Microfluidics has seen an explosion in growth in the past few years, providing researchers with new and exciting lab-on-chip platforms with which to perform a wide variety of biological and biochemical experiments. In this work, a volume quantification tool is developed, demonstrating the ability to measure the volume of individual cells at high resolution and while enabling microfluidic sample manipulations. Care is taken to maximise measurement sensitivity, range and accuracy, though novel use of buoyancy and dynamically tunable microchannels. This first demonstration of a microfluidic tunable volume sensor meant volume sensing over a much wider range, enabling the detection of ̴ 1 µm3 E.coli that would otherwise go undetected. Software was written that enables pressure-driven flow control on the scale of individual cells, which is used to great success in (a) sorting cells based on size measurement and (b) monitoring the growth of cells. While there are a number of macroscopic techniques capable of sorting cells, microscopic lab-on-chip equivalents have only recently started to emerge. In this work, a label-free, volume sensor operating at high resolution is used in conjunction with pressure-driven flow control to actively extract particle/cell subpopulations. Next, a microfluidic growth monitoring device is demonstrated, whereby a cell is flowed back and forth through a volume sensor. The integration of sieve valves allows cell media to be quickly exchanged. The combination of dynamic trapping and rapid media exchange is an important technological contribution to the field, one that opens the door to studies focusing on cell volumetric response to drugs and environmental stimuli. This technology was designed and fabricated in-house using soft lithography techniques readily available in most biotechnology labs. The main thesis body contains four scientific articles that detail this work (Chapters 2-5), all published in peer-reviewed scientific journals. These are preceded by an introductory chapter which provides an overview to the theory underlying this work, in particular the non-intuitive physics at the microscale and the Coulter principle.

Microfluidics has seen an explosion in growth in the past few years, providing researchers with new and exciting lab-on-chip platforms with which to perform a wide variety of biological and biochemical experiments. In this work, a volume quantification tool is developed, demonstrating the ability to measure the volume of individual cells at high resolution and while enabling microfluidic sample manipulations. Care is taken to maximise measurement sensitivity, range and accuracy, though novel use of buoyancy and dynamically tunable microchannels. This first demonstration of a microfluidic tunable volume sensor meant volume sensing over a much wider range, enabling the detection of ̴ 1 µm3 E.coli that would otherwise go undetected. Software was written that enables pressure-driven flow control on the scale of individual cells, which is used to great success in (a) sorting cells based on size measurement and (b) monitoring the growth of cells. While there are a number of macroscopic techniques capable of sorting cells, microscopic lab-on-chip equivalents have only recently started to emerge. In this work, a label-free, volume sensor operating at high resolution is used in conjunction with pressure-driven flow control to actively extract particle/cell subpopulations. Next, a microfluidic growth monitoring device is demonstrated, whereby a cell is flowed back and forth through a volume sensor. The integration of sieve valves allows cell media to be quickly exchanged. The combination of dynamic trapping and rapid media exchange is an important technological contribution to the field, one that opens the door to studies focusing on cell volumetric response to drugs and environmental stimuli. This technology was designed and fabricated in-house using soft lithography techniques readily available in most biotechnology labs. The main thesis body contains four scientific articles that detail this work (Chapters 2-5), all published in peer-reviewed scientific journals. These are preceded by an introductory chapter which provides an overview to the theory underlying this work, in particular the non-intuitive physics at the microscale and the Coulter principle.

This master thesis deals with the use of microfluidics for the purpose of microfluidic enzymatic reactor for drug screening. At first it considers the issue from a theoretical point of view – describes microfluidics as a newly developing and promising field of production of microfluidic devices, materials, biomedical applications and advantages and disadvantages of microfluidics overall. Furthermore, it focuses on an area of analytical utilization of enzymes within enzyme reactors. In the first part of the experimental section, conditions for the testing of enzymes of xenobiotics metabolism in the liver were optimized, namely the model of coumarin metabolism via the spectrofluorimetry method. The second part of the experimental work dealt with optimization of the fabrication conditions of microfluidic chips from OSTE (off-stoichiometry Thiol Ene) via the soft lithography method. Subsequently, the functionality of the produced chips was tested. Based on the results of both parts of the experimental work, an evaluation was carried out to assess the suitability of their interconnection for future research – screening of microsomal enzyme activity and model biotransformation of drugs within the channels of the fabricated devices.

