84 research outputs found

    Surface plasmon resonance photonic biosensors based on phase-sensitive measurement techniques.

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    Law Wing Cheung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.Includes bibliographical references.Abstracts in English and Chinese.Abstract --- p.IAcknowledgements --- p.VList of Publications related to this project --- p.VIContents --- p.VIIChapter Chapter 1 --- Introduction --- p.1-1Chapter Chapter 2 --- Literature ReviewChapter 2.1 --- Surface Plasmon Waves --- p.2-2Chapter 2.2 --- Excitation of Surface Plasmon --- p.2-4Chapter 2.2.1 --- Surface Plasmon Coupling Schemes --- p.2-6Chapter 2.3 --- Detection Techniques used in SPR sensors --- p.2-13Chapter 2.3.1 --- Angular Interrogation --- p.2-14Chapter 2.3.2 --- Wavelength Interrogation --- p.2-15Chapter 2.3.3 --- Intensity Interrogation --- p.2-16Chapter 2.3.4 --- Phase Interrogation --- p.2-16Chapter 2.3.5 --- Commercial SPR biosensors --- p.2-18Chapter 2.3.6 --- Comparison between Detection Techniques --- p.2-19Chapter 2.4 --- Applications of SPR biosensors --- p.2-21Chapter Chapter 3 --- Principle of Surface Plasmon Resonance Sensing TechnologyChapter 3.1 --- SPR Phenomenon --- p.3-1Chapter 3.2 --- Conditions for Surface Plasmon Resonance --- p.3-5Chapter 3.3 --- Wave-vectors --- p.3-7Chapter 3.4 --- Surface Plasmon Resonance described by Fresnel's Theory --- p.3-8Chapter 3.5 --- Concept of Surface Plasmon Resonance Biosensing --- p.3-10Chapter Chapter 4 --- ExperimentsChapter 4.1 --- Highly sensitive differential phase-sensitive surface plasmon resonance biosensor based on Mach-Zehnder configuration --- p.4-1Chapter 4.1.1 --- Materials required --- p.4-1Chapter 4.1.2 --- Experimental Setup --- p.4-2Chapter 4.1.3 --- Principle of Differential Phase Measurement --- p.4-3Chapter 4.1.4 --- Photodetector Circuitry --- p.4-6Chapter 4.1.5 --- Digital Signal Processing --- p.4-7Chapter 4.1.6 --- Polymer based Micro-fluidic System Integrated with SPR Biosensor --- p.4-9Chapter 4.2 --- Phase-sensitive Surface Plasmon Resonance Biosensor using the Photoelastic Modulation Technique --- p.4-12Chapter 4.2.1 --- Materials required --- p.4-12Chapter 4.2.2 --- Experimental Setup --- p.4-13Chapter 4.2.3 --- Principle of Photoelastic Modulation Technique and Signal Processing --- p.4-14Chapter 4.2.4 --- Operation Principle of Photoelastic Modulator --- p.4-17Chapter 4.3 --- Sample Preparations --- p.4-18Chapter 4.3.1 --- Glycerin-water Mixtures --- p.4-18Chapter 4.3.2 --- "PBS, BSA and BSA antibody" --- p.4-19Chapter 4.3.3 --- "RPMI, Trypsin, Cells and SDS" --- p.4-20Chapter Chapter5 --- Results amd DiscussionsChapter 5.1 --- Experimental setup I: Highly sensitive differential phase-sensitive surface plasmon resonance biosensor based on Mach-Zehnder configuration --- p.5-1Chapter 5.1.1 --- Measuring various glycerin-water concentration mixture with silver-gold sensing layer --- p.5-1Chapter 5.1.2 --- Comparison between the sensitivity of our setup and reported setup based on phase detection --- p.5-4Chapter 5.1.3 --- Discussion on 0.01° system resolution --- p.5-7Chapter 5.1.4 --- Experiment on monitoring BSA-BSA antibody binding reaction --- p.5-9Chapter 5.1.5 --- Matching oil and glass slide --- p.5-11Chapter 5.1.6 --- Experiments on monitoring BSA-BSA antibody binding reaction with integrated microfluidic system --- p.5-12Chapter 5.1.7 --- Experiment on observing cell adhesion properties on gold surface under the influence of trypsin --- p.5-14Chapter 5.1.8 --- Discussion on the non-specific binding between trypsin and gold surface --- p.5-16Chapter 5.1.9 --- Modifying the gold surface with BSA layer --- p.5-17Chapter 5.1.10 --- Experiment on observing cell adhesion properties on the gold surface under the influence Sodium Dodecyl Sulfate (SDS) --- p.5-18Chapter 5.2 --- Experimental setup II: Phase-sensitive surface plasmon resonance biosensor using the photoelastic modulation technique --- p.5-21Chapter 5.2.1 --- Measurement on difference glycerin-water concentration mixture --- p.5-21Chapter 5.2.2 --- Experiment on monitoring BSA-BSA antibody binding reaction --- p.5-23Chapter Chapter 6 --- Conclusions and Future WorksChapter 6.1 --- Conclusions --- p.6-1Chapter 6.2 --- Future Works --- p.6-2References --- p.R-1AppendixChapter A. --- Phase Extraction Routine written by Matlab --- p.A-1Chapter B. --- Mathematical expressions for calculating the phase angle in the experiment of SPR biosensor using the Photoelastic Modulation Technique --- p.A-6Chapter C. --- Relationship between Concentration and Refractive Index of Glycerin-Water Mixture --- p.A-11Chapter D. --- Physical Properties of Bovine Serum Albumin --- p.A-12Chapter E. --- Simulation Curve written by Matlab --- p.A-1

