2. http://www.me.umn.edu/~lixxx099/EFRI_CAES/Research/texturing.htm Characteristic micro- and nano- surface morphology combined with low surface energy chemical functionality allows for water droplets to roll and bounce freely on the surface.

3. The surface texture can greatly reduce the solid-liquid surface contact area and leads to an apparent contact angle: θ* Surfaces with high θ* ( 150° ~ 180°) and low water contact angle hysteresis (10°) are superhydrophobic. Superhydrofobicity can be explained by two independently developed models: the Wenzel model and the Cassie-Baxter model.

4. http://soft-matter.seas.harvard.edu/index.php/Pitcher_plant_inspired_non- stick_surface cos θ CB* = φ(cos θ + 1) – 1 Φ: fraction of solid liquid contact

5. Metastable Cassie State: If a Wenzel state is less energetic any perturbation of the Cassie Drop Can provoke its perturbation to the Wenzel state. Energy barrier: E = (γ SL − γ SA )(r − 1)=−γ (r − 1) cos θ Can be overcome by throwing the drop on the surface, pressing or by vibration. This energy barrier in general too large to be overcome by thermal energy. http://www.annualreviews.org/doi/abs/10.1146/annurev.matsci.38.060407.132434

6. The smaller the drop, the larger the δ is. When it becomes of the order of the pillar height, h, a solid/liquid contact can nucleate on the substrate and propagate. Critical radius for a Cassie drop scaling: R ∗ ∼ p 2 /h. The radius R ∗ can be much larger than p if h < p. This can be achieved by making h large or by reducing both p and h. http://www.annualreviews.org/doi/abs/10.1146/annurev.matsci.38.060407.132434

7. Spider leg http://www.asknature.org/media/image/16996 Fly eye http://www.asknature.org/media/image/16996