This thesis presents technological advancements in microfluidics. The overall goals of the work are to develop new miniaturized tests for point-of-care diagnostics and robust super-lubricating surfaces for friction reduction. To achieve these goals, novel materials, surfaces and manufacturing methods in microfluidics have been developed. Point-of-care diagnostic tests are portable miniaturized instruments that downscale and automate medical tests previously performed in the central laboratories of hospitals. The instruments are used in the doctor’s office, in the emergency room or at home as self-tests. By bringing the analysis closer to the patient, the likelihood of an accurate diagnosis, or a quick therapy adjustment is increased. Already today, there are point-of-care tests available on the market, for example blood glucose tests, rapid streptococcus tests and pregnancy tests. However, for more advanced diagnostic tests, such as DNA-tests or antibody analysis, integration of microfluidic functions for mass transport and sample preparation is required. The problem is that the polymer materials used in academic development are not always suited for prototyping microfluidic components for sensitive biosensors. Despite the enormous work that has gone into the field, very few technical solutions have been implemented commercially. The first part of the work deals with the development of prototype point of-care tests. The research has focused on two major areas: developing new manufacturing methods to leverage the performance of existing materials and developing a novel polymer material platform, adapted for the extreme demands on surfaces and materials in miniaturized laboratories. The novel manufacturing methods allow complex 3D channel networks and the integration of materials with different surface properties. The novel material platform is based on a novel off-stoichiometry formulation of thiol-enes (OSTE) and has very attractive material and manufacturing properties from a lab-on-chip perspective, such as, chemically stable surfaces, low absorption of small molecules, facile and inexpensive manufacturing process and a biocompatible bonding method. As the OSTE-platform can mirror many of the properties of commercially used polymers, while at the same time having an inexpensive and facile manufacturing method, it has potential to bridge the gap between research and commercial production. Friction in liquid flows is a critical limiting factor in microfluidics, where friction is the dominant force, but also in marine applications where frictional losses are responsible for a large part of the total energy consumption of sea vessels. Microstructured surfaces can drastically reduce the frictional losses by trapping a layer of air bubbles on the surface that can act as an air bearing for the liquid flow. The problem is that these trapped air bubbles collapse at the liquid pressures encountered in practical applications. The last part of the thesis is devoted to the development of novel low fluidfriction surfaces with increased robustness but also with active control of the surface friction. The results show that the novel surfaces can resist up to three times higher liquid pressure than previous designs, while keeping the same friction reducing capacity. The novel designs represent the first step towards practical implementation of micro-structured surfaces for friction reduction. / <p>QC 20110907</p>

Materials based on novel Off-Stoichiometry Thiol-Ene polymers, abbreviated OSTE, show promising properties as materials forlow cost and scalable manufacturing of micro- and nanosystems such as lab-on-chip devices. The OSTE materials have tunablemechanical properties, offer possibility for low temperature bonding to many surfaces via tunable surface chemistry, and can beused in soft lithography. Unlike the commonly used elastomer poly(dimethylsiloxane), PDMS, the OSTE materials have lowpermeability for gasses, are resistant to common solvents and can be more permanently surface modified.In this master’s thesis project, the OSTE materials have been evaluated with focus on compatibility with cells, possibility fornanostructuring using soft lithography and the use of OSTE as a flexible support for conducting polymers.Results from cell seeding studies with HEP G2 cells suggest that cells can proliferate on a low thiol off-stoichiometry OSTEmaterial for at least five days. The biocompatibility for this type of OSTE material may be similar to poly(styrene). However, highlevels of free thiol monomers in the material decrease cell viability considerably.By using soft lithography techniques it is possible to fabricate OSTE nanochannels with at least the dimensions of 400 nm x 15nm. Combined with the advantages of using the OSTE materials, such as low temperature bonding and possibility for stablesurface modifications, a candidate construction material for future development of systems for DNA analysis is at hand.OSTE can serve as a flexible support for an adsorbed film of a conducting polymer with the possibility for future applicationssuch as electronic interfaces in microsystems. In this project, a film of PEDOT:PSS with the electrical resistance of ~5 kΩ wascreated by adsorption to an flexible OSTE material. Furthermore, results suggest that it is possible to further optimize theconductivity and water resistance of PEDOT:PSS films on OSTE.

