The <i>Salvinia</i> Paradox: Superhydrophobic Surfaces with Hydrophilic Pins for Air Retention Under Water

TLDR

Its floating leaves are evenly covered with complex hydrophobic hairs that retain a layer of air when submerged. The Salvinia Effect offers an innovative concept for developing biomimetic surfaces with long‑term air‑retention capabilities for underwater applications. Hydrophilic patches at the hair tips stabilize the air layer by pinning the air–water interface. A novel mechanism for long‑term air retention under water is found in the sophisticated surface design of the water fern Salvinia, where surprisingly the terminal cells of the hairs are hydrophilic. © Martin Oeggerli / www.Micronaut.ch, original SEM scan by Prof.; Barthlott.

Abstract

A novel mechanism for long-term air retention under water is found in the sophisticated surface design of the water fern Salvinia. Its floating leaves are evenly covered with complex hydrophobic hairs retaining a layer of air when submerged under water. Surprisingly the terminal cells of the hairs are hydrophilic. These hydrophilic patches stabilize the air layer by pinning the air–water interface. This "Salvinia Effect" provides an innovative concept to develop biomimetic surfaces with long-term air-retention capabilities for under water applications. © Martin Oeggerli / www.Micronaut.ch, original SEM scan by Prof. Barthlott.