Water Harvesting of Bioinspired Microfibers with Rough Spindle‐Knots from Microfluidics

Abstract

Heterostructure rough spindle‐knot microfibers (HRSFs) are fabricated via a flexible parallel‐nozzle microfluidic method. In this method, the bioinspired HRSF with a roughness gradient between spindle‐knots and joints, can be manufactured in large‐scale, and with which the size of the spindle‐knots and joints can be precisely adjusted by regulating flow rates. The HRSFs, fabricated with chitosan and calcium alginate, have strong mechanical properties and corrosion resistance in acid environment (pH = 5) and alkaline environment (pH = 9), respectively. More attractively, under controlled treatment conditions, the morphology of the spindle‐knots on the HRSFs can be effectively managed by changing the composite content of calcium chloride in the fluid. During the water collection process, tiny droplets of moisture can be captured on the surface of the HRSFs, subsequently, the droplets can coalesce and be transported from joint to spindle‐knot sections. It is demonstrated that the surface morphology of spindle‐knots directly influences the water collection efficiency, where a higher roughness gradient generates higher water collection efficiency. This parallel‐nozzle microfluidic technology provides a low‐cost and flexible method to manufacture high biocompatibility bioinspired rough spindle‐knot microfibers, which has many potential applications in large‐scale water collection, sustained drug release, and directional water collection.

Droplet Bouncing: Fundamentals, Regulations, and Applications

“…Surface Wettability Gradient: Making millimeter-sized droplet move toward the designed direction is desired in wide liquid-manipulation-related [125][126][127][128][129][130][131][132][133] applications like liquid collection, [134][135][136][137][138][139][140][141][142][143][144][145][146][147][148][149][150] printing, [151] hydropower utilization optimization [152,153] or microfluidics. [154,155] By designing a nonwetting solid surface with a wettability gradient, vertical momentum of impacting droplet can be transferred to horizontal momentum with the designed direction.…”

Fog Harvesting Devices Inspired from Single to Multiple Creatures: Current Progress and Future Perspective

“…[81,82] Therefore, it is desired to construct the "spindle-knots/joints" structure to achieve fog harvesting properties. [83][84][85][86][87][88][89] Both the surface morphology of the spindle knots and the size of the spindle-knots and joints could affect the fog harvesting efficiency directly. To investigate the suitable structure and size of spindle-knots and joints, Zheng et al fabricated a heterostructure rough spindle-knot microfibers based on CaCl 2 and chitosan via electrostatic spinning.…”

Bioinspired materials for water-harvesting: focusing on microstructure designs and the improvement of sustainability

“…By imitating spider silk, scientists successfully prepared a series of bioinspired artificial spider silk (BAS). 36,61,62 Bai et al 63 used the dip coating method to produce a series of BASs with spindle junctions, in which the chemical composition and surface nanostructure were cleverly designed. When nylon fiber was immersed in the polymer solution and pulled out horizontally, due to Rayleigh instability, a string of polymer droplets fell on the fiber and became spindle knots after drying (Fig.…”

“…Inspired by nature, the research on bioinspired materials came into being and became a hot topic. [30][31][32][33][34][35][36][37][38][39][40][41][42] In the past ten years, it has made great achievements. 43 According to the previous literature, by imitating the micro-nano structure, morphology, and wettability of organisms such as spider silk, cactus, and desert beetles, a variety of design and preparation methods of bioinspired water collection materials have been produced.…”