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Drag reduction effect of ultraviolet laser-fabricated superhydrophobic surface
摘要： Superhydrophobic (SH) surface has been found effective for drag reduction in wall-bounded turbulence for decades, especially the metallic durable SH surfaces are believed very promising for improving the velocity and voyage of marine vehicles. We present stainless steel SH surfaces with U-groove patterns that fabricated by ultraviolet laser texturing and coating modifier treatment. The drag-reducing effects of the SH surfaces are tested by a self-built gravity sliding speed improving evaluation device. The results show that the different drag-reduction performance of the SH surfaces can be achieved by adjusting the line spacing of the crossing U-groove patterns. With the line spacing equalling to 80 μm, the ultraviolet laser textured stainless steel SH surface acquires the static contact angle of 161.5° and the dynamic sliding angle of only 2°, which leads to the maximum speed improving rate of 29.7%.
关键词： drag reduction,Superhydrophobic surface,stainless steel,laser texturing
更新于2025-09-23 15:23:52
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Creation of Superhydrophobic and Superhydrophilic Surfaces on ABS Employing a Nanosecond Laser
摘要： A nanosecond green laser was employed to obtain both superhydrophobic and superhydrophilic surfaces on a white commercial acrylonitrile-butadiene-styrene copolymer (ABS). These wetting behaviors were directly related to a laser-induced superficial modification. A predefined pattern was not produced by the laser, rather, the entire surface was covered with laser pulses at 1200 DPI by placing the sample at different positions along the focal axis. The changes were related to the laser fluence used in each case. The highest fluence, on the focal position, induced a drastic heating of the material surface, and this enabled the melted material to flow, thus leading to an almost flat superhydrophilic surface. By contrast, the use of a lower fluence by placing the sample 0.8 μm out of the focal position led to a poor material flow and a fast cooling that froze in a rugged superhydrophobic surface. Contact angles higher than 150? and roll angles of less than 10? were obtained. These wetting behaviors were stable over time.
关键词： superhydrophilic,superhydrophobic,surface wettability,nanosecond laser surface modification,ABS (Acrylonitrile-Butadiene-Styrene)
更新于2025-09-04 15:30:14
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Light-actuated droplets coalescence and ion detection on the CAHTs-assisted superhydrophobic surface
摘要： Coalescence and mixing of the complex chemical reagents on the droplet-based open micro?uidics are considered to be critical steps for the sample processing and the follow-up reactions and chromogenic/?uorescence analyses. Recently, using the light to actuate the droplets coalescence has been demonstrated to be able to create the ?exible, precise and high-throughput optical droplet-based reaction/analysis platforms. Particularly, the photothermal e?ect, which is one of the ?uid-light interactions, is promising in the droplets coalescence by the light-induced phase change. In present study, a contact angle hypothesis traps (CAHTs)-assisted optical droplet-based reaction/analysis platform was developed. With the triple-phase contact line extension caused by the light-heating induced wetting transition, the coalescence of two neighboring droplets on the CAHTs was induced to facilitate the rapid mixing and detection. It was also con?rmed that with the o?-center light heating, the orientable extension of the irradiated droplet was realized, which could increase the critical CAHTs gap required for the occurrence of the droplets coalescence. With the developed platform, an ion detection by processing a chromogenic reaction was presented as a proof of concept. It is believed that this concept has the signi?cant potential in many applications, including biomedicine, pharmacy, clinical diagnosis and chemosynthesis.
关键词： Ion detection,Superhydrophobic surface,Contact angle hypothesis traps,Photothermal e?ect,Droplets coalescence,Orientable extension
更新于2025-09-04 15:30:14