Imagine being trapped under rubble after a natural disaster until a cockroach wriggles in from under a rock. Minutes later, the ruble is removed, and you're pulled to safety. Wait a minute - did a cockroach save your life? Not exactly. While researchers in Japan have actually created cyborg cockroaches to help find survivors trapped under rubble after earthquakes, that's not what we're talking about. We're talking about microbots - tiny robots designed to replicate the movements of small creatures like bugs to reach spaces that humans can't for everything from search and rescue to inspection to even space exploration.

Microbots are most commonly used in the biotech industry to develop diagnostic and targeted therapeutics to monitor and treat disease. But they've been used for environmental monitoring, soil remediation, agricultural research, jet engine inspection, and search and rescue. Not only that - they're about to be used for a ton more stuff as this technology has advanced rapidly over the past few years. In this report, we cover how small robots work and what they can do, and then cover the most incredible opportunities that are about to be unlocked with this technology.

What small robots can do today

Everyone knows those giant robot arms used on automotive assembly lines to make cars. In contrast, there's a myth that small robots are nonindustrial, inflexible toys. But many industrial manufacturers use small robots to mass produce and assemble automotive electronic control units, cell phones, medical devices, printed circuit boards, and syringes.

Benchtop robots are used for knitting, machine tending, parts feeding, test, and inspection tasks, and can dispense adhesives, polish and tighten screws and solder parts on assembly lines. These small robots are typically classified by their reach of 500 millimeters or less with a payload capacity under 3 kilograms. One benchtop unit is only 12 inches tall, with a base the size of the palm of your hand and weighs less than 5 kilograms. Another is the size of an 8.5 by 11 sheet of paper.

Then, there's MiGriBot - the Miniaturized Gripper Robot. MiGriBot is the world's fastest microbot. It can grasp and move a micro-object 720 times per minute with the accuracy of a micrometer. That's a millionth of a meter. These MiGriBots will soon be used to create mini assembly lines for microfactories. They'll assemble microelectronics for smartphones, computers, or even nanotechnology such as nanosensors to detect toxic chemicals or cancer cells. And the ability to produce microtechnology en mass without the need for giant arms could reduce electricity on a massive scale.

Now if you thought MiGriBot was small… Meet peaky - the smallest remote-controlled walking robot ever created. Only a half-millimeter wide, Peaky is smaller than a flea. Developed after a peekytoe crab, it can bend, crawl, twist, and jump. These microbots are intended to repair small structures or assemble tiny machines. But they're nowhere near industrial scale yet. Powering robots of this size can be a problem. In Peaky's case, no batteries are required. It uses a shape-memory alloy that deforms and reforms as a laser beam hits it to create movement.

The same team created millimeter-sized robots inspired by beetles, crickets, and inchworms, as well as a winged microchip. This chip became the world's smallest flying human-made structure at the size of a grain of sand. These tiny, sensor-carrying, solar-powered devices replicate dandelions blown by the wind. While 30x as heavy as a 1-milligram dandelion, it can still travel the length of a football field in a moderate breeze, then share data up to 60 meters away. Their wireless sensors can monitor temperature and humidity changes across farms or forests or track air contamination like GHG emissions or airborne disease.

Many microbot creators use biomimicry to style microbots, classified by components with dimensions smaller than a millimeter and larger than a micrometer, after insects some of the smallest organisms in our world. This jumping bugbot is meant to perform structural evaluations or take water samples where only bugs can reach. Another bot mimics the ability of animals to use springtails to right themselves in mid-flight.

Small, self-navigating drones are meant to think and move like bees to pollinate flowers. The autonomous RoboBee will explore hazardous environments, perform search and rescue, and just like its natural inspiration, assist with agriculture. Scientists plan to use the RoboFly to find gas leaks or harvest energy from radio frequencies.

Beyond agriculture, potential applications of insect-inspired bots include manufacturing, surveillance and defense. The Black Hornet Nano helicopter weighs only 16 grams, is four inches long, and is built to sustain storms. Currently priced at $200K, the military uses it for situational awareness and to find potential threats on the battlefield. The US Navy has the Gecko Robotics Phased Array robotic platform that crawls in 3D spaces to inspect damages in places sailors can't reach. Both of these could soon be replaced with even smaller robots.

Last year, researchers from MIT and Harvard made tiny, agile drones that maneuver like actual bugs. The researchers created artificial muscles for these aerial robots to hover for 20 seconds and weigh less than a fourth of a penny. Researchers previously created autonomous underwater explorers that work together and communicate in swarms. Recent tests used vibrations to influence how hundreds and thousands of microbot collectives move, operating like a literal hive mind.

For all these robots to operate autonomously, they'll need computer vision tools to see. LiDar, used to power some self-driving cars, relies on large, clunky sensors. This has gotten smaller too. The smallest, lightest scanning LiDar available is called SF45 and has been added to a tiny drone rover. But this will need to be scaled down even further to be used by microbots.

Microbots plus nanotechnology equals... nanobots!

Smaller than microbots are nanobots, with parts smaller than a micrometer in the nanometer range. Nanomaterials were developed for drug delivery, electronics, fuel and solar cells, and could someday be used for space exploration - but more on this later.

