👉 Surface fluid refers to the layer of liquid that coats the interface between two solid surfaces or between a solid and a gas. This thin film of liquid plays a crucial role in various physical, chemical, and biological processes by reducing friction and adhesion between surfaces, facilitating the transfer of heat and mass, and enabling phenomena like capillary action. In industrial applications, it is essential for lubrication in machinery, enhancing the efficiency and longevity of moving parts. In biological systems, surface fluid is vital for processes such as cell adhesion, mucus formation, and the transport of substances across cell membranes.