Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Mécanique fluide, Fluid mechanics, Mecánica flúido, Amélioration, Improvement, Mejora, Analyse chimique, Chemical analysis, Análisis químico, Application, Aplicación, Choix, Choice, Elección, Conception, Design, Diseño, Dispositif, Device, Dispositivo, Haute pression, High pressure, Alta presión, Haute température, High temperature, Alta temperatura, Limitation, Limitación, Microfluidique, Microfluidics, Microfluidic, Moule, Mold, Molde, Méthode, Method, Método, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Qualité, Quality, Calidad, Robustesse, Robustness, Robustez, Réseau (arrangement), Array, Red, Styrène polymère, Styrene polymer, and Estireno polímero

Microfluidic cell-based systems have enabled the study of cellular phenomena with improved spatiotemporal control of the microenvironment and at increased throughput. While poly(dimethylsiloxane) (PDMS) has emerged as the most popular material in microfluidics research, it has specific limitations that prevent microfluidic platforms from achieving their full potential. We present here a complete process, ranging from mold design to embossing and bonding, that describes the fabrication of polystyrene (PS) microfluidic devices with simllar cost and time expenditures as PDMS-based devices. Emphasis was placed on creating methods that can compete with PDMS fabrication methods in terms of robustness, complexity, and time requirements. To achieve this goal, several improvements were made to remove critical bottlenecks in existing PS embossing methods. First, traditional lithographic techniques were adapted to fabricate bulk epoxy molds capable of resisting high temperatures and pressures. Second, a method was developed to emboss through-holes in a PS layer, enabling creation of large arrays of independent microfluidic systems on a single device without need to manually create access ports. Third, thermal bonding of PS layers was optimized in order to achieve quality bonding over large arrays of microsystems. The choice of materials and methods was validated for biological function in two different cell-based applications to demonstrate the versatility of our streamlined fabrication process.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Traitements de surface, Surface treatments, Amélioration, Improvement, Mejoría, Fabrication, Formation motif, Patterning, Formacíon motivo, Haute résolution, High-resolution methods, Microlentille, Microlenses, Microélectrode, Microelectrodes, Photolithographie, Photolithography, Prototypage rapide(industrie), Rapid prototyping (industrial), Structure 2 dimensions, Two dimensional structure, and Estructura 2 dimensiones

This paper extends rapid prototyping for several types of lithography to the 8-25-μm size range, using transparency photomasks prepared by photoplotting. It discusses the technical improvement in photomask quality achieved by photoplotting, compared to the currently used image setting, and demonstrates differences in the resolution that can be obtained with photomasks with features in the 8-100-μm size range. These high-resolution photomasks were used to microfabricate microelectrodes, microlenses, and stamps for microcontact printing, following methods described previously.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Capteur chimique, Chemical sensor, Captador químico, Dispositif fluidique, Fluidic devices, Détecteur électrochimique, Electrochemical detector, Detector electroquímico, Détection multicanal, Multichannel detection, Detección multicanal, Evaluation performance, Performance evaluation, Evaluación prestación, Microappareillage, Microequipment, Microequipo, Microminiaturisation, Microminiaturization, Microminiaturización, Photolithographie, Photolithography, Fotolitografía, Polymère silicium, Silicon polymer, Polímero silicio, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Siloxane(diméthyl) polymère, Dimethylsiloxane polymer, and Siloxano(dimetil) polímero

This paper describes a procedure for making topologically complex three-dimensional microfluidic channel systems in poly(dimethylsiloxane) (PDMS). This procedure is called the membrane sandwich method to suggest the structure of the final system: a thin membrane having channel structures molded on each face (and with connections between the faces) sandwiched between two thicker, flat slabs that provide structural support. Two masters are fabricated by rapid prototyping using two-level photolithography and replica molding. They are aligned face to face, under pressure, with PDMS prepolymer between them. The PDMS is cured thermally. The masters have complementary alignment tracks, so registration is straightforward. The resulting, thin PDMS membrane can be transferred and sealed to another membrane or slab of PDMS by a sequence of steps in which the two masters are removed one at a time; these steps take place without distortion of the features. This method can fabricate a membrane containing a channel that crosses over and under itself, but does not intersect itself and, therefore, can be fabricated in the form of any knot. It follows that this method can generate topologically complex microfluidic systems; this capability is demonstrated by the fabrication of a basketweave structure. By filling the channels and removing the membrane, complex microstructures can be made. Stacking and sealing more than one membrane allows even more complicated geometries than are possible in one membrane. A square coiled channel that surrounds, but does not connect to, a straight channel illustrates this type of complexity.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biochimie analytique, structurale et metabolique, Analytical, structural and metabolic biochemistry, Biochimie analytique: généralités, techniques, appareillages, Analytical biochemistry: general aspects, technics, instrumentation, Génie biomédical, Biomedical engineering, Ingeniería biomédica, Aminoacide, Aminoacid, Aminoácido, Conception miniaturisée, Miniaturized design, Concepción miniaturizada, Conception, Design, Diseño, DNA, Electrophorèse capillaire, Capillary electrophoresis, Electroforesis capilar, Electrophorèse, Electrophoresis, Electroforesis, Fabrication, Manufacturing, Fabricación, Mastic base élastomère, Elastomeric sealant, Masilla base elastomer, Microfluide, Microfluid, Microfluido, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Siloxane(diméthyl) polymère, Dimethylsiloxane polymer, Siloxano(dimetil) polímero, Structure microscopique, Microscopic structure, Estructura microscópica, Tube capillaire, Capillary tube, and Tubo capilar