Within healthcare there is a market pull for biomedical devices that can rapidly perform laboratory processes, such as diagnostic testing, in a hand-held format. For this reason, biomedical devices must become smaller, more sophisticated, and easier to use for a reasonable cost. However, despite the accelerating academic research on biomedical microdevices, and especially plastic-based microfluidic chips, there is still a gap between the inventions in academia and their benefit to society. To bridge this gap there is a need for new materials which both exhibit similar properties as industrial thermoplastics, and that enable rapid prototyping in academia. In this thesis, thiol-ene and thiol-ene-epoxy thermosets are evaluated both in terms of their suitability for rapid prototyping of biomedical microdevices and their potential for industrial manufacturing of “lab-on-chips”. The first part of the thesis focuses on material development of thiol-ene and thiol-ene-epoxy thermosets. Chemical and mechanical properties are studied, as well as in vitro biocompatibility with cells. The second part of the thesis focuses on microfabrication methods for both thermosets. This includes reaction injection molding, photostructuring, and surface modification. It is demonstrated how thiol-ene and thiol-ene-epoxy both provide advantageous thermo-mechanical properties and versatile surface modifications via “thiol-click chemistry”. In the end of the thesis, two applications for both polymer platforms are demonstrated. Firstly, thiol-ene is used for constructing nanoliter well arrays for liquid storage and on-demand electrochemical release. Secondly, thiol-ene-epoxy is used to enhance the biocompatibility of neural probes by tuning their flexibility. It is concluded that both thiol-ene and thiol-ene-epoxy thermosets exhibit several properties that are highly suitable for rapid prototyping as well as for scalable manufacturing of biomedical microdevices. / <p>QC 20171003</p>

In novel drug delivery system, the encapsulation of therapeutic cells in microparticles has great promises for the treatment of a range of health con- ditions. Therefore, the encapsulation material and technology are of great importance to the validity and efficiency of the advanced medical therapy. Several unsolved challenges in regards to versatile microparticle synthesis ma- terials and methods form the main obstacle for a translation of novel cell therapy concepts from research to clinical practice. Thiol-ene based polymer systems have emerged and gained great popular- ity in material development in general and in biomedical applications specif- ically. The thiol-ene platform is broad and therefore of interest for a variety of applications. At the same time, many aspects of this material platform are largely unexplored, for example material and manufacturing technology developments for microfluidic applications . In this Ph.D. thesis, thiol-ene materials are explored for use in cell encap- sulation. The marriage of these two technology fields breeds the possibility for a novel microfluidic cell encapsulation approach using a novel encapsulation material. To this end, several new manufacturing technologies for thiol-ene and thiol-ene-epoxy droplet microfluidic devices were developed. Moreover, core-shell microparticle synthesis for cell encapsulation based on a novel co- synthesis concept using a thiol-ene based material was developed and inves- tigated. Finally, a thiol-ene-epoxy system was also used for the formation of microwells and microchannels that improve protein analysis on microarrays. The first part of the thesis presents the background and state-of-the-art technologies in regards to cell therapy, microfluidics, and thiol-ene based ma- terials. In the second part of the thesis, a novel manufacturing approach of thiol-ene-epoxy material as well as core-shell particle co-synthesis in micro- fluidics using thiol-ene based material are presented and characterized. The third part of the thesis presents the cell viability studies of encapsulated cells using the novel encapsulation material and method. In the final part of the thesis, two applications of thiol-ene-epoxy gaskets for protein detection mi- croarrays are presented. / Inkapsling av levande celler i mikrokapslar för terapeutiska ändamål är mycket lovande för frmatida behandling av många olika sjukdomar. Emeller- tid är en behandlings effektivitet i hög grad beroende av vilka material som används för inkapsling och vilken teknisk lösning som används för att ska- pa mikrokapslarna. För närvarande återstår det många utmaningar för att omvandla grundforskningresultat till klinisk verklighet, vilken kräver mer än- damålsenliga tillvägagångssätt för att tillverka mikrokapslar i material som är kompatibla med användningsområdena. De senaste åren har tiol-en baserade polymerer har blivit mycket använda för materialutveckling i stort och för biomedicinska tillämpningar i synnerhet. Med tiol-en kemi kan en mycket stor mängd helt olika syntetiska material framställas, vilket gör tiol-ener intressanta för en mängd applikationer. För närvarande är dock mycket inom denna materialklass outforskat, t.ex. inom material och tillverkningmetodik för mikrofluidiktillämpningar. I denna avhandling används tiol-ener för cellinkapsling. Sammanslagning av dessa teknologier möjliggör en ny typ av cellinkapsling med nya materi- alegenskaper. En mängd olika tillverkningssätt där tiol-en eller tiol-en-epoxi används för droplet-mikrofluidiksystem utvecklades. Core-shell mikrokapsel- syntes för cell-inkapsling baserat på en ny metod för samtidig syntes av både core och shell utvecklades och karaktäriserades. Slutligen utvecklades ett tiol- en-epoxi system för enkel integrering med proteinmikroarrayer på objektsglas. I avhandlingens första del presenteras bakgrund och dagens bästa teknolo- gier för terapeutisk cellinkapsling, mikrofluidik och tiol-en baserade material. I avhandlingens andra del presenteras en ny tillverkningsmetod för mikro- strukturerade tiol-en-epoxi artiklar och samtidig syntes av core och shell för mikrokapslar med användande av mikrofluidik. I den tredje delen presenteras cellöverlevandsstudier för de celler som inkapslats med de nya materialen och de nyutvecklade metoderna. I den avslutande delen beskrivs två specifika fall där tiol-en-epoxi komponenter används för proteindetektion och mikroarrayer. / <p>QC 20171122</p>