Developing Droplet Based 3D Cell Culture Methods to Enable Investigations of the Chemical Tumor Microenvironment

Adaptation of cancer cells to changes in the biochemical microenvironment in an expanding tumor mass is a crucial aspect of malignant progression, tumor metabolism, and drug efficacy. In vitro, it is challenging to mimic the evolution of biochemical gradients and the cellular heterogeneity that characterizes cancer tissues found in vivo. It is well accepted that more realistic and controllable in vitro 3D model systems are required to improve the overall cancer research paradigm and thus improve on the translation of results, but multidisciplinary approaches are needed for these advances. This work develops such approaches and demonstrates that new droplet-based cell-encapsulation techniques have the ability to encapsulate cancer cells in droplets for standardized and more realistic 3D cell culture and cancer biology applications. Three individual droplet generating platforms have been designed and optimized for droplet-based cell encapsulation. Each has its own advancements and challenges. Together, however, these technologies accomplish medium to high-throughput generation (10 droplets/second to 25,000 droplets/second) of biomaterial droplets for encapsulation of a range of cell occupancies (5 cells/droplet to 400 cells/droplet). The data presented also demonstrates the controlled generation of cell-sized small droplets for biomolecule compartmentalization, droplets with diameters ranging between 100-400 μm depending on device parameters, and the generation of instant spheroids. Standardized assays for analyzing cells grown within these new 3D environments include proliferation assays of cells grown in mono- and co-cultures, the generation of large and uniform populations of scaffold supported multicellular spheroids, and a new system for culturing encapsulated cells in altered environmental conditions

Establishment of a fully automatized microfluidic platform for the screening and characterization of novel Hepatitis B virus capsid assembly modulators

El procés de descobriment de fàrmacs s'enfronta a importants desafiaments a causa de la constant disminució dels guanys per medicament atesa la disminució en les noves aprovacions de la FDA combinada amb el constant augment dels costos i el temps de desenvolupament. Les plataformes integrades de detecció usant microfluídica van sorgir com a possibles solucions per accelerar el desenvolupament de molècules actives i reduir els requisits de temps i costos. El projecte VIRO-FLOW té com a objectiu identificar nous agents curatius per al virus de l'hepatitis B (VHB), integrant els avantatges de la química de flux continu amb tecnologies de bioassaigs in vitro en microfluídica. Durant aquesta tesi es va construir un sistema microfluídic aplicant dispositius modulars automatitzats. Es van redactar protocols d'avaluació per a les dades de fluorescència i reflexió, permetent el càlcul del factor Z, les desviacions estàndard, les corbes de dilució i els valors de concentracions efectives mitjanes màximes (EC50). La proteïna central del VHB (HBc) es va seleccionar com a objectiu principalEl proceso de descubrimiento de fármacos se enfrenta a importantes desafíos debido a la constante disminución de las ganancias por medicamento dada la disminución en las nuevas aprobaciones de la FDA combinada con el constante aumento de los costes y el tiempo de desarrollo. Las plataformas integradas de detección usando microfluídica surgieron como posibles soluciones para acelerar el desarrollo de moléculas activas y reducir los requisitos de tiempo y costes. El proyecto VIRO-FLOW tiene como objetivo la identificación de nuevos agentes curativos para el virus de la hepatitis B (VHB), integrando las ventajas de la química de flujo continuo con tecnologías de bioensayos in vitro en microfluídica. Durante la presente tesis se construyó un sistema microfluídico aplicando dispositivos modulares automatizados. Se redactaron protocolos de evaluación para los datos de fluorescencia y reflexión, permitiendo el cálculo del factor Z, desviaciones estándar, curvas de dilución y valores de concentraciones efectivas medias máximas (EC50). La proteína central del VHB (HBc) se seleccionó como objetivo principal.Drug Discovery as known today faces major challenges due to the constant decrease of earnings per drug given the decrease in new FDA approvements combined with the steadily rising development costs and time. Integrated microfluidic screening platforms emerged as possible solutions by accelerating the hit-to-lead development cycle and reducing time and cost requirements. The VIRO-FLOW project aims at the fast and efficient identification of novel curative agents for the Hepatitis B Virus (HBV), integrating the advantages of continuous flow chemistry with in vitro microfluidic bioassay technologies. During the present thesis a microfluidic system was built, applying automatized modular devices. Evaluation protocols were written for the fluorescence and reflection data, allowing the Z´-factor calculation, standard deviations, dilution curves, and half‐maximal effective concentrations (EC50) values. HBV core protein (HBc) was selected as primary target due to the ongoing demand for a functional cure to reduce the economic and social challenges imposed by the chronic diseas

