In live animal models, Purdue University engineers have demonstrated that a rectangular robot as small as a few human hairs can fly across a colon by doing back flips.
Why the flips in the back? Since the aim is to use these robots to transport drugs to humans who have rough terrain on their colons and other organs. Side flips also work.
Why the back-flipping drug delivery robot? Getting a drug directly to its target site may prevent side effects that the drug could otherwise cause by interfering with other organs along the way, such as hair loss or stomach bleeding.
The research , published in the Micromachines journal, is the first demonstration of in vivo tumbling of a microrobot via a biological system. The microrobot is operated and controlled wirelessly from the outside by a magnetic field, as it is too small to hold a battery.
Said David Cappelleri, a Purdue associate professor of mechanical engineering, “When we add a spinning external magnetic field to these robots, they rotate just like a car tyre would go over rugged terrain.” “Also, the magnetic field safely penetrates various types of media, which is necessary for the human body to use these robots.”
For in vivo studies , the researchers chose the colon because it has a simple entry point — and it’s really messy.
Luis Solorio, an assistant professor at Purdue’s Weldon School of Biomedical Engineering, said, “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.”
“You have all these fluids and materials in the colon that follow the road, but the robot goes in the opposite direction. It’s just not an easy ride.”
But amid these harsh conditions, the researchers’ experiments showed, this magnetic microrobot would successfully tumble in the colon. On YouTube at https:/youtu.be/9OsYpJFWnN8, a video explaining the work is available.
Under anesthesia, the team performed in vivo experiments in the colons of live mice, inserting the microrobot through the rectum in a saline solution. To observe in real time how much the microrobot was moving about, they used ultrasound devices.
In colons excised from pigs, the microrobots could also topple, the researchers found, which have identical guts to humans.
“It may take hundreds of robots to travel up to large animals or humans, but it also means you can target multiple locations with multiple drug payloads,” said Craig Goergen, Leslie A. Geddes Associate Professor of Biomedical Engineering at Purdue, whose research group led work on imaging the microrobot across different tissue types.
Solorio ‘s laboratory tested the ability of the microrobot in a vial of saline to hold and release a drug payload. The researchers coated a fluorescent mock drug with the microrobot, which the microrobot successfully held in a tumbling motion in the solution until the payload slowly diffused from its body an hour later.
“We were able to bring the drug payload to a good, controlled release. This means that we could theoretically direct the microrobot to a position in the body, leave it there, and then allow the drug to come out slowly. And since the microrobot has a polymer coating, before reaching a target spot, the drug will not fall off,” Solorio said.
The study showed that magnetic microrobots, cheaply made of polymer and metal, are nontoxic and biocompatible. Each of these robots was built and constructed by the Cappelleri research group using facilities at the Birck Nanotechnology Center in Purdue ‘s Discovery Park.
Hundreds of these microrobots could theoretically be produced at once by widely used roll-to-roll production machinery, Cappelleri said.
The researchers claim that, in addition to drug delivery vehicles, microrobots may serve as diagnostic tools.
“From a diagnostic perspective, by helping to gather tissue, these microrobots could eliminate the need for minimally invasive colonoscopies. Or they could deliver payloads without having to do the preparatory work required for conventional colonoscopies,” Goergen said.
Source of Story: Purdue University provides the materials. Published originally by Kayla Wiles. Note: For style and length, material can be edited.
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