Nanotechnology is currently used in soil remediation, where nanomaterials are released directly into the soil. Nanomaterials detect and treat soil pollutants and can stabilize solid waste as well as control soil erosion. Recent developments in nanotech have increased the effectiveness of adsorbent materials to provide new innovative systems to improve environmental remediation. Researchers have shown how tiny self-propelled "nano-swimmers" could release nanomaterials themselves to improve remediation or water filtration. And researchers have already developed nanosystems and nanomaterials to remove pollutants like heavy metals or even radioactive waste from water. Researchers have also created a proof of concept to use microbots to break down microplastics from drinking water or wastewater.

Controls to make this nanotech work autonomously will be the most difficult aspect of development. Researchers recently created the world's smallest walking robot. The width of a human hair, they walk autonomously with a circuit on board and no external controls - a huge feat. While microscale now, similar techniques will need to be printed at nanoscale for nanobots.

The tiny doctor is in - small bots in medicine

Micro and nanotechnology is most in demand for healthcare applications, where biomimicry is also applied. These micro-scallops, only a fraction of a millimeter in size, are designed to navigate the human bloodstream - and even the human eye. Scientists already directed a swarm of microscopic swimming robots to clear out pneumonia microbes from the lungs of mice.

An equivalent intravenous antibiotic injection would need to be 3,000x higher to achieve the same result. This could improve antibiotic penetration to save more lives - as one million adults in the US are hospitalized for pneumonia, and 50,000 die yearly. Worldwide, pneumonia kills 2.5 million people on average.

This nanobot taken as a pill can inject drugs such as insulin directly into the intestine, where the user doesn't feel the pain of the shot. Microbotics have also led to the creation of the world's smallest pacemaker. Researchers at Penn Dental have used microbots to treat difficult-to-reach areas of the root canal for biofilms, drug delivery, or retrieval of diagnostic samples. Shapeshifting microbots have also been used to brush and floss teeth. Robots 10x smaller than a red blood cell may soon be used to fight cancer cells, controlled by ultrasound waves. Or magnets could be used to deliver medicine via nanorods directly to the spinal cord. Other microbots can change shape and harden to mimic bone growth.

Nanobots can also spread targeted antibiotics throughout an entire wound, a major improvement compared to typical antibiotics that only kill bacteria where locally administered. This technology could be used to fight bacteria hiding in the knee or other joint implants or to treat kidney stones. Bacteria is the fourth largest cause of death in US hospitals and kills approximately 1.2 million people per year.

Microbots have taken the form of everything from magnetic slime to pasta to navigate the human body and retrieve objects once inside. Eventually, these microbots could be assembled into swarms to deliver drugs or unblock arteries. One company, Bionaut Labs, plans clinical trials within two years for its microbots injected into the body and guided by magnets to treat congenital brain malformations and tumors. It's not just humans microbots could heal. Similar applications could be used to create nanorobots that heal themselves, too. Researchers have made nanobots that self-repair themselves when broken apart and repair circuits when they become damaged, such as those used to power electric car batteries.

MIT has even created microbots that self-assemble into larger structures. If one robot isn't enough to build the structure, it copies itself and splits the work. Once applied on the nano level, this could work like the nanobots of science fiction - with amazing and potentially dangerous applications.

Future opportunities of microbots

The next microbot medical frontier will be tiny biohybrid robots, remote-controlled to perform high-precision biochemical operations. They'll be no bigger than a biological cell, or even smaller, to travel through the circulatory system, the ideal delivery route. Biohybrid nanobots could eventually remove blood clots from the brain without surgery, deliver drugs directly to organs, or assist with fertilization.

Nanomedicine is particularly focused on localized therapies to combat cancer, and plenty of progress has been made. Scientists most recently tested magnets to deliver cancer-killing microbots directly to tumors. Nanobots could eventually enhance CRISPR too. Recent funding for CRISPR-based approaches to detect and treat sepsis included hybrid bio-inorganic nanobot applications. There's even a proof of concept microbot that could bioprint healthy cells directly inside the human body, where we need them to grow or heal - like to repair gastric wounds. It's currently believed that biohybrid nanobots like this could begin to inhabit our bodies by 2030 at the earliest.

The farthest out nanobot application is space exploration, as many space agencies have various types and stages of plans in the works to add nanosensors and nanorobots to improve the performance of spaceships, spacesuits, and space rovers. For example, carbon nanotubes could make more lightweight spaceships, space elevators, or solar sails. Layers of bio-nano robots to space suits could self-repair damage, seal punctures, or even provide drugs to astronauts directly during medical emergencies.

Space agencies could also use nanosensors could search planets like Mars for essential chemicals like water, or monitor trace levels of harmful chemicals as part of a ship's life support system. Scientists could also create nanoships (or nanoprobes) to even explore the universe. NASA had plans for an autonomous nanotechnology swarm known as ANTS, and more recently, the SWIM concept was awarded $600,000 in funding. SWIM could potentially replace NASA's Ingenuity helicopter to inform rovers about their environment, arming each robot in the swam with its own propulsion and communication systems. NASA also announced plans for its "starchip" project in 2016, but collisions with gas and dust floating in space would be enough to be catastrophic to the crafts, so it's still in progress.

With accelerating exponential advancements in AI, it's conceivable the technology to send these self-replicating nanoprobes into space could be ready by 2050. But we'll let Michio Kaku have the last word on this one.