Proceedings of Abstracts Engineering and Computer Science Research Conference 2019

© 2019 The Author(s). This is an open-access work distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. For further details please see https://creativecommons.org/licenses/by/4.0/. Note: Keynote: Fluorescence visualisation to evaluate effectiveness of personal protective equipment for infection control is © 2019 Crown copyright and so is licensed under the Open Government Licence v3.0. Under this licence users are permitted to copy, publish, distribute and transmit the Information; adapt the Information; exploit the Information commercially and non-commercially for example, by combining it with other Information, or by including it in your own product or application. Where you do any of the above you must acknowledge the source of the Information in your product or application by including or linking to any attribution statement specified by the Information Provider(s) and, where possible, provide a link to this licence: http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/This book is the record of abstracts submitted and accepted for presentation at the Inaugural Engineering and Computer Science Research Conference held 17th April 2019 at the University of Hertfordshire, Hatfield, UK. This conference is a local event aiming at bringing together the research students, staff and eminent external guests to celebrate Engineering and Computer Science Research at the University of Hertfordshire. The ECS Research Conference aims to showcase the broad landscape of research taking place in the School of Engineering and Computer Science. The 2019 conference was articulated around three topical cross-disciplinary themes: Make and Preserve the Future; Connect the People and Cities; and Protect and Care

