The bird demonstrates cutting-edge technology for devising self-folding nanoscale robots.
Cornell University has just announced what may be the smallest origami bird ever folded. While a typical origami animal is the product of an artist's dexterous hands, the Cornell bird was folded by the strategic application of small electrical voltages. It had to be: The material of which the bird is comprised is just 30 atoms thick.
Creative expression isn't the point of the university's little avian — its construction previews principles and techniques that will lead to new generations of moving, nano-scaled robots that "can enable smart material design and interaction with the molecular biological world," says Dean Culver of the U.S. Army Combat Capabilities Development Command's Army Research Laboratory, which supported the research.
According to Cornell's Paul McEuen, "We humans, our defining characteristic is we've learned how to build complex systems and machines at human scales, and at enormous scales as well. But what we haven't learned how to do is build machines at tiny scales. And this is a step in that basic, fundamental evolution in what humans can do, of learning how to construct machines that are as small as cells."
The lead author of the paper describing the tiny bird is postdoctoral researcher Qingkun Liu. The paper, "Micrometer-Sized Electrically Programmable Shape Memory Actuators for Low-Power Microrobotics," is the cover story of the March 17 issue of the journal Science Robotics.
A minuscule swarm of helpers
The project is the result of a collaboration between physical scientist McEeuen and physicist Itai Cohen, both of Cornell's College of Arts and Sciences. It's already resulted in a (very) small herd of nanoscale machines and devices.
Cohen explains, "We want to have robots that are microscopic but have brains on board. So that means you need to have appendages that are driven by complementary metal-oxide-semiconductor (CMOS) transistors, basically a computer chip on a robot that's 100 microns on a side."
The idea is that these minuscule workhorses—a metaphor, no nanoscale origami horses yet exist—are released from a wafer, fold themselves into the desired form factor, and then go on about their business. Additional folding would endow them with motion as they work, change shapes to move their limbs and manipulate microscopic objects. The researchers anticipate that these nanobots will eventually be able to achieve similar functionality to their larger brethren.
Credit: nobeastsofierce/Adobe Stock
How a tiny robot is made and works
The project combines materials science with chemistry, since the folding is achieved with the strategic deployment of electrochemical reactions. Liu explains, "At this small scale, it's not like traditional mechanical engineering, but rather chemistry, material science, and mechanical engineering all mixed together."
"The hard part," says Cohen, "is making the materials that respond to the CMOS circuits. And this is what Qingkun and his colleagues have done with this shape memory actuator that you can drive with voltage and make it hold a bent shape."
The bots are constructed from a nanometer-thick platinum layer that's coated with a titanium oxide film. Rigid panels of silicon oxide glass are affixed to the platinum. A positive voltage creates oxidation, forcing oxygen atoms into the platinum seams between the glass panels, and forcing platinum atoms out. This causes the platinum to expand, which bends the entire glass-platinum structure to a desired angle.
Because the oxygen atoms collect to form a barrier, a bend is retained even after the charge is switched off. To undo a fold, a negative charge can be applied that removes the oxygen atoms from the seam, allowing it to relax and unbend.
This all happens very quickly — a machine can fold itself within just 100 milliseconds. The process is also repeatable. The team reports that a bot can flatten and refold itself thousands of times, and all it takes is a single volt of electricity.
Artistry after all
None of this really removes what one might consider the artistry. Working out how and where to apply voltages to effect the desired shape is not a simple thing to do. McEuen says, "One thing that's quite remarkable is that these little tiny layers are only about 30 atoms thick, compared to a sheet of paper, which might be 100,000 atoms thick. So it's an enormous engineering challenge to figure out how to make something like that have the kind of functionalities we want."
Still, the group is getting quite good at microscopic robotics, and has already been awarded the Guinness World Record for assembling the smallest-ever walking robot. The little 4-legged dude is 40 microns wide and between 40 and 70 microns long. They're angling for a new record with their 60-micron-wide origami bird.
Says Cohen, "These are major advances over current state-of-the-art devices. We're really in a class of our own."
Scientists envision a new type of organism ready to assist humans.
- Computers designed, and scientists have constructed, programmable living robots.
- Study announces potentially self-healing, biodegradable, purpose-build automatons.
- Two "xenobots" are already bumbling their way around dishes of water in a lab.
