Magnetic Cilia to Propel Soft Biomedical Robots
Researchers at the Eindhoven University of Technology in The Netherlands have developed artificial cilia that can beat just like the real thing. The tiny projections typically adorn the outside of certain cells in nature, and this artificial version could help to propel tiny biomedical robots or power microfluidic pumps. The artificial cilia rely on magnetic fields to generate movement, and the researchers have already shown that they can move tiny soft robots in a variety of ways, including allowing them to ‘walk’ up vertical surfaces and even upside down.
Soft robots have enormous biomedical potential. Their physical properties make them a good match for our tissues and allow them to accomplish tasks that would be difficult or impossible for a rigid device. Scientists have been expanding what is possible in this field, and this latest development provides new capabilities for tiny robots.
The idea of tiny robots that can perform therapeutic functions inside our bodies has been around for a long time, and new developments are bringing this concept from the realm of science fiction to reality. However, manipulating such small devices is challenging, requiring some ingenuity. These researchers took inspiration from hair-like projections called cilia, which certain cells use to move around or move liquids near them. These projections beat like a whip and are highly effective at producing coordinated wave-like movements that resemble a traveling wave created by sports fans in a stadium.
To achieve this using artificial materials, the researchers incorporated carbonyl iron powder particles into a polymer mixture and used this to create small cilia-like projections by pouring the polymer into a mold. As the polymer cured, the team placed magnets near the molds, resulting in slightly different particle alignment and magnetic properties in each cilium.
Once they removed the structure from the mold, the researchers used rotating magnets to create a magnetic field around the resulting soft robot, and this stimulated the cilia to move in a traveling wave because of the slightly different magnetic properties in adjacent cilia.
If the cilia are placed on the bottom of the structure, they can propel it along. The resulting movements are quite impressive, with the robot being able to scale vertical surfaces and even walk along upside down on an inverted horizontal surface. Spinning the magnets in the opposite direction causes the robot to reverse its direction. Aside from medical robots, the technology could also be useful to propel very small amounts of water through microfluidic systems.
See a video about the technology below:
Study in ACS Appl. Mater. Interfaces: Metachronal μ-Cilia for On-Chip Integrated Pumps and Climbing Robots