Imagen-Microrobotic Revolution: How Bee-Sized Robots Navigate Multiple Environments

Introduction

Imagine robots as small as bees that can fly through the air, dive underwater, walk on liquid surfaces, and leap like fleas. This isn't science fiction – it's the cutting-edge reality of microrobotics. In a recent episode of the Veritasium podcast hosted by Derek Muller, viewers were given unprecedented access to some of the world's leading microrobotics laboratories, including those at MIT and Harvard. The conversation with experts like Dr. Kevin Chen and his team reveals how these tiny marvels work and what revolutionary applications they might enable.

The development of insect-scale robots represents a fundamental shift in robotics. Unlike their larger counterparts, these microrobots face unique physical challenges that require innovative solutions, from navigating surface tension to developing power systems that function at microscopic scales. As we'll explore, these tiny machines could one day work in swarms to save lives, perform inspections in places humans can't reach, and potentially transform our relationship with technology.

The Physics of Small-Scale Robotics: When Size Changes Everything

One of the most fascinating aspects of microrobotics is how differently physics behaves at such small scales. As Derek explains during the podcast, the surface area to volume ratio increases dramatically as objects get smaller, which transforms how these robots must move through their environments.

"Larger objects typically have less surface area relative to their volume," Derek notes, demonstrating this principle with a mathematical example. A 10-centimeter cube has a surface area to volume ratio of 0.6 to 1, while a much smaller 1-centimeter cube has a ratio of 6 to 1—ten times greater.

This difference is crucial because drag depends on surface area. With more surface area relative to their mass, microrobots experience much more drag and have less inertia to overcome it. This explains why small insects like bees can't soar like birds but instead must flap their wings hundreds of times per second.

"What they're doing is generating swirls of air above the top of the wing, and those vortices create low-pressure zones," Derek explains. "When combined with the high pressure below the wing, that is what generates lift."

This fundamental understanding of small-scale physics guides the design of these microrobots, leading to engineering solutions that work with—rather than against—these natural forces.

Breaking Barriers: Conquering Surface Tension

For robots operating at insect scale, surface tension—the property that allows water striders to walk on water—becomes a significant obstacle. Dr. Chen's lab at MIT has developed several ingenious approaches to overcome this challenge.

One of their most remarkable creations is a tiny yellow submarine that can both swim and fly. Weighing just 175 milligrams ("about the mass of two Cheerios," as Derek puts it), this robot faces a major challenge when transitioning between water and air due to surface tension.

"That's a consequence of physics at a smaller scale," one researcher explains. "The surface tension is like a wall that blocks the transition process."

To solve this problem, the submarine employs an innovative solution: it splits water into hydrogen and oxygen gases and stores them in a buoyancy chamber. The buoyancy helps bring the robot's fragile wings above the water surface without damaging them. But the robot is still trapped by surface tension, so it ignites the stored gases with a spark, creating an explosion that launches the robot 30 centimeters into the air—breaking free of the water's surface barrier.

Another robot uses a different approach: water-repellent copper pads on its feet allow it to walk on water, but when it needs to submerge, it applies 600 volts to create a positive charge that breaks the hydrophobic barrier, enabling it to sink on command.

These solutions demonstrate the ingenuity required to work with natural forces at microscopic scales rather than trying to overpower them.

Powering the Impossibly Small: From Artificial Muscles to Micro Explosions

One of the greatest challenges in microrobotics is power. Traditional electric motors don't scale down effectively to insect size, as the magnets and coils become inefficient at such small scales.

The first generation of Harvard's RoboBees used piezoelectric crystals that contract slightly when voltage is applied. However, these crystals are fragile and provide only minimal movement—about 0.1% contraction, as Derek notes—requiring mechanical amplification to generate enough wing motion for flight.

Dr. Chen's lab at MIT has developed a revolutionary alternative: soft polymers that function like artificial muscles. These polymers are coated with carbon nanotubes on each side, creating conductive plates. When opposite charges are applied to these plates, they pull together, stretching the polymer; when like charges are applied, they repel, causing the polymer to shrink.

"By cycling the voltage hundreds of times per second, these muscles drive the RoboBees' wings," Derek explains. These flexible muscles can stretch up to 25% of their length and, remarkably, can self-heal if damaged.

"When high current is cycled, the carbon nanotubes that are touching burn off, and so the muscle self-heals," Derek notes. The team has even developed laser surgery techniques to repair damaged muscles, isolating defects to maintain functionality.

Another groundbreaking approach comes from Cameron's lab, where they've developed a penny-sized combustion engine that runs on methane and oxygen.

"We just said, let's just sail past all of that and just use a video game cheat code and just power our robot with the smallest explosions possible," Cameron explains with enthusiasm. His tiny engine uses a flexible polymer membrane as a piston, with the natural elasticity of the material eliminating the need for a complex return mechanism.

Interestingly, the continuous flow of methane and oxygen doesn't cause the fuel line to catch fire. This is because at smaller scales, explosions lose heat more quickly as their volume shrinks faster than their surface area—another example of how physics changes at the microscale.

Applications: From Disaster Response to Industrial Inspection

While some of these robots might seem like fascinating curiosities, they have serious real-world applications that could transform industries and save lives.

