4 research outputs found

    3D printed microfluidic probes

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    In this work, we fabricate microfluidic probes (MFPs) in a single step by stereolithographic 3D printing and benchmark their performance with standard MFPs fabricated via glass or silicon micromachining. Two research teams join forces to introduce two independent designs and fabrication protocols, using different equipment. Both strategies adopted are inexpensive and simple (they only require a stereolithography printer) and are highly customizable. Flow characterization is performed by reproducing previously published microfluidic dipolar and microfluidic quadrupolar reagent delivery profiles which are compared to the expected results from numerical simulations and scaling laws. Results show that, for most MFP applications, printer resolution artifacts have negligible impact on probe operation, reagent pattern formation, and cell staining results. Thus, any research group with a moderate resolution (</=100 microm) stereolithography printer will be able to fabricate the MFPs and use them for processing cells, or generating microfluidic concentration gradients. MFP fabrication involved glass and/or silicon micromachining, or polymer micromolding, in every previously published article on the topic. We therefore believe that 3D printed MFPs is poised to democratize this technology. We contribute to initiate this trend by making our CAD files available for the readers to test our "print & probe" approach using their own stereolithographic 3D printers

    Pixelated microfluidics for drug screening on tumour spheroids and ex vivo microdissected tumour explants

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    ABSTRACT: Anticancer drugs have the lowest success rate of approval in drug development programs. Thus, preclinical assays that closely predict the clinical responses to drugs are of utmost importance in both clinical oncology and pharmaceutical research. 3D tumour models preserve the tumoral architecture and are cost- and time-efficient. However, the short-term longevity, limited throughput, and limitations of live imaging of these models have so far driven researchers towards less realistic tumour models such as monolayer cell cultures. Here, we present an open-space microfluidic drug screening platform that enables the formation, culture, and multiplexed delivery of several reagents to various 3D tumour models, namely cancer cell line spheroids and ex vivo primary tumour fragments. Our platform utilizes a microfluidic pixelated chemical display that creates isolated adjacent flow sub-units of reagents, which we refer to as fluidic ‘pixels’, over tumour models in a contact-free fashion. Up to nine different treatment conditions can be tested over 144 samples in a single experiment. We provide a proof-of-concept application by staining fixed and live tumour models with multiple cellular dyes. Furthermore, we demonstrate that the response of the tumour models to biological stimuli can be assessed using the platform. Upscaling the microfluidic platform to larger areas can lead to higher throughputs, and thus will have a significant impact on developing treatments for cancer

