Half a century after Neil Armstrong memorably uttered the words “one giant leap for mankind,” technological innovation has gotten smaller. Yes, we still thrill to enormous, sky-scraping buildings and the gravity-defying power of rockets, but many of the biggest advances take place on a scale that’s unimaginably tiny next to those of yesteryear. New generations of mobile devices — be they laptops, smartphones and smart watches — shave mere millimeters off the thickness of their already thin predecessors; making already small and portable devices even smaller and more portable. CRISPR/cas9 technology allows scientists to edit single genes; potentially eradicating deadly diseases as a result. New nanometer-scale processes allow chip designers to squeeze ever more transistors onto the surface of integrated circuits; doubling computing power every 12-18 months in the process.
The world of robotics is no different. Think that robots like Boston Dynamics’ canine-inspired Spot robot or humanoid Atlas robot are at the top of the innovation pile, simply because they’re the most visible? Not so fast! On the tinier end of the spectrum, the advances may not be quite so apparent — but, at their scale, they may be even more exciting.
Welcome to the world of microscale robots, a genre of robotics that’s less stop-and-stare attention-grabbing than its metallic big brothers and sisters, but potentially every bit as transformative. These robots could be useful for a broad range of applications, from carrying out microscale or nanoscale surgical feats to exploring other planets.
Examples are everywhere
Demonstrations of this technology in action are everywhere. Recently, researchers at the University of Southern California built a flying, insect-inspired robot that weighs just 95 milligrams and is smaller than a penny.
Meanwhile, at Germany’s Max Planck Institute for Intelligent Systems, for instance, engineers have built a small steerable car. That doesn’t sound particularly unusual until you hear that the car in question isn’t a small car like a Chevrolet Spark or a Ford Fiesta, but rather a car-shaped robot just 40 to 50 micrometers in size. That’s around half the diameter of a single human hair. The lab has built a series of such self-assembling mobile micromachines that can be programmed to assemble in a wide variety of different formations depending on what is required of them. And that’s not all.
“Our team has proposed [a number of] new synthetic and bio-hybrid microrobots,” Dr. Metin Sitti, director of Max Planck Institute’s Physical Intelligence Department, told Digital Trends. “As synthetic small-scale robots, we have demonstrated various soft shape-programmable wireless mobile robots with multi-locomotion and multi-functional operation capability. Such soft tiny robots have been inspired by soft small-scale animals such as jellyfishes, caterpillars, warms, spermatozoids, and beetle larvae. As bio-hybrid microrobots, we have [also] proposed bacteria- and alga-driven microswimmers for delivering the attached cargo in target regions while they sense microenvironment, [such as] chemical or oxygen gradients, pH changes, and light.”
“[Microrobots could be useful] for non-invasive or minimally invasive medical diagnosis and treatment for short or long durations.”
The word “they,” as in plural, is thrown around a lot when people talk about microbots. We might consider having multiple large size robots work together, but it is likely to be only a few functioning in conjunction with one another. To paraphrase Green Day’s “Boulevard of Broken Dreams,” robots of this scale are designed to walk (or roll, or crawl, or swim, or leap) alone. Not the case on the smaller end of the spectrum.
“With traditional robots, the robots need to be sophisticated and able to perform complex task usually by themselves,” said Dea Gyu Kim, a PhD candidate working on micro-robots at Georgia Tech. “However, with micro-robots they can be more cheap and simple. Instead of relying on [a] single robot to perform one specific complex action, a large group of them can interact in different ways to accomplish different actions.”
The robots Kim has been working on are a couple of millimeters in length, about the size of an ant. (Although, in the future, the team hopes to make smaller still.) Called “bristle-bots,” the 3D-printed creations walk on four or six bristle-like legs. Thanks to the presence of a piezoelectric actuator made of lead zirconate titanate on their backs, they can be steered using tiny vibrations.
How will we use them?
“The most ideal real world application [for these robots] for me is to use large group of bristle-bots to access hard to reach areas, such as cracks inside of large infrastructure or small gaps in complex machinery, where humans or typical robots can’t go and perform surveys,” Kim continued. “[They could work by] mimicking insect foraging behaviors and [transmitting] back data of interest.”
Metin Sitti, meanwhile, thinks the medical field is where these tiny robots will be of most use. “I believe the highest scientific and societal impact of mobile microrobotics would be in healthcare, where wireless microrobots can access unprecedented or hard-to-reach areas inside the human body,” Sitti continued. “[That could be useful] for non-invasive or minimally invasive medical diagnosis and treatment for short or long durations. Therefore, my group has focused on applying our new microrobots for various medical applications, such as targeted cancer therapy, embolization, blood clot opening, biopsy, and microsurgery.”
There are plenty more ideas where those two came from, as well. From continuous imaging agents to micro-teams of robots able to move objects much larger than themselves to magnet-controlled micro-robots which can remove heavy metals from contaminated water, there are few areas where micro-robots could not prove useful in some capacity. As researchers have increasingly shown their ability to move over an assortment of terrains, ranging from treacherous inclines to swimming through bodily fluids, they will only become more useful.
Bottlenecks still exist, of course. As with larger robots, these include the challenge of powering robots without having to keep them tethered, making them more agile, and mass-manufacturing them more easily. In the case of medical applications, they will also need to be proven to be safe before they can be used for Fantastic Voyage-style missions through the human body. But these challenges are being worked on, refined and, in many cases, solved by ever-growing numbers of researchers around the world.
As physicist Richard Feynman once said about the field of nanotechnology, smaller cousin of micro-robotics, “There’s plenty of room at the bottom.” But that’s certainly not through lack of interest!
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