亲/疏水性不同壁面组成微通道的深宽比与通道内液体的自发毛细流动

研究了聚合物芯片上由亲/疏水性不同壁面组成的微通道内流体的流动行为。为了实现该类微通道内液体的自发毛细流动和被操作液体的自发毛细输运,根据系统总表面自由能极小原理,提出了微通道内毛细输运自发实现时微通道的临界深宽比条件。在以二聚二甲基硅氧烷(PDMS)和玻璃为材料的微流控芯片上进行了三面疏水一面亲水微通道内水的毛细输运实验。针对165μm,200μm和265μm3种深度的通道,理论计算的临界深宽比为0.5,而实验得到的值分别为0.4714,0.4878和0.4818,实验结果与理论预测结果基本相符,从而验证了由亲疏水性不同的壁面组成的微通道内毛细输运自发实现的临界深宽比条件。

Aspect ratio for microchannels with nonuniform surface properties and spontaneous capillary

The flow characteristics of the fluid in microchannels formed by different hydrophobic and hydrophilic walls on the polymeric microfluidic chips were researched in this study.To achieve the spontaneous capillary of the liquid in a microchannel, the aspect ratio condition of the microchannels for the smoothing capillary was proposed on the basis of the free energy minimization approach. The experiments of the capillary transportation in the microchannels with three Polydimelhysiloxane(PDMS) walls and one glass wall were performed to confirm the aspect ratio condition. According to proposed theory, the critical aspect ratio of the microchannels with the depths 165 μm, 200 μm and 265 μm is 0.5000. In our experiment, the critical aspect ratios are 0.4714,0.4878 and 0.4818 respectively.Obtain data show that the experimental results are in good agreement with the theoritical one,which verifies the aspect ratio obtained by our experiments.