This paper describes a procedure that makes it possible to design and fabricate (including sealing) microfluidic systems in an elastomeric material-poly(dimethylsiloxane) (PDMS)-in less than 24 h. A network of microfluidic channels (with width >20 μm) is designed in a CAD program. This design is converted into a transparency by a high-resolution printer; this transparency is used as a mask in photolithography to create a master in positive relief photoresist. PDMS cast against the master yields a polymeric replica containing a network of channels. The surface of this replica, and that of a flat slab of PDMS, are oxidized in an oxygen plasma. These oxidized surfaces seal tightly and irreversibly when brought into conformal contact. Oxidized PDMS also seals irreversibly to other materials used in microfluidic systems, such as glass, silicon, silicon oxide, and oxidized polystyrene; a number of substrates for devices are, therefore, practical options. Oxidation of the PDMS has the additional advantage that it yields channels whose walls are negatively charged when in contact with neutral and basic aqueous solutions; these channels support electroosmotic pumping and can be filled easily with liquids with high surface energies (especially water). The performance of microfluidic systems prepared using this rapid prototyping technique has been evaluated by fabricating a miniaturized capillary electrophoresis system. Amino acids, charge ladders of positively and negatively charged proteins, and DNA fragments were separated in aqueous solutions with this system with resolution comparable to that obtained using fused silica capillaries.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Capteur chimique, Chemical sensor, Captador químico, Dispositif fluidique, Fluidic devices, Détecteur électrochimique, Electrochemical detector, Detector electroquímico, Détection multicanal, Multichannel detection, Detección multicanal, Evaluation performance, Performance evaluation, Evaluación prestación, Microappareillage, Microequipment, Microequipo, Microminiaturisation, Microminiaturization, Microminiaturización, Photolithographie, Photolithography, Fotolitografía, Polymère silicium, Silicon polymer, Polímero silicio, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Siloxane(diméthyl) polymère, Dimethylsiloxane polymer, and Siloxano(dimetil) polímero

This paper describes a practical method for the fabrication of photomasks, masters, and stamps/molds used in soft lithography that minimizes the need for specialized equipment. In this method, CAD files are first printed onto paper using an office printer with resolution of 600 dots/ in. Photographic reduction of these printed patterns transfers the images onto 35-mm film or microfiche. These photographic films can be used, after development, as photomasks in 1:1 contact photolithography. With the resulting photoresist masters, it is straightforward to fabricate poly(dimethylsiloxane) (PDMS) stamps/molds for soft lithography. This process can generate microstructures as small as 15 μm; the overall time to go from CAD file to PDMS stamp is 4-24 h. Although access to equipment-spin coater and ultraviolet exposure tool-normally found in the clean room is still required, the cost of the photomask itself is small, and the time required to go from concept to device is short. A comparison between this method and all other methods that generate film-type photomasks has been performed using test patterns of lines, squares, and circles. Three microstructures have also been fabricated to demonstrate the utility of this method in practical applications.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Application, Aplicación, Cire, Wax, Cera, Dispositif, Device, Dispositivo, Formation motif, Patterning, Formacíon motivo, Hauteur, Height, Altura, Impression, Printing, Impresión, Lampe, Lamp, Lámpara, Membrane liquide, Liquid membrane, Membrana líquida, Moule, Mold, Molde, Méthode, Method, Método, Papier, Paper, Papel, Substrat, Substrate, Substrato, Transfert, Transfer, Transferencia, Utilisation, Use, Uso, Volume, and Volumen

