Self-regulated flow control in microchannels by the modification of walls with stimuli-responsive polymer

近十年来，由芯片上加工的微通道构成的微分析系统得到了极大的研究和广泛的应用。本文提出了一种新的复杂微通道流体控制方法。刺激响应性聚合物通过刺激改变其疏水-疏水特性，用于修饰通道壁。通过将硅烷偶联剂键合到玻璃表面，再通过N-异丙基丙烯酰胺与具有能与目标化合物键合的官能团的单体进行水自由基共聚，成功地实现了对玻璃表面的改性。我可以成功地控制表面润湿性的刺激，如温度，盐，或表面活性剂。润湿性变化导致流的开-关或流动方向的切换。采用高疏水性十八烷基硅烷和刺激响应性聚合物复合改性后，润湿性对比度得到显著改善。此外，对具有亚微米级粗糙度的表面进行改性对于获得高度疏水性和沃茨性的表面都是非常有效的。含羧基或咪唑基团的聚合物可根据酸碱条件改变其疏水性能。含有能与糖结合的苯基硼酸酯取代基的聚合物对葡萄糖无反应。另一方面，具有苯硼酸盐和二甲氨基基团的聚合物的疏水性通过葡萄糖的存在而增加。通过这种刺激响应性聚合物的改性，将是有效的，用于制造葡萄糖响应性流动控制系统。

In this decade, micro-analytical systems composing of fabricated micro-channels on chips has extremely investigated and applied to the wide areas. In the present study, a novel methodology for the fluid control complicate micro-channels was developed. The stimuli-responsive polymer that changes its hydrophilic-hydrophobic properties by stimuli was used to modify the wall of channels. The modification was successfully achieved by binding silane coupling agent on glass walls and the subsequent aqueous radical co-polymerization of N-isopropylacrylamide and a certain monomer having functional group that can bind to the objective compound. I could successfully control the surface wettability by stimuli such as temperature, salt, or surfactants. The wettability change results in the on-off of the stream or switching the flow direction. The contrast of the wettability was significantly improved by the modification with highly hydrophobic octadecylsilane accompanying with stimuli-responsive polymer. Furthermore, the modification onto the surfaces having sub-micro meter order of asperity was quite effective for obtaining-both of highly wettable and waters repellent surfaces. The polymer containing carboxyl or imidazole moieties can varied the hydrophilic-hydrophobic properties depending on the acid-alkaline conditions. The polymer including phenylborate substituents that can bind to sugar could not respond against glucose. On the other hand, the hydrophobicity of the polymer having the both of phenylborate and dimethylamino groups increased by the presence of glucose. The modification by such stimuli-responsive polymer will be effective for making glucose-responsive flow control system.