最後綜合上述實驗結果，以將矽試片拉出蝕刻液之方法，製備出具有梯度結構之多孔矽試片，並觀察其接觸角與液珠滑動之情形。實驗結果顯示，液珠於梯度結構表面之驅動力過小，但透過一頃斜平台轉動角度使液珠滑動可得知，液珠於大接觸角端所需滑動之臨界角度小於小接觸角端之滑動臨界角，並且其液珠加速度之提升更為快速。 ;In recent years, nanoporous silicon plays an important role in the semiconductor industry and energy industry. Two-step metal assisted chemical etching method has the advantages of low cost and simple processes. In biomedical and microfluidic systems, the hydrophobicity of materials must be considered. We can control a fluid drop to move on a solid surface by changing the hydrophobicity of surface material with nano structures.
We deposit silver particles with electro-less plating deposition method, followed by the anisotropic etch of the silicon surface by oxidation of etchant and silver particles. We apply different temperature to see how it affects the etching depths and the structures. Appropriate temperature helps to achieve best etching depth and porousity. We also determine the effects of different surface structures on droplet contact angles.
We find that the driving force to make the droplet move is too small on the nano porous silicon surface we made. So we use a tilt platform to increase the driving force to observe the effects easily. The critical angle at the larger contact angle side is smaller than the one at the smaller contact angle side, and is faster in the increase of the acceleration of the droplet.
