While facial and body hair have significantly decreased over the course of human development, eyelashes have continued to be a distinctive characteristic. It has long been disputed whether eyelashes serve a physiological or functional role, such as capturing dust or filtering air.
However, the properties of human eyelashes have lately been clarified by a group of Chinese experts. According to their research, eyelashes are made up of a flexible, hydrophobic array of curved fibers with surface micro-ratchets and a macro-curvature that approximates the Brachistochrone curve. This structure maintains clean eyesight by allowing eyelashes to quickly and directionally discharge entering moisture.
Little emphasis has been paid to the hydrodynamic benefits of eyelashes, namely their capacity to remove extraneous liquids from the eye to preserve visual acuity. For example, the eyes are exposed to large volumes of water or perspiration during facial cleaning or vigorous exercise without impairing vision.
Prof. JIANG Lei and his team from the Chinese Academy of Sciences’ Technical Institute of Physics and Chemistry carried out the study, which was published in Science Advances on December 20.
The goal of the study was to find out how water and the flexible fiber array of eyelashes interact. They started by describing the composition, wettability, and mechanism of water drainage of human eyelashes. They then investigated the effects of the fiber array’s curvature, wettability, and flexibility on water drainage.
Based on their findings, the researchers identified the control mechanism that governs contact time and transfer direction. This mechanism is caused by the fiber array’s heterogeneous elastic deformations and multi-scale asymmetric structures. In order to determine the elastic forces operating on the fiber array, they also created a quantitative computational model.
The creation of eyelash-mimetic quick liquid transfer edges, such as vented structures, waterproof imaging devices, and visually beautiful and protected fake eyelashes, has also resulted from this research.
