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A new method for the fabrication of large-area metal and semiconductor nanobridge arrays is proposed. The method combines the possibilities offered by the nanotransfer printing technique and by UV lithography. The essence of the method consists in the formation of an array of metal or semiconductor nanostrips "imprinted" into a smooth layer of resist and in subsequent exposure of the resist to UV radiation through an additional mask defining the regions where the suspended nanostrip bridges will be formed during subsequent development of the resist layer. Large-area arrays of Au and Ti/Au nanobridge, 100 nm wide, 25–35 nm thick and 1–4 μm long, with their ends embedded into the SU-8 resist layer, were fabricated. SiGe nanobridge arrays of 18 nm thick and 1 μm long, with their ends embedded into the Shipley 1813 resist layer were fabricated. The proposed method is simple and low-cost, and it does not require using expensive reactive plasma-etching facilities and can be implemented both on solid and polymer substrates on the areas at the excess of 150 cm2. • The simple and low-cost method for fabrication of suspended metal and semiconductor nanostructures have proposed. • The method can be implemented both on solid and polymer substrates on areas in excess of 150 cm2. • High-quality large-area arrays of Au and Ti/Au nanobridges were successfully fabricated. [ABSTRACT FROM AUTHOR]

Highlights • Microlattice is a mechanical metamaterial with ultralow density and mass productivity. • Under out-of-plane compression, its strength is over-estimated due to frictional contact. • We suggest a method to add in-plane truss elements on the outer faces. • Under in-plane compression, the added in-plane elements show significant reinforcement. • The strengths and failure modes estimated by analytic solutions agree with the test results. Abstract Microlattice is the most advanced version of truss cellular materials with ultralow density and high mass productivity, thanks to the mask-based lithography. However, its structure lacks in-plane truss elements, which results in low structural stability. This paper investigates the effect of the structural incompleteness on its mechanical behavior of Microlattice by comparison with that of another Microlattice with in-plane truss elements added on its outer faces. The mechanical properties of the Microlattices with and without in-plane elements were evaluated through compression tests of the single-layered specimens in two different directions. Under out-of-plane compression, the in-plane elements added to the conventional Microlattice specimens did not show any effect and failed to enhance the strength and stiffness. Finite element analysis revealed that high friction at contacts caused the unexpected results. In contrast, under in-plane compression, the in-plane elements showed significant enhancement. Simple analytic solution of the compressive strength of the enhanced Microlattices under in-plane compression agreed fairly well with the experimental results, and explained well the failure mode transition. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Surface modification of PET film was achieved by two sequential atmospheric pressure plasma jet (APPJ) treatments. • PET film treated by APPJ-coating showed super-hydrophobicity and subsequent APPJ-oxidation made the film super-hydrophilic. • UV lithography technique combined with APPJ-coating produced super hydrophobic/hydrophilic mosaic patterns on PET surface. • Combination of APPJ-coating and APPJ/UV oxidation is applicable to wettability and contamination control of various solids. Abstract The surface modification of poly (ethylene terephthalate) (PET) film was achieved by two sequential atmospheric pressure plasma jet (APPJ) treatments: plasma-induced polymer coating with hexamethyldisiloxane (HMDSO) and plasma oxidation with nitrogen gas. For comparison with APPJ-oxidation, oxidation by excimer ultra violet (UV) light irradiation was performed. The sessile drop and Wilhelmy contact angle measurements revealed that the PET film subjected to APPJ-coating showed superior water repellency and subsequent APPJ- or UV-oxidation made the PET film super-hydrophilic. UV-oxidation was also performed on the PET film treated by APPJ-coating, covered by a metal mesh. The difference in the contact angles between the surface areas covered with and without the metal strip mask was evident based on the Wilhelmy contact angle measurement. Both hydrophobic and hydrophilic surfaces did not exhibit contact angle hysteresis and had excellent stability of wettability. Furthermore, the hydrophilic surface treated only by APPJ- or UV-oxidation exhibited contact angle hysteresis and hydrophobic recovery with prolonged storage. Field emission scanning electron microscopy (FE-SEM) and SEM observation revealed that the morphology of the PET surface became granular after APPJ-coating. From the analyses of X-ray photoelectron spectroscopy (XPS) and grazing-angle attenuated total reflectance Fourier transform infrared (GATR-FTIR) spectroscopy, the APPJ-coated film composed mainly of inorganic SiO 2 with traces of carbon derived from CH 3 group, which makes the coating surface more hydrophobic. The subsequent oxidation process of APPJ or UV light leads to the decomposition of the methyl group at the surface. The antifouling properties of the PET surface against soil particulates deposited from air and their removal in aqueous detergent solution, were improved by APPJ-coating and subsequent APPJ-oxidation, respectively. [ABSTRACT FROM AUTHOR]

