Medical “microrobots” could one day treat bladder disease, other human illnesses

A group of engineers from the University of Colorado Boulder created small robots that can move by themselves and quickly swim through liquids. These robots might be used in the future to carry medicine to difficult-to-reach areas inside our bodies.

The researchers describe their mini healthcare providers in a paper published last month in the journal Small.

Jin Lee, the lead author of the study and a researcher at the Department of Chemical and Biological Engineering, expressed the idea of using microrobots for performing tasks inside the body without invasive surgeries. Instead of traditional methods that involve cutting the patient, these robots could be introduced into the body through a pill or injection, and they would independently carry out the required procedure.

Lee and his colleagues aren’t there yet, but the new research is big step forward for tiny robots. 

The microrobots developed by the group are incredibly tiny, with each one being only 20 micrometers wide, which is much smaller than a human hair. Despite their small size, these robots are remarkably fast, able to move at speeds of approximately 3 millimeters per second. To put it into perspective, they can travel about 9,000 times their own length in just one minute. In relative terms, this makes them much faster than a cheetah.

These microrobots show great potential. In the recent study, the group used a group of these robots to deliver doses of dexamethasone, a widely used steroid medication, to the bladders of laboratory mice. The findings indicate that microrobots could be a valuable tool for treating bladder diseases and other illnesses in humans.

C. Wyatt Shields, an assistant professor of chemical and biological engineering and co-author of the study, highlighted the appeal of microscale robots. While these robots have generated significant interest among scientists, what makes them particularly intriguing is their potential to be designed for practical purposes inside the human body.

Fantastic Voyage

If this concept sounds like it belongs in a science fiction story, that’s because it does. In the classic film “Fantastic Voyage,” a team of explorers uses a miniaturized submarine to enter the body of a comatose man. The idea of exploring the human body at a tiny scale has long been a fascination in science fiction.

“The movie was released in 1966. Today, we are living in an era of micrometer- and nanometer-scale robots,” Lee said.

He imagines that, just like in the movie, microrobots could swirl through a person’s blood stream, seeking out targeted areas to treat for various ailments.

The team manufactures its microrobots using biocompatible polymers, employing a technology similar to 3D printing. These robots have a resemblance to small rockets and are equipped with three tiny fins. Interestingly, each robot contains a small trapped air bubble, similar to what happens when a glass is submerged upside-down in water. When the robots are exposed to an acoustic field, such as the type used in ultrasound, the trapped air bubbles start to vibrate intensely. This vibration causes the water to be pushed away forcefully, propelling the robots forward.

The new study also involved other co-authors from CU Boulder. These include Nick Bottenus, an assistant professor of mechanical engineering; Ankur Gupta, an assistant professor of chemical and biological engineering; as well as engineering graduate students Ritu Raj, Cooper Thome, Nicole Day, and Payton Martinez.

To take their microrobots for a test drive, the researchers set their sights on a common problem for humans: bladder disease.

Bringing relief

Interstitial cystitis, which is also referred to as painful bladder syndrome, is a condition that impacts a significant number of Americans and is characterized by intense pelvic pain. Unfortunately, the treatment of this disease can be equally unpleasant. Typically, patients are required to visit a clinic multiple times over several weeks, where a doctor administers a strong dexamethasone solution directly into the bladder using a catheter.

Lee believes that microrobots may be able to provide some relief.

During laboratory trials, scientists created clusters of microrobots containing concentrated amounts of dexamethasone. These microrobots were subsequently introduced into the bladders of mice as part of an experiment. The outcome resembled a scene from “Fantastic Voyage,” as the microrobots spread throughout the organs and adhered to the walls of the bladder, potentially posing challenges for excretion through urination.

Once situated in the bladder, the microrobots commenced a gradual release of dexamethasone over a period of approximately two days. This controlled and continuous administration of medication has the potential to extend the duration of drug exposure for patients, as noted by Lee. Consequently, this could lead to improved patient outcomes by providing a sustained therapeutic effect.

Lee further emphasized that there is still a significant amount of research and development required before microrobots can safely navigate the human body. One of the primary goals for the team is to enhance the biodegradability of these machines, ensuring that they can eventually dissolve within the body without causing any long-term harm. This step is crucial to ensure the safety and effectiveness of microrobot applications in the future.

“If we can make these particles work in the bladder,” Lee said, “then we can achieve a more sustained drug release, and maybe patients wouldn’t have to come into the clinic as often.”