This report describes the use of patterned paper as a low-cost, flexible substrate for rapidly prototyping PDMS microdevices via liquid molding. The entire fabrication process consists simply of three steps: (1) fabrication of patterned paper in NC membrane by direct wax printing (or modified wax printing that we call transfer wax printing); (2) formation of liquid mold on wax-patterned NC membrane; (3) PDMS molding and curing on wax-patterned NC membrane anchored with liquid micropattems. All these procedures can be finished within only 1.5 h without the use of a photomask, photoresist, UV lamp, etc. Through the use of wax-patterned NC membrane coupled with a liquid mold as a template, different PDMS microdevices such as microwells and microchannels have been fabricated to demonstrate the usefulness of the method for PDMS microfabrication. The height of microwells and microchannels can also be tailored flexibly by adjusting the liquid filling volume. This method for prototyping PDMS microdevices has some favorable merits including simple operation procedures, fast concept-to-device time, and low cost, indicating its potential for simple PDMS microdevice fabrication and applications.

Biotechnology, Biotechnologies, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Réactions catalytiques, Catalytic reactions, Sciences appliquees, Applied sciences, Genie chimique, Chemical engineering, Réacteurs, Reactors, Catalyseur, Catalyst, and Catalizador

The microstructure of the support determines a key property of porous catalysts-effective diffusivity. Typically, supporting materials with bimodal pore size distribution are used that involve both meso- and macropores. Spatial distribution of active metal crystallites within the porous support then influences reaction rates and conversions. To optimize the catalyst support microstructure and ultimately the whole catalyst, it is necessary to relate quantitatively the morphological features of the porous structure both to its preparation conditions and to the final transport properties and catalyst performance under reaction conditions. In this paper we demonstrate the application of novel models based on the generalized volume-of-fluid method and 3D digital reconstruction of a porous structure. The procedure includes simulation of porous support formation (virtual packing of primary particles of defined shapes and sizes), drying and crystallization of impregnated metal solution (growth of metal nanopartides), and solution of reaction and transport within the final virtual catalyst structure to obtain volume-averaged reaction rates that are then used in a full-scale model of a catalytic monolith reactor. A parametric study is performed to investigate the effects of the sizes of primary particles (influencing the meso- and macroporosity and pore sizes) and active metal impregnation conditions (influencing the distribution of active catalytic surface area) on the macroscopic activity of a catalytic monolith with Pt/γ-Al2O3 washcoat used for automotive exhaust gas aftertreatment.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Méthodes électrochimiques, Electrochemical methods, Mécanique fluide, Fluid mechanics, Mecánica flúido, Application, Aplicación, Bore, Boron, Boro, Cellule échantillon, Sample cell, Célula muestra, Compression, Compresión, Conception, Design, Diseño, Diamant, Diamond, Diamante, Dispositif, Device, Dispositivo, Détection, Detection, Detección, Electrocatalyse, Electrocatalysis, Electrocatálisis, Electrode carbone, Carbon electrode, Electrodo carbono, Fabrication, Manufacturing, Fabricación, Fiabilité, Reliability, Fiabilidad, Limite, Limit, Límite, Microfluidique, Microfluidics, Microfluidic, Modification chimique, Chemical modification, Modificación química, Méthode électrochimique, Electrochemical method, Método electroquímico, Or, Gold, Oro, Oxydation, Oxidation, Oxidación, Polymère, Polymer, Polímero, Réduction, Reduction, Reducción, Régime permanent, Steady state, Régimen permanente, Simulation, Simulación, Substrat, Substrate, Substrato, Technique, Técnica, Temps, Time, Tiempo, Utilisation, Use, Uso, Volume, and Volumen

Here we demonstrate the use of microstereolithography (MSL), a 3D direct manufacturing technique, as a viable method to produce small-scale microfluidic components for electrochemical flow detection. The flow cell is assembled simply by resting the microfabricated component on the electrode of interest and securing with thread! This configuration allows the use of a wide range of electrode materials. Furthermore, our approach eliminates the need for additional sealing methods, such as adhesives, waxes, and screws, which have previously been deployed. In addition, it removes any issues associated with compression of the cell chamber. MSL allows a reduction of the dimensions of the channel geometry (and the resultant component) and, compared to most previously produced devices, it offers a high degree of flexibility in the design, reduced manufacture time, and high reliability. Importantly, the polymer utilized does not distort so that the cell maintains well-defined geometrical dimensions after assembly. For the studies herein the channel dimensions were 3 mm wide, 3.5 mm long, and 192 or 250 μm high. The channel flow cell dimensions were chosen to ensure that the substrate electrodes experienced laminar flow conditions, even with volume flow rates of up to 64 mL min-1 (the limit of our pumping system). The steady-state transport-limited current response, for the oxidation of ferrocenylmethyl trimethylammonium hexaflorophosphate (FcTMA+), at gold and polycrystalline boron doped diamond (pBDD) band electrodes was in agreement with the Levich equation and/or finite element simulations of mass transport. We believe that this method of creating and using channel flow electrodes offers a wide range of new applications from electroanalysis to electrocatalysis.