Magneto-capillary valve for integrated biological sample preparation

A major technological trend in in-vitro diagnostics is the integration and miniaturization of laboratory procedures into so-called ‘lab-on-chip’ devices. The aim is to achieve better integration of diagnostics into the medical workflow by providing compact devices that can analyze patient samples at the point of care, close to the patient. Ease-of-use is an important characteristic of point-of-care diagnostics. One specific feature that enables such easy-to-use devices is a ‘sample in – result out’ type of performance. However, in many cases a raw body fluid is not directly suitable for analysis. Therefore, an elaborate multi-step process of sample preparation is required before actual analysis of the sample can take place. While many detection technologies have been fully automated and successfully miniaturized and integrated into a lab-on-chip format, sample preparation has been staying behind on this trend. As a result, sample preparation requires a substantial amount of manual handling by a trained operator and is often the bottleneck in the process from sample to result. Integration and miniaturization of automated sample preparation is thus required to provide the ease-of-use and portability that is needed to bring diagnostics closer to the patient. This thesis aims at advancing the level of integration and miniaturization of automated biological sample preparation to enable point-of-care applications with a ‘sample in – result out’ type of performance. For this purpose, a novel microfluidic actuation concept is proposed: the magneto-capillary valve (MCV). The MCV technology is based on stationary microfluidics, in which discrete units of liquid are present at fixed positions in a microfluidic device. The MCV cartridge is a capillary device, in which aqueous liquids are confined by capillary forces resulting from specific features of the cartridge. Magnetic particles are transported through a hydrophobic valve medium from one stationary liquid to another by externally applied magnetic forces. The MCV technology provides a means for solid phase extraction, which is a common type of sample preparation. Analytes are coupled to magnetic particles in the sample matrix and are transported through one or more washing buffers to be finally eluted from the particles in a buffer that is appropriate for detection of the analyte. A key advantage of the MCV is its high valving efficiency due to the minimal quantity of liquid that is co-transported with the particles carrying the analyte. Moreover, by choosing a large sample volume and a small elution volume, the sample can be enriched and its volume matches the sample volume requirements for lab-on-chip devices. The envisioned system consists of a low-cost disposable cartridge that is driven by an instrument containing a magnetic actuation system like, for example, a movable permanent magnet. Many cartridges of different designs and various architectures were fabricated with a lead time of less than a week, due to a well-defined and yet very flexible fabrication process. In total, almost 1000 cartridges were fabricated over a period of about 2 years. This large number of cartridges was necessary to investigate the principles of magneto-capillary valving, to create options and define limitations of the MCV concept, and to test the performance of the MCV concept in biological sample preparation. Several MCV instruments were built as experimental setup to investigate the behavior of the valve and as instrument to enable experiments of biological sample preparation. The setup allows for quantification of the magnetic force that is applied to the particles. This quantification is realized by combining recorded images of the magnetic particle cloud with the measured susceptibility of the particles and the calculated magnetic field of the magnet. The behavior of the valve is described by a model that balances magnetic forces, capillary forces and friction forces. The performance of the MCV was evaluated by investigating the physics of magneto-capillary valving. The valving efficiency, the transport of magnetic particles, and pinch-off were investigated experimentally to characterize the valve operation. The conditions for successful operation of the valve were defined as a function of several design parameters. Investigation of the friction forces resulted in understanding of the intra-chamber dynamics, leading to the concept of force gradient mixing. Experimental results of DNA purification from spiked water and plasma samples demonstrate the feasibility of integrated biological sample preparation using the MCV technology. The performance of DNA purification in MCV cartridges was comparable to the performance of common commercially available solutions, while the MCV cartridge technology is much less complex. Integrated enrichment of DNA from 800 µl water samples showed an effective enrichment of 40 times, thus providing a substantial increase in detection sensitivity. DNA was also extracted successfully from samples with THP1 cells, which is a step further towards the total integration of a molecular test. The enrichment of proteins that was demonstrated in the MCV technology enables a whole new range of applications based on immunocapture of biomolecules. The approach of stationary microfluidics provides a strong reduction in complexity of the system, which is particularly valuable for point-of-care devices. From evaluation of the various valve architectures, the geometrical air valve appears to be the most suitable magneto-capillary valve architecture for integrated biological sample preparation. It features at the same time the best performance for a wide range of biochemical assays, as well as simplicity, which is essential for integration and for the concept of low-cost disposable cartridges. With that, the MCV technology has the potential to open new opportunities for integration and miniaturization of automated biological sample preparation

Methodology for Trace and Ultratrace Analysis of Primary Amines

In the study of lipids, or lipidomics, methods for the separation and identification of specific trace compounds are highly sought. Microdroplet techniques have allowed for the ability to handle and detect these trace amounts. The use of low volumes allows for a decrease of the effective mean free path allowing chemical reactions to be carried out efficiently at lower concentrations by performing the reactions in microdroplets as opposed to bulk containers. Microdroplets created on microfluidic devices as segmented flow plugs have the advantage of efficient mixing and minimal dilution or dispersion relative to other nanoliter scale capillary reaction methods. The most sensitive detection techniques are needed for ultratrace analyses. Laser induced fluorescence (LIF) is the most attractive choice for ultratrace analysis. We show two methods for the derivatization and detection of primary amines with 3-(2-furoyl)quinoline-2-carboxaldehyde (FQCA) and with naphthalene-2,3-dicarboxaldehyde (NDA). The method has shown to be successful down to the sub-picomolar level in bulk solutions using an HPLC coupled with a fluorescence detector. The method has been transferred to microfluidic chips to explore the reaction and detection limits of the derivatized amines. Laser induced fluorescence (LIF) by a solid state blue violet laser was used as the detection method for the microfluidic platform. Successful usage of this methodology would allow for ultratrace detection of bioactive amines from small samples