<div> <div> <div> <p>Microfluidics is a new and emerging field that has applications in a myriad of microfluidic industrial applications such as biochemical engineering, analytical processing, biomedical engineering and separation of cells. Microfluidics operations are carried out in microfluidic chips, and the traditional method of fabrication is carried out in a cleanroom. However, this fabrication method is very costly and also requires professional trained personnel. In this thesis, a low-cost fabrication platform was developed based on soft-lithography technique developed to fabricate the microfluidic devices with resolution at microscale. This fabrication method is advantageous and novel because it is able to achieve the microscale fabrication capability with simple steps and lower-level laboratory configuration. In the developed fabrication platform, an array of ultraviolet light was illuminated onto a photoresist film that has a negative photomask with a microfluidic design on it. The photoresist film is then developed, and a silicon polymer of polydimethylsiloxane (PDMS) is chosen to be the material for the device. In this work, the performance and resolution of the fabrication system was evaluated using scanning electron microscopy (SEM), polymer resolution test and light intensity analysis. </p> <p>Based on the success of the development of microfluidics fabrication platform, various experiment of mixing and separation was conducted and studied because the utilization of the microfluidic device for mixing and separation is very valuable in biomedical and chemical engineering. Although there are a lot of applications reported, the precise separation and mixing at microscale still meet some difficulties. Mixing in micromixers is extremely time-consuming and requires very long microchannels due to laminar flow and low Reynolds number. Particle separation is also hard to be achieved because the size of micron bioparticles is very small and thus the force is not strong enough to manipulate their motion. The integration of magnetic field is an active method to strengthen both mixing and separation that has been widely applied in the biomedical industry overcome these difficulties because of its compatibility with organic particles. However, most magnetic mixing and separation use bulky permanent magnets that leave a large footprint or electromagnets that generate harmful Joule heat to organic and bio-particles. In this work, microscale magnet made of a mixture of neodymium powder and polydimethylsiloxane was developed and integrated into microfluidic system to achieve both rapid mixing of ferrofluids and separation of microparticles. Systematic experiments were conducted to discuss the effect of various parameters on the performance of magnetic mixing and separation of microparticles. It was found that channel geometry, flow filed, and magnetic properties will affect the transport phenomena of ferrofluid and microparticles, and thus mixing and separation efficiency. These findings are of great significance for the high throughput sorting of cancer cells and its mixing between drug for therapy treatment.</p></div></div></div>