General chemistry, physical chemistry, Chimie générale, chimie physique, Crystallography, Cristallographie cristallogenèse, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Méthodes de nanofabrication, Methods of nanofabrication, Nanolithographie, Nanolithography, Traitements de surface, Surface treatments, Surface cleaning, etching, patterning, Composé minéral, Inorganic compounds, Métal transition, Transition elements, Argent, Silver, Caractéristique courant tension, IV characteristic, Contact ohmique, Ohmic contacts, Décomposition, Decomposition, Etude expérimentale, Experimental study, Faisceau ion, Ion beams, Faisceau électron, Electron beams, Formation motif, Patterning, Interconnexion, Interconnections, Microscopie électronique transmission, Transmission electron microscopy, Nanocontact, Nanocontacts, Nanofil, Nanowires, Nanolithographie, Nanolithography, Nanomatériau, Nanostructured materials, Nanostructure, Nanostructures, Nanotube carbone, Carbon nanotubes, Platine, Platinum, Recuit, Annealing, Ag, C, and Pt

Rapid prototyping of bottom-up nanostructure circuits is demonstrated, utilizing metal deposition and patterning methodology based on combined focused ion and electron beam induced decomposition of a metal-organic precursor gas. Ohmic contacts were fabricated using electron beam deposition, followed by the faster process of ion beam deposition for interconnect formation. Two applications of this method are demonstrated: three-terminal transport measurements of Y-junction carbon nanotubes and fabrication of nanocircuits for determination of electromechanical degradation of silver nanowires.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Méthodes chromatographiques et méthodes physiques associées à la chromatographie, Chromatographic methods and physical methods associated with chromatography, Autres méthodes chromatographiques, Other chromatographic methods, Mécanique fluide, Fluid mechanics, Mecánica flúido, Acrylique dérivé copolymère, Acrylic copolymer, Acrílico derivado copolímero, Adsorption, Adsorción, Colorant xanthénique, Xanthene dye, Colorante xanténico, Dispositif planaire, Planar device, Dispositivo planar, Efficacité, Efficiency, Eficacia, Electrophorèse, Electrophoresis, Electroforesis, Enrichissement chimique, Chemical enrichment, Enriquecimiento químico, Ethylène oxyde copolymère, Ethylene oxide copolymer, Etileno óxido copolímero, Fluorescéine, Fluorescein, Fluoresceína, Isothiocyanate, Isothiocyanates, Isotiocianato, Liaison covalente, Covalent bond, Enlace covalente, Microfluidique, Microfluidics, Microfluidic, Modification chimique, Chemical modification, Modificación química, Peptide, Peptides, Péptido, Protéine, Protein, Proteína, Système sur puce, System on a chip, and Sistema sobre pastilla

A poly(ethylene glycol)-functionalized acrylic copolymer was developed for fabrication of microfluidic devices that are resistant to protein and peptide adsorption. Planar microcapillary electrophoresis (μCE) devices were fabricated from this copolymer with the typical cross pattern to facilitate sample introduction. In contrast to most methods used to fabricate polymeric microchips, the photopolymerization-based method used with the copolymer reported in this work was of the soft lithography type, and both patterning and bonding could be completed within 10 min. In a finished microdevice, the cover plate and patterned substrate were bonded together through strong covalent bonds. Additionally, because of the resistance of the copolymer to adsorption, fabricated microfluidic devices could be used without surface modification to separate proteins and peptides. Separations of fluorescein isothiocyanate-labeled protein and peptide samples were accomplished using these new polymeric μCE microchips. Separation efficiencies as high as 4.7 x 104 plates were obtained in less than 40 s with a 3.5-cm separation channel, yielding peptide and protein peaks that were symmetrical.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Méthodes chromatographiques et méthodes physiques associées à la chromatographie, Chromatographic methods and physical methods associated with chromatography, Autres méthodes chromatographiques, Other chromatographic methods, Méthodes spectrométriques et optiques, Spectrometric and optical methods, Acide aspartique, Aspartic acid, Acido aspártico, Acide glutamique, Glutamic acid, Acido glutámico, Aminoacide, Aminoacid, Aminoácido, Colorant xanthénique, Xanthene dye, Colorante xanténico, Electroosmose, Electroosmosis, Electro-osmosis, Electrophorèse capillaire, Capillary electrophoresis, Electroforesis capilar, Ester polymère, Ester polymer, Ester polímero, Evaluation performance, Performance evaluation, Evaluación prestación, Fabrication, Manufacturing, Fabricación, Glycine, Glicina, Microfluidique, Microfluidics, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Spectrométrie RX, X ray spectrometry, Espectrometría RX, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, Thermodurcissable, Thermosetting resin, and Termoestable