Advances in Microfluidics Technology for Diagnostics and Detection

Microfluidics and lab-on-a-chip have, in recent years, come to the forefront in diagnostics and detection. At point-of-care, in the emergency room, and at the hospital bed or GP clinic, lab-on-a-chip offers the potential to rapidly detect time-critical and life-threatening diseases such as sepsis and bacterial meningitis. Furthermore, portable and user-friendly diagnostic platforms can enable disease diagnostics and detection in resource-poor settings where centralised laboratory facilities may not be available. At point-of-use, microfluidics and lab-on-chip can be applied in the field to rapidly identify plant pathogens, thus reducing the need for damaging broad spectrum pesticides while also reducing food losses. Microfluidics can also be applied to the continuous monitoring of water quality and can support policy-makers and protection agencies in protecting the environment. Perhaps most excitingly, microfluidics also offers the potential to enable entirely new diagnostic tests that cannot be implemented using conventional laboratory tools. Examples of microfluidics at the frontier of new medical diagnostic tests include early detection of cancers through circulating tumour cells (CTCs) and highly sensitive genetic tests using droplet-based digital PCR.This Special Issue on “Advances in Microfluidics Technology for Diagnostics and Detection” aims to gather outstanding research and to carry out comprehensive coverage of all aspects related to microfluidics in diagnostics and detection

Automated liquid-handling operations for robust, resilient, and efficient bio-based laboratory practices

Increase in the adoption of liquid handling devices (LHD) can facilitate experimental activities. Initially adopted by businesses and industry-based laboratories, the practice has also moved to academic environments, where a wide range of non-standard/non-typical experiments can be performed. Current protocols or laboratory analyses require researchers to transfer liquids for the purpose of dilution, mixing, or inoculation, among other operations. LHD can render laboratories more efficient by performing more experiments per unit of time, by making operations robust and resilient against external factors and unforeseen events such as the COVID-19 pandemic, and by remote operation. The present work reviews literature that reported the adoption and utilisation of LHD available in the market and presents examples of their practical use. Applications demonstrate the critical role of automation in research development and its ability to reduce human intervention in the experimental workflow. Ultimately, this work will provide guidance to academic researchers to determine which LHD can fulfil their needs and how to exploit their use in both conventional and non-conventional applications. Furthermore, the breadth of applications and the scarcity of academic institutions involved in research and development that utilise these devices highlights an important area of opportunity for shift in technology to maximize research outcomes

Microfluidics: a new look at cell migration analysis

This thesis explores the development and employment of microfluidic devices as a tool for studying the effect of the surrounding environment on embryonic stem cells during the migration phenomena. Different single-cell microchips were designed and manufactured to study mouse embryonic fibroblasts (MEFs) migration towards an environmental variation (increase of serum concentration in the culture medium) that was expected to function as a motility stimuli. Considering the experimental, cells were injected into the microchips chambers and individually isolated by dedicated cell traps with view to a single-cell analysis. Once fribroblasts were attached to the surface, culture medium with an increased serum level was subsequently injected in an adjacent chamber to promote the formation of a serum concentration gradient. The gradient established between the chambers could be sensed by the fibroblasts and thus triggered the cells mobilization towards and in the direction of the richer serum medium. Additionally, the experiment allowed the observation of MEFs’ structural reorganization when migrating through micro-tunnels containing widths below the cell size, suggesting a cytoskeleton rearrangement on account of the nutritional stimulus introduced. Furthermore, results indicate that fibronectin promotes MEFs adhesion to the substrate and that MEFs migration is characterized as haptotactic

Hydrogel-based logic circuits for planar microfluidics and lab-on-a-chip automation

