Slippery Liquid-Infused Porous Surfaces (SLIPS)

Researchers have developed synthetic `Slippery Liquid-Infused Porous Surfaces’, known as SLIPS. These are a type of liquid-impregnated surface (LIS) that build upon the concept of hemi-wicking. They use nano or micro-structured substrates to lock in place a lubricating fluid which spreads across the substrate. The surface is very slippery because liquid-solid contact is replaced by liquid-lubricant contact.

A SLIPS surface created using lithography is shown schematically below.

Schematic illustration of a Slippery Liquid-Infused Porous Surface

SLIPS surfaces are inherently self-healing because if damaged, the lubricating fluid will spontaneously fill any damaged voids.

Water drop sliding on a SLIPS surface tilted at 0.8 degrees.

SLIPS surfaces use the same wettability mechanisms employed by Nepenthes pitcher plants. However, whereas the pitcher plants have surfaces that are lubricated by water and repel oil, SLIPS surfaces can be lubricated by oil and repel water. By using perflorinated fluids as the wetting lubricant, it is possible to create omniphobic surfaces that repel most things.