Self-Propelled Medical Microrobots Could Perform Non-Invasive Surgeries

Interstitial cystitis, or painful bladder syndrome, affects millions of people and causes intense pelvic pain. The treatment process for the disease can be similarly distressing, often necessitating multiple clinic visits over several weeks, where a potent solution of dexamethasone, a widely used steroid medication, is introduced into the bladder via a catheter. Now, microrobots may be able to provide some relief, according to new research that marks a huge step forward for tiny robots. Moreover, these microrobots may be able to conduct specific tasks within the body, like non-invasive surgeries.

A team of engineers at the University of Colorado Boulder (Boulder, CO, USA) has designed a new class of tiny, self-driven robots capable of moving incredibly fast through liquid. This innovation might pave the way for transporting prescription drugs to hard-to-access regions within the human body in the future. The size of these microrobots is remarkably small, each only 20 micrometers wide, which is several times tinier than the diameter of a human hair. Additionally, they possess astonishing speed, reaching about 3 millimeters per second or roughly 9,000 times their length per minute, outpacing a cheetah in relative terms.

Image: Microrobot seen under a scanning electron microscope (Photo courtesy of Shields Lab)

These microrobots are constructed from materials known as biocompatible polymers using a technique similar to 3D printing. Resembling tiny rockets with three miniature fins, they each harbor a small air bubble, similar to an inverted glass submerged in water. When these robots are subjected to an acoustic field, like that used in ultrasound, the trapped air bubbles begin to vibrate vigorously, pushing water away and propelling the robots forward.

To test their invention, the researchers focused on bladder disease. In lab experiments, they created swarms of microrobots encapsulating high doses of dexamethasone. They then injected thousands of these robots into the bladders of laboratory mice. The microrobots spread throughout the organs and latched onto the bladder walls, making them difficult to excrete through urination. Once in position, they gradually released the dexamethasone over approximately two days. This sustained medication delivery could enable patients to receive a greater dosage over a prolonged period, thereby enhancing treatment outcomes. The researchers still have significant ground to cover before these microrobots can travel through real human bodies. To begin with, the researchers aim to make these robots fully biodegradable, so they eventually disintegrate within the body.

“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.”

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