Researchers have discovered that human eyelashes have special features that help keep water away from the eyes. By studying eyelashes and artificial fibers that mimic them, the researchers found that the exterior of an eyelash acts like a “micro-ratchet,” with overlapping scales that repel water. This unique design allows water to flow easily from root to tip, but not in the opposite direction, making the eyelashes hydrophobic.
Eyelashes are shaped like a brachistochrone curve, a shape that minimizes the time it takes to travel between two points under the force of gravity. Comparing eyelashes to nylon fibers with similar dimensions and elasticity, the researchers found that droplets slid off the brachistochrone-shaped fibers the fastest. This unique shape of eyelashes helps fling water away from the eyes, providing clear vision during rainstorms and other situations where water may be present.
While eyelashes are commonly known for guarding against dust, their water-wicking superpower has not been widely recognized. This ability to repel water can come in handy during activities such as bathing, sweating, or crying. However, beauty treatments like mascara and curling the lashes can alter their shape and affect their ability to repel water. Mascara, for example, can make eyelashes attract water instead of repelling it.
Researchers believe that understanding the unique features of human eyelashes could have practical applications in developing water-repellent materials or improving beauty products. The discovery sheds light on the intricate design of eyelashes and how they play a crucial role in keeping the eyes clear and protected from external elements. Further research in this area could lead to innovative solutions in various fields, from cosmetics to materials science.
