If we can't shrink down to microscopic sizes and steer a tiny ship through the bloodstream Fantastic Voyage-style, microscopic fish-shaped robots steered by magnets may be the next best thing.
An innovative new 3D-printing technique made it possible for researchers at the University of California, San Diego to create robots that are smaller than the width of a human hair, but contain complex structures that allow them to be self-propelled and magnetically-steered. The researchers have already successfully used these microfish to clean up toxins and hope to one day employ them for targeted drug delivery.
"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," co-first author Wei Zhu, a nanoengineering Ph.D. student at UC San Diego, said in a statement.
This new 3D printing method is called microscale continuous optical printing, and it is fast, flexible, and precise. It uses incredibly tiny mirrors to shine UV light onto a material that solidifies when this type of light hits it. By arranging the mirrors in different ways, the researchers can use this technique to create a variety of shapes layer by ultra-thin layer. While designing these microfish, the researchers also tried out shark and manta ray shapes.
The key aspect of this process is that it allows scientists to easily add particles that serve particular purposes exactly where they want in the design by incorporating them into certain layers. In this case, they added nanoscale particles of platinum, which react with hydrogen peroxide in a way that propels the microfish forward. Iron oxide nanoparticles in the head of the microfish make it possible to steer them with magnets. In the future, this method may be used to incorporate nanocapsules filled with drugs that these tiny robots can take wherever they need to go.
So far, the researchers tested the concept by having the microfish go around and collect toxins such as those found in bee venom. When the specialized nanoparticles in the microfish bind with the toxins, they emit red light so that it's easy to tell whether they've done their job. The red glow that the researchers saw when they tested the system out indicated that the microfish successfully captured the toxins.
The potential applications of a tiny, steerable robotic fish are already vast, but the researchers are thinking even bigger.
"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 in a statement.
