The fabrication of PDMS-based functional surface mimicking the namib desert beetle back for collecting water vapor in the air

This paper presents novel functional surface designed for collecting water vapor, which is combined of PDMS and the micro level hydrophilic metal alloy ball. To imitate biological structure, the metallic balls are designed as hydrophilic part and PDMS substrate as hydrophobic structure. The ball is used as nucleation centers to absorb water vapor in the air to form droplet. Then, with the drop gradually growing up, it will fall off from the ball by gravity. The hydrophobic property of PDMS could promote tumbling of drop more smoothly without adhesion. This device is fabricated by micromachining process, where using PMMA as reverse mold and depositing fluorocarbon films on the PDMS to further enhance the hydrophobic property. The test results prove that this idea and water collection can be achieved obviously.