We introduced a novel technique to fabricate a Microlattice-cored miniature sandwich panel with an ultralow density. This sandwich panel was made of a monolithic Ni-P foil without any bonding between the core and the faces. As a preliminary study, the mechanical properties were evaluated under compression in two different loading directions, and the effects of the face sheets added on the top and bottom were investigated in comparison to the conventional Microlattice without the face sheets. Under the out-of-plane compression, almost no difference was evident between the conventional Microlattice and the Microlattice sandwich in their compressive behaviors, because of the high friction with the compression platens. However, under the in-plane compression, the addition of the face sheets to the conventional Microlattice significantly increased the strength and stiffness, when the wall thickness was higher than a certain limit. Otherwise, the reinforcing effect became much less significant, because the very thin face sheets were easily buckled across the entire area even at the beginning of the loading. [ABSTRACT FROM AUTHOR]

We present for the first-time light emitting ultraviolet (UV) curable active PbS quantum dots-polymer composite optical waveguides fabricated by vacuum assisted microfluidic (VAM) soft lithography technique. PbS quantum dots were synthesized by colloidal chemistry methods with tunable sizes resulting in light emissions in near infrared wavelengths. UV curable polymer of selective refractive index were synthesized facilitating waveguide mode confinement and good PbS quantum dots solubility. Photoluminescence of the composite exhibited ∼ 30 times better brightness than PbS-SU-8 composites. Light emitting multi-mode waveguides of about 50 × 42 μ m cross-sectional dimension were successful demonstrated. Light emitting single-mode waveguides were fabricated by VAM technique with sectional flow tapers. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new highly inorganic ZrO2 based system, synthesized by sol–gel route, is proposed. [•] The developed ZrO2 resist has been successfully patterned by UV and EB lithography. [•] Several structures spanning from the micron range down to less than 50nm. [•] DNA has been selectively immobilized on the surface of ZrO2 microstructures. [Copyright &y& Elsevier]

Abstract: A 3D model is set up to simulate the exposure process of inclined/rotated UV lithography for negative SU-8 resists. The formation of inclined resist pillars and microstructures with truncated cone shapes is simulated based on a 3D exposure model in combination with a post exposure bake model for chemically amplified resists and the Mack development model. As one of the interesting applications employing this promising lithography technique for MEMS fabrication, a solid microneedle for drug delivery is simulated. [Copyright &y& Elsevier]

Abstract: In this paper, we present the results of resist evaluation for the fabrication of metallic stamps used in the injection moulding of micro/nano fluidic devices. The resist was evaluated in terms of its suitability to combine direct proton beam writing (PBW) and UV lithography techniques for incorporating few tens of micron and micron- to millimeter sized features respectively. In a first step PBW is used to generate the fine features with smooth sidewall profiles in AR-P 3250, here the resist shows negative behavior. Following PBW, masked i-line UV lithography was used to create larger features to complete the device design, here the AR-P 3250 acts as a positive resist. After developing, the resist was used to generate the final mould through Ni electroplating, resulting in a high quality metallic stamp. [Copyright &y& Elsevier]

Abstract: A simple and fast methodology for protein patterning on silicon substrates is presented, providing an insight into possible issues related to the interaction between biological and microelectronic technologies. The method makes use of standard photoresist lithography and is oriented towards the implementation of biosensors containing Complementary Metal-Oxide-Semiconductor (CMOS) conditioning circuitry. Silicon surfaces with photoresist patterns were prepared and hydroxylated by means of resist- and CMOS backend-compatible solutions. Subsequent aminosilane deposition and resist lift-off in organic solvents resulted into well-controlled amino-terminated geometries. The discussion is focused on resist- and CMOS-compatibility problems related to the used chemicals. Some samples underwent gold nanoparticle (Au NP) labeling and Scanning Electron Microscopy (SEM) observation, in order to investigate the quality of the silane layer. Antibodies were immobilized on other samples, which were subsequently exposed to a fluorescently labeled antigen. Fluorescence microscopy observation showed that this method provides spatially selective immobilization of protein layers onto APTES-patterned silicon samples, while preserving protein reactivity inside the desired areas and low non-specific adsorption elsewhere. Strong covalent biomolecule binding was achieved, giving stable protein layers, which allows stringent binding conditions and a good binding specificity, really useful for biosensing. [Copyright &y& Elsevier]