This paper presents a simple procedure for the fabrication of thermoset polyester (TPE) microfluidic systems and discusses the properties of the final devices. TPE chips are fabricated in less than 3 h by casting TPE resin directly on a lithographically patterned (SU-8) silicon master. Thorough curing of the devices is obtained through the combined use of ultraviolet light and heat, as both an ultraviolet and a thermal initiator are employed in the resin mixture. Features on the order of micrometers and greater are routinely reproduced using the presented procedure, including complex designs and multilayer features. The surface of TPE was characterized using contact angle measurements and X-ray photoelectron spectroscopy (XPS). Following oxygen plasma treatment, the hydrophilicity of the surface of TPE increases (determined by contact angle measurements) and the proportion of oxygen-containing functional groups also increases (determined by XPS), which indicates a correlated increase in the charge density on the surface. Native TPE microchannels support electroosmotic flow (EOF) toward the cathode, with an average electroosmotic mobility of 1.3 × 10-4 cm2 V-1 s-1 for a 50-μm square channel (20 mM borate at pH 9); following plasma treatment (5 min at 30 W and 0.3 mbar), EOF is enhanced by a factor of 2. This enhancement of the EOF from plasma treatment is stable for days, with no significant decrease noted during the 5-day period that we monitored. Using plasma-treated TPE microchannels, we demonstrate the separation of a mixture of fluorescein-tagged amino acids (glycine, glutamic acid, aspartic acid). TPE devices are up to 90% transparent (for ∼2-mm-thick sample) to visible light (400-800 nm). The compatibility of TPE with a wide range of solvents was tested over a 24-h period, and the material performed well with acids, bases, alcohols, cyclohexane, n-heptane, and toluene but not with chlorinated solvents (dichloromethane, chloroform).

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Analyse chimique, Chemical analysis, Análisis químico, Appareillage, Instrumentation, Instrumentación, Conception assistée, Computer aided design, Concepción asistida, Microfluidique, Microfluidics, Procédé fabrication, Manufacturing process, and Procedimiento fabricación

A solid-object printer was used to produce masters for the fabrication of microfluidic devices in poly(dimethylsiloxane) (PDMS). The printer provides an alternative to photolithography for applications where features of >250 μm are needed. Solid-object printing is capable of delivering objects that have dimensions as large as 250 x 190 x 200 mm (x, y, z) with feature sizes that can range from 10 cm to 250 pm. The user designs a device in 3-D in a CAD program, and the CAD file is used by the printer to fabricate a master directly without the need for a mask. The printer can produce complex structures, including multilevel features, in one unattended printing. The masters are robust and inexpensive and can be fabricated rapidly. Once a master was obtained, a PDMS replica was fabricated by molding against it and used to fabricate a microfluidic device. The capabilities of this method are demonstrated by fabricating devices that contain multilevel and tall features, devices that cover a large area (∼150 cm2), and devices that contain nonintersecting, crossing channels.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Méthodes chromatographiques et méthodes physiques associées à la chromatographie, Chromatographic methods and physical methods associated with chromatography, Autres méthodes chromatographiques, Other chromatographic methods, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biochimie analytique, structurale et metabolique, Analytical, structural and metabolic biochemistry, Biochimie analytique: généralités, techniques, appareillages, Analytical biochemistry: general aspects, technics, instrumentation, Appareil analyse chimique, Instrument for chemical analysis, Aparato análisis químico, Caractéristique appareillage, Equipment specifications, Característica equipo, Caractéristique fonctionnement, Performance characteristic, Característica funcionamiento, Dispositif fluidique, Fluidic devices, Détecteur fluorescence, Fluorescence detector, Detector fluorescencia, Electrophorèse capillaire, Capillary electrophoresis, Electroforesis capilar, Evaluation performance, Performance evaluation, Evaluación prestación, Macromolécule biologique, Biological macromolecule, Macromolécula biológica, Microminiaturisation, Microminiaturization, Microminiaturización, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Puce électronique, Chip, and Pulga electrónica