    Methods for immobilizing receptors in microfluidic devices: A review

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    In this review article, we discuss state-of-the-art methods for immobilizing functional receptors in microfluidic devices. Strategies used to immobilize receptors in such devices are essential for the development of specific, sensitive (bio)chemical assays that can be used for a wide range of applications. In the first section, we review the principles and the chemistry of immobilization techniques that are the most commonly used in microfluidics. We afterward describe immobilization methods on static surfaces from microchannel surfaces to electrode surfaces with a particular attention to opportunities offered by hydrogel surfaces. Finally, we discuss immobilization methods on mobile surfaces with an emphasis on both magnetic and non-magnetic microbeads, and finally, we highlight recent developments of new types of mobile supports

    Microfluidic Organ/Body-on-a-Chip Devices at the Convergence of Biology and Microengineering

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    Recent advances in biomedical technologies are mostly related to the convergence of biology with microengineering. For instance, microfluidic devices are now commonly found in most research centers, clinics and hospitals, contributing to more accurate studies and therapies as powerful tools for drug delivery, monitoring of specific analytes, and medical diagnostics. Most remarkably, integration of cellularized constructs within microengineered platforms has enabled the recapitulation of the physiological and pathological conditions of complex tissues and organs. The so-called organ-on-a-chip technology, which represents a new avenue in the field of advanced in vitro models, with the potential to revolutionize current approaches to drug screening and toxicology studies. This review aims to highlight recent advances of microfluidic-based devices towards a body-on-a-chip concept, exploring their technology and broad applications in the biomedical field.European Regional Development Fund-Project FNUSA-ICRC [CZ.1.05/1.1.00/02.0123]; Fundacao para a Ciencia e a Tecnologia (FCT), Portugal [UID/BIM/04773/2013]; Internal Research Grant Program, Universita Campus Bio-Medico di Romainfo:eu-repo/semantics/publishedVersio

    Advances in Optofluidics

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    Optofluidics a niche research field that integrates optics with microfluidics. It started with elegant demonstrations of the passive interaction of light and liquid media such as liquid waveguides and liquid tunable lenses. Recently, the optofluidics continues the advance in liquid-based optical devices/systems. In addition, it has expanded rapidly into many other fields that involve lightwave (or photon) and liquid media. This Special Issue invites review articles (only review articles) that update the latest progress of the optofluidics in various aspects, such as new functional devices, new integrated systems, new fabrication techniques, new applications, etc. It covers, but is not limited to, topics such as micro-optics in liquid media, optofluidic sensors, integrated micro-optical systems, displays, optofluidics-on-fibers, optofluidic manipulation, energy and environmental applciations, and so on

    Simplified fabrication of complex multilayer microfluidics: enabling sophisticated lab-on-a-chip and point-of-care platforms

