Scientists used simplified 3-D printing technology to create multipurpose fish-shaped microrobots that are powered using nanoparticles that react to hydrogen peroxide and magnets.
These "microfish" could lead to a new generation of tiny smart robots for applications in detoxification, sensing and directed drug delivery, the University of California, San Diego reported. The printing method allowed the researchers to add functional platinum nanoparticles into the robots' tails to react to the peroxide and propel them forward, as well as iron nanoparticles into the heads to steer them using magnets.
"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 student at the Jacobs School of Engineering at UC San Diego.
The new 3-D printing method is called microscale continuous optical printing (μCOP), and can print an array containing hundreds of microfish in a matter of seconds.
"With our 3D printing technology, we are not limited to just fish shapes. We can rapidly build microrobots inspired by other biological organisms such as birds," Zhu said.
The key to the technology's success is a digital micromirror array device (DMD) chip containing about two million micromirrors. These tiny mirrors can be controlled to project UV light in a desired pattern, such as a fish shape, onto a solidifying photosensitive material. The microfish are printed one layer at a time, which allows nanoparticles to be placed in specific parts of the robot.
To prove the robots' ability, the researchers incorporated toxin-neutralizing nanoparticles throughout their bodies and placed them in a solution containing pore-forming toxins like ones found in bee venom. The powerful swimming abilities of the microfish allowed them to effectively clean up the contaminants.
"The neat thing about this experiment is that it shows how the microfish can doubly serve as detoxification systems and as toxin sensors," Zhu said.
The researchers noted that in the future, the microfish could also be used to encapsulate medicine and deliver it directly to drug targets.
The findings were published in a recent edition of the journal Advanced Materials.
