Scientists invent medical robots small enough to travel through the body

Their hope is that they can deliver medicine to hard-to-reach places inside the human body.
Loukia Papadopoulos
An illustration of the tiny robots.jpg
An illustration of the tiny robots.

Shields Lab 

Researchers at CU Boulder have engineered a new class of tiny robots that can zip through liquid at phenomenal speeds. Their hope is that one day they may be able to deliver prescription drugs inside the human body.

This is according to a press release by the institution published Wednesday.

“Imagine if microrobots could perform certain tasks in the body, such as non-invasive surgeries,” said Jin Lee, lead author of the study and a postdoctoral researcher in the Department of Chemical and Biological Engineering.

“Instead of cutting into the patient, we can simply introduce the robots to the body through a pill or an injection, and they would perform the procedure themselves.”

Of course, this development has not come to pass yet, but the innovation is a huge step forward. 

The group’s microrobots each measure only 20 micrometers wide, several times smaller than the width of a human hair, and can travel at speeds of about 3 millimeters per second, or roughly 9,000 times their own length per minute. 

During the research, the team was successful at deploying fleets of these machines to transport doses of dexamethasone, a common steroid medication, to the bladders of lab mice. 

“Microscale robots have garnered a lot of excitement in scientific circles, but what makes them interesting to us is that we can design them to perform useful tasks in the body,” said C. Wyatt Shields, a co-author of the new study and assistant professor of chemical and biological engineering.

The microrobots are made out of materials called biocompatible polymers using a technology similar to 3D printing.

Relieving bladder disease

The tiny machines were tested on a common problem for humans: bladder disease.

They sought to bring relief to those suffering from interstitial cystitis, also known as painful bladder syndrome, through laboratory experiments where the researchers fabricated schools of microrobots encapsulating high concentrations of dexamethasone. 

They introduced thousands of those bots into the bladders of lab mice and watched as they dispersed through the organs before sticking onto the bladder walls, which would likely make them difficult to pee out.

The machines then proceeded to slowly release their dexamethasone over the course of about two days, allowing patients to receive more drugs over a longer span of time. 

Despite this successful trial, the team needs to do much work before the microrobots can travel through real human bodies, such as making the machines fully biodegradable so that they would eventually dissolve in the body. 

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

The research was published last month in the journal Small.

Study abstract:

Remotely powered microrobots are proposed as next-generation vehicles for drug delivery. However, most microrobots swim with linear trajectories and lack the capacity to robustly adhere to soft tissues. This limits their ability to navigate complex biological environments and sustainably release drugs at target sites. In this work, bubble-based microrobots with complex geometries are shown to efficiently swim with non-linear trajectories in a mouse bladder, robustly pin to the epithelium, and slowly release therapeutic drugs. The asymmetric fins on the exterior bodies of the microrobots induce a rapid rotational component to their swimming motions of up to ≈150 body lengths per second. Due to their fast speeds and sharp fins, the microrobots can mechanically pin themselves to the bladder epithelium and endure shear stresses commensurate with urination. Dexamethasone, a small molecule drug used for inflammatory diseases, is encapsulated within the polymeric bodies of the microrobots. The sustained release of the drug is shown to temper inflammation in a manner that surpasses the performance of free drug controls. This system provides a potential strategy to use microrobots to efficiently navigate large volumes, pin at soft tissue boundaries, and release drugs over several days for a range of diseases.

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