    Highly Multiplexable Open-Space Microfluidics

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    La manipulation de liquide est le fondement de toute recherche en sciences de la vie. MalgrĂ© son importance, la majoritĂ© de la manipulation de liquide est toujours basĂ©e sur le pipetage de fluides, une mĂ©thode datant de plus d’un siĂšcle. La vague d’automatisation massive qui a dĂ©butĂ© dans les annĂ©es 70 a grandement augmentĂ© le dĂ©bit de tests pouvant ĂȘtre effectuĂ©s. Cependant, Ă  mesure que le dĂ©bit de tests requis augmente et que les volumes des tests diminuent, le pipetage de fluides devient de plus en plus problĂ©matique. L’importance relative des forces en jeu change lorsque l’échelle du systĂšme diminue. La viscositĂ© et la tension de surface deviennent importantes, ce qui entraine une augmentation des imprĂ©cisions des fluides pipetĂ©s. Une mĂ©thode pour se sortir de cette « tyrannie du pipetage » est d’utiliser des puces microfluidique, qui sont conçues pour manipuler des fluides Ă  l’échelle submillimĂ©trique dans des rĂ©seaux de microcanaux afin de rĂ©aliser diverses tĂąches expĂ©rimentales. Les systĂšmes microfluidiques se libĂšrent du paradigme des plaques de puits. En effets, ils sont plutĂŽt basĂ©s sur des circuits fluidiques dans lesquels les expĂ©riences prennent place. ProcĂ©der Ă  des expĂ©riences dans des systĂšmes microfluidiques vient cependant avec son lot de difficultĂ©s et de dĂ©fis. Une grande partie des Ă©chantillons en sciences de la vie sont des surfaces ouvertes, que ce soit des cultures 2D en PĂ©tri, des tranches de tissu ou des puces Ă  protĂ©ines. Injecter des Ă©chantillons dans des systĂšmes microfluidiques nĂ©cessite des modifications majeures aux protocoles habituels. De plus, certains Ă©chantillons sont incompatibles avec les systĂšmes microfluidiques, par exemple certains types de cellules particuliĂšrement sensibles aux contraintes de cisaillement. Le champ de recherche de la microfluidique sur surface ouverte s’attaque Ă  ces problĂ©matiques. La microfluidique sur surface ouverte englobe une multitude de systĂšmes conçus afin d’interagir avec des surfaces. L’idĂ©e gĂ©nĂ©rale derriĂšre ces systĂšmes est de permettre le dĂ©pĂŽt localisĂ© de fluides sur des surfaces, et donc de ne pas nĂ©cessiter l’insertion des Ă©chantillons dans le systĂšme. Les systĂšmes de microfluidique ouverte tels que les sondes microfluidiques, qui sont l’inspiration principale derriĂšre ce projet de recherche, ont dĂ©jĂ  dĂ©montrĂ© leur potentiel en traitement de surface. Ils ont notamment Ă©tĂ© utilisĂ©s pour le marquage immunohistochimique localisĂ© et la lyse cellulaire sĂ©lective. Cependant, alors que les dispositifs de microfluidique sur surface ouverte permettent habituellement le contrĂŽle extrĂȘmement prĂ©cis de fluides sur une surface, il n’y a pour l’instant aucune maniĂšre viable de parallĂ©liser ces dispositifs. Cela nuit largement Ă  leur adoption puisqu’ils ne peuvent pas ĂȘtre utilisĂ©s pour des expĂ©riences nĂ©cessitant un grand dĂ©bit de test. Cette thĂšse porte sur la conception, la fabrication et l’évaluation d’une nouvelle gĂ©nĂ©ration de systĂšmes microfluidiques sur surface ouverte qui peuvent ĂȘtre parallĂ©lisĂ©s et reconfigurĂ©s. Ces nouveaux dispositifs, les multipĂŽles microfluidiques, fonctionnent en utilisant les mĂȘmes principes que les sondes microfluidiques. Cependant, leur parallĂ©lisation permet d’augmenter le nombre de tests pouvant ĂȘtre effectuĂ©s, et leur reconfiguration permet de les utiliser afin d’automatiser des expĂ©riences multi-Ă©tapes. Dans cette thĂšse, une mĂ©thode de fabrication de multipĂŽles microfluidiques compatible avec des systĂšmes de toute taille est prĂ©sentĂ©e. Cette mĂ©thode couvre la totalitĂ© du procĂ©dĂ© de fabrication, de la conception des dessins vectoriels Ă  l’aide de scripts jusqu’à l’assemblage des systĂšmes. Les rĂ©sultats dĂ©montrent qu’il est possible de produire des multipĂŽles microfluidiques formĂ©s de plus de 300 ouvertures, avec une taille d’ouverture de 160 ”m. Les rĂ©sultats d’expĂ©rience dĂ©montrent que les multipĂŽles fabriquĂ©s ne comportent pas de dĂ©fauts et de dĂ©formations affectant significativement les motifs d’écoulement des fluides. Dans une deuxiĂšme section de cette thĂšse, la maniĂšre la plus efficace afin de multiplexer et de reconfigurer des multipĂŽles microfluidiques formĂ©s d’un petit nombre d’ouvertures est investiguĂ©e. Plusieurs architectures et concepts de multipĂŽles sont Ă©tudiĂ©s et testĂ©s. Le grand potentiel de reconfigurabilitĂ© des multipĂŽles est dĂ©montrĂ©, et un stroboscope chimique permettant le contrĂŽle d’impulsion d’un rĂ©actif sur une surface est testĂ©. Cette section de mon projet de recherche culmine avec l’automatisation d’un test immunologique Ă  l’aide d’un multipĂŽle microfluidique. La derniĂšre section de cette thĂšse porte sur l’élaboration d’un multipĂŽle microfluidique hautement parallĂšle. La piĂšce centrale afin d'atteindre cet objectif consiste en l’élaboration d’une unitĂ© multipolaire modulaire, les pixels microfluidiques, pouvant paver une surface avec des zones de confinement indĂ©pendantes. Le rĂ©sultat est l’afficheur chimique pixĂ©lisĂ©, un sous-type de multipĂŽle microfluidique. Ce type de systĂšme peut thĂ©oriquement ĂȘtre Ă©tendu Ă  n’importe quel nombre de pixels, et des systĂšmes formĂ©s de 144 pixels ont Ă©tĂ© testĂ©s expĂ©rimentalement. Les afficheurs chimiques pixĂ©lisĂ©s, comme les autres multipĂŽles, peuvent ĂȘtre reconfigurĂ©s afin de gĂ©nĂ©rer des sĂ©quences « d’images chimiques », ce qui permet l’automatisation d’expĂ©riences multiĂ©tapes. Les afficheurs chimiques ont la particularitĂ© de pouvoir ĂȘtre utilisĂ©s sur des surfaces immergĂ©es ou sĂšches, ce qui est habituellement impossible pour un multipĂŽle microfluidique. Afin de dĂ©montrer cette possibilitĂ©, le traitement de surface de film plastique est effectuĂ© avec un afficheur chimique intĂ©grĂ© dans un systĂšme « roll-to-roll ». Cette section de ma thĂšse se termine par une dĂ©monstration d’un afficheur chimique Ă©tant opĂ©rĂ© uniquement par deux pompes Ă  pression. De maniĂšre gĂ©nĂ©rale, cette thĂšse a pour objectif de prĂ©senter une nouvelle approche de la microfluidique sur surface ouverte. Les multipĂŽles microfluidiques prĂ©sentĂ©s dans cette thĂšse sont les premiers dispositifs du genre Ă©tant reconfigurables, ainsi que les premiers permettant l’automatisation d’expĂ©riences multi-Ă©tapes. Les afficheurs chimiques pixĂ©lisĂ©s permettent une parallĂ©lisation qui est sans prĂ©cĂ©dent en microfluidique sur surface ouverte.