Eyelashes play a key role in expelling liquids to maintain clear vision, with their unique structure inspiring new technological innovations.

Throughout human evolution, body and facial hair have significantly reduced, yet eyelashes have persisted as a distinctive feature. The physiological or functional role of eyelashes, once thought to be for tasks like trapping dust or filtering air, has been the subject of much debate (1^✔ ✔Trusted Source
Rapid water drainage on human eyelashes of a hydrophobic Brachistochrone fiber array

Go to source

).
Recently, a team of Chinese researchers has shed light on the properties of human eyelashes. Their study reveals that eyelashes are made up of a hydrophobic, curved, and flexible fiber arrangement, with surface micro-ratchets and a macro-curvature resembling the Brachistochrone curve. This structure allows eyelashes to quickly and efficiently expel liquid in a specific direction, helping to maintain clear vision.

Eyelashes as a Protective Barrier for Clear Vision

The hydrodynamic advantages of eyelashes, particularly their ability to expel unwanted liquids from the eye to maintain visual clarity, have received little attention. For instance, during facial washing or intense physical activity, the eyes are exposed to significant amounts of water or sweat without compromising clear vision.

This study, published in Science Advances, was conducted by Prof. Jiang Lei and his group from the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences.

Investigating the Interaction Between Water and Eyelashes

The research team aimed to investigate the interaction between water and the flexible fiber array of eyelashes. They began by characterizing the structure, wettability, and water drainage process of human eyelashes. Next, they explored how the flexibility, wettability, and curvature of the fiber array influence water drainage.

Developing a Computational Model for Eyelash Elastic Forces

Based on their findings, the researchers revealed the control mechanism governing transfer direction and contact time, which arise from the multi-scale asymmetric structures and heterogeneous elastic deformations of the fiber array. They also developed a quantitative computational model to calculate the elastic forces acting on the fiber array.

Aesthetic and Protective False Eyelashes

This research has also led to the design of eyelash-mimetic rapid liquid transfer edges, including aesthetically pleasing and protective false eyelashes, waterproof imaging devices, and ventilated structures.

Reference:

1. Rapid water drainage on human eyelashes of a hydrophobic Brachistochrone fiber array – (https://pubmed.ncbi.nlm.nih.gov/39705366/)

Source-Medindia