3-D-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. Credit: J. Warner, UC San Diego Jacobs School of Engineering.
These microrobots are powered by H2O2 and magnetically controlled. They will inspire a new generation of ‘smart’ microrobots that have diverse capabilities such as detoxification, sensing and directed drug delivery, the nanoengineers of University of California, SD said.
The technique used to fabricate the microfish provides many improvements over other methods with locomotion mechanisms, eg 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.
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.
“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 Wei Zhu, PhD.
As a proof-of-concept demonstration, the researchers incorporated toxin-neutralizing nanoparticles throughout the bodies of the microfish. ie polydiacetylene (PDA) nanoparticles, which capture harmful pore-forming toxins such as the ones found in bee venom. 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. They could monitor the detoxification ability of the microfish by the intensity of their red glow. “The neat thing about this experiment is that it shows how the microfish can doubly serve as detoxification systems and as toxin sensors,” said Zhu.
Method; rapid, high-resolution 3D printing technology called microscale continuous optical printing (μCOP) which has speed, scalability, precision and flexibility + does not require the use of harsh chemicals. AS μCOP technology is digitized, they can experiment with different designs for their microfish, including shark and manta ray shapes, even birds.
~The key component is a digital micromirror array device (DMD) chip, which contains ~2 million micromirrors. Each micromirror is individually controlled to project UV light in the desired pattern (in this case, a fish shape) onto a photosensitive material, which solidifies upon exposure to UV light. The microfish are built using a photosensitive material and are constructed one layer at a time, allowing each set of functional nanoparticles to be “printed” into specific parts of the fish bodies.
“This method has made it easier for us to test different designs for these microrobots and to test different nanoparticles to insert new functional elements into these tiny structures. It’s my personal hope to further this research to eventually develop surgical microrobots that operate safer and with more precision,” said Li. http://www.jacobsschool.ucsd.edu/news/news_releases/release.sfe?id=1797
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