微纳米间隙受限液体边界滑移与表面润湿性试验

Experimental study of boundary slip in confined liquids in micro/nano scale systems and the effect of interfacial wetting

为了研究微纳米间隙下固液界面间流体的流动及输运特性,采用修饰的原子力显微镜针尖,针对微纳米间隙下受限液体的边界滑移现象选用不同润湿特性的固-液界面进行了试验。固体壁面样品采用Si(100)面和OTS自组装膜,试验液体采用去离子水和十六烷。结果表明,当微间隙临界尺度小于6.67×10-3时,边界滑移效应对流体动压力有重要作用;润湿性极好的表面也会产生边界滑移,对试验液体具有10nm左右的滑移长度;润湿性差的光滑表面的边界滑移长度值明显大于润湿性好的表面。所得结果对于微流体输运与控制有重要的理论意义与实际价值。

The flow and transport characteristics of liquids in micro/nano scale systems were investigated using a commercial atomic force microscope with a 45 μm diameter glass ball attached to the end of the cantilever to form a nanoscale ball-disk contact point which was used to investigate boundary slip in confined liquids and the influence of interracial wetting. The systems were Si（100） and OTS film surfaces with deionized water and hexadecane. The results indicated that when the critical dimension less than 6.67 × 10^-3, boundary slip results in an obvious decrease in the hydrodynamic force applied to the ball. The boundary slip length is about 10 nm even for a hydrophilic surface. The slip length of a poorly wetting solid surface was much larger than on a well wetting surface. The results are important for the research of the flow properties of confined liquids.