This paper describes a prototype of an integrated fluorescence detection system that uses a microavalanche photodiode (pAPD) as the photodetector for microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The prototype device consisted of a reusable detection system and a disposable microfluidic system that was fabricated using rapid prototyping. The first step of the procedure was the fabrication of microfluidic channels in PDMS and the encapsulation of a multimode optical fiber (100-μm core diameter) in the PDMS; the tip of the fiber was placed next to the side wall of one of the channels. The optical fiber was used to couple light into the microchannel for the excitation of fluorescent analytes. The photodetector, a prototype solid-state μAPD array, was embedded in a thick slab (1 cm) of PDMS. A thin (80 pm) colored polycarbonate filter was placed on the top of the embedded μAPD to absorb scattered excitation light before it reached the detector. The pAPD was placed below the microchannel and orthogonal to the axis of the optical fiber. The close proximity (∼200 μm) of the μAPD to the microchannel made it unnecessary to incorporate transfer optics; the pixel size of the pAPD (30 μm) matched the dimensions of the channels (50 μm). A blue light-emitting diode was used for fluorescence excitation. The pAPD was operated in Geiger mode to detect the fluorescence. The detection limit of the prototype (∼25 nM) was determined by finding the minimum detectable concentration of a solution of fluorescein. The device was used to detect the separation of a mixture of proteins and small molecules by capillary electrophoresis; the separation illustrated the suitability of this integrated fluorescence detection system for bioanalytical applications.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biochimie analytique, structurale et metabolique, Analytical, structural and metabolic biochemistry, Biochimie analytique: généralités, techniques, appareillages, Analytical biochemistry: general aspects, technics, instrumentation, Dispositif fluidique, Fluidic devices, Disruption électrique, Electric breakdown, Disrupción eléctrica, Evaluation performance, Performance evaluation, Evaluación prestación, Microappareillage, Microequipment, Microequipo, Microminiaturisation, Microminiaturization, Microminiaturización, Méthode analyse, Analysis method, Método análisis, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Technique ELISA, ELISA assay, and Técnica ELISA

This paper describes microfluidic devices that contain connections that can be opened by the user after fabrication. The devices are fabricated in poly(dimethylsiloxane) (PDMS) and comprise disconnected fluidic channels that are separated by 20 μm of PDMS. Applying voltages above the breakdown voltage of PDMS (21 V/pm) opened pathways between disconnected channels. Fluids could then be pumped through the openings. The voltage used and the ionic strength of the buffer in the channels determined the size of the opening. Opening connections in a specific order provides the means to control complex reactions on the device. A device for ELISA was fabricated to demonstrate the ability to store and deliver fluids on demand.

Chemistry, Chimie, Chemical industry parachemical industry, Industrie chimique et parachimique, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Appareillage et mise en oeuvre, Machinery and processing, Matières plastiques, Plastics, Moulage, Moulding, Injection, Injection moulding, Dépôt chimique, Chemical deposition, Depósito químico, Fabrication, Manufacturing, Fabricación, Forme libre, Free form, Forma libre, Forme solide, Solid form, Forma sólida, Moulage, Molding, Moldeo, Moule, Mold, Molde, Prototypage rapide, Rapid prototyping, and Prototipificación rápida

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Chemistry, Chimie, Organic chemistry, Chimie organique, Atomic molecular physics, Physique atomique et moléculaire, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Traitements de surface, Surface treatments, Formation motif, Patterning, Microscopie force atomique, Atomic force microscopy, Mélange polymère, Polymer blends, Nanolithographie, Nanolithography, Polymère soufre, Sulfur containing polymer, Polímero azufre, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Styrène polymère, Polystyrene, Séparation phase, Phase separation, Thiophène dérivé polymère, Thiophene derivative polymer, Tiofeno derivado polímero, Traitement surface, Surface treatments, and Thiophène(3-hexyl) polymère

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Divers, Miscellaneous, Mécanique fluide, Fluid mechanics, Mecánica flúido, Anticorps, Antibody, Anticuerpo, Application, Aplicación, Attaque chimique, Chemical etching, Ataque químico, Colorant, Dyes, Colorante, Construction, Construcción, Cytokine, Citoquina, Dispositif, Device, Dispositivo, Enzyme, Enzima, Faisceau ionique, Ion beam, Haz iónico, Hybridation DNA, DNA hybridization, Microfluidique, Microfluidics, Microfluidic, Moule, Mold, Molde, Méthode immunologique, Immunological method, Método inmunológico, Oxygène, Oxygen, Oxígeno, Plasma, Production, Producción, RNA, Réseau (arrangement), Array, Red, Substrat, Substrate, Substrato, Support, Soporte, Technique ELISA, ELISA assay, Técnica ELISA, Technique rapide, Rapid technique, Técnica rápida, Utilisation, Use, Uso, Verre, Glass, and Vidrio

