Cilia, the Latin word for eyelashes, are microscopic, hairlike structures and are a primordial cornerstone of nature's organic design. Found within everything from the bristling fibers lining the human nasal passage and windpipe to the photoreceptors of the retina, cilia prove vital to the functioning of cells and organs and the transportation of light and fluid within them.
That's why researchers at the Massachusetts Institute of Technology wanted to make synthetic cilia that could take advantage of the microhairs' remarkable biology and be manipulated using magnetic fields. A team of four engineers crafted pillars of nickel one fourth the diameter of a human hair and grafted them to transparent silicone. The result: using magnets, the material's microhairs could be tilted to direct the flow of liquid and filter light.
"Depending on the field's orientation, the microhairs can tilt to form a path through which fluid can flow; the material can even direct water upward, against gravity," explained Jennifer Chu of the MIT News Office. The results were published this month in the journal Advanced Materials.
"You could coat this on your car windshield to manipulate rain or sunlight," said graduate student Yangying Zhu, a co-author on the paper alongside MIT's Evelyn Wang, Rong Xiao, and Dion Antao. "So you could filter how much solar radiation you want coming in, and also shed raindrops. This is an opportunity for the future." Other uses could be rain-resistant clothing too.
Even more fascinating, however, could be the implications of the material structures in chip design, specifically the burgeoning area of research known as lab-on-a-chip. That term applies to a type of diagnostic and research tool that boils down multiple lab functions onto a single micro-electronic device that can more quickly turn around test results, check for chromosome mutations that would indicate cancer, and simulate organic processes like organ blood flow and tissue functioning.
For instance, because these cilia-like materials respond to magnetic changes and direct both fluid and light, attaching them to a diagnostic chip would allow researchers to magnetically direct the flow of cells.
"Depending on how you design the magnetic field, you could get the pillars to close in like a flower," Wang said. "You could do a lot of things with the same platform."