While we typically think of robots as being constructed from metal, circuitry, and plastic, a team of researchers from Tufts University in Medford, Massachusetts and the University of Vermont in Burlington, Vermont have just announced the creation of task-specific robots made of living cells scraped from frog embryos. (They are not called "ribits.") Biologist Michael Levin tells The Guardian, "They are living, programmable organisms."
Levin and his colleagues call the tiny automatons "xenobots," after Xenopus laevis, the African clawed frogs from whom their cells came. They're proofs of a larger concept the researchers have invented: a method, or "pipeline," theoretically capable of creating living bots for all sorts of tasks.
Aside from being a somewhat shocking development, the robots raise obvious ethical and practical issues. "These are entirely new lifeforms. They have never before existed on Earth," points out Levin. Team member Sam Kreigman says, "What's important to me is that this is public, so we can have a discussion as a society and policymakers can decide what is the best course of action."
How the xenobots are made and how they work
Image source: Kriegman, Blackiston, Levin, and Bongard
The primary purpose of the research is the development of a workable, scalable pipeline that produces robots selected, or "programmed," for specific capabilities. It works like this:
Computer algorithms set to work iterating 500 to 1,000 virtual 3D structures using models of actual cells — whose behaviors are known — as building blocks. For the xenobots, models of passive and contractive (heart muscle) skin cells from frog embryos were used. Upon identifying designs that function in a desired manner, the scientists then painstakingly construct a real-world version using the actual, living cells.
In the case of the xenobots, the contractive skin muscles contract and expand, like an engine. Through this action, a xenobot can move itself around on a pumping pair of stumpy legs. One xenobot has a hole in its middle that's been formed into a pouch allowing it, theoretically, to carry a tiny payload of some sort. The xenobots can survive for about 10 days.
Since the research is really about the pipeline, the xenobots are primarily intended as a demonstration of the system's potential. If you're wondering why we might want living robots, you're not alone. According to senior researcher roboticist Joshua Bongard, "It's impossible to know what the applications will be for any new technology, so we can really only guess."
Even so, the researchers propose a few possible applications, including eating up and digesting microplastics in the ocean, and doing the same for toxins in the human body, delivering drugs to patients, and cleaning plaque from human artery walls.
All of these assume that the system can mature into a means of creating robots capable of performing multiple interlinked tasks such as identifying and then digesting toxins. If this becomes doable, there are some obvious benefits inherent in living-cell robots: They can heal themselves if the become damaged—this has already been demonstrated with the xenobots—and they are made of eminently biodegradable materials.
Ethical and practical issues
Image source: Kriegman, Blackiston, Levin, and Bongard
Chief among the ethical concerns regarding living robots is the notion that, as living organisms, the robots may be reasonably entitled to moral status as individuals.
L. Syd M Johnson, bioethicist at SUNY Upstate Medical University tells Big Think: "As with any new technology, how it is used or will be used raises important ethical concerns. As humans, we've shown time and again that we are really not good at predicting the future consequences of technological innovations. But when novel living organisms are created, I have concerns about potential harms to those organisms themselves. Humans have been creating and manipulating animals for millennia with little concern for how it affects the animals themselves. Will these xenobots be more like bacteria, which are alive, but not sentient, so we need not worry about their welfare? Or will they be more like jellyfish or corals, animals about whom we might reasonably wonder what they feel? In principle, xenobots are arguably animals, and could be created using neural cells, and to have a nervous system that would make it easier to "program" them to respond to and navigate the world. Releasing them into the world, and creating them to be potentially capable of feeling are both possibilities that I find worrying."
On a practical level, it's worth noting that among the possible uses mentioned by the researchers is an illustration of the type of problem the robots couldn't really solve. If they ate microplastics from the sea and then died, what would happen to their plastic-filled corpses? Wouldn't they eventually be eaten by other ocean organisms, merely shifting the plastic to a different rung in the ecological ladder? (Removing toxins from a human body would be less of an issue—the robot could simply be eliminated through the patient's digestive system.)
These concerns notwithstanding, the researchers remain excited by the possibilities, even beyond making living robots. "The aim is to understand the software of life," says Levin. "If you think about birth defects, cancer, age-related diseases, all of these things could be solved if we knew how to make biological structures, to have ultimate control over growth and form."