Microfluidics for plasmonic sensors

Abstract

In this thesis, we integrate microfluidics with grating-coupled surface plasmon configurations for sensing applications. First, in order to observe optimal excitations, we introduce procedures for modification of the surface profiles of gratings acquired from commercially available optical storage disks. A must requirement in plasmonic systems, thin film metal deposition is performed. Soft lithographic techniques are applied to coated disks to transfer the surface topography of the disks to an elastomeric material, PDMS. Optical lithography is used to fabricate microfluidic channels to where fluid will be injected. After fabricating the final structure, ellipsometric measurement is used to investigate the device performance. Experimental results were in consistence with the theoretical simulations providing similar behaviours of reflection spectra. The resonance wavelengths are found to be occuring very near to the expected values along with high quality factors. However, to the device structure, an intensity loss is observed which can be further improved. We achieved the tuning of the resonance wavelength by changing the refractive index of the medium inside the microchannel. Integration of the microfluidic channel to surface plasmon studies may open up many applications such as biomolecular sensing.