----------ABSTRACT Liquid handling is at the forefront of life science research. Despite its importance, it has been based on the same principle, the pipetting of fluids in wells, for over a century. The massive automation boom starting from the 70’ has greatly increased the throughput that can be achieved. However, as the required throughput increased and the wells and reagent volumes are decreased further and further, pipetting fluids become more and more problematic. It is due to fluid viscosity and surface tension becoming more important as the scale of the problem decrease, leading to increased imprecision. A way out of the “tyranny of pipetting” is to use microfluidic devices that are designed to operate with fluid at the microscale. Microfluidic systems break free from the well plate paradigm and are based on fluidic circuits in which the whole experiment usually takes place. However, processing samples in microfluidic systems come with its own challenges and limitation. A lot of standards samples in life science are surfaces, such as cultures in Petri, tissue slices or protein arrays. Moreover, injecting samples in a microfluidic system often require important modification to the experimental protocol. Some biological samples are also incompatible with microsystems, such as certain types of cells that are extremely vulnerable to shear stress. The subfield of open-space microfluidic tries to address those limitations. Open-space microfluidics encompasses many systems that aim at processing and interacting with open surfaces. The general idea behind those systems is to allow the localized deposition of fluids directly on surfaces, and thus not require the insertion of the samples into the systems. Open-space microfluidic systems such as the microfluidics probe, which is the main inspiration being this project, have already demonstrated their potential in surface patterning. They have been successfully used for applications such as immunohistochemical staining and selective cell lysis. However, while the open-space microfluidic systems can precisely confine a fluid in an area, a viable method to parallelize those devices remains virtually inexistent. This greatly limit their adoption since they cannot be used for experiment requiring high throughput. This research project revolves around the design, fabrication, and evaluation of a new generation of open-space microfluidic devices that are parallelizable and reconfigurable. These new devices, the microfluidic multipoles (MFMs), operate on the same principles as the previous microfluidic probe. However, their parallelization allows for an increase in throughput, and flow pattern reconfiguration open the possibility to perform multistep experiments. In this thesis, a fabrication method for MFMs of any size, from a few apertures to several hundreds of apertures is presented. This method covers the whole process, from the script-assisted CAD design to the assembly of multipoles. The results demonstrate the possibility to fabricate MFMs with as many as 313 apertures with a size as small as 160 ”m. Experiment have demonstrated that MFMs could be reliably printed without defects and warping that would deform the flow. This fabrication method is, furthermore, simple, inexpensive and versatile. A second section of this thesis investigate the best way to parallelize and reconfigure MFMs that are comprised of a limited number of apertures. Different multipole architectures are proposed and tested. The high reconfiguration potential of MFMs is demonstrated, and a chemical stroboscope allowing the spatiotemporal pulse of chemicals on a surface is presented. This part of my work culminates with the automation of an immunofluorescence assay, which demonstrates the potential use of MFMs to automatize long-term multistep experiments. The last section of my work is an all-out attempt at highly parallel open-space systems. This section revolves around the use of modular MFM units, the microfluidic pixels, to tessellate whole surfaces in independent confinement areas. This results a Pixelated Chemical Display (PCD), a subtype of MFM. This device architecture can theoretically be expanded to any size and was experimentally tested for systems formed of up to 144 pixels. PCDs, just like other MFMs, can be reconfigured to create sequences of “chemical images”. That allows them to be used to automatize multistep experiments. Moreover, they can be made compatible with dry surfaces, which is not expected from an open-space microfluidic system. We demonstrated that capability by patterning dry plastic films in a custom roll-to-roll setup. This section of my thesis end with a demonstration of how to operate large PCDs using only two pressure pumps. Overall, this thesis aims at offering a new way of approaching open-space microfluidics. MFMs presented in this thesis are the first reconfigurable microfluidic multipole, and the first open-space system to be used to automate multistep experiments. Moreover, PCDs presented in this work offer a parallelization potential which is unprecedented in open-space microfluidics
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