Abstract: The sol–gel synthesis of hybrid materials offers special opportunities to combine polymer and glass properties and to create promising candidates for photonic applications. We report on the optical and morphological characterization of a new photosensitive epoxy based sol–gel system. Germanium ethoxide and 3-Glycidoxypropyltrimethoxysilane were used as precursors for hybrid sol-gel planar coatings. A photoacid generator was added to solution in order to allow the epoxy photopolymerization when the films are selectively exposed to UV light. The refractive index increase (Δn =0.015) induced by UV light allows the direct patterning of waveguiding structures having good morphological quality. Stripes and beam splitters were defined by direct UV exposition on silicon substrates. Moreover, we present structures made by thermal imprinting method. Silicon masters have been used to transfer relief gratings on the photopolymerizable epoxy sol-gel materials. Combining thermal imprinting technique and UV light exposition through a photomask, complex structures can be realized such as light couplers, sensors and wavelength filters. [ABSTRACT FROM AUTHOR]

Abstract: The integration of polymers into microelectronic devices is a challenging task, because the standard processes used in device fabrication, most notably photolithography, are not fully compatible with such materials. In this study, we demonstrate a possible route for the integration of micron size organic based Schottky diodes in a crossbar architecture, by standard UV lithography. The proposed integration route features a limited number of process steps and prevents the exposure of the active materials to UV. This approach was developed using poly(3-hexylthiophene) as a model compound and was successfully applied to different organic semiconductors. The electrical characteristics of the as prepared junctions reveal the successful patterning and demonstrate the compatibility of the process sequence steps with the organic materials. [Copyright &y& Elsevier]

Abstract: In this paper, we report a research work on the fabrication and selective metallization of high aspect ratio cured SU-8 polymer microstructures on silicon substrate using UV lithography technology and selective electroless plating method. Electroless plating of metal films on both the top and sidewall surfaces of microstructures was achieved while the silicon substrate was not coated. The details of the successfully developed procedures are presented, including the surface modification of cured SU-8 microstructures and the electroless plating of gold and copper. The surface modification was realized through attaching Au colloidal film to amine group, that forms a seed layer on cured SU-8 polymer for electroless plating of copper after the polymer surfaces were exposed under large UV irradiation. Experiments demonstrated that UV exposure dosage and illumination direction are two of the most dominant parameters in the selective electroless plating process. The approach can also be easily adapted to electroplating other metals with different electroless plating baths in theory. [Copyright &y& Elsevier]

Abstract: A novel layer-by-layer fabrication approach for the manufacturing of long embedded microchannels is presented. The methodology is based on the use of two epoxy based photoresist layers with different photo acid generator (PAG) concentration. Using this methodology long, functional microchannels are demonstrated. The technology has been optimized through tuning of the epoxy molecular weight, PAG concentrations and processing conditions. Finally, a basic microfluidic application is presented. [Copyright &y& Elsevier]

The divergences in superwettability between lotus leaves and rose petals result from minute differences in their morphological features. The fabrication of these hierarchical structures with unique wetting behaviors is fascinating but challenging. In this paper, a simple and cost-effective approach for controllable fabrication of hierarchical surfaces is presented. Two kinds of hierarchical polymethyl methacrylate (PMMA) structures, including microhemispherical and micropillar arrays covered with nanowires, were obtained by directly molding from anodic aluminum oxide (AAO) templates using UV lithography and two anodization steps. Multiscale structural features and surface chemical compositions influenced the adhesiveness of water droplets to the surfaces. The surface morphologies were precisely controlled by regulating the anodization condition of the AAO templates. The hierarchical surface with either a microhemispherical or micropillar array exhibits excellent hydrophobicity. Surfaces bearing micropillar arrays with –COOH modification show a rose petal effect but switch to a lotus effect after fluorination of the surface. In contrast, surfaces bearing microhemisphere arrayed hierarchical structures always show a rose petal effect, independent of the chemical composition of the surfaces. The controllable fabrication of surfaces with different wettability behaviors and switching between the lotus and rose petal effect is important for the design and fabrication of surfaces with desired properties. [Display omitted] • Various hierarchical surfaces of PMMA are achieved. • Transition from petal effect to lotus effect is demonstrated. • Multiscale structures and chemical compositions are keys for superwettability. [ABSTRACT FROM AUTHOR]