A rapid fabrication and prototyping technique to incorporate microwell arrays with sub-10 μm features within a single layer of microfluidic circuitry is presented. Typically, the construction of devices that incorporate very small architecture within larger components has required the assembly of multiple elements to form a working device. Rapid, facile production of a working device using only a single layer of molded polydimethylsiloxane (PDMS) and a glass support substrate is achieved with the reported fabrication technique. A combination of conventional wet-chemical etching for larger (≥20 μm) microchannel features and focused ion beam (FIB) milling for smaller (≤10 μm) microwell features was used to fabricate a monolithic glass master mold. PDMS/glass hybrid chips were then produced using simple molding and oxygen plasma bonding methods. Microwell structures were loaded with 3 μm antibody-functionalized dye-encoded polystyrene spheres, and a sandwich immunoassay for common cytokines was performed to demonstrate proof-of-principle. Potential applications for this device include highly parallel multiplexed sandwich immunoassays, DNA/RNA hybridization analyses, and enzyme linked immunosorbent assay (ELISA). The fabrication technique described can be used for rapid prototyping of devices wherever submicrometer- to micrometer-sized features are incorporated into a microfluidic device.

Analytical chemistry, Chimie analytique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie analytique, Analytical chemistry, Généralités, appareillage, General, instrumentation, Bulle, Bubble, Ampolla, Laser pulsé, Pulsed laser, Láser pulsado, Microanalyse, Microanalysis, Microanálisis, Microfluidique, Microfluidics, Prototype, Prototipo, Verre, Glass, and Vidrio

Microfluidic and nanofluidic technologies have long sought a fast, reliable method to overcome the creative limitations of planar fabrication methods, the resolution limits of lithography, and the materials limitations for fast prototyping. In the present work, we demonstrate direct 3D machining of submicrometer diameter, subsurface fluidic channels in glass, via optical breakdown near critical intensity, using a femtosecond pulsed laser. No postexposure etching or bonding is required; the channel network (or almost any arbitrary-shaped cavity below the surface) is produced directly from art-to-part. The key to this approach is to use very low energy, highly focused, pulses in the presence of liquid. Microbubbles that result from laser energy deposition gently expand and extrude machining debris from the channels. These bubbles are in a highly damped, low Reynolds number regime, implying that surface spalling due to bubble collapse is unimportant. We demonstrate rapid prototyping of three-dimensional jumpers, mixers, and other key components of complex 3D microscale analysis systems in glass substrates.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Divers, Miscellaneous, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Propriété biologique, Biological properties, Propiedad biológica, Adhérence cellulaire, Cell adhesion, Adherencia celular, Aminolyse, Aminolysis, Aminolisis, Biomatériau, Biomaterial, Caprolactone polymère, Polycaprolactone, Caprolactona polímero, Charpente, Framework, Armadura, Copulation chimique, Chemical coupling, Copulación química, Diépoxyde, Diepoxide, Diepóxido, Etude expérimentale, Experimental study, Estudio experimental, Fabrication, Manufacturing, Fabricación, Fibre synthétique, Synthetic fiber, Fibra sintética, Fibroblaste, Fibroblast, Fibroblasto, Filage, Spinning, Hilado, Génie tissulaire, Tissue engineering, Ingeniería de tejidos, Matériau bioactif, Bioactive material, Material bioactivo, Modification chimique, Chemical modification, Modificación química, Nanoindentation, Nanoindentacion, Peptide, Peptides, Péptido, Procédé dépôt, Deposition process, Procedimiento revestimiento, Profondeur pénétration, Penetration depth, Profundidad penetración, Propriété mécanique, Mechanical properties, Propiedad mecánica, Réaction liquide solide, Liquid solid reaction, Reacción líquido sólido, Réaction surface, Surface reaction, Reacción superficie, Conjugué polymère peptide, and Peptide GRGDY

