Nanotechnology has a variety of applications and is applicable to a wide range of fields including environmental monitoring, medical diagnostics, and detecting compounds in a laboratory setting. This research presents the development of a sensor composed of gold and silica nanoparticles that will be used for detecting organic compounds in water, as well as silica nanoparticle crystals that can be used for photonics, chemical separations, filtration, and sensing applications. We present our methods of synthesizing gold nanoparticles of a controlled size as well as the development of a crystalline structure composed of gold and silica nanoparticles that serves as the main component of the sensor. Gold nanoparticles have unique optical properties that change depending on which environment they are in. The silica nanoparticles make up the majority of the sensor, providing strength to the structure, and stabilizing the gold nanoparticles. Additionally, the physical properties of pure silica nanoparticle crystals will be analyzed more in-depth. These crystals are typically only loosely held together until treated with high-temperature sintering. However, new evidence suggests that a well-packed colloidal crystal, in the form of a thin film, can be made resistant to dispersion by adjusting its deposition process. The goal of this work is to form these silica nanoparticle films and compare the effect of deposition and sintering on its hardness. The crystals were formed by either vertical evaporative deposition or spin-coating of silica nanoparticles from an ethanolic solution onto a quartz substrate. Some samples were exposed to calcining and sintering, while others acted as a control. Film thickness was adjusted in the evaporative deposition by the concentration of nanoparticles in solution, while for spin-coating, the number of coats was adjusted. The impact of heat treatment and deposition method on the hardness of deposited silica crystals was then measured by nanoindentation.

Synthesis and deposition of silica and gold nanoparticles for sensing applications

2019 Spring National Meeting

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