3D-printed
microfish contain functional nanoparticles that enable them to be
self-propelled,
chemically powered and magnetically steered.
The microfish are
also capable of removing and sensing toxins.
Image credit: J.
Warner, UC San Diego Jacobs School of Engineering.
Researchers demonstrate a novel method to build microscopic
robots with complex shapes and functionalities
(August 26, 2015) Nanoengineers
at the University of California, San Diego used an innovative 3D printing
technology they developed to manufacture multipurpose fish-shaped microrobots —
called microfish — that swim around efficiently in liquids, are chemically
powered by hydrogen peroxide and magnetically controlled. These
proof-of-concept synthetic microfish will inspire a new generation of “smart”
microrobots that have diverse capabilities such as detoxification, sensing and
directed drug delivery, researchers said.
The technique used to fabricate the microfish provides
numerous improvements over other methods traditionally employed to create
microrobots with various locomotion mechanisms, such as microjet engines,
microdrillers and microrockets. Most of these microrobots are incapable of
performing more sophisticated tasks because they feature simple designs — such
as spherical or cylindrical structures — and are made of homogeneous inorganic
materials. In this new study, researchers demonstrated a simple way to create
more complex microrobots.
Schematic
illustration of the process of functionalizing the microfish.
Platinum
nanoparticles are first loaded into the tail of the fish for
propulsion via
reaction with hydrogen peroxide. Next, iron oxide nanoparticles
are loaded into
the head of the fish for magnetic control.
Image credit: W.
Zhu and J. Li, UC San Diego Jacobs School of Engineering.
The research, led by Professors Shaochen Chen and Joseph
Wang of the NanoEngineering Department at the UC San Diego, was published in
the Aug. 12 issue of the journal Advanced Materials.
By combining Chen’s 3D printing technology with Wang’s
expertise in microrobots, the team was able to custom-build microfish that can
do more than simply swim around when placed in a solution containing hydrogen
peroxide. Nanoengineers were able to easily add functional nanoparticles into
certain parts of the microfish bodies. They installed platinum nanoparticles in
the tails, which react with hydrogen peroxide to propel the microfish forward,
and magnetic iron oxide nanoparticles in the heads, which allowed them to be
steered with magnets.
Fluorescent image
demonstrating the detoxification capability of the
microfish
containing PDA nanoparticles.
Image credit: W.
Zhu and J. Li, UC San Diego Jacobs School of Engineering.
“We have developed an entirely new method to engineer
nature-inspired microscopic swimmers that have complex geometric structures and
are smaller than the width of a human hair. With this method, we can easily
integrate different functions inside these tiny robotic swimmers for a broad
spectrum of applications,” said the co-first author Wei Zhu, a nanoengineering
Ph.D. student in Chen’s research group at the Jacobs School of Engineering at
UC San Diego.
As a proof-of-concept demonstration, the researchers
incorporated toxin-neutralizing nanoparticles throughout the bodies of the
microfish. Specifically, the researchers mixed in polydiacetylene (PDA)
nanoparticles, which capture harmful pore-forming toxins such as the ones found
in bee venom. The researchers noted that the powerful swimming of the microfish
in solution greatly enhanced their ability to clean up toxins. When the PDA
nanoparticles bind with toxin molecules, they become fluorescent and emit
red-colored light. The team was able to monitor the detoxification ability of
the microfish by the intensity of their red glow.