All-terrain microrobot flips through a live colon

Date:
October 15, 2020
Source:
Purdue University
Summary:
A rectangular robot as tiny as a few human hairs can travel
throughout a colon by doing back flips, engineers have demonstrated
in live animal models.



FULL STORY ==========================================================================
A rectangular robot as tiny as a few human hairs can travel throughout a
colon by doing back flips, Purdue University engineers have demonstrated
in live animal models.


==========================================================================
Why the back flips? Because the goal is to use these robots to transport
drugs in humans, whose colons and other organs have rough terrain. Side
flips work, too.

Why a back-flipping robot to transport drugs? Getting a drug directly to
its target site could remove side effects, such as hair loss or stomach bleeding, that the drug may otherwise cause by interacting with other
organs along the way.

The study, published in the journal Micromachines, is the first
demonstration of a microrobot tumbling through a biological system in
vivo. Since it is too small to carry a battery, the microrobot is powered
and wirelessly controlled from the outside by 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 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 for in vivo experiments because it has an easy point of
entry -- and it's 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." But this magnetic microrobot can successfully
tumble throughout the colon despite these rough conditions, the
researchers' experiments showed. A video explaining the work is available
on YouTube at https://youtu.be/9OsYpJFWnN8.

The team conducted the in vivo experiments in the colons of live mice
under anesthesia, inserting the microrobot in a saline solution through
the rectum.

They used ultrasound equipment to observe in real time how well the
microrobot moved around.

The microrobots could also tumble in colons excised from pigs, the
researchers found, which have similar guts to humans.



========================================================================== "Moving up to large animals or humans may require dozens of robots,
but that also means you can target multiple sites with multiple drug
payloads," said Craig Goergen, Purdue's Leslie A. Geddes Associate
Professor of Biomedical Engineering, whose research group led work on
imaging the microrobot through various kinds of tissue.

Solorio's lab tested the microrobot's ability to carry and release a
drug payload in a vial of saline. The researchers coated the microrobot
with a fluorescent mock drug, which the microrobot successfully carried throughout the solution in a tumbling motion before the payload slowly
diffused from its body an hour later.

"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 said.

The magnetic microrobots, cheaply made of polymer and metal, are
nontoxic and biocompatible, the study showed. Cappelleri's research
group designed and built each of these robots using facilities at the
Birck Nanotechnology Center in Purdue's Discovery Park.

Commonly-used roll-to-roll manufacturing machinery could potentially
produce hundreds of these microrobots at once, Cappelleri said.

The researchers believe that the microrobots could act as diagnostic
tools in addition to drug delivery vehicles.

"From a diagnostic perspective, these microrobots might prevent the need
for minimally invasive colonoscopies by helping to collect tissue. Or
they could deliver payloads without having to do the prep work that's
needed for traditional colonoscopies," Goergen said.


========================================================================== Story Source: Materials provided by Purdue_University. Original written
by Kayla Wiles. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Elizabeth E. Niedert, Chenghao Bi, Georges Adam, Elly Lambert, Luis
Solorio, Craig J. Goergen, David J. Cappelleri. A Tumbling Magnetic
Microrobot System for Biomedical Applications. Micromachines,
2020; 11 (9): 861 DOI: 10.3390/mi11090861 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201015173131.htm

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