Adhesion Forces and Contact Angles of Water Strider Legs

Abstract

This study investigated the adhesion (pull-off) force and contact angles of a water strider's leg. During hydrostatic experiments, the adhesion force was found to be 2 dyn. The image of a cross section of a live leg contacted with a deformed water surface provided the contact angle of 168.8 degrees . A numerical scheme was proposed to determine the water surface on a groove wall of a seta. The results showed that the asperities of a seta are almost wetted, and the fraction of the wetted projection area was 0.69. Thus, the contact angle of a seta was 124.8 degrees .

Peach skin effect: a quasi-superhydrophobic state with high adhesive force

“…DP s ; S is the area of the contact region between the water droplet and the surface; G is the gravitational force acting on the lower part of the water droplet, and F c is the surface tension from Eq. (2).…”

“…Therefore, exploring the relationship between surface wettability and micro-/nanostructures of biological species is the first step to prepare smart bio-inspired surface materials [1][2][3][4][5][6][7][8][9]. In nature, some plant surfaces, including their fruits, play an important role in protecting plants from water loss, UV and visible radiation, temperature extremes, and so forth [10].…”

Fabrication of Polymer Film with Low Adhesion and High Hydrophobicity Using Locust Wing as a Bio-template

“…However, little has been focused on another special contact state of a droplet on hydrophobic surface called "Gecko state" (high adhesive superhydrophobicity). The superhydrophobic material with high adhesion can be used as a "mechanical hand" in no-loss microfluidic transport [3]. After millions of years of evolution, many animals and plants have possessed distinctive body surfaces which are superhydrophobic, self-cleaning, anti-adhesive, anti-corrosive and anti-wearing [4].…”

Effect of Hierarchical Structure and Orientation on Water-Repellent Legs of Water-Walking Insects

“…The front legs are equipped with a hunting hook approximately the same size as the leg diameter. The front legs are also used to dewet the middle and back legs [21]. The entire insect is coated in an organic wax, which is typically assumed in literature to have contact angle ~105° with water [1,18,22].…”

“…In the case of water striders, it has been shown that both orders of roughness in the hierarchical structure must be present in order for the strider leg to be physically capable of achieving the measured 170° contact angle [1]. The following equation incorporates setae features into the Cassie-Baxter wettability equation [1,21]:…”