Research On Controllable Fabrication Of Anisotropic Micro/Nano-Structured Surfaces Based On Laser Interference Lithography

Micro/nano structures with anisotropic distribution can enhance or give anisotropic functions on the surfaces of materials.With the continuous development of surface engineering and micro/nano-fabrication technologies,the research hotspot of functional surfaces has gradually developed from the fabrication of single functions to the fabrication of multi-functional composite surfaces.Among them,anisotropic micro/nano-structured surfaces have important application value in the design and fabrication of multi-functional composite surfaces.Laser interference lithography(LIL)is one of the most promising micro/nano-fabrication technologies due to its high flexibility,low-cost and high controllability.Based on the theoretical basis of laser interference,this thesis studied the light intensity distribution characteristics,regulation mechanism and fabrication technology characteristics of multi-beam interference field.The spatial light intensity distribution model of the interference field was established,and the anisotropic spatial distribution model of the micro/nano-structured surfaces and the evaluation model of the anisotropic micro/nanostructured surfaces were derived to study the controllable preparation of the anisotropic micro/nano-structured surfaces.A method to improve the two-beam LIL system was proposed,combining with the double-exposure technology,the controllable fabrication on the surface with macro-micro cross-scale anisotropic microstructures from micron to millimeter scales was realized.Based on LIL technology,the controllable preparation of anisotropic wetting surfaces was realized by studying the controllable transition method of wettability,and the regulatory effect of topology on the growth of SH-SY5 Y cells was studied by combining the anisotropic micro-nano structure surface.The main work and results achieved in this thesis were as follows:1)The intensity distribution of multi-beam interference field and the micro/nanostructured surface fabrication based on LIL technologyBased on Maxwell’s equations,the principle of multi-beam interference field’s light intensity distribution was analyzed,and the influence of azimuth angles,polarization and incidence angles on the period,intensity,spatial distribution and contrast of intensity distribution were studied.The multi-beam LIL systems were constructed,and the micro/nano-structured surface fabrication mechanisms of direct and indirect LIL technologies on materials were analyzed,which provided a theoretical basis and fabrication methods for the work in this thesis.2)Study on the controllable fabrication of anisotropic micro/nano-structured surfacesThe Fourier transform was used to establish the spatial intensity distribution model of the interference field,and the correspondence between the spatial light intensity distribution and the spectrum was theoretically analyzed.The Fast Fourier transform(FFT)and Gaussian fitting algorithm were used to establish a spatial distribution model and an anisotropy evaluation model on the surface of micro-nano structures was proposed.Using the above established model,through the analysis and calculation of the characteristic parameters of the surface of the micro/nano structure,the preparation parameters such as incidence angle and spatial angle were directly estimated,and the preparation error of the structure and the construction error of the LIL system were identified and corrected,which used to realize the controllable preparation of the anisotropic micro/nano-structured surface.3)Study on the controllable fabrication of cross-scale anisotropic micro/nano-structured surfacesBased on the analysis and evaluation model of anisotropic micro/nano-structured surfaces,the effects of rotation angle and energy parameters on the structure distribution were analyzed,the structural shape and anisotropy of two-beam double-exposure technology were studied.To break through the limitations of light source and optical systems on the preparation of macro-period structures,an improved method for the two-beam LIL system was proposed to realize the regulation of macroscopic Moiré stripe size.The macroscopic Moiré stripe and two-beam double-exposure technology were used to realize the controllable preparation of cross-scale anisotropic micro/nano-structured surfaces.4)Study on anisotropic wetting surfaces and their regulation of SH-SY5 Y cell growthBased on the patterned Ti-6Al-4V alloy surface processed by LIL direct writing technology,an anisotropic wettability controllable conversion method with high efficiency,stability and good biocompatibility was proposed.By studying the regulatory mechanism of surface non-polar organic molecule adsorption during low vacuum treatment and the acceleration mechanism of surface homeostasis formation during high vacuum treatment,the controllable transition of wettability within 2-8 h by low vacuum adsorption was realized,and the controllable preparation of anisotropic wetted surfaces was achieved.By studying the regulatory mechanism of anisotropic two-dimensional array structure surface and onedimensional chain structure surface on the growth morphology and synaptic elongation of SH-SY5 Y cells,the guiding effects of anisotropic micro-nanostructure surface and its anisotropic wettability on cell polar growth were revealed.