It’s science-fiction-turned-reality: Researchers are developing micro- and nanoscale robots that move freely in the body, communicate with each other, perform jobs, and degrade when their mission is complete. These tiny robots will someday “have a major impact” on disease diagnosis, treatment, and prevention, according to a new review in Science Robotics from a top nanoengineering team at the University of California, San Diego.
The review highlights four areas of medicine where tiny robots have been successfully used in proof-of-concept studies: targeted delivery, precision surgery, sensing of biological targets, and detoxification. Of those, “active drug delivery is primarily the most promising commercial application of medical microrobots,” said paper co-author Joseph Wang, chair of nanoengineering at UCSD, in an email to IEEE Spectrum. In December, for example, researchers at ETH Zurich in Switzerland showed that a wire-shaped nanorobot could be wirelessly steered toward a location and then triggered by a magnetic field to release drugs to kill cancer cells.
To get to know these little machines better before we meet them in the doctor’s office, here are five things to know about micro- and nanorobots:
1. They are hard to move—and even harder to power.
Two of the key challenges of miniaturizing robots to the micro- and nanoscales are locomotion and power. You simply can’t fit gears or a battery on these guys. Many of the robots employ a swimming strategy and are either chemically powered or externally powered by magnetic fields or other energies, including light, heat, or electricity. One of Wang’s favorites is a “nanorocket” his team developed that propels itself in the stomach or gastrointestinal tract using gastric fluid as fuel and leaving a trail of bubbles in its wake. Still, the field continues to look for new energy sources that last longer that current sources and will work autonomously, without a technician’s intervention.
2. They can perform surgery.
Robot-assisted surgery is now common, translating doctors’ hand movements to smaller, precise motions inside a patient’s body. Now, imagine that on the nanoscale. Scientists are developing nanodrillers, microgrippers, and other tools to be injected into the body, travel to particular areas in the body, and then capture or remove certain tissues, such as a clump of cells for biopsy. In one recent example, researchers constructed a tube-like microrobot that performed surgery, injecting a needle into the back of a living rabbit’s eye. The motion of the robot was controlled with magnetic fields.
3. They’ll cooperate via swarm intelligence.
Micro- and nanorobots aren’t expected to work alone; hundreds to thousands of units will cooperate to do a job. “These microrobots can swarm into small schools to perform a collective action,” says Wang. For that to happen, scientists will need to instill de-centralized communication called swarm intelligence. That can be done using group motion planning and machine learning, according to the paper.
4. They’re designed to destroy themselves after completing a mission.
Let’s be honest—no one wants a bunch of nanobots sticking around inside of their body once the job is done, whether it be surgery, drug delivery, or something else. So scientists are constructing the robots out of biodegradable materials that stay in a patient’s body for a limited amount of time, and then are cleared or disappear once the job is completed.
5. They’re being used in live animals.
Wang’s nanorocket, mentioned earlier, was the first artificial micromotor to be tested in a live mouse model. Today, more labs are testing their tech in live animals, says Wang, including at ETH Zurich and the University of Montreal. If successful, this in vivo work should lead to clinical trials in humans, says Wang. Who wants to sign up first?