The requirement of a multifunctional scaffold for tissue engineering capable to offer at the same time tunable structural properties and bioactive interface is still unpaired. Here we present three-dimensional (3D) biodegradable polymeric (PCL) scaffolds with controlled morphology, macro-, micro-, and nano-mechanical performances endowed with bioactive moieties (RGD peptides) at the surface. Such result was obtained by a combination of rapid prototyping (e.g., 3D fiber deposition) and surface treatment approach (aminolysis followed by peptide coupling). By properly designing process conditions, a control over the mechanical and biological performances of the structure was achieved with a capability to tune the value of compressive modulus (in the range of 60―90 MPa, depending on the specific lay-down pattern). The macromechanical behavior of the proposed scaffolds was not affected by surface treatment preserving bulk properties, while a reduction of hardness from 0.50―0.27 GPa to 0.1―0.03 GPa was obtained. The penetration depth of the chemical treatment was determined by nanoindentation measurements and confocal microscopy. The efficacy of both functionalization and the following bioactivation was monitored by analytically quantifying functional groups and/or peptides at the interface. NIH3T3 fibroblast adhesion studies evidenced that cell attachment was improved, suggesting a correct presentation of the peptide. Accordingly, the present work mainly focuses on the effect of the surface modification on the mechanical and functional performances of the scaffolds, also showing a morphological and analytical approach to study the functionalization/bioactivation treatment, the distribution of immobilized ligands, and the biological features.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Gels colloïdaux. Sols colloïdaux, Colloidal gels. Colloidal sols, Matériaux poreux, Porous materials, Gel colloïdal, Colloidal gel, Gel coloidal, Aldéhyde, Aldehyde, Aldehído, Aminoacide, Aminoacid, Aminoácido, Azoture, Azides, Azoturo, Cire, Wax, Cera, DNA, Différenciation, Differentiation, Diferenciación, Dépôt, Deposition, Depósito, Glycol, Glicol, Greffage, Grafting, Injerto, Géométrie, Geometry, Geometría, Hydrogel, Hidrogel, Matériau poreux, Porous material, Material poroso, Minéralisation, Mineralization, Mineralización, Modélisation, Modeling, Modelización, Os, Bone, Hueso, Oxime, Oxima, Peptide, Peptides, Péptido, Pore, Poro, Protéine, Protein, Proteína, Résidu, Residue, and Resíduo

The objective of this work was to investigate the combined effect of grafting the peptide corresponding to amino acid residues 162―168 of ( osteopontin (OPD peptide) and the peptide corresponding to amino acid residues 73―92 of bone morphogenetic protein-2 (BMP peptide) to an RGD-conjugated inert hydrogel on osteogenic and vasculogenic differentiation of bone marrow stromal (BMS) cells. RGD-conjugated three-dimensional (3D) porous hydrogel scaffolds with well-defined cylindrical pore geometry were produced from sacrificial wax molds fabricated by fused deposition modeling rapid prototyping system. Propargyl acrylate and 4-pentenal were conjugated to the hydrogel for orthogonal grafting of BMP and OPD peptides by click reaction and oxime ligation, respectively. The OPD peptide was grafted by the reaction between aminoooy moiety of aminoooy-mPEG-OPD (mPEG = mini-poly(ediylene glycol)) and the aldehyde moiety in the hydrogel. The BMP peptide was grafted by the reaction between the azide moiety of Az-mPEG-BMP and the propargyl moiety in the hydrogel. The hydrogels seeded with BMS cells were characterized by biochemical, immunocytochemical, and mRNA analyses. Groups included RGD control hydrogel (RGD), RGD and BMP peptides without OPD (RGD+BMP), RGD and BMP peptides with mutant OPD (RGD+BMP+mOPD), and RGD and BMP peptides with OPD (RGD+BMP+OPD) grafted hydrogels. The extent of mineralization of RGD, RGD+BMP, RGD+BMP+mOPD, and RGD +BMP+OPD groups after 28 days was 650 ± 70, 990 ± 30, 850 ± 30, and 1150 ± 40 mg/(mg of DNA), respectively, indicating that the BMP and OPD peptides enhanced osteogenic differentiation of the BMS cells. The BMS cells seeded on RGD+BMP +OPD grafted hydrogels stained positive for vasculogenic markers α-SMA, PECAM-1, and VE-cadherin while the groups without OPD peptide (RGD+BMP and RGD+BMP+mOPD) stained only for α-SMA but not PECAM-t or VE-cadherin. These results were consistent with the significantly higher PECAM-1 mRNA expression for RGD+BMP+OPD group after 21 and 28 days, compared to the groups without OPD. These findings suggest that the RGD+BMP+OPD peptides provide a favorable microenvironment for concurrent osteogenic and vasculogenic differentiation of progenitor marrow-derived cells.