3D Printed Micro-Fish Robots May Soon Join The Fight Against Disease, Inside Our Bodies

Professors Shaochen Chen and Joseph Wang of the Nano Engineering Department at the University of California, San Diego have 3D printed tiny robots – thinner than the width of a human hair -- they’re calling micro-fish, that may one day be used to treat a variety of human ailments.

These micro-fish aren’t printed using off-the-shelf 3D printers, however. To create their micro-fish, the team at UC San Diego used a bleeding-edge, high-resolution 3D printing technology called microscale continuous optical printing, or μCOP, which was developed in Professor Chen's lab. μCOP 3D printing technology leverages an array of 2 million micro-mirrors called a DMD (digital micro-mirror array device). The mirrors in the array are individually controlled to direct beams of UV light at a photosensitive material. When the UV light hits the material, it solidifies and can take virtually any shape, like a fish for example.

The 3D printed micro-fish on their own are akin to simple delivery vehicles or frames. But Chen and Wang affixed platinum nanoparticles to the fishes’ tails, which react with hydrogen peroxide, and can be used to push the fish forward. Magnetic iron oxide nanoparticles affixed to the heads of the fish were also used to help steer the fish with the aid of magnets. With the heads and tails of the micro-fish configured for propulsion, the bodies can be used to deliver other substances.

To prove their concept, Chen and his team installed toxin-neutralizing polydiacetylene (PDA) nanoparticles on the bodies of the micro-fish. PDA binds with pore-forming toxins like the the ones found in bee venom and when it does, it fluoresces with a red glow. When placed in a solution with the toxin, the PDA-equipped micro-fish swam through the solution and nabbed the toxin along the way. During the experiment, the researchers monitored the intensity of the red-glow emitted from the PDA attached to the micro-fish to measure their effectiveness.

In addition to detoxification, the researchers at UC San Diego believe their micro-fish can be used for targeted drug delivery or as sensors. The technology is still in its infancy, but shows great promise and was backed by grants from the Defense Threat Reduction Agency-Joint Science and Technology Office for Chemical and Biological Defense, the National Science Foundation, and the National Institutes of Health . The research was published in the Aug. 12 issue of the journal Advanced Materials.