Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/27501
Title: DEVELOPMENT OF INTEGRATED MICROFLUIDIC SYSTEMS WITH ADDED OPTICAL FUNCTIONALITY
Authors: HOI SIEW KIT
Keywords: microfluidics, cell sorting, optical separation, lab on a chip, colloidal crystal, opto fluidics
Issue Date: 6-Aug-2010
Source: HOI SIEW KIT (2010-08-06). DEVELOPMENT OF INTEGRATED MICROFLUIDIC SYSTEMS WITH ADDED OPTICAL FUNCTIONALITY. ScholarBank@NUS Repository.
Abstract: In recent years, research into microfluidic devices is becoming increasingly important in the fields of biology and medicine, since they promise cheap and fast sample analysis with infinitesimal sample volume requirements. Various ongoing work deals with the combination of different analysis steps like mixing, sorting, reaction, and optical or electrical detection on one chip, often referred to as lab-on-a-chip. In the field of optical micromanipulation, the ability to trap microparticles is no longer something new, but indeed to separate or sort micro particles and cells is a topic of current interest. Light from a laser would transfer photon momentum to the impinged matter and exert significant forces on microscopic particles. In the first part of the work, through careful application of optical forces, we have successfully demonstrated a combination of optical tweezers and microfluidics to isolate, separate or sort a wide variety of suspensions of microscale biological or colloidal particles within a microfluidic system. The advantages of such technique include versatility, accuracy, contactless operation, reconfigurable as well as biocompatible system. The success in this technique prompted the development of a more advance and more practical device to overcome the shortcomings of the existing light based separation methods. On chip integration of miniaturized optical components such as embedded fibers and microlens have been used to extend the capabilities of the microfluidic chip in order to remove the needs for bulky and expensive microscope. A laser beam was coupled into the optical fibers and re-directed locally by the integrated microlens. The integrated microlens provided a method for adjusting the angle with which optical forces interact with the microparticles. The effective switching demonstrated supports its potential as a valuable miniaturized component for realizing a relatively cheap and portable cell interrogation tool with far reaching applications in point of care (POC) diagnosis. In second part of the work, colloidal photonic crystal was utilized to manifest its strength as integrated optical filter in microfluidic chips. The complementary combination of colloidal photonic crystals with microfluidics endow special optical and photonic functions to microfluidic devices, which cannot be realized by fluids alone. From an optofluidic point of view, colloidal photonic crystals present novel means for optofluidics because the shapes and geometries are easily controllable by manipulating external conditions. However, the conventional techniques for fabrication of colloidal photonic crystals have drawbacks like time-consuming and requirement for large volume of sample. Hence, in our work, a simple, fast and more practical way was adopted to facilitate the controlled preparation of colloidal photonic crystals inside microfluidic channels. Structural and optical characterizations to the confined crystalline structure were carried out. The special photonic functionalities granted by colloidal photonic crystal was utilized to perform unique multifunctional optical components in microfluidic chips. The feasibility and potential of colloidal photonic crystal as practical built-in optical filter for on-chip detection was also successfully demonstrated. The flexibility of such colloidal crystal based filter allows it to be readily combined with other miniaturized microfluidic components, rendering improved potential in lab-on-a-chip devices or micrototal-analytical systems.
URI: http://scholarbank.nus.edu.sg/handle/10635/27501
Appears in Collections:Ph.D Theses (Open)

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