Future developments in nanophotonics require facile, inexpensive and parallelizable fabrication methods and need a fundamental understanding of the spectroscopic properties of such nanostructures. These challenges can be met through colloidal self-assembly where pre-synthesized colloids are arranged over large areas at reasonable cost. As so-called colloidal building blocks, plasmonic nanoparticles and quantum dots are used because of their localized light confinement and localized light emission, respectively. These nanoscopic colloids acquires new hybrid spectroscopic properties through their structural arrangement. To explore the energy transfer between these nanoscopic building blocks, concepts from physical optics are used and implemented with the colloidal self-assembly approach from physical chemistry. Through an established synthesis, the nanocrystals are now available in large quantities, any they receive the tailored spectroscopic properties through directed self-assembly. Moreover, the tailored properties of the colloids and the use of stimuli-responsive polymers allow a functionality that goes beyond current developments. The basics developed in this habilitation thesis can lead to novel functional devices in the field of smart sensors, dynamic light modulators, and large-area quantum devices.:1 Abstract 2 2 State of the art 4 2.1 Metallic and semiconductive nanocrystals as colloidal building blocks 4 2.2 Concept of large-scale colloidal self-assembly 7 2.3 Functional optical nanomaterials by colloidal self-assembly 9 2.4 Scope 13 2.5 References 14 3 Single colloidal cavities 20 3.1 Nanorattles with tailored electric field enhancement 20 4 Colloidal -to-film coupled cavities 31 4.1 Template-assisted colloidal self-assembly of macroscopic magnetic metasurfaces 31 4.2 Single particle spectroscopy of radiative processes in colloid-to-film-coupled nanoantennas 50 4.3 Active plasmonic colloid-to-film coupled cavities for tailored light-matter interactions 65 5 Colloidal polymers 74 5.1 Direct observation of plasmon band formation and delocalization in quasi-infinite nanoparticle chains 74 6 Colloidal lattice 84 6.1 Hybridized guided-node resonances via colloidal plasmonic self-assembled grating 84 6.2 Mechanotunable surface lattice resonances in the visible optical range by soft lithography templates and directed self-assembly 94 6.3 Tunable Circular Dichroism by Photoluminescent Moiré Gratings 103 7 Conclusion and perspective 112 8 Appendix 113 8.1 Further publications during the habilitation period 113 8.2 Curriculum vitae of the author 116 9 Acknowledgments 117 10 Declaration 118 / Zukünftige Entwicklungen in der Nanophotonik erfordern einfache, kostengünstige und parallelisierbare Herstellungsmethoden und benötigen ein grundlegendes Verständnis der spektroskopischen Eigenschaften solcher Nanostrukturen. Diese Herausforderungen können durch kolloidale Selbstorganisation erfüllt werden, bei der kostengünstige und zuvor synthetisierte Kolloide großflächig angeordnet werden. Als sogenannte kolloide Bausteine werden wegen ihrer lokalisierten Lichtfokussierung unterhalb der Beugungsbegrenzung plasmonische Nanopartikel sowie wegen ihrer lokalisierten Lichtemission Quantenpunkte verwendet. Diese nanoskopischen Kolloide werden in dieser Habilitationsschrift verwendet und durch Selbstanordnung in ihre gewünschte Nanostruktur gebracht, die neue hybride Eigenschaften aufweist. Um den Energietransfer zwischen diesen nanoskopischen Bausteinen zu untersuchen, werden Konzepte aus der physikalischen Optik verwendet und mit dem kolloidalen Selbstorganisationskonzept aus der physikalischen Chemie großflächig umgesetzt. Durch eine etablierte Synthese sind die Nanokristalle nun in großen Mengen verfügbar, wobei sie durch gerichtete Selbstorganisation die gewünschten spektroskopischen Eigenschaften erhalten. Darüber hinaus ermöglicht die Verwendung von stimulierbaren Polymeren eine Funktionalität, die über die bisherigen Entwicklungen hinausgeht. Die in dieser Habilitationsschrift entwickelten Grundlagen können bei der Entwicklung neuartiger Funktionsgeräte im Bereich für intelligente Sensorik, dynamischer Lichtmodulatoren und großflächiger Quantengeräte genutzt werden.:1 Abstract 2 2 State of the art 4 2.1 Metallic and semiconductive nanocrystals as colloidal building blocks 4 2.2 Concept of large-scale colloidal self-assembly 7 2.3 Functional optical nanomaterials by colloidal self-assembly 9 2.4 Scope 13 2.5 References 14 3 Single colloidal cavities 20 3.1 Nanorattles with tailored electric field enhancement 20 4 Colloidal -to-film coupled cavities 31 4.1 Template-assisted colloidal self-assembly of macroscopic magnetic metasurfaces 31 4.2 Single particle spectroscopy of radiative processes in colloid-to-film-coupled nanoantennas 50 4.3 Active plasmonic colloid-to-film coupled cavities for tailored light-matter interactions 65 5 Colloidal polymers 74 5.1 Direct observation of plasmon band formation and delocalization in quasi-infinite nanoparticle chains 74 6 Colloidal lattice 84 6.1 Hybridized guided-node resonances via colloidal plasmonic self-assembled grating 84 6.2 Mechanotunable surface lattice resonances in the visible optical range by soft lithography templates and directed self-assembly 94 6.3 Tunable Circular Dichroism by Photoluminescent Moiré Gratings 103 7 Conclusion and perspective 112 8 Appendix 113 8.1 Further publications during the habilitation period 113 8.2 Curriculum vitae of the author 116 9 Acknowledgments 117 10 Declaration 118

Self-assembled lipid tubules are particularly attractive for inorganic synthesis and drug delivery because they have hollow cylindrical shapes and relatively rigid mechanical properties. In this thesis work, we have synthesized lipid tubules of 1,2-bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC) by self-assembly and polymerization in solutions. We demonstrate for the first time that both uniform and modulated molecular tilt orderings exist in the tubule walls, which have been predicted by current theories, and therefore provide valuable supporting evidences for self-assembly mechanisms of chiral molecules. Two novel methods are developed for studying the axial and radial deformations of DC8,9PC lipid tubules. Mechanical properties of DC8,9PC tubules are systematically studied in terms of persistence length, bending rigidity, strain energy, axial and radial elastic moduli, and critical force for collapse. Mechanisms of recovery and surface stiffening are discussed. Due to the high aspect ratio of lipid tubules, the hierarchical assembly of lipid tubules into ordered arrays and desired architectures is critical in developing their applications. Two efficient methods for fabricating ordered arrays of lipid tubules on solid substrates have been developed. Ordered arrays of hybrid silica-lipid tubes are synthesized by tubule array-templated sol-gel reactions. Ordered arrays of optical anisotropic fibers with tunable shapes and refractive indexes are fabricated. This thesis work provides a paradigm for molecularly engineered structures.