HAMR, a cockroach-inspired robot from Harvard, demonstrates this potential. It's incredibly fast—running 10.5 body lengths per second, which is faster than a horse in relative terms—and versatile. Its special foot pads can apply voltage to polarized metal surfaces, creating an opposite charge that allows it to stick to and climb metal surfaces.

Rolls-Royce and Harvard are working together to put HAMR inside jet engines to inspect for turbine cracks. Currently, turbine inspections cost tens of thousands of dollars and can take a full day, with manufacturers performing them every 3000 flight cycles or 180 days. HAMR could potentially transform this process, making inspections faster, cheaper, and more thorough.

Disaster response represents another promising application. Derek recounts how robots were first deployed during the 9/11 search for survivors at Ground Zero, but they proved ineffective—they were too large, too expensive, and frequently got stuck. The ideal rescue robot needs to navigate tight spaces, withstand damage, operate across varied environments, and be inexpensive enough to be replaceable.

"The material cost is actually quite low for making the robot," notes Dr. Chen. "Couple of dollars per robot, but it's really not that much." This affordability opens the possibility of deploying swarms of insect-sized microrobots to search for survivors in disaster zones—potentially saving lives in situations where human rescuers cannot safely go.

Ethical Considerations: Between Science Fiction and Reality

Of course, technologies this powerful inevitably raise ethical questions. The concept of swarms of tiny robots immediately conjures dystopian images from science fiction, as Derek points out:

"Swarms of miniature killer robots are straight out of dystopian sci-fi. Think the hunter-seeker from 'Dune' or the killer robot bees from 'Black Mirror.'"

Dr. Chen acknowledges this connection: "You might be familiar with that famous 'Black Mirror' TV episode where all the bees... When that came out, everybody that I had ever met in my entire life sent me a text message and was like, 'Hey bro, you seen this?'"

Surveillance is perhaps the most obvious concern—tiny flying robots that look like insects could potentially be used for covert monitoring. "I can still easily imagine a world where these same robots that are supposed to help in a disaster are secretly being used to spy on me," Derek reflects. "I mean, it's a bug that would literally look like a bug. That's terrifying."

When asked about ethical concerns, Dr. Chen provides a thoughtful response: "We really focus on the fundamental science and solving the fun technical problems. And as a society in general, we all should think about collectively how to prevent those new technology from doing harm."

It's worth noting that most current microrobots aren't yet capable of autonomous surveillance—they require external power, sensing, and computation. However, Harvard's RoboBee has achieved short bursts of untethered autonomous flight, suggesting that fully independent operation isn't far off.

The Future of Microrobotics: Driven by Curiosity

Despite the practical applications and potential concerns, many researchers in this field are ultimately driven by scientific curiosity rather than commercial or military interests.

"If it's about application, we should all like make a startup and try to think about what we can do to make money, right?" Dr. Chen reflects. "We think there are nice applications, like inspection and search and rescue, but I would say as a research lab, we are mostly driven by curiosity. I think that's a very honest answer."

This pursuit of knowledge for its own sake has led to remarkable achievements. Cameron's combustion-powered robot, despite weighing just 1.6 grams ("about as much as a gummy bear," he notes), can jump two feet in the air and carry 22 times its body weight—comparable to a cockroach or beetle.

"We'll be able to put a fuel tank, you know, microelectronics, sensors, a camera battery, and still have weight left over to go, and this thing will still chug along," Cameron enthuses. "That's the future. That's the goal."

Conclusion: Small Robots, Big Implications

The world of microrobotics stands at a fascinating intersection of biology, physics, materials science, and engineering. By understanding and working with the unique physics of small scales, scientists have created robots that can fly like bees, walk on water, and perform feats impossible for their larger counterparts.

While we're still years away from fully autonomous swarms of insect robots, the progress is remarkable and accelerating. These tiny machines could transform how we inspect industrial equipment, respond to disasters, and interact with environments hostile to humans.

As Dr. Chen and his colleagues continue their work, driven by scientific curiosity as much as practical applications, we can expect even more impressive capabilities from these miniature marvels. The fundamental challenges of power, control, and autonomy remain, but the creative solutions emerging from labs around the world suggest that the age of microrobotics is just beginning.

Perhaps most importantly, this field reminds us that sometimes the most revolutionary technologies come not from trying to overpower nature, but from deeply understanding and working with its fundamental principles—especially when those principles operate differently at the smallest scales.

Key Points

• Microrobots at insect-scale can navigate multiple environments, including flying, swimming, jumping, and transitioning between air and water
• Surface tension presents a significant challenge for tiny robots moving between environments, requiring innovative engineering solutions
• Scale fundamentally changes the physics of movement - smaller robots face higher drag relative to their mass, requiring different approaches to flight and mobility
• Powering microrobots remains challenging - traditional batteries are inefficient at small scales, leading to solutions like artificial muscles and micro-combustion engines
• Practical applications include search and rescue in disaster zones, industrial inspections in confined spaces, and potentially environmental monitoring
• While dystopian concerns exist about surveillance applications, researchers emphasize their focus on fundamental science and solving technical challenges
• Despite practical applications, many roboticists in the field are primarily driven by scientific curiosity rather than commercial applications

For the full conversation, watch the video here.