Controllable Preparation Of Silicon Nanowire Arrays For Microscale Materials Separation

Silicon nanowire is a new kind of one-dimensional semiconductor material,silicon nanowire arrays by a certain orientation of silicon nanowires are arranged in the basal surface of the formation of the nanowire arrays.Metal-assisted chemical etching is a simple,controllable,large-area,repeatable and high aspect ratio silicon nanowires preparation method.However,the preparation process of this method is affected by many factors.In order to prepare silicon nanowire arrays with controllable size,it is necessary to systematically study the experimental parameters that affect the size and morphology of silicon nanowire arrays.In the process of experimental exploration,it is found that under different experimental parameters,the surface pore spacing of silicon nanowire array is different.In this experiment,based on metal-assisted chemical etching method,a silicon nanowire array with controllable size was prepared by exploring the experimental parameters affecting the morphology factors of silicon nanowires.By surface modification of silicon nanowire arrays,hydrophilic and hydrophobic silicon nanowire arrays were obtained.Based on silicon nanowire arrays with different surface pore sizes,the Si NWAs chip was prepared,the separation system device was built,and the theoretical separation system model was constructed.The experiment of separating cells of different sizes from whole blood was carried out,which provided theoretical basis for the separation of cells of different sizes from whole blood and single cell detection in the future.The research contents and experimental results are as follows:1.The silicon nanowire arrays with high aspect ratio,controllable size and different surface pore spacing were prepared by metal-assisted chemical etching.By adjusting the surface roughness,silver plating time,hydrofluoric acid solution,etching liquid volume and etching time of silicon wafer,silicon nanowire arrays with length of 16-72 μm and surface pore spacing of 500 nm-22 μm were obtained.2.Using piranha solution and HF solution to modify the surface of the silicon nanowire array,it was proved by scanning electron microscopy,X-ray photoelectron spectroscopy and water contact angle test that the Si-OH bond and Si-H bond were formed on the surface of the silicon nanowire array,and hydrophilic P-Si NWAs and hydrophobic H-Si NWAs were obtained.3.Due to the different pore sizes on the surface of different Si NWAs,the ability to capture micro-scale particles is different.With the help of fluid driving force,the separation of particles of two different sizes can be realized in three-dimensional space.Hydrophilic Si NWAs chip as the core,the use of micro injection pump fluid power,build the system of separation device,by adjusting the fluid velocity and static time,realized 5 μm and 10 μm particle separation,and preliminarily realized the separation of red blood cells in whole blood,as for the future to realize separation of different size in whole blood cells and single cell test.