Freefrom-based optofluidic devices towards surface-enhanced raman spectroscopy (SERS)

Scriptie/Masterproef: Doctoral Thesis


Material identification is of great importance in industrial production, scientific research and daily life of human beings. Optical detection technologies, among all physical and chemical methods, have become indispensable tools to qualitatively and quantitatively characterize the composition, concentration and properties of the sample under test by analyzing the light emitted by the substances, or by refraction, reflection, scattering or absorption of external sources. Laser induced Raman spectroscopy, one of the common optical detection technologies, achieve the detection purposes by providing fingerprint information of the molecular vibrational modes in a label-free and non-invasive approach, which is essential in various application domains to eliminate the interference from external factors.
Today, Raman spectroscopy has made a splash in identifying mycotoxins, which are toxic secondary metabolite compounds naturally produced by certain types of fungi (molds) in food and have adverse effects on human health ranging from acute poisoning to long-term effects such as cancers and immune deficiency. Raman spectroscopy is also a powerful tool in clinical diagnostics such as tumor detection, as well as biological research of single-cell analysis. Today, many Raman spectroscopy setups are already commercially available, but most of them are traditional bulky instruments with considerable requirements in terms of time, volume consumption and manual sampling of substances of interest. Today, there is a growing demand for compact, integrated and intelligent Raman spectroscopy systems for various application domains.
In this PhD, we aim for the miniaturization of traditional bulky Raman spectroscopy setups and for the integration of several laboratory functionalities in a polymer-based lab-on-chip for microfluidic detection with high sensitivity. First, a Raman probe design for a lab-on-chip was developed by miniaturizing and optimizing the optical components, which allowed remote and robust Raman detection. In addition, freeform reflector embedded lab-on-chips have been designed for hot embossing mass manufacturing, which could substantially reduce the sample consumption, experimental complexity and the cost of detection. The performance of the Raman probe working in combination with the lab-on-chip were assessed by a non-sequential ray tracing simulation approach, and the simulation results showed a good agreement with the experimental results. In addition, we fabricated different nanostructures by two-photon polymerization (2PP) 3D lithography for Surface-Enhanced Raman Spectroscopy (SERS) applications, such as mycotoxin detection. The performance of our 2PP printed SERS substrates were evaluated by Finite-Difference Time-Domain (FDTD) simulations and experimental approaches respectively. Furthermore, we implemented a segmented freeform reflector-based tunable Raman spectroscopy setup for microfluidic lab-on-chips that allows both conventional and surface-enhanced Raman detection. Our tunable Raman spectroscopy setup is compatible with our mass fabricated polymer lab-on-chips as well as many commercial microfluidic chips.
Datum prijs10 jun 2020
Originele taalEnglish

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