Self-propelled ‘microrobots’ could quickly deliver drugs inside the body

A new class of tiny, self-propelled robots can zip through liquid at “incredible” speeds, according to their creators.

The ‘microrobots’, which could one day be used to deliver medicine or carry out surgery in hard-to-reach places inside the body, were developed by engineers at the University of Colorado.

“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.”

Each microrobot is only 20 microns wide, several times smaller than the width of a human hair. They can travel at speeds of about 3mm per second, roughly 9,000-times their own length per minute – many times faster than a cheetah, in relative terms. 

The team made the devices out of biocompatible polymers. They each feature three fins, and a small bubble of trapped air that vibrates ‘wildly’ when exposed to an acoustic field, pushing water away and propelling the robot forward.

In a new study, the researchers deployed ‘fleets’ of the devices to transport doses of dexamethasone, a common steroid medication, to the bladders of lab mice. The results suggest that microrobots may be a useful tool for treating bladder diseases and other illnesses in people.

Interstitial cystitis is sometimes known as bladder pain syndrome, and treating the disease can be equally uncomfortable. The millions of patients who have it often have to come into a clinic several times over a period of weeks, and a doctor injects a harsh solution of dexamethasone into the bladder through a catheter. 

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

The team has a lot of work to do before microrobots can travel through human bodies. For a start, the group wants to make the machines fully biodegradable, so they eventually dissolve in the body. 

The work was published in the journal Small.