The transport of vital nutrient supply in fluids as well as the exchange of specific chemical signals from cell to cell has been optimized over billion years of natural evolution. This model from nature is a driving factor in the field of microfluidics, which investigates the manipulation of the smallest amounts of fluid with the aim of applying these effects in fluidic microsystems for technical solutions. Currently, microfluidic systems are receiving attention, especially in diagnostics, \textit{e.g.} as SARS-CoV-2 antigen tests, or in the field of high-throughput analysis, \textit{e.g.} for cancer research. Either simple-to-use or large-scale integrated microfluidic systems that perform biological and chemical laboratory investigations on a so called Lab-on-a-Chip (LoC) provide fast analysis, high functionality, outstanding reproducibility at low cost per sample, and small demand of reagents due to system miniaturization. Despite the great progress of different LoC technology platforms in the last 30 years, there is still a lack of standardized microfluidic components, as well as a high-performance, fully integrated on-chip automation. Quite promising for the microfluidic system design is the similarity of the Kirchhoff's laws from electronics to predict pressure and flow rate in microchannel structures. One specific LoC platform technology approach controls fluids by active polymers which respond to specific physical and chemical signals in the fluid. Analogue to (micro-)electronics, these active polymer materials can be realized by various photolithographic and micro patterning methods to generate functional elements at high scalability. The so called chemofluidic circuits have a high-functional potential and provide “real” on-chip automation, but are complex in system design. In this work, an advanced circuit concept for the planar microfluidic chip architecture, originating from the early era of the semiconductor-based resistor-transistor-logic (RTL) will be presented. Beginning with the state of the art of microfluidic technologies, materials, and methods of this work will be further described. Then the preferred fabrication technology is evaluated and various microfluidic components are discussed in function and design. The most important component to be characterized is the hydrogel-based chemical volume phase transition transistor (CVPT) which is the key to approach microfluidic logic gate operations. This circuit concept (CVPT-RTL) is robust and simple in design, feasible with common materials and manufacturing techniques. Finally, application scenarios for the CVPT-RTL concept are presented and further development recommendations are proposed.:1 The transistor: invention of the 20th century 2 Introduction to fluidic microsystems and the theoretical basics 2.1 Fluidic systems at the microscale 2.2 Overview of microfluidic chip fabrication 2.2.1 Common substrate materials for fluidic microsystems 2.2.2 Structuring polymer substrates for microfluidics 2.2.3 Polymer chip bonding technologies 2.3 Fundamentals and microfluidic transport processes 2.3.1 Fluid dynamics in miniaturized systems 2.3.2 Hagen-Poiseuille law: the fluidic resistance 2.3.3 Electronic and microfluidic circuit model analogy 2.3.4 Limits of the electro-fluidic analogy 2.4 Active components for microfluidic control 2.4.1 Fluid transport by integrated micropumps 2.4.2 Controlling fluids by on-chip microvalves 2.4.3 Hydrogel-based microvalve archetypes 2.5 LoC technologies: lost in translation? 