Tiny Microbots to Jump Around Your Colon, Delivering Controlled Release Drugs

The robots are only the size of a few hairs.
Loukia Papadopoulos
The microrobot can be seen just to the right of the “U” in United States on this U.S. penny.Purdue University image/Georges Adam

Researchers have long been designing tiny robots for use inside the human body. The microbots can collect tissue samples and deliver drugs.

Now, researchers at Purdue University have invented a rectangular microbot just the size of a few human hairs that can rush through the human colon by jumping around and deliver drug therapy where it is needed most.


This novel invention would allow drugs to be administered only on their intended target site avoiding nefarious side effects such as hair loss or stomach bleeding. The microbot is too tiny to carry a battery, so it is wirelessly controlled via a magnetic field.

“When we apply a rotating external magnetic field to these robots, they rotate just like a car tire would to go over rough terrain,” said in a statement David Cappelleri, a Purdue associate professor of mechanical engineering. “The magnetic field also safely penetrates different types of mediums, which is important for using these robots in the human body.”

The researchers chose the colon as the testing ground for their new project as it is easy to enter and very messy.

“Moving a robot around the colon is like using the people-walker at an airport to get to a terminal faster. Not only is the floor moving, but also the people around you,” said Luis Solorio, an assistant professor in Purdue’s Weldon School of Biomedical Engineering.

“In the colon, you have all these fluids and materials that are following along the path, but the robot is moving in the opposite direction. It’s just not an easy voyage.”

The team conducted in vivo experiments in the colons of both mice and pigs under anesthesia. Pig colons are particularly similar to human ones.

They then used ultrasound to test in real-time how well the microrobot moved around and even tested the microrobot’s ability to carry and release a drug payload in a vial of saline. All these experiments proved very successful.

“We were able to get a nice, controlled release of the drug payload. This means that we could potentially steer the microrobot to a location in the body, leave it there, and then allow the drug to slowly come out. And because the microrobot has a polymer coating, the drug wouldn’t fall off before reaching a target location,” Solorio concluded.

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