Physical Processes-aided Periodic Micro/nanostructured Arrays By Colloidal Template Technique And Their Applications In Biosensing

Two dimensional (2D) ordered micro/nanostructured arrays have attracted considerable interest in recent years because of their promising applications in a variety of fields, such as surface-enhanced Raman scattering (SERS) active substrates, chemical and biological sensors, superhydrophobic surfaces, and optoelectronic as well as microfluidic devices. In this thesis, a series of micro/nanostructured arrays with novel morphology and controllable structure were constructed effectively and efficiently on a large-scale based on physical routes combining with PS colloidal monolayer template, such as sputtering deposition, thermal evaporation deposition, heat treatment, reactive ion etching. Several performances including activity and stability of SERS substrate, wettability, and biosensing property correlated with morphology and microstructures were investigated.The main points are summarized as follows:(1) An effective and inexpensive method is developed to fabricate periodic arrays by sacrificial colloidal monolayer template route by chemical deposition and further physical deposition. By a colloidal template induced precursor solution dipping strategy, different periodic arrays were obtained by different conditions. After magnetron sputtering deposition, their morphologies were changed to novel micro/nanostructured arrays. After coating a gold thin layer, these periodic micro/nanostructured arrays were used as SERS active substrates and demonstrated a very uniform SERS performance compared with periodic arrays achieved by direct colloidal template induced chemical deposition. Such uniform SERS performance is useful to practical applications in portable Raman detecting devices to detect organic molecules.(2) Periodic hexagonal spherical nanoparticle arrays are fabricated by sacrificial colloidal monolayer template route by chemical deposition and further physical deposition. The regular network structured arrays are first templated by colloidal monolayers and then they are changed to novel periodic spherical nanoparticle arrays. The nanogaps between two adjacent spherical nanoparticles could be well tuned by controlling deposition time. The periodic nanoparticle arrays with10nm gaps display much stronger SERS enhancement due to electromagnetic coupling. The chemically modified nanoparticle arrays show good hydrophobicity, which shorten process of detecting probe molecules using them as SERS active substrates by localized concentration of droplet evaporation and a low detection limit of organic molecules could be achieved without solution wasting in a short time. The hydrophobic substrate offers a simple, convenient, and economical method to examine SERS performance by rapid concentration of solution on it.(3) An effective and efficient strategy has been developed to fabricate ordered Au hexagonal non-close-packed arrays with tunable periodicity and size in large scale. A certain thick layer of Au film was deposited onto the colloidal monolayer by sputtering deposition, followed by calcination to decompose the colloidal template, and then annealing to obtain spherical shaped Au nanoparticle arrays. The periodicity of arrays was controlled by changing the size of PS colloidal spheres; additionally, the size of Au particles could be controlled by tuning the thickness of film deposited on the PS colloidal spheres or by repeated deposition-annealing cycle on an existed smaller particle. After decoration of functional group molecules on the surface, the peak of SPR of periodic arrays exhibit sensitive biosensing and a low detection limit of1mM glucose could be achieved. Moreover, the diffraction peak induced by periodic configuration displayed the similar phenomena. Therefore, the concentration of biomolecules could be confirmed by duplicated routes. Additionally, the presented methods also can be applied to fabricate other particle arrays including Ag, Cu and so on.(4) An acile strategy has been proposed for mass fabrication of wafer-scale morphology-controlled periodic SiO2arrays by using monolayer colloidal nanosphere lithography (NSL) combined with reactive ion etching (RIE). By well-controlling the experimental conditions of RIE, the morphology of periodic SiO2micro/nanostructured array could be tuned from dome-shaped one to circular truncated cone one, and finally to circular cone one. After depositing a silver thin layer, these periodic micro/nanostructured arrays were used as SERS active substrates and demonstrated obvious SERS signals of4-Aminothiophenol (4-ATP). This offered a practical platform to conveniently prepare SERS active substrates.(5) Periodic SiO2nanocolumn arrays with tunable periodicity and size in large scale are fabricated by using monolayer Au nanosphere lithography combined with reactive ion etching. And then a certain thick layer of Ag film was deposited onto the top and sidewall of nanocolumns, Ag particle decorated SiO2nanocolumn arrays were formed after annealing process. By well-controlling the depositing conditions of Ag film, the size of Ag particles could be tuned from some dozen to several hundred nanometers. These periodic micro/nanostructured arrays were used as SERS active substrates and demonstrated obvious SERS signals of4-ATP and R6G.A general summary about this thesis and the prospects for further work are presented.