2.6 Microfluidic platforms providing logic operations 2.6.1 Hybrids: MEMS-based logic concepts 2.6.2 Intrinsic logic operators for microfluidic circuits 2.7 Research objective: microfluidic hydrogel-based logic circuits 3 Stimuli-responsive polymers for microfluidics 3.1 Introduction to hydrogels 3.1.1 Application variety of hydrogels 3.1.2 Hydrogel microstructuring methods 3.2 Theory: stimuli-responsive hydrogels 3.3 PNIPAAm: a multi-responsive hydrogel 4 Design, production and characterization methods of hydrogel-based microfluidic systems 4.1 The semi-automated computer aided design approach for microfluidic systems 4.2 The applied design process 4.3 Fabrication of microfluidic chips 4.3.1 Photoresist master fabrication 4.3.2 Soft lithography for PDMS chip production 4.3.3 Assembling PDMS chips by plasma bonding 4.4 Integration of functional hydrogels in microfluidic chips 4.4.1 Preparation of a monomer solution for hydrogel synthesis 4.4.2 Integration methods 4.5 Effects on hydrogel photopolymerization and the role of integration method 4.5.1 Photopolymerization from monomer solutions: managing the diffusion of free radicals 4.5.2 Hydrogel adhesion and UV light intensity distribution in the polymerization chamber 4.5.3 Hydrogel shrinkage behavior of different adhesion types 4.6 Comparison of the integration methods 4.7 Characterization setups for hydrogel actuators and microfluidic measurements . 71 4.7.1 Optical characterization method to describe swelling behavior 4.7.2 Setup of a microfluidic test stand 4.8 Conclusion: design, production and characterization methods 5 VLSI technology for hydrogel-based microfluidics 5.1 Overview of photolithography methods 5.2 Standard UV photolithography system for microfluidic structures 5.3 Self-made UV lithography system suitable for the mVLSI 5.3.1 Lithography setup for the DFR and SU-8 master exposure 5.3.2 Comparison of mask-based UV induced crosslinking for DFR and SU-8 5.4 Mask-based UV photopolymerization for mVLSI hydrogel patterning 5.4.1 Lithography setup for the photopolymerization of hydrogels 5.4.2 Hydrogel photopolymerization: experiments and results 5.4.3 Troubleshooting: photopolymerization of hydrogels 5.5 Conclusion: mVLSI technologies for hydrogel-based LoCs 6 Components for chemofluidic circuit design 6.1 Passive components in microfluidics 6.1.1 Microfluidic resistor 6.1.2 Planar-passive microfluidic signal mixer 6.1.3 Phase separation: laminar flow signal splitter 6.1.4 Hydrogel-based microfluidic one-directional valves 6.2 Hydrogel-based active components 6.2.1 Reversible hydrogel-based valves 6.2.2 Hydrogel-based variable resistors 6.2.3 CVPT: the microfluidic transistor 6.3 Conclusion: components for chemofluidic circuits 7 Hydrogel-based logic circuits in planar microfluidics 7.1 Development of a planar CVPT logic concept 7.1.1 Challenges of planar microfluidics 7.1.2 Preparatory work and conceptional basis 7.2 The microfluidic CVPT-RTL concept 7.3 The CVPT-RTL NAND gate 7.3.1 Circuit optimization stabilizing the NAND operating mode 7.3.2 Role of laminar flow for the CVPT-RTL concept 7.3.3 Hydrogel-based components for improved switching reliability 7.4 One design fits all: the NOR, AND and OR gate 7.5 Control measures for cascaded systems 7.6 Application scenarios for the CVPT-RTL concept 7.6.1 Use case: automated cell growth system 7.6.2 Use case: chemofluidic converter 7.7 Conclusion: Hydrogel-based logic circuits 8 Summary and outlook 8.1 Scientific achievements 8.2 Summarized recommendations from this work Supplementary information SI.1 Swelling degree of BIS-pNIPAAm gels SI.2 Simulated ray tracing of UV lithography setup by WinLens® SI.3 Determination of the resolution using the intercept theorem SI.4 Microfluidic master mold test structures SI.4.1 Polymer and glass mask comparison SI.4.2 Resolution Siemens star in DFR SI.4.3 Resolution Siemens star in SU-8 SI.4.4 Integration test array 300 μm for DFR and SU-8 SI.4.5 Integration test array 100 μm for SU-8 SI.4.6 Microfluidic structure for different technology parameters SI.5 Microfluidic test setups SI.6 Supplementary information: microfluidic components SI.6.1 Compensation methods for flow stabilization in microfluidic chips SI.6.2 Planar-passive microfluidic signal mixer SI.6.3 Laminar flow signal splitter SI.6.4 Variable fluidic resistors: flow rate characteristics SI.6.5 CVPT flow rate characteristics for high Rout Standard operation proceduresDer Transport von lebenswichtigen Nährstoffen in Flüssigkeiten sowie der Austausch spezifischer chemischer Signale von Zelle zu Zelle wurde in Milliarden