Acoustic-Powered Microrobots for Bladder Disease Treatment

Engineers at the University of Colorado at Boulder have developed a medical microrobot that is powered by acoustic waves. The tiny devices, which are 20 micrometers wide and considerably smaller than the width of a human hair, can move incredibly fast for their size, achieving a speed of 3 millimeters per second. To put this in context, if a microrobot and a cheetah the same size had a race, the microrobot would win comfortably. The tiny structures are made using biocompatible polymers and include a series of three fins and a cavity that holds an air bubble. The bubble generates movement through vibration, which is stimulated by externally delivered acoustic waves. The robots have significant potential for drug delivery, and the Colorado researchers are already investigating the potential of using them to deliver drugs to the bladder.

Microrobots continue to evolve under the stewardship of an increasing number of research teams. The goal for biomedical researchers is simple and at one time was considered fantastical – to create tiny machines that can perform functions within the body, such as drug delivery or even surgical procedures. “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 researcher involved in the project.

“Imagine if microrobots could perform certain tasks in the body, such as non-invasive surgeries,” added Jin Lee, another researcher involved in the project. “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.”

These latest robots have been geared towards bladder diseases, such as interstitial cystitis, which is also known as painful bladder syndrome. At present, patients must attend a clinic several times over a few weeks and receive catheter-mediated delivery of dexamethasone. These researchers wished to develop a technology that would reduce the number of visits required by patients and provide more durable and sustained drug delivery.

Their solution is a bladder-delivered microrobot that can offer sustained release of dexamethasone for several days, helping patients to avoid as many appointments. The tiny robots look like small propellers and contain a tiny air bubble within them. This bubble begins to vibrate when an external acoustic signal is present, propelling the microrobots around their environment.

So far, the researchers have tested the microrobots in mice. They delivered thousands of robots to the mouse bladders, where they stuck to the bladder walls, reducing the risk that they would simply be urinated out again.

See a video of the robots below: