Author｜David Levin
Translator｜Zhao Jinyu
Editor｜D
Core Idea: How can we create a truly intelligent microbot that can operate independently? A robotics expert provides a detailed answer to this question and describes the medical tasks these microbots can perform for us.In the near future, the “surgeons” treating our ailments may be microbots traveling through our bodies, capable of tracking cancer tumors or clearing clots even in the smallest arteries. If this sounds like a science fiction scenario, you’re not mistaken: concepts like this have been explored in films such as Fantastic Voyage and Innerspace, imagining machines shrunk down to the size of individual cells. However, advancements in robotics and materials science over the past few years have brought this idea closer to reality.Bradley Nelson, a robotics expert at ETH Zurich, has dedicated his career to creating such micro devices. He states that while engineers have already manufactured robots about the size of microorganisms that can move around and sense their environment, they still require human remote control. He says the next major challenge will be to imbue these machines with some form of intelligence so that they can perform tasks independently, completely free from human operators.
Bradley Nelson, robotics expert at ETH Zurich (Image source: JAMES PROVOST)But how can we create a truly intelligent microbot? How can we deploy them in the real world? Authors of an article in the 2022 Annual Review of Control, Robotics, and Autonomous Systems posed these questions. Co-author Nelson spoke with Knowable magazine about why the prospects in this direction are so challenging and what the future of intelligent micro machines might look like. To ensure brevity and clarity, this article has been edited for coherence.What is a microbot? How small is it?Generally speaking, any robot, regardless of size, is a device that can operate in uncertain environments; it can adapt to its surroundings, move around, and achieve specific goals. The traditional view holds that robotics relies on three pillars: first, perception—robots must collect information about their environment in some way. Second, mobility—they must have some form of drive mechanism to interact with the world. Third, computation—they must figure out what actions to take in specific situations.In my work, I often try to incorporate these elements into micro machines, ranging in size from single-cell dimensions to hundreds of micrometers. I am not particularly interested in things smaller than that. Once you go below one micrometer, the various physical properties dominating the environment change. You have to start considering how phenomena like Brownian motion (the random movement of atoms and molecules) will affect your device; that becomes the primary interaction between your robot and the environment, so the study becomes more like chemistry than robotics.
To give cell-sized robots true “intelligence,” engineers must integrate various systems. The hypothetical microbot depicted above includes a central processor, a means of locomotion, a power source, sensors, mechanical arms, and other functions. This conceptual diagram illustrates its basic structure and its biological analogs.What does “intelligence” mean for the microbots you are trying to build? What can such small devices do?Well, that’s an interesting philosophical question that can be discussed over a beer. We can define intelligence in many ways, but when I think something is intelligent, my perspective is very anthropomorphic. Am I surprised by its behavior and how it adapts to its environment? Can it do something in a way that I find remarkable and interesting? If it can adapt to its environment in that way, I consider it intelligent.For example, consider bacteria like E. coli. Each E. coli bacterium is a single cell, perhaps only one or two micrometers long. Its surface has chemical receptors that can sense surrounding amino acids or other nutrients. It has a communication channel leading to its flagellum (a rotating appendage that enables movement), allowing it to change its cruising behavior in your digestive tract (or elsewhere).E. coli also has a kind of “software”: DNA fragments floating within it control how it rebuilds or repairs itself, allowing it to sustain life. So, in a sense, it is a microbot of nature. It has sensors, communication channels, sensing algorithms, control software for guiding motors—and it can make basic decisions. In fact, E. coli does this so well that some robotics experts are using it as part of their devices. They typically build microbots on top of microorganisms, letting them handle all the sensing and movement.How do you make a microbot dance? By firing a laser at it, of course. Mark Miskin, a robotics expert at the University of Pennsylvania, has developed a new type of buildable and controllable cell-sized robot: using focused lasers, he can power the tiny built-in circuits on the robot’s back, causing its legs to bend instantly. By alternating the laser beam between two different circuits, he can induce the robot to “walk” in a specific direction. In the video above, you can see this process in action—notice the tiny white flashes appearing on the back of Miskin’s robot. (Source: MARC MISKIN / UNIVERSITY OF PENNSYLVANIA AND CORNELL UNIVERSITY)Have your microbots drawn inspiration from bacteria?Absolutely. The way they move in their environment is incredible. They use a strategy I never thought of—initially, they move randomly, but when they start sensing something good, like amino acids or other nutrients, they swim a bit longer, which often leads them to gradually move in that direction. This is what we call “biased random walk.” As an engineer, you think, “Oh, this method is really great.” They are essentially following a chemical gradient.You can imagine creating microbots that can achieve similar functions: they could follow temperature gradients, pH gradients, or chemical signatures of certain diseases. So yes, nature has provided me with a lot of inspiration. The extremely rich and complex “intelligent” behaviors evolved