Jahren natürlicher Evolution optimiert. Dieses Vorbild aus der Natur ist ein treibender Faktor im Fachgebiet der Mikrofluidik, welches die Manipulation kleinster Flüssigkeitsmengen erforscht um diese Effekte in fluidischen Mikrosystemen für technische Lösungen zu nutzen. Derzeit finden mikrofluidische Systeme vor allem in der Diagnostik, z.B. wie SARS-CoV-2-Antigentests, oder im Bereich der Hochdurchsatzanalyse, z.B. in der Krebsforschung, besondere Beachtung. Entweder einfach zu bedienende oder hochintegrierte mikrofluidische Systeme, die biologische und chemische Laboruntersuchungen auf einem sogenannten Lab-on-a-Chip (LoC) durchführen, bieten schnelle Analysen, hohe Funktionalität, hervorragende Reproduzierbarkeit bei niedrigen Kosten pro Probe und einen geringen Bedarf an Reagenzien durch die Miniaturisierung des Systems. Trotz des großen Fortschritts verschiedener LoC-Technologieplattformen in den letzten 30 Jahren mangelt es noch an standardisierten mikrofluidischen Komponenten sowie an einer leistungsstarken, vollintegrierten On-Chip-Automatisierung. Vielversprechend für das Design mikrofluidischer Systeme ist die Ähnlichkeit der Kirchhoff'schen Gesetze aus der Elektronik zur Vorhersage von Druck und Flussrate in Mikrokanalstrukturen. Ein spezifischer Ansatz der LoC-Plattformtechnologie steuert Flüssigkeiten durch aktive Polymere, die auf spezifische physikalische und chemische Signale in der Flüssigkeit reagieren. Analog zur (Mikro-)Elektronik können diese aktiven Polymermaterialien durch verschiedene fotolithografische und mikrostrukturelle Methoden realisiert werden, um funktionelle Elemente mit hoher Skalierbarkeit zu erzeugen.\\ Die sogenannten chemofluidischen Schaltungen haben ein hohes funktionales Potenzial und ermöglichen eine 'wirkliche' on-chip Automatisierung, sind jedoch komplex im Systemdesign. In dieser Arbeit wird ein fortgeschrittenes Schaltungskonzept für eine planare mikrofluidische Chiparchitektur vorgestellt, das aus der frühen Ära der halbleiterbasierten Resistor-Transistor-Logik (RTL) hervorgeht. Beginnend mit dem Stand der Technik der mikrofluidischen Technologien, werden Materialien und Methoden dieser Arbeit näher beschrieben. Daraufhin wird die bevorzugte Herstellungstechnologie bewertet und verschiedene mikrofluidische Komponenten werden in Funktion und Design diskutiert. Die wichtigste Komponente, die es zu charakterisieren gilt, ist der auf Hydrogel basierende chemische Volumen-Phasenübergangstransistor (CVPT), der den Schlüssel zur Realisierung mikrofluidische Logikgatteroperationen darstellt. Dieses Schaltungskonzept (CVPT-RTL) ist robust und einfach im Design und kann mit gängigen Materialien und Fertigungstechniken realisiert werden. Zuletzt werden Anwendungsszenarien für das CVPT-RTL-Konzept vorgestellt und Empfehlungen für die fortlaufende Entwicklung angestellt.:1 The transistor: invention of the 20th century 2 Introduction to fluidic microsystems and the theoretical basics 2.1 Fluidic systems at the microscale 2.2 Overview of microfluidic chip fabrication 2.2.1 Common substrate materials for fluidic microsystems 2.2.2 Structuring polymer substrates for microfluidics 2.2.3 Polymer chip bonding technologies 2.3 Fundamentals and microfluidic transport processes 2.3.1 Fluid dynamics in miniaturized systems 2.3.2 Hagen-Poiseuille law: the fluidic resistance 2.3.3 Electronic and microfluidic circuit model analogy 2.3.4 Limits of the electro-fluidic analogy 2.4 Active components for microfluidic control 2.4.1 Fluid transport by integrated micropumps 2.4.2 Controlling fluids by on-chip microvalves 2.4.3 Hydrogel-based microvalve archetypes 2.5 LoC technologies: lost in translation? 