Preparation Of Micro-nano Array Structure By Liquid Surface Assisted Method And Its Application

As a method which can build macro-nano scale structures,macro-nano fabrication technology has been widely applied in industrial production and scientific research.Because of costs and energy consumption,traditional macro-nano fabrication technologies such as electron beam lithography and focused ion beam lithography are unaffordable for users who are sensitive to price.In recent years,microspheres self-assembly method which can fabricate large area macro-nano structures with low cost has received extensive attention.This thesis includes four parts to report our work in nanostructures array fabricating method and application by using microspheres self-assembly method.(1)Flexible SERS-sensitive Au/Ag nanoparticles coated PDMS by molding a 2D-inverse-opal structure on PDMS with a close-packed PS spheres self-assembled on a solid surfaceIn this part,polystyrene(PS)spheres monolayer template on a solid surface was fabricated by using self-assembly method.After that,transfer printing was employed to obtain polydimethylsiloxane(PDMS)film with inverse opal nanostructure from PS spheres template.After solution synthesis process,Au/Ag nanoparticles coated inverse opal PDMS film was obtained.This film as a surface enhanced Raman spectroscopy(SERS)substrate with advantage of low cost,flexible,high sensitivity and signal repeatability was used for sampling and testing analyte on curved surface.The limit of detection of Nile Blue A was 1× 10-10M,relative standard deviation of SERS signal was 13.1%and signal enhancement factor was 3 x 107,by using the SERS substrate.Malachite green was sampling from lobster surface and the limit of detection was 2.7×10-7 M.This work can be extended to be applied in the preparation of low cost and flexible sensors.(2)Flexible SERS-sensitive Ag coated PDMS by molding a 2D-inverse-opal structure on PDMS with a close-packed PS spheres self-assembled on a liquid surfaceIn this part,we used self-assembly method to fabricate PS spheres monolayer template and mold PDMS on a liquid surface.This method can enlarge the size of obtained PDMS film,and avoid the crack of PS spheres monolayer termplate and nanostructure defect on PDMS film.After PS removal and Ag coating,large-scale and flexible Ag coated PDMS film as SERS substrate was obtained.The limit of detection ofNile Blue A and Malachite green were 1 × 10-10M and 2.7 × 10-7M respectively,signal enhancement factor was 1.8 × 107.Since the defect on PDMS film was avoided,relative standard deviation of SERS signal was 9.7%.This work can be extended to be applied in the preparation of low cost sensors and photonic crystal in the future.(3)Precision-trimming 2D-inverse-opal structure on wettability tunable PDMS to ordered nanostructures with variable size and morphologyIn this part,a low-cost and scalable method was developed for producing large-area PDMS film with controllable ordered surface structures.In this method,crosslinking degree,Young modulus and solvent resistance of PDMS were controlled by setting additional thermal curing temperature and time to realize the precision-trimming process.After precision-trimming process by solvent dissolution,deep dimple,sharp pillar,dull pillar and shallow dimple were obtained on PDMS surface by setting different thermal curing temperature,respectively.We also demonstrate,water droplets on PDMS surface with different surface structure are in Wenzel state,metastable Cassie state and Cassie state,respectively.This method is simple,low-cost,and scalable;it thus holds relevance in developing practical applications such as engineering wettability,adhesion,friction,and other surface functionalities.(4)Tuning triboelectric current-voltage responses by varying the 2D-inverse-opal micro-structure of PDMS in a glass-ITO/PDMS/PET triboelectric-generatorIn this part,PDMS films as an electrode with surface structure tunable were fabricated by using the method in part(3),and glass-ITO/PDMS/PET triboelectric generators with good transparency were obtained by assembling the PDMS films and ITO electrode.The triboelectric current-voltage responses were tuned,by varying the 2D-inverse-opal surface structure of PDMS.We demonstrate that the triboelectric generator with high triboelectric current-voltage responses can be obtained due to PDMS electrode with high surface roughness was employed.The peak of open circuit vo ltage and short circuit current were 27.7 V and 0.8?A,respectively.The output voltage,current and peak power were related to the resistance of external load,and the peak power reached maximum value when the resistance of external load was 10 M?.The triboelectric generator also showed electrical output stability during 600 work circles.This work can be extended to be applied in the preparation of touch screen in the future.