Autonomous directional water flow was demonstrated on a laser-microstructured steel-supported polymethylmetacrylate (PMMA) film with a surface tension gradient. For this purpose, a 4 μ m-thick PMMA layer on AISI 304 steel surface was raster-scanned in air in ablative mode by a 1064 nm, 100 ns laser beam in a number of lines, with the amount and topography of ablated PMMA analyzed by optical microscopy, profilometry and IR spectroscopy. Such scanning, performed at increasing incident fluences, produced a series of chemically and topographically modified, differently water-wet neighbouring mm-sized spots, autonomously driving single-droplet water flow along the surface tension (contact angle) gradient.

中文翻译：

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聚甲基丙烯酸甲酯涂层钢表面上激光工程化微流梯度结构中的定向自主水流

在具有表面张力梯度的激光微结构钢支撑聚甲基丙烯酸甲酯（PMMA）薄膜上证明了自主定向水流。为此，在AISI 304钢表面上的4μm厚PMMA层在空气中以多条线通过1064 nm，100 ns的激光束在烧蚀模式下进行光栅扫描，分析了烧蚀PMMA的数量和形貌通过光学显微镜，轮廓测定法和红外光谱。这种扫描以增加的入射通量进行，产生了一系列化学和地形修饰的，不同水润湿的相邻毫米大小的斑点，从而自动驱动单滴水沿表面张力（接触角）梯度流动。