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    Complex multilayer microfluidics have generated a lot of interest in recent years. Early research introduced elastomer microvalves and postulated they would bring about a revolution for microfluidic systems, similar in scale to introduction of the transistor for electronic systems. In the following years, many researchers have been active in the use of complex multilayer microfluidic systems, with numerous high impact research outcomes using these systems as precise and active control components, providing fluidic isolation, switching or fluidic actuation, and allowing unprecedented sophistication and precise control and automation of experimental conditions. While application of complex multilayer microfluidic platforms has been demonstrated in numerous research settings, there is little evidence that the technology has become ubiquitously accepted, with a lack of evidence for point-of-care application, or widespread acceptance within the research community. While the advantages that the technology offers have been well documented, the field seems to have failed to gain traction, or facilitate the revolution that was predicted on its introduction. There are various possible explanations for this lack of acceptance, as with any technology, there are caveats to the application of complex multilayer microfluidic systems, however given the broad range of demonstrated applications, it is unlikely that the bottleneck in their application is related to a fundamental application related limitation. In contrast, fabrication technology utilised in realisation of complex multilayer microfluidic systems, has not advanced at the same rate to the multitude of application-based publications in the past decade. This thesis explores the hypothesis that one of the fundamental limiting factors in widespread application of complex multilayer microfluidic systems, is related to the challenges associated with fabrication of these systems. To explore this hypothesis, firstly, a new fabrication approach is introduced which aims to eliminate many of the challenges associated with traditional multilayer fabrication methods, this technique is demonstrated in a proof of concept capacity, fabricating common multilayer microfluidic structures and doing so with surprising ease. Having developed method with simpler fabrication, it is possible to explore whether overcoming the multilayer fabrication bottleneck would allow the advantages inherent to complex multilayer microfluidic systems to be applied to fields which would otherwise be considered prohibitively difficult, if reliant on traditional fabrication methods. This hypothesis is investigated through harnessing the new, simplified fabrication technique to advance point-of-care photonic biosensor research through short term collaborative engagements.  It is found that the use of modular building blocks and the simple, rapid fabrication enables sophisticated microfluidic chip prototypes to be developed in a very short period of time achieving multiple iterations over a matter of weeks and even facilitating collaboration on these integrated platforms remotely. The outcomes of these short-term collaborations have produced publications automating the fluid handling of highly sensitive interferometric waveguide biosensors and environmental control for a single cell analysis platform utilising integrated plasmonic biosensors.       Having demonstrated that simplifying complex microfluidic fabrication can accelerate the development and deployment of these systems to enhance research platforms, the next step was to explore whether this simplified system could also lower the barrier to deployment in a clinical setting. The ability for the fluidic system to handle whole blood was chosen as a deliberately challenging target with great sensitivity to fluid dynamics and large variability in patient samples and environmental factors, requiring large number of replicate devices to determine statistical significance. Here the fabrication technique is applied to enable a study investigating the hemocompatibility of common multilayer control components, paving the way for point of care blood handling devices.  It is shown that not only can the technique be used to rapidly develop platforms that can be used with blood, but the same technique can produce even hundreds of replicates required for limited clinical trials, leading the collaborating clinicians to seriously consider these complex microfluidics for future point of care diagnostics. In Summary, it has been demonstrated that access to complex multilayer microfluidic systems without the fabrication overheads generally associated with these systems can allow their application to areas that would otherwise be prohibitively difficult. The fabrication method presented can allow rapid development, and rapid and reliable deployment to various research applications, while allowing the consistency and throughput required enabling large volume fabrication required for clinical investigations.  The fact that such a large advancement toward real world application within the scope of a single PhD is possible, supports the hypothesis that lowering the barrier to fabricating complex microfluidic devices has the potential to significantly increase their scope of application

    Fundamentals of SARS-CoV-2 Biosensors

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    COVID-19 diagnostic strategies based on advanced techniques are currently essential topics of interest, with crucial roles in scientific research. This book integrates fundamental concepts and critical analyses that explore the progress of modern methods for the detection of SARS-CoV-2

    Development of Spectroscopic Methods for Dynamic Cellular Level Study of Biochemical Kinetics and Disease Progression

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    One of the current fundamental objectives in biomedical research is understanding molecular and cellular mechanisms of disease progression. Recent work in genetics support the stochastic nature of disease progression on the single cell level. For example, recent work has demonstrated that cancer as a disease state is reached after the accumulation of damages that result in genetic errors. Other diseases like Huntingtons, Parkinsons, Alzheimers, cardiovascular disease are developed over time and their cellular mechanisms of disease transition are largely unknown. Modern techniques of disease characterization are perturbative, invasive and fully destructive to biological samples. Many methods need a probe or enhancement to take data which alters the biochemistry of the cells and may not be a true representations of cellular mechanisms. Current methods of characterizing disease progression cannot measure dynamics of a process but rely on an average state of a system at a fixed endpoint. They track cellular changes at a population level that rely on static ensemble averages that compare the same population at different time points or populations exposed to different stimuli. Ensemble averaging obscures spatiotemporal and dynamic molecular and cellular mechanism information by only measuring changes before and after disease transitions which neglects mechanistic information. This type of snap shot measurement contains no information regarding the transition into a disease state. The use of an ensemble averages ignores single cell level changes by assuming cells in a population are similar. In reality individual cell-to-cell variability in the same cell population can cause one cell to transition to disease state while another cell does not. Fluctuations are indicators of disease and if cellular processes are not studied spatiotemporally then key molecular changes are undetected. If the path to disease progression is known on an individual cell level, then treatments can be modified to alleviate or prevent disease through early detection. The aim of this thesis is to quantitatively and dynamically measure a biomedical sample on the single cell level without destroying or manipulating it significantly to characterize cellular mechanisms. The technique developed uses microRaman Spectroscopy to analyze molecular signatures of single cells and compare differences between signatures of cells in different populations
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