's biomechanics. The team found that a sheet of cultured rat heart muscle tissue contracted when electrically stimulated in liquid. They used a silicone polymer to make the artificial Medusoid's body, a thin membrane with eight armlike appendages, and matched the subcellular, cellular, and supracellular jellyfish muscle architecture with the rat heart muscle cells. When the researchers placed Medusoid in a container of salt water and shocked it, the device began swimming with synchronized muscle contractions.
Is it an android? Maybe not quite yet. The researchers’ next steps will include incorporating simple intelligence so the artificial jellyfish can respond to its environment with more advanced behaviors, such as moving toward a light source, and modifying it so it can move in a particular direction.
Interesting that the military has such a large role in robotics developments, Ann. I would imagine it's like an iceberg -- what the militrary reveals is probably a small portion of the overall work in this area. A good portion of it is probably secret.
Thanks for explaining, Rob. From what I've seen, most of the new, exploding research is aimed at solving very specific problems, and much of it is being funded by the military. A considerably smaller amount, such as Medusoid, is aimed at fundamental, or "raw", research, but a lot of that looks applicable to some the purpose-driven work.
What made me curious, Ann, was the growing number of robotic developments that don't seem to be specifically tied to solving problems. Seems like a lot of the developments are raw research -- which I think if great. I would guess that part of it is that working on robots is fun.
Rob, as I mentioned, several trends are coming together and interacting to boost robotics development, including open source software and cheaper and better electronics (such as cameras and MEMS gyros and other sensors). No doubt motion control advances figure in there, too. Did you have some specific one sin mind? In addition, the Medusoid is an example of the emergence of biorobotics we're starting to see more of.
Since the article mentioned that that the device (maybe not the right word there) using living tissue, I was wondering what they are doing to keep it alive? Is it simply extracting the nutrients it needs out of the solution it is operating in? Taking that thought one step further, what is the life-span of something like this and how are the non-living parts recycled with new heart muscle?
By the way, I was thinking the same thing that naperlou said. From the title, I was wondering about a robotic cell phone.
Ann, what are some of the other trends driving developments in robotics? I would imagine advances in motion control is a factor. From you articles, it also sounds like funding at universities is helping. Military funding also seems to be a factor. The filling of specific needs seems to be less of a factor. But I may be wrong about that.
Ann, great article and I loved the video. Though crude, the movement was much more lifelike than I anticipated. My mind reels at the possible applications to real-life biological systems. I expect the field of bio-ethics to explode in the next 10 years as we humans grappled with these developments. As you say, this is the stuff of Science Fiction staring us right in the face. Exciting to say the least.
Hmm. I didn't realize open source software was part of the development process of these robots, Ann. I'm sure that's hugely helpful. At any rate, we seem to be in some golden age for developments in robots.
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