No description available.

Afin de réaliser des dispositifs en polymère à forte valeur ajoutée, l'industrie de la plasturgie s'intéresse depuis quelques années à la convergence possible entre les microtechnologies et les méthodes industrielles de mise en oeuvre des polymères (le thermoformage et la thermo-injection). Dans ce contexte, l'objectif de cette thèse est de démontrer l'intérêt d'une approche à base de microtamponnage pour l'intégration de capteurs à base métallique dans des circuits microfluidiques en thermoplastique réalisés par thermoformage. Pour ces matériaux, cette approche apparait plus pertinente en terme de production de masse qu'une approche de photolithographie classique. Nous avons choisi de démontrer ce concept en étudiant l'intégration d'un capteur de pH et d'un capteur de température dans un système microfluidique en copolymère d'oléfine cyclique (COC) réalisé par thermoformage. En effet, la mesure de ces paramètres physico-chimiques est extrêmement répandue dans différents domaines d'application allant de la chimie à la biologie et à la médecine. Pour le capteur de pH, nous avons développé une couche sensible au pH à base d'oxyde d'iridium (IrOx) électrodéposé sur or. L'influence de différents paramètres (solution d'électrodépôt, méthode d'électrodéposition, nature du substrat métallique et son mode de préparation) sur la réponse au pH de ces couches a été étudiée. Nous avons ainsi pu démonter qu'une approche par microtamponnage passive est adaptée à la préparation de capteurs de pH sur un substrat en COC/Au ayant une sensibilité de -72 mV/pH et une durée de vie de 1 an. Pour le capteur de température, la solution retenue est basée sur le principe d'une thermorésistance. Les capteurs ont été élaborés en utilisant une approche par microtamponnage actif avec croissance d'une couche de nickel (dont l'épaisseur varie entre 0,2 et 5 μm) par métallisation autocatalytique sur polyimide. La dérive des capteurs est actuellement trop importante pour une application pratique. Finalement, des résultats préliminaires d'intégration de ces capteurs dans un microsystème fluidique thermoformé sont présentés avec notamment une configuration originale de mesure différentielle du pH / The plastics industry has been interested for some years in the possible convergence between microtechnologies and conventional polymer manufacturing (hot embossing and injection molding). In this context, this thesis aims at demonstrating the potential of a process based on microcontact printing in order to integrate metal based sensors in thermoplastic microfluidic devices shaped by hot embossing. For the mass production of thermoplastic devices, this approach appears more relevant than conventional photolithography. We chose to demonstrate this concept by investigating the integration of both a pH sensor and a temperature sensor in a thermoformed Cyclo Olefin Copolymer (COC) microfluidic system. Indeed, the measurement of these physicochemical parameters are extremely widespread in different applicative areas ranging from chemistry tobiology and medicine. For the pH sensor, we developed a pH-sensitive layer based on electrodeposited iridium oxide (IrOx) on Au. The influence of various parameters (plating solution and method , nature of the metal substrate and its method of preparation) on the pH response of these layers was studied. We were able to demonstrate that microcontact printing based on a passive approach is suitable for the preparation of pH sensors on a COC substrate with a sensitivity of -72 mV/pH and a 1 year lifetime. As regards the temperature sensor, the solution was to design a thermistor. Sensors were implemented with an approach based on active microcontact printing followed by electroless deposition of nickel (thickness varies between 0,2 and 5 μm) on polyimide. The drift of these sensors is too large for practical application. Finally, preliminary results presenting the integrating of these sensors in a fluidic microsystem are reported using an original configuration based on differential measurement of pH

