Fabrication and Characterization of Nanostructured Surfaces: Plasmonic Thin Films, Nanowires, Nanorings and Nanochannels.

摘要

This work demonstrates a method for enhancing the sensitivity of a surface plasmon resonance biosensor, and develops novel nanostructured sensing surfaces. It is divided into the following four sections: Surface plasmon resonance phase imaging on gold thin films, optical diffraction of gold nanowires, fabrication of plasmonic nanoring arrays, and fabrication of nanofluidic channels and networks.;The technique of surface plasmon resonance phase imaging (SPR-PI) was implemented in a linear microarray format. SPR-PI measured the phase shift of p-polarized light incident at the SPR angle reflected from a gold thin film by monitoring the position of a fringe pattern on the interface created with a polarizer-wedge depolarizer combination. SPR-PI was used to measure a self-assembled monolayer of 11-mercaptoundecamine (MUAM) as well as to monitor in situ DNA hybridization. The phase shifts were correctly calculated with a combined Jones matrix and Fresnel equation theory.;Arrays of Au or Pd nanowires were fabricated via the electrochemical process of lithographically patterned nanowire electrodeposition (LPNE) and then characterized with scanning electron microscopy (SEM) and a series of optical diffraction measurements. Up to 60 diffraction orders were observed from the nanowire gratings with separate oscillatory intensity patterns appearing in the even and odd diffraction orders. The presence of these intensity oscillations is attributed to LPNE array fabrication process, and is explained with the Fourier transform of a mathematical model to predict the diffraction intensity patterns.;A novel nanoring fabrication method that combines the process of LPNE with colloidal lithography is described. SEM measurements and Fourier transform near infrared (FT-NIR) absorption spectroscopy were used to characterize the strong NIR plasmonic resonance of the nanoring arrays. The absorption maximum wavelength varied linearly from 1.25 to 3.33 microns as predicted by a simple standing wave model linear antenna theory. This nanoring array fabrication method was also used to electrodeposit concentric double gold nanoring arrays that exhibited multiple NIR plasmonic resonances.;Arrays and networks of nanochannels were created in PDMS from LPNE nanowires in a master-replica process and characterized with SEM, AFM and fluorescence imaging measurements. The PDMS replica was bonded to a glass substrate to create linear arrays of nanofluidic channels that filled with a 99% successful rate as determined from fluorescence imaging and the electrophoretic injection of both dye and nanoparticles. A double LPNE fabrication method was also used to create two-dimensional networks of crossed nanofluidic channels.