Programmable Droplet Bouncing on Bionic Functional Surfaces for Continuous Electricity Generation

Abstract

The natural phenomenon of droplets bouncing on various surfaces holds remarkable potential for applications like water transportation, self‐cleaning, antifreezing, etc. However, achieving precisely controlled patterned droplet bouncing on functional surfaces with accurately controlled factors like bouncing velocity and trajectory in three dimensions remains a formidable challenge. In this context, a concept of bionic hydrophobic functional surfaces composed of mushroom‐like microstructures is introduced. These microstructures are crafted using the projection microstereolithography (PµSL) based 3D printing technique, subsequently coated with a hydrophobic spray. By finely adjusting the geometric attributes and inclination angles of these micromushrooms, the ability is gained to meticulously manipulate the bouncing velocity and trajectory of water droplets. The most optimal performance is demonstrated by a droplet exhibiting a maximal jumping distance and height respectively of 2.5 and 7.1 mm with 50° inclined micromushrooms. Notably, these specially designed micromushrooms orchestrate diverse behaviors in droplet bouncing, encompassing patterned bouncing, antigravity jumps, and directional water transportation. Additionally, the functional surface's adaptable self‐cleaning capability facilitates the harnessing of energy from rainfall on large surfaces, offering potential applications in realms, such as self‐cleaning mechanisms, droplet capture, water conveyance, and clean energy generation.

Functional microfluidics: theory, microfabrication, and applications

“…Yang et al [251] proposed a bionic surface diode with amazing performance of directional droplet sliding and precise control of droplet friction. Zhan et al [254] developed a bionic surface with inclined micro-mushrooms for programmable droplet bouncing, offering applications in water transportation, self-cleaning, antigravity bouncing, and clean energy generation (figure 11(k)).…”

“…CC BY 4.0. (k) A bioinspired functional surface with inclined micromushrooms for programmable and patterned droplet bouncing[254] [254]. John Wiley & Sons.…”

A tree-root mimicked Janus evaporator for solar evaporation of saturated saline water

“…Herein, inspired by the structures of poplar trees, 35 which can transport salts out of trunks through a special urinary salt system, we propose a unique solar evaporation system based on three-dimensional (3D) printing technology. 36–41 The evaporator consists of a layer of solar absorber, microchannels and macrochannels. Salty water can be lifted to the surface of the solar absorber due to the strong capillary force of the microchannels.…”