Durant les dernières décennies, de plus en plus de types de cellules se sont révélées capables de sonder leur environnement mécanique par l'application de forces. Ce phénomène appelé «Mecanosensing» est lié à l'adhésion et la mécanique cellulaire, et est souvent étudié grâce à l'interaction des cellules avec des substrats artificiels. Dans des études distinctes, des surfaces chimiquement structurées avec une répartition des ligands spécifiques ont montré une forte influence sur l’adhésion et la mécanique cellulaire. Cependant, la relation entre les deux phénomènes n'a pas été beaucoup explorée, en partie parce que la fonctionnalisation de substrats mous s’est révélée être un défi technique.Pour résoudre ce problème, nous avons développé une technique simple et rentable nommée «reverse contact printing», afin de fabriquer des plots de protéines sub-microniques sur un élastomère d'élasticité contrôlée, le polydiméthylsiloxane (PDMS). Mon travail de thèse a focalisé sur la standardisation et la compréhension du procédé de transfert. A l’aide de mesures de forces réalisées par AFM nous avons mesuré l’élasticité du PDMS, ainsi que les forces de cohésion et d'adhésion effectives impliquées dans le processus. Nous avons également étudié l'adhésion cellulaire avec des lymphocytes-T sur des surfaces de PDMS d'élasticité variable. Nous avons montré que contrairement à la plupart des autres types de cellules, les cellules-T s'étalent davantage sur substrat mou que sur dur. Finalement nous avons réalisé des expériences pilotes d'adhésion cellulaire sur PDMS structuré. / In the past decade, more and more types of cells have been shown to be capable of probing the mechanics of their environment by application of forces. The stiffness of the environment strongly influences a host of cellular parameters including cell adhesion and mechanics. In separate studies, the spatial distribution of ligands, modulated by chemical patterning of a target surface, has been shown to strongly influence cell adhesion and mechanics. However, the cross-talk between the two phenomena has not been much explored, partly because patterned functionalization of soft substrates is an engineering challenge. To address this issue, we have developed a simple and technique named "reverse contact printing" for fabrication of nanometric protein patches on PDMS (polydimethylsiloxane) elastomer. My PhD work consisted of deciphering the molecular mechanisms that underlie this technique. We realized that the rate of transfer crucially depended on the molecular groups on the protein and on the nature of the PDMS surface. We used atomic force microscopy (AFM) force measurements to measure PDMS elasticity as well as protein-substrate interactions to understand the molecular mechanism governing the transfer. We have identified that a successful reverse transfer is facilitated by the grafting of appropriate chemical groups on the protein, and depends on the PDMS surface treatment and elasticity. We also studied adhesion and mechanics of T lymphocytes on PDMS. We found that surprisingly T lymphocytes spread more on softer than on harder PDMS. In on-going pilot experiments, cells on patterned soft PDMS seem to exhibit different behavior as compared to cells on patterned glass.

Integration and miniaturisation in electronics has undoubtedly revolutionised the modern world. In biotechnology, emerging lab-on-a-chip (LOC) methodologies promise all-integrated laboratory processes, to perform complete biochemical or medical synthesis and analysis encapsulated on small microchips. The integration of electrical, optical and physical sensors, and control devices, with fluid handling, is creating a new class of functional chip-based systems. Scaled down onto a chip, reagent and sample consumption is reduced, point-of-care or in-the-field usage is enabled through portability, costs are reduced, automation increases the ease of use, and favourable scaling laws can be exploited, such as improved fluid control. The capacity to manipulate single cells on-chip has applications across the life sciences, in biotechnology, pharmacology, medical diagnostics and drug discovery. This thesis explores multiple applications of optical manipulation within microfluidic chips. Used in combination with microfluidic systems, optics adds powerful functionalities to emerging LOC technologies. These include particle management such as immobilising, sorting, concentrating, and transportation of cell-sized objects, along with sensing, spectroscopic interrogation, and cell treatment. The work in this thesis brings several key applications of optical techniques for manipulating and porating cell-sized microscopic particles to within microfluidic chips. The fields of optical trapping, optical tweezers and optical sorting are reviewed in the context of lab-on-a-chip application, and the physics of the laminar fluid flow exhibited at this size scale is detailed. Microfluidic chip fabrication methods are presented, including a robust method for the introduction of optical fibres for laser beam delivery, which is demonstrated in a dual-beam optical trap chip and in optical chromatography using photonic crystal fibre. The use of a total internal reflection microscope objective lens is utilised in a novel demonstration of propelling particles within fluid flow. The size and refractive index dependency is modelled and experimentally characterised, before presenting continuous passive optical sorting of microparticles based on these intrinsic optical properties, in a microfluidic chip. Finally, a microfluidic system is utilised in the delivery of mammalian cells to a focused femtosecond laser beam for continuous, high throughput photoporation. The optical injection efficiency of inserting a fluorescent dye is determined and the cell viability is evaluated. This could form the basis for ultra-high throughput, efficient transfection of cells, with the advantages of single cell treatment and unrivalled viability using this optical technique.