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Study on the Effect of in Situ Surface Treatments of Medical Microfluidic Systems Obtained Through Additive Manufacturing

Csapai Alexandra, Țoc Dan-Alexandru, Pașcalău Violeta, Toșa Victor, Opruța Dan, Popa Florin, Popa Catalin

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 3

1071--1078

EN

This paper presents a comparative study on the effects of the in-situ surface modifications performed on “H” type microfluidic systems obtained via additive manufacturing. The microsystem was printed using a polylactic acid filament on an Ender-5 Pro printer. The surface modification of the main channel was done using chloroform by two different methods: vapor smoothing and flushing. The obtained surface roughness was studied using an optical microscope and the ImageJ software, as well as scanning electron microscopy. The effect of the channel surface treatment upon the characteristics of the fluid flow was assessed. The microfluidic systems were used for the dynamic study of biofilm growth of Candida albicans (ATCC 10231). The influence of the surface roughness of the main channel on the formation and growth of the biofilm was studied using quantitative methods, scanning electron microscopy imaging as well as optical coherence tomography.

2

Inżynieria komórkowa w systemach lab-on-a-chip

Tomecka E., Tokarska K., Jastrzębska E., Chudy M., Brzózka Z.

Wiadomości Chemiczne

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2015

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[Z] 69, 9-10

909--929

EN

Lab-on-a-chip systems are promising tools in the field of cell engineering. Microfluidic systems are integrated microlaboratories consisting of many microstructures such as microchannels and microchambers, which can be used for cell analysis and cell culture. Appropriately designed geometry of the chip allows to mimic in vivo conditions. Microsystems enables continuous culture medium perfusion. During cell culture, regulation of the flow rate of medium is possible, which allows to control conditions of the cultivation. In this paper we present a review of microfluidics systems which are used in cell engineering. We describe methods of microsystems fabrication, parameters which influence cell proliferation in microscale and examples of microsystems for cell analysis and cell culturing. Microfluidic systems for maintaining cell culture are mainly fabricated of poly(dimethylsiloxane) (PDMS) and glass, non-toxic materials for cells. The most commonly used method for fabrication of PDMS microsystems is photolithography and replica molding techniques. Cell culture in microsystems can be carried out in two ways: as a two-dimensional (2D) cell culture and three-dimensional (3D) cell culture. In two-dimensional culture cells grow as a monolayer on a flat surface of microchambers or microchannels. Microsystems for two-dimensional cell culture are widely described in the literature. They are mainly used for: (i) cell proliferation after exposure to external stimuli, (ii) testing the activity of cytotoxic drugs, (iii) interactions and cell migration and (iv) the evaluation of procedures applicable in tumor therapy e. g. photodynamic therapy. However, two-dimensional cell culture do not mimic fully in vivo conditions. In living organisms cells grow spatially creating three-dimensional structures like tissues. Therefore, nowadays microsystems for 3D cell culture are being developed intensively. Three-dimensional cell culture in microfluidic systems can be achieved in three ways: by the design of suitable geometry and topography of microchannels, by the use of hydrogels or by spheroids formation. Three-dimensional cell culture in microfluidic systems are much better experimental in vitro models than cell culture in traditional culture vessels. It is the main reason why microsystems should be still improved, as to become widely used research tools in cellular engineering.

3

System-level modeling of a Lab-On-Chip for micropollutants detection

Guiton S, Rezgui A, Madec M., Lallement C., Rufi F, Haiech J.

International Journal of Microelectronics and Computer Science

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2014

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Vol. 5, nr 3

116--125

EN

The issue addressed by this paper is system-level modeling of Lab-On-Chip (LOC) level. These microsystems integrate within a single chip many functions from several domains such as electronics, thermic, biochemistry or microﬂuidics. The modeling of these systems in a single environment and the interface between different domains is very challenging. In this paper, we propose some methods to model the entire system in VHDL-AMS. The models are developed and assembled from elementary building blocks, with a validation through experiments or numerical simulation on a reference tool, toward the complete LOC. For each domain, the modeling methodology is described. The principle is applied to a specific use case: a LOC designed for the detection of micro-pollutants in drinking water. It is based on the ELISA test leading to a pH-shift which is in turn detected by an Ion-Sensitive Field Effect Transistor (ISFET). In the last part of the paper, the ﬁrst results obtained with the complete zero-order model of the LOC are described. Of course, this model has to be improved in order to be faithful to the actual LOC but it will undoubtedly be a major asset for the optimization and reliability improvement of the LOC.

4

Modelowanie hydrodynamiki w układach mikroprzepływowych

Ilnicki F., Wawro B., Pijanowska B., Torbicz W.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 10

27-29

PL

Stosowanie narzędzi inżynierskich służących do modelowania procesów fizycznych i chemicznych daje możliwość znacznej obniżki niezbędnych kosztów oraz czasu, związanych z projektowaniem i wdrażaniem nowych technologii oraz urządzeń. W artykule omówiono zastosowanie modelowania FEM do optymalizacji i analizy hydrodynamiki w układach mikroprzepływowych typu lab-on-a-chip. Przedstawiono przykładowe symulacje komputerowe hydrodynamiki w mikroreaktorze przeznaczonym do hodowli komórkowych oraz ogniskowania hydrodynamicznego w mikrocytometrze przepływowym.

EN

Dynamic progress in computer science results in development and optimization of engineering tools for designing and modeling of physical and chemical processes and phenomena. They reduce costs and time devoted to design and implementation of new technologies and devices. For these purposes, computational numeric methods such as: finite element, volume and finite difference method (FEM, FVM and FDM, respectively) are the most frequently used. In this paper, application of the FEM based modeling for optimization and analysis of hydrodynamics in lab-on-a-chip type microfluidic systems are presented. Exemplary results on computer simulations of hydrodynamics in flow-through microreactors for cell culturing and hydrodynamic focusing in flow microcytometer are discussed. Computer simulations were performed with a simulation software package COMSOL 3.5.

5

Formation of bubbles and droplets in microfluidic systems

Garstecki P., Ganan-Calvo A.M., Whitesides G.M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2005

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Vol. 53, nr 4

361-372

EN

This mini-review reports the recent advances in the hydrodynamic techniques for formation of bubbles of gas in liquid in microfluidic systems. Systems comprising ducts that have widths of the order of 100 micrometers produce suspensions of bubbles with narrow size distributions. Certain of these systems have the ability to tune the volume fraction of the gaseous phase - over the whole range from zero to one. The rate of flow of the liquids through the devices determines the mechanism of formation of the bubbles - from break-up controlled by the rate of flow of the liquid (at law capillary numbers, and in the presence of strong confinement by the walls of the microchannels), to dynamics dominated by inertial effects (at high Weber numbers). The region of transition between these two regimes exhibits nonlinear behaviours, with period doubling cascades and irregular bubbling as prominent examples. Microfluidic systems provide new and uniquely controlled methods for generation of bubbles, and offer potential applications in micro-tlow chemical processing, synthesis of materials, and fluidic optics.