Anisotropic etching is a powerful technique for fabrication of micro/nanostructures. However, methods used to perform anisotropic etching, are very limited and costly. Wet chemical etching is a cost-effective and convenient method but it generally forms isotropic features. Here, the anisotropic wet etching of porous anodic alumina (PAA) using phosphoric acid to controllably form various structures is presented. Using photo-patterned SU-8 as protective layers and 5 wt% phosphoric acid as etchants at 60 °C, the exposed areas of PAA are vertically etched along the direction of inherent nanopores, while the areas coated with SU-8 are protected from etching. Arbitrary alumina micropillar arrays are achieved and the length of micropillar is determined by the thickness of the PAA films. In addition to cylindrical pillar arrays, sharp and concentric cone-shaped pillar arrays are obtained upon fine-tuning the etching conditions. The as-prepared super-hydrophilic alumina substrates with considerable surface roughness can be transformed into super-hydrophobic surfaces of 150° water contact angle. Hole arrays have also been fabricated using a reversed pattern protective layer before etching. These substrates are further used as templates to replicate various structures of polymers and thus provide a facile approach to fabricate hierarchical structures for a range of applications. Controllable wet chemical etching, either anisotropic or isotropic, has been performed on porous anodic alumina. A range of hierarchical structures with various interfacial properties have been fabricated and investigated. The reported technique provides a facile and cost-effective approach for the generation of micro/nano-structures for broad applications. [Display omitted] • Anisotropic wet etching is demonstrated on porous anodic alumina (PAA). • Various hierarchical structures of PAA are achieved. • The etching behavior depends on the structures of PAA and the concentration of etchants. • Hierarchical polymer structures are fabricated by molding from PAA templates. [ABSTRACT FROM AUTHOR]

Abstract: A T-NIL/UVL hybrid process offers the potential to combine the advantages of thermal nanoimprint (T-NIL) – to define patterns in the nanometre range in parallel over large areas, with the advantages of photolithography in the ultraviolet range (UVL) – to define large patterns easily. It is attractive for the preparation of e.g. sensors, where typically nm-scaled electrodes are connected to macroscopic contacts. We address the critical issues of such a process that until now have hampered its application in praxis. Major aspects result from the required compatibility of both processes, asking for resists that are imprintable at temperatures well below any deterioration of the photoactive components. Furthermore, the lithography step has to be performed over a pre-patterned surface, which may require overexposure; the pre-patterned surface is also crucial during an eventually required post-exposure bake, where pattern loss may result from unintended viscous flow during crosslinking. Examples with SU-8 as a chemically amplified negative resist demonstrate that the hybrid process works, if some processing parameters are well tuned. [Copyright &y& Elsevier]

Abstract: This paper presents a novel strategy for aligning patterns created with nano-imprint lithography (NIL) and UV lithography, similar to a mix-and-match process, which allows for the fabrication of large and small features in a single layer of resist. The resin used to demonstrate this new imprinting scheme is SU-8, a very widely used negative photoresist. Rapid stamp manufacturing using ma-N 2405 photoresist is also demonstrated. The processing scheme is a promising candidate for patterning of sensors featuring nanometre sized electrodes. [Copyright &y& Elsevier]

Abstract: Small size Schottky junctions using two different synthesized organic semiconductors (oligophenylenevinylenes) were integrated by standard UV lithography into crossbar arrays. The proposed integration scheme can be applied to a wide class of organics without affecting material properties. Current–voltage characteristics were studied in order to investigate which of the tested compounds could possibly reach the requirements for non-volatile memory applications. All the investigated devices displayed good rectifying properties, ranging from 102 to 104. On the other hand, one of the compounds reveals higher conductivity and possible reasons for this behavior are discussed. [Copyright &y& Elsevier]