in tiny organisms are exciting, and if I can find a way to replicate these behaviors in robots, it would be thrilling.What obstacles need to be overcome to create such robots?Oh, there are many obstacles. Since 2003, I have been working in the field of microbot creation. Initially, we were just trying to figure out how to make these things move and how to control them. Later, we began to think about what functions they should achieve. What kind of chemical or physical functions do we want to add to these devices? Is there a way to give them some autonomy?We are still exploring that last question. We have started investigating polymers and materials that can respond to their environment in some way, such as automatically changing shape to navigate through narrow spaces, etc. But the biggest obstacle is integrating all the different components. Successful microbots must be able to sense their environment and respond to complete a specific task.Assuming we can achieve this, how do you think microbots will be used in the real world? How will they improve existing technologies? I believe the first applications we will see will be in the medical field. This is a logical progression. We are already using increasingly smaller medical devices and robots for surgeries; compared to other technologies, these medical tools can penetrate deeper into your body and cause less trauma, such as catheters that can reach deep into the brain to treat aneurysms or clear clots. In the future, we will continue to see further developments in this technology, but there are limits to how small we can make these devices.Using advanced new materials, Nelson’s lab has developed tiny remote-controlled devices that can change shape and “swim” in response to magnetic fields. With such technology, it is possible to create microbots for drug delivery or to perform medical procedures inside the human body. (Source: EPFL)Naturally, the next step will be to have microbots enter tiny spaces within the body and initiate treatment at the early stages of disease. Imagine a device that can enter your lungs and detect and treat cancer before it spreads. Or treat blood clots deep in your brain, in areas inaccessible to catheters—simple microbots could potentially reach blocked areas and help clear them.These tasks sound quite complex. Do you need artificial intelligence to perform these tasks?No, not for now. I mean, currently, it is impossible to incorporate artificial intelligence into microbots. The amount of computation required for such small devices is too great. But if we could reach that level, it would be incredibly cool, and I am sure we could come up with some practical uses for it, but that is beyond my professional scope and may not happen in my lifetime.However, it is important to note that we may not actually need something as powerful as artificial intelligence for this issue. You can still use simple intelligence and autonomous decision-making to build a very useful microbot. If you have a micro device that can recognize changes in the environment and alter its behavior accordingly, it can perform surprisingly complex tasks. For example, delivering chemotherapy. If a microbot can detect the pH or temperature gradient of a tumor, it can slowly move in that direction and release highly toxic drugs directly into the cancerous tissue without affecting other parts of the body.Devices like this may only possess microbial-level intelligence, but they could still be extremely effective for disease detection and drug delivery. As an engineer, I always keep this goal in mind: what is the most streamlined way I can design a machine to accomplish a task? It doesn’t have to play chess; it just needs to get the job done.The renowned physicist Richard Feynman envisioned a future filled with micro machines in his 1959 speech “There’s Plenty of Room at the Bottom.” In a video shot many years later, he revisited these concepts for a new audience. (Source: MUON RAY)Do you think microbots will be commercially used in the near future? If so, how far do you think we are from that goal?Yes, everyone wants to know how long it will take! In the past, I always said we had five years to go. Now I would say three years. Although there are still many uncertainties, the timeline is shortening. Others in the field are manufacturing electronic devices at increasingly smaller scales, placing tiny transistors and other components on microbots, and directly building circuits within them. We are beginning to realize that we can embed some basic computational elements directly into microbots.The question is, how much computation will they ultimately need? How much onboard memory will they require? How much do you want them to learn? With our current technology, microbots will be very simple in the foreseeable future.
AuthorDavid Levin is a freelance science writer based in Boston. You can contact him through his website www.davidlevineditorial.com.
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Translation Reference Table:
Fantastic Voyage Fantastic Voyage
Innerspace Innerspace
Bradley Nelson Bradley Nelson
ETH Zürich ETH Zurich
Annual Review of Control, Robotics, and Autonomous Systems Annual Review of Control, Robotics, and Autonomous Systems
rotating appendage rotating appendage
MARC MISKIN Mark Miskin
Richard Feynman Richard Feynman
There’s Plenty of Room at the Bottom There’s Plenty of Room at the Bottom
Copyright Notice
This article is a licensed translation from Knowable Magazine, published by Annual Reviews. Click at the end of the article to read the original text and subscribe to their English newsletter.
Annual Reviews is a non-profit organization dedicated to providing highly summarized, comprehensive information to researchers, focusing on publishing review journals.
Original title “Making microbots smart,” by David Levin, published on June 27, 2022, in Knowable Magazine.
Cover image CREDIT: TY HUANG ET AL, from Knowable Magazine website.
Link:
https://knowablemagazine.org/article/technology/2022/making-microbots-smart
Typesetting｜Matthew
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