Infrared Chemical Imaging of Custom-Made Microfluidic Devices
Date
2024-01-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0001-8447-6414
Type
Thesis
Degree Level
Masters
Abstract
Microfluidic devices are designed to streamline and improve the operation of chemical processes in a wide variety of industries. Miniaturization has a vast number of advantages; most notably, the large surface area to volume ratio which allow for enhanced control over the physical properties within devices. Such precision leads to more efficient reactions and higher quality products making on-chip chemical synthesis desirable. Optimization of device performance requires an in-depth analysis of the flow profiles, requiring in-situ characterization techniques. Infrared (IR) imaging integrated within microfluidic devices is a label-free, non-invasive detection strategy which provides an in-situ probe to visualize flow patterns and can be utilized to identify and quantify molecules on-chip. IR light is quickly attenuated by optically dense matter such as solvents and device materials when samples are probed in transmission or reflectance modes. In attenuated total reflection (ATR) mode, IR light is directed through a high refractive index material such as a Si internal reflective element (IRE) interrogating the sample-IRE interface with an evanescent wave, limited to within one micron of the surface in the wavelengths of interest. Such a localized probe depth allows for design freedom in both the channel depth and materials. Within a microfluidic device, this imaging technique probes the solution near the no-slip boundary; fluid near channel extremes is flowing at a much slower rate than the bulk due to resistance of the solution with the walls of the channels. As a comparison of the experimental results with the physical phenomena within the devices is crucial to justify the technique, flow profiles must be modelled with both commercial software and mathematical predictions.
This thesis aims to develop and demonstrate the focal plane array (FPA) imaging capabilities of the horizontal ATR microscope at the Mid-IR beamline of the Canadian Light Source by imaging fluid flow in custom-made microfluidic devices. Resulting images are compared to expected flow profiles generated by simulations. This work is highly motivated by a desire to implement synchrotron IR imaging using this endstation and offers a prerequisite study for larger field-of-view optimization with a globar source before the extension to synchrotron light, with lower noise and smaller spatial resolution, may be realized.
Description
Keywords
Microfluidics, ATR-FTIR, ATR-FTIR Imaging, hATR Microscope, FPA, No-Slip Interface, In-Situ Characterization Techniques, Microfabrication
Citation
Degree
Master of Science (M.Sc.)
Department
Chemistry
Program
Chemistry