Microfluidic motion for a direct investigation of the structural dynamics of glass-forming liquids.

Glass-forming liquids, polymer solutions, and biofluids have additional inertial and elastic macroscopic degrees of freedom that are related to the elasticity of the molecular coils and affect the determination of the structural dynamical parameters. In this work, we propose a new approach for the direct evaluation of the fundamental material parameters (viscosity, fragility, glass transition temperature) of a viscoelastic liquid in a capillary flow inside a microfluidic device. The proposed technique substantially reduces the complexity of the theoretical analysis and provides an evaluation of the most relevant functional parameters of the fluid dynamics. Moreover, the approach allows the investigation of localization phenomena in geometrical confined systems, such as those required in miniaturized devices

Bicolor Electroluminescent Pixels from Single Active Molecular Material

We report on the fabrication of the first bicolor micropixelated OLED from a single molecular material using a single-step bottom up procedure, The implementation of a deposition technique, based on a spatial-switch and con formational-sensitive STD surface-tension-driven lithography, has allowed us to exploit the spontaneous supramolecular properties and the conformational flexibility of a conjugated thiophene-based material, 6-bis-(50-hexyl-[2, 20]bithiophen-5-yl)-3, 5-dimethyl-dithieno[3, 2-b: 20, 30-d]-thiophene (DTT7Me). The existence of two regularly alternating emitting regions on a micrometer scale allows obtaining electroluminescent emission at two different wavelengths from a single material

Engineering transfer of micro- and nanometer-scale features by surface energy modification.

Micropatterning of surfaces is gaining importance in various applications ranging from biosensors to microfluidic and lab-on-a-chip devices, where the control of the surface chemistry is of great importance for the application. In this paper, we introduce a patterning technique of topographical features, which is applicable on different substrates by modifying their surface energy. The textured surface is obtained via polydimethylsiloxane (PDMS) transfer, and the topographical parameters can be systematically tailored by selective treatment with oxygen plasma of either the PDMS stamp, the substrate, or both. Our approach is an alternative technique to create micro- and nanopatterns of various height and shape over a large area on different substrates. The possibility to control cell behavior on different surfaces tailored with this microtransfer patterning approach was also evaluated. The cell culture on patterned surfaces showed the possibility of modulating cell adhesion. Our method is based on simple transfer of silicone elastomeric patterns to the surface, and therefore, it is very simple and fast compared to other complex techniques. These observations could have implications for tissue-scaffold engineering science in areas such as microfluidic devices and control of cell adhesion

Microfluidic behaviour of perfluoropolyether fluids in poly(dimethylsiloxane) micro-channels

Two different perfluoropolyether-based fluids, namely the unfunctionalized GALDEN SV90® and the dihydroxy derivative FOMBLIN Z-DOL® 2000 were employed as liquid samples in a poly(dimethylsiloxane) (PDMS) microfluidic setup, fabricated by soft-lithography techniques. The results of our investigation were compared with the behaviour of the low viscosity and high-fragility polyurethane structural adhesive (NOA72®), that is well known as an excellent material for the fabrication of sub-micrometer structures by soft-lithography techniques, and whose structural elastic properties inside restricted geometric systems have been recently investigated

Superhydrophobicity Due to the Hierarchical Scale Roughness of PDMS Surfaces

Wettability control has been widely investigated in the last decades for technological applications such as microfluidic devices and self-cleaning surfaces by modifying both the chemical composition and the geometric structure of the surfaces. Inspired by the typical morphology of superhydrophobic leaves (such as lotus leaves), we have developed a dual-scale roughness, micro- and nanosized, on polydimethylsiloxane (PDMS) surfaces. By combining different geometric parameters and plasma treatment conditions, the structures were controlled hierarchically, at different independent length scales. Both the microsized replicated pillars and the nanosized etched posts tuned the wettability of the PDMS surfaces in a very simple way, up to contact angles of 170°. Furthermore, changes in the influence of micro- and nanoscale geometrical structures were investigated. Hysteresis and contact angles of water droplets are evaluated as a combined effect of micropillars and a superimposed roughness, resulting in high advan..

Positive Negative Arrays of Organic Light Emitting Diodes by a Surface Tension driven approach

A surface-tension-driven technique to pattern molecular arrays of organic light-emitting diodes by using a metallic grid to induce the geometrical confinement was presented. The technique enables the controlled replication of the micrometer-scale template, allowing the fabrication of arrays of OLED pixels of a well-defined geometry. The principle of this approach is the controlled dewetting of the molecular compounds in the feature of the template, allowing to realize either negative or positive patterns. The molecular TPD-patterned layer was realized by taking advantage of the combination of both liquid instability, following the dewetting phenomena, and geometrical confinement, induced by a template mes

Influence of Chemistry and Topology Effects on Superhydrophobic CF4-Plasma-Treated Poly(dimethylsiloxane) (PDMS)

Superhydrophobic surfaces are gaining considerable interest in a lot of different applications, and nonetheless, precise control over the wettability properties of such surfaces is still a challenge due to difficulties when controlling the effects independently induced on superhydrophobicity by the chemical and topological surface characteristics. We have fabricated engineered superhydrophobic surfaces onto poly(dimethylsiloxane) (PDMS) substrates by means of suitable CF4-plasma treatments. These treatments allowed the modification of both the morphological properties of the PDMS surface, due to a preferential etching of certain components of its macromolecules, and the chemical ones, by the deposition of a fluorinated layer. Chemical effects were separated from topological ones by performing a double replica molding process of the CF4-plasma-treated surfaces. This allowed us to obtain positive copies of the structured surfaces without the overlaying fluorinated coating affecting the surface chemistry. Su..

A Functional End-Use of Avocado (cv. Hass) Waste through Traditional Semolina Sourdough Bread Production

In recent years, a main goal of research has been to exploit waste from agribusiness industries as new sources of bioactive components, with a view to establishing a circular economy. Non-compliant avocado fruits, as well as avocado seeds and peels, are examples of promising raw materials due to their high nutritional yield and antioxidant profiles. This study aimed to recycle avocado food waste and by-products through dehydration to produce functional bread. For this purpose, dehydrated avocado was reduced to powder form, and bread was prepared with different percentages of the powder (5% and 10%) and compared with a control bread prepared with only semolina. The avocado pulp and by-products did not alter organoleptically after dehydration, and the milling did not affect the products' color and retained the avocado aroma. The firmness of the breads enriched with avocado powder increased due to the additional fat from the avocado, and alveolation decreased. The total phenolic content of the fortified breads was in the range of 2.408-2.656 mg GAE/g, and the antiradical activity was in the range of 35.75-38.235 mmol TEAC/100 g (p < 0.0001), depending on the percentage of fortification

Fabrication of Molecular Micro-NanoStructures by Surface-Tension-Driven Technique

We present the fabrication of a pixels structure by a well-defined pattern replication of a micrometer template driven by a surface free-energy lithographic technique, realized by molecular aggregation in dewetting conditions and by confining the liquid solution with geometric boundaries. The organization in the solid-state of the selected thiophene-based molecular materials allows to realize a bicoloured, green and red-emitting pixels structure, by exploiting the molecular structural arrangement, induced during a dewetting process, and the great conformational flexibility of DTT7Me