2.6 Microfluidic platforms providing logic operations 2.6.1 Hybrids: MEMS-based logic concepts 2.6.2 Intrinsic logic operators for microfluidic circuits 2.7 Research objective: microfluidic hydrogel-based logic circuits 3 Stimuli-responsive polymers for microfluidics 3.1 Introduction to hydrogels 3.1.1 Application variety of hydrogels 3.1.2 Hydrogel microstructuring methods 3.2 Theory: stimuli-responsive hydrogels 3.3 PNIPAAm: a multi-responsive hydrogel 4 Design, production and characterization methods of hydrogel-based microfluidic systems 4.1 The semi-automated computer aided design approach for microfluidic systems 4.2 The applied design process 4.3 Fabrication of microfluidic chips 4.3.1 Photoresist master fabrication 4.3.2 Soft lithography for PDMS chip production 4.3.3 Assembling PDMS chips by plasma bonding 4.4 Integration of functional hydrogels in microfluidic chips 4.4.1 Preparation of a monomer solution for hydrogel synthesis 4.4.2 Integration methods 4.5 Effects on hydrogel photopolymerization and the role of integration method 4.5.1 Photopolymerization from monomer solutions: managing the diffusion of free radicals 4.5.2 Hydrogel adhesion and UV light intensity distribution in the polymerization chamber 4.5.3 Hydrogel shrinkage behavior of different adhesion types 4.6 Comparison of the integration methods 4.7 Characterization setups for hydrogel actuators and microfluidic measurements . 71 4.7.1 Optical characterization method to describe swelling behavior 4.7.2 Setup of a microfluidic test stand 4.8 Conclusion: design, production and characterization methods 5 VLSI technology for hydrogel-based microfluidics 5.1 Overview of photolithography methods 5.2 Standard UV photolithography system for microfluidic structures 5.3 Self-made UV lithography system suitable for the mVLSI 5.3.1 Lithography setup for the DFR and SU-8 master exposure 5.3.2 Comparison of mask-based UV induced crosslinking for DFR and SU-8 5.4 Mask-based UV photopolymerization for mVLSI hydrogel patterning 5.4.1 Lithography setup for the photopolymerization of hydrogels 5.4.2 Hydrogel photopolymerization: experiments and results 5.4.3 Troubleshooting: photopolymerization of hydrogels 5.5 Conclusion: mVLSI technologies for hydrogel-based LoCs 6 Components for chemofluidic circuit design 6.1 Passive components in microfluidics 6.1.1 Microfluidic resistor 6.1.2 Planar-passive microfluidic signal mixer 6.1.3 Phase separation: laminar flow signal splitter 6.1.4 Hydrogel-based microfluidic one-directional valves 6.2 Hydrogel-based active components 6.2.1 Reversible hydrogel-based valves 6.2.2 Hydrogel-based variable resistors 6.2.3 CVPT: the microfluidic transistor 6.3 Conclusion: components for chemofluidic circuits 7 Hydrogel-based logic circuits in planar microfluidics 7.1 Development of a planar CVPT logic concept 7.1.1 Challenges of planar microfluidics 7.1.2 Preparatory work and conceptional basis 7.2 The microfluidic CVPT-RTL concept 7.3 The CVPT-RTL NAND gate 7.3.1 Circuit optimization stabilizing the NAND operating mode 7.3.2 Role of laminar flow for the CVPT-RTL concept 7.3.3 Hydrogel-based components for improved switching reliability 7.4 One design fits all: the NOR, AND and OR gate 7.5 Control measures for cascaded systems 7.6 Application scenarios for the CVPT-RTL concept 7.6.1 Use case: automated cell growth system 7.6.2 Use case: chemofluidic converter 7.7 Conclusion: Hydrogel-based logic circuits 8 Summary and outlook 8.1 Scientific achievements 8.2 Summarized recommendations from this work Supplementary information SI.1 Swelling degree of BIS-pNIPAAm gels SI.2 Simulated ray tracing of UV lithography setup by WinLens® SI.3 Determination of the resolution using the intercept theorem SI.4 Microfluidic master mold test structures SI.4.1 Polymer and glass mask comparison SI.4.2 Resolution Siemens star in DFR SI.4.3 Resolution Siemens star in SU-8 SI.4.4 Integration test array 300 μm for DFR and SU-8 SI.4.5 Integration test array 100 μm for SU-8 SI.4.6 Microfluidic structure for different technology parameters SI.5 Microfluidic test setups SI.6 Supplementary information: microfluidic components SI.6.1 Compensation methods for flow stabilization in microfluidic chips SI.6.2 Planar-passive microfluidic signal mixer SI.6.3 Laminar flow signal splitter SI.6.4 Variable fluidic resistors: flow rate characteristics SI.6.5 CVPT flow rate characteristics for high Rout Standard operation procedure