刻蚀-相分离法表面疏液处理提升液态金属基微流体惯性开关阈值性能

Preparation of Lyophobic Surface via Etching-phase Separation Method for Improving Threshold Performance of Microfluidic Inertial Switch

液态金属基微流体惯性开关,因其集感控于一体而得到重点关注。在开关设计中,改变流体与微通道壁面的接触角可以实现开关阈值范围的调节,提高微流体惯性开关的灵敏性。面向镓铟锡合金基微流体惯性开关,研究通过刻蚀-相分离法对微流道基底(Polymethyl methacrylate,PMMA)进行表面超疏液改性,使PMMA表面同时发生化学刻蚀、相分离和SiO2沉淀过程,进而形成PMMA-SiO2的梯度粗糙表面。详细研究溶剂配置、成分配比和反应工艺参数对PMMA表面粗糙度的影响,并且开展超景深显微镜、扫描电子显微镜(Scanning electron microscope,SEM)、原子力显微镜(Atomic force microscope,AFM)和红外光谱仪的表征,发现使用四氢呋喃和无水乙醇按1∶1比例配比,且加入15 mg/mL的二氧化硅时,能够得到更有利于PMMA疏液性的表面粗糙结构。最终,通过此表面改性方法,成功实现镓铟锡合金基微流体加速度开关阈值从52.54g改进到了28.62g,满足了原液态开关的设计要求。

Microfludic inertial switch with integrating sensing and actuating functions has drawn the increasing attention.In design,adjusting the contact angle between the fluid and the wall of the microchannel is able to adjust the threshold of the microfluidic inertial switch and improve its sensitivity.As to Galinstan-based microfluidic inertial switch,the super lyophobic surface of polymethyl methacrylate(PMMA)has been prepared by etching-phase separation method,where chemical etching,phase separation and SiO2 deposition prompts the formation of the hierarchical surface roughness with PMMA-SiO2.The influences from recipe,proportion of ingredients and process are studied by using optical microsocope,scanning electron microscope(SEM),atomic force microscope(AFM)and infrared spectrometer.It is found that that,when the solvents are prepared as C4H8O to C2H5OH as 1:1 in volume ratio and the SiO2content is 15 mg/mL,the optimized surface roughness is obtained.In final,the threshold of microfluidic inertial switch is improved from 52.52g to 28.62g,in matching with the requirements of the mercury-based switch.