Structure and Response Relationship of Microgel-Based Etalon Devices for Sensing Applications
Creators: Hunter, Haley K
Publisher: name: University of Alberta Library
Year: 2024

<p>This dissertation is focused on exploring and optimizing a specific polymer-based photonic device with the aim of these devices being used for the development of easy-to-use, colour changing sensors for different applications. Sensors that detect an analyte or target at the site they are required are called point of need (PON) sensors. These sensors represent a large, growing area of research in numerous fields. In healthcare, these types of sensors are desired to speed up diagnostics, relieve pressure on the medical system, and further the reach of medical care to rural/less populated areas. They are also desirable for folks living with a chronic illness, to help monitor their conditions at home rather than having to make frequent hospital visits. PON sensor research is also popular for environmental monitoring. They allow for tests to be performed and results obtained rapidly, at the site of sampling. <br>
Colorimetric or optical sensors are popular for this research. Photonic materials are a common choice for colorimetric PON sensor development. These materials rely of the periodic spacing of a dielectric material, where the spacing between the layers and the refractive index of the materials will dictate the color. When these types of materials are being developed for sensor applications, they often incorporate stimuli responsive polymers, or polymers that respond to changes in their surroundings through variations of their chemical or physical properties.<br>
The research presented here explores the effects of metal film structure on the responses of photonic devices called microgel-based etalons. These devices are composed of a stimuli responsive polymer layer sandwiched between 2 thin Au films. They produce color due to the constructive and destructive interference of light within the etalon cavity, which is dependent on the distance between the Au films, or the size of the polymer layer. These devices have been developed by the Serpe Group and the contents of these chapters further investigate how the continuity of the metal top layer of the etalon is affected by deposition technique and composition in addition to how this overlayer’s structure impacts the device’s response to various changes in environment or exposure to analytes.<br>
The application of etalons with certain top layer film structures for monitoring humidity and organic vapours in the air is included. For this study the etalons are used in their dry state and their responses to relative humidity, as well as 5 different organic vapours are presented. The etalon is shown to have reproducible response with good hysteresis to relative humidity and certain organic vapours. A study of the colorimetric detection of ssDNA in aqueous solution using these etalons is also presented.  The study explores the impacts of acrylic acid content, solution pH, and ssDNA nucleotide length on the etalon response. The results of this study will be applied for development of a magnetic particle strand displacement assay with visual readout utilizing the etalons. <br>
The studies presented here illustrate the importance of studying the relationship between device structure and corresponding function. As well as how this knowledge can be applied for photonic material development and sensing applications.</p>