【作者】 郑冬梅；

【导师】 刘长松；

【作者基本信息】 青岛理工大学 ， 机械制造及其自动化， 2010， 硕士

【摘要】 近年来,微流体的驱动控制技术引起了越来越多人的注意。表面张力驱动是微流体器件中流体驱动的一种重要方式,其实现依赖于润湿性表面的可控性。本文利用自组装单分子膜的光响应性,通过真空紫外光照,制备了能使液滴自发运动的梯度表面能表面,进而研究了不同液滴在各种梯度表面上的运动情况。同时还研究了氧化锌薄膜表面的润湿性可逆转变特性。经研究发现:(1)随着光照时间的增加,自组装单分子膜的刻蚀作用逐渐增强,从而导致接触角逐渐减小,表面能逐渐增大。利用这一特性,通过对十七氟癸基三甲氧基硅烷单分子膜(FAS-SAM)进行连续光照,制备出了梯度表面能表面。(2)液滴在梯度表面能表面可以由低表面能区域向高表面能区域运动,其运动过程可分为加速阶段和减速阶段。对于体积为2μl的水滴,在上述梯度表面能表面上的接触角在4.23mm的距离内变化了约39°,由55.82°减小到了16.74°,其最大运动速度约为23.28mm/s。(3)液滴的运动速度与液滴的体积成正比,与挡板的运动速度成反比,即液滴体积越大,挡板速度越小,液滴运动速度越快。此外,水滴在水平梯度表面上的运动速度要高于倾斜梯度表面上的运动速度,而且水滴的运动速度要大于相同体积的甲酰胺和二甘醇液滴在同一梯度表面上的运动速度。(4)改变光照距离同样也可以制备出梯度表面能表面。液滴在该种梯度表面的运动情况与改变光照时间得到的梯度表面上的运动情况相似。(5)通过真空紫外光照十八烷基三甲氧基硅烷单分子膜(ODS-SAM)表面和粗糙的FAS-SAM表面也可以形成梯度,但液滴在这些表面却不能自发的运动。(6)玻璃基底上制备的氧化锌薄膜具有亲水特性,经过低温加热转变为疏水状态;然后再经过高温加热处理,又会转变为亲水状态,即该种薄膜具有疏水/亲水的可逆转变特性。而且经实验证明:氧化锌薄膜表面发生润湿性转变的临界温度为165℃。这种可控润湿性的氧化锌薄膜有望制备梯度表面能表面。更多还原

【Abstract】 In recent years, the preparation of microfluidic driving technology has attract more and more attention, and controllable surface wettability plays a key role in its realization. In this thesis, we fabricated surfaces with gradient surface energy by VUV irradiation, which can make liquid droplets move on it. Then the movement of different liquid on gradient surfaces was studied in detail. Finally, it was studied that the characteristics of reversible change between superhydrophilic and superhydrophobic on ZnO film. The result revealed that:(1) Along with the illumination time increasing, the etching strengthened gradually, which resulted in the decreasing of contact angle and the increasing of surface energy. Base on this effect, surfaces with gradient surface energy were prepared on FAS-SAM.(2) The droplet could move from low surface energy regions to the high ones. The motion of the droplet on the gradient surface was divided into the accelerating stage and the decelerating stage. The change of contact angle was about 39°in the range of 4.23mm, which is from 55.82°to 16.74°. The maxium velocity of the water droplet (2μl) is about 23.28mm/s.(3) The velocity of droplet was proportional to the size of the liquid droplet and was inversely proportional to the velocity of the baffle. That is to say, the larger of the drop size was and the slower of the baffle moved, the quicker of the droplet moved. In addition, the velocity of droplet on the horizontal surface was larger than that on the inclined surface, the velocity of water was larger than the velocity of the form amide droplet and the diglycol droplet on the same horizontal surface.(4) The gradient surface also could be fabricated by changing the illumination distance. The movement station was similar to that fabricated by changing the illumination time.(5) The gradient surface also could be fabricated on ODS-SAM surface and FAS-SAM surface, but the droplet could not move spontaneously.(6) The ZnO film was hydrophilic in the beginning. After stored in the dark for many days or heated by low temperature, the film could turn to hydrophobic state ; then treated by vacuum ultraviolet (VUV) or high temperature, the ZnO film would be superhydrophilic with the contact angle of 0°. That is to say, this film could be reversed between hydrophilic and hydrophobic state. It has been demonstrate that the critical temperature of wetting transition was 165℃. This ZnO film can fabricate gradient energy surface.Surface tension-driven has many potential applications in MEMS. The research about Surface tension change controllably and droplet motion will be significant for our study of MEMS.更多还原