Fabrication of photonic devices based on nanosphere colloidal suspensions for sensing applications

Abstract

In this thesis work we will fabricate different types of colloidal crystals, made of electrosprayed layers of polystyrene nanospheres of 300nm size, some of them with an upper deposition of alumina (Al2O3). The colloidal crystals are meant to be used in a future application in touching sensors, so robust samples are required and this alumina deposition will be an attempt to increase it. The resulting devices will be characterized by measuring the transmittance/reflectance with a spectrophotometer. In this work a custom made spectrophotometer consisting on a detector and a microprocessor will be used. Samples made over a film of Indium Tin Oxide (ITO) will be also characterized. This study has been made in order to check if this Al2O3 layer modifies the properties of the crystal (comparing them with non-deposited Al2O3 samples). The obtained results depict that the structure present a noticeable reduction of reflectance peak over the expected wavelength, however exhibiting that the encapsulation methods are a good way to improve the robustness of the samples. The spectrophotometer device shows consistent results compared with commercial devices, nevertheless, further development is required to reduce signal noise.