Yamada Yutaka, Isobe Kazuma, Horibe Akihiko
Graduate School of Natural Science and Technology, Okayama University Okayama 700-8530 Japan
RSC Adv. 2022 May 10;12(22):13917-13923. doi: 10.1039/d1ra09244h. eCollection 2022 May 5.
Droplet transportation using a wettability gradient surface has attracted much attention owing to applications such as in microfluidic devices. A surface with a spatial structural gradient was prepared through a simple and cost-effective process even though understanding of droplet behavior on the structure was still limited. Here, we report impinging droplet motion on a gradient wrinkled surface. Surfaces were prepared through hard film deposition on soft pre-strained polydimethylsiloxane (PDMS) with a mask installed with a slit to control the amount of deposition, which is related to the wavelength of the wrinkles. Droplets were impinged with varying position with respect to the structure, and the droplet motion was observed in the direction away from the region under the slit. We found an asymmetric contact angle and alternate motion on both sides of the three-phase contact line during the motion according to the gradient of the wrinkle wavelength. These results may help not only to understand the behavior of droplet impingement on a gradient structural surface but also to further develop applications using directional droplet transfer.
由于在微流控设备等方面的应用,利用润湿性梯度表面进行液滴传输已备受关注。通过简单且经济高效的工艺制备了具有空间结构梯度的表面,尽管对结构上液滴行为的理解仍有限。在此,我们报告了撞击在梯度皱纹表面上的液滴运动。通过在带有安装有狭缝的掩膜的软预应变聚二甲基硅氧烷(PDMS)上进行硬膜沉积来制备表面,该狭缝用于控制沉积量,沉积量与皱纹波长相关。液滴相对于结构以不同位置撞击,并在远离狭缝下方区域的方向上观察液滴运动。我们发现,根据皱纹波长的梯度,在运动过程中三相接触线两侧存在不对称接触角和交替运动。这些结果不仅有助于理解液滴在梯度结构表面上的撞击行为,还有助于进一步开发使用定向液滴转移的应用。