Researchers in Zurich reported today that they have invented a manufacturing technique to build “micromachines” out of metal and plastic in which these two materials are interlocked as closely as links in a chain.
These robots are so tiny that they can maneuver through blood vessels and deliver medications to certain points in the body — a goal that researchers have been pursuing for years — the scientists wrote in a paper published in the journal Nature Communications.
Eidgenöissche Technische Hochschule (ETH) professor Salvador Pané has been working with a high-precision 3D printing technique that produces complex objects on the micrometer level, a technique known as 3D lithography. The ETH scientists applied this method to produce a kind of mold or template for their micromachines. These templates have narrow grooves that serve as a “negative” and can be filled with the chosen materials. Using electrochemical deposition, the scientists fill some of the grooves with metal and others with polymers before ultimately dissolving the template away with solvents.
“Metals and polymers have different properties, and both materials offer certain advantages in building micromachines. Our goal was to benefit from all these properties simultaneously by combining the two,” said Carlos Alcântara, formerly a doctoral student in Pané’s group at the Institute of Robotics and Intelligent Systems and one of the two lead authors of the paper.
As a rule, micromachines are powered from outside the body using magnetic fields, which means they must have magnetic metal parts installed. Polymers, however, have the advantage that they can be used to construct soft, flexible components as well as parts that dissolve inside the body. If medication is embedded in this kind of soluble polymer, it is possible to selectively supply active substances to certain points in the body.
As a proof of principle for making micromachines by interlocking materials, the ETH scientists created various minuscule vehicles with plastic chassis and magnetic metal wheels powered by means of a rotating magnetic field. Some of the vehicles can be propelled across a glass surface, while others — depending on the polymer used — can float in liquid or on a liquid surface.
“Our interdisciplinary group consists of electrical engineers, mechanical engineers, chemists and materials scientists who all work closely together,” said co-lead author Fabian Landers, a doctoral student in Pané’s group, in a news release. “That was the key to developing this method.”
The scientists are now planning to refine their two-component micromachines and experiment with other materials. In addition, they will attempt to create more complex shapes and machines, including some that can fold and unfold themselves. Besides serving as “ferries” that distribute active substances, future applications of micromachines include treating aneurysms or performing other surgical procedures. Another research goal is to make stents that unfold themselves and can be positioned at a specific place in the body using magnetic fields.
You can watch a video of the micromachines here.