Tiggelaar R M, Verdoold V, Eghbali H, Desmet G, Gardeniers J G E
Institute for Nanotechnology, University of Twente, AE, Enschede, The Netherlands.
Lab Chip. 2009 Feb 7;9(3):456-63. doi: 10.1039/b812301b. Epub 2008 Nov 13.
Properties of porous silicon which are relevant for use of the material as a stationary phase in liquid chromatography chips, like porosity, pore size and specific surface area, were determined with high-resolution SEM and N(2) adsorption-desorption isotherms. For the anodization conditions investigated, porosity is between 20 and 60%, pore sizes between 2 and 5 nm and specific surface area between 130 and 410 m(2)/cm(3). It was established that under identical anodization conditions, porous layer formation is 10-15% slower on micromachined pillars than on flat substrates, and depends on geometrical parameters like pillar diameter and height and interpillar spacing. In microchannels containing pillars with a porous silicon shell, chromatographic experiments on a coumarin dye mixture were performed, which in comparison with non-porous pillars showed a significant increase of the retention factors, resulting from the large internal surface of the porous pillars. The increased relative retention of one of the coumarin dyes, C480, could be correlated quantitatively with the measured internal surface of the porous layer. Due to the small pore size, these porous shell columns are particularly suitable for analytical or preparative separation of low-molecular weight molecules, with applications in metabolomics, food quality control, or medical diagnostics.
利用高分辨率扫描电子显微镜（SEM）和N₂吸附-脱附等温线测定了多孔硅的性质，这些性质与该材料作为液相色谱芯片固定相的应用相关，如孔隙率、孔径和比表面积。在所研究的阳极氧化条件下，孔隙率在20%至60%之间，孔径在2至5纳米之间，比表面积在130至410平方米/立方厘米之间。已确定在相同的阳极氧化条件下，微加工柱上多孔层的形成比在平坦衬底上慢10 - 15%，并且取决于柱直径、高度和柱间距等几何参数。在含有带多孔硅壳柱的微通道中，对香豆素染料混合物进行了色谱实验，与无孔柱相比，由于多孔柱的大内部表面积，保留因子显著增加。一种香豆素染料C480增加的相对保留率可以与多孔层的测量内表面定量相关。由于孔径小，这些多孔壳柱特别适用于低分子量分子的分析或制备分离，可应用于代谢组学、食品质量控制或医学诊断。
