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Anodized aluminum oxide (AAO) molds were used for the production of large-area and inexpensive superhydrophobic polymer films. A controlled anodization methodology was developed for the fabrication of hierarchical micro–nanoporous (HMN) AAO imprint molds (HMN-AAO), where phosphoric acid was used as both an electrolyte and a widening agent. Heat generated upon repetitive high-voltage (195 V) anodization steps is effectively dissipated by establishing a cooling channel. On the HMN-AAO, within the hemispherical micropores, arrays of hexagonal nanopores are formed. The diameter and depth of the micro- and nanopores are 18/8 and 0.3/1.25 µm, respectively. The gradual removal of micropatterns during etching in both the vertical and horizontal directions is crucial for fabricating HMN-AAO with a high aspect ratio. HMN-AAO rendered polycarbonate (PC) and polymethyl methacrylate (PMMA) films with respective water contact angles (WCAs) of 153° and 151°, respectively. The increase in the WCA is 80% for PC (85°) and 89% for PMMA (80°). On the PC and PMMA films, mechanically robust arrays of nanopillars are observed within the hemispherical micropillars. The micro–nanopillars on these polymer films are mechanically robust and durable. Regular nanoporous AAO molds resulted in only a hydrophobic polymer film (WCA = 113–118°). Collectively, the phosphoric acid-based controlled anodization strategy can be effectively utilized for the manufacturing of HMN-AAO molds and roll-to-roll production of durable superhydrophobic surfaces. [ABSTRACT FROM AUTHOR]

In this paper we present polymer surfaces inspired by the calamistrum of cribellate spiders. The calamistrum resembles a micro-comb with a finger-print-like nanorippled topography, which allows cribellate spiders to handle and process nanofibers, without sticking to them. Due to its morphology, the calamistrum has a reduced surface for contact with the nanofibers, which therefore reduces the adhesive forces. Three different types of structured surfaces were prepared: nanostructured surfaces (ripples), microstructured surfaces (lines), and a combination of micro- and nanostructured surfaces (lines superimposed with ripples). Polymer lines were created using UV mask lithography. Nanoripples, i.e., laser-induced periodic surface structures, were fabricated by exposure to a KrF* laser beam. Nanofibers were produced and deposited onto each sample by electrospinning. To quantify each samples’ adhesiveness, a peel-off test was used, and the results were plotted and compared against the control samples–a flat polymer film. Our results indicate that lines have a stronger influence on the adhesion reduction than the nanoripples: nanoripples reduce fiber adhesion by 7%, whereas the lines reduce it by 28%. The highest adhesion reduction of 33% is obtained for the polymer surfaces with a combination of both lines and nanoripples. Our results open new insights in the field of artificial nanofiber adhesion on micro- and nanopatterned surfaces, which are essential when designing tools for nanofiber handling. [ABSTRACT FROM AUTHOR]

In this paper we present polymer surfaces inspired by the calamistrum of cribellate spiders. The calamistrum resembles a micro-comb with a finger-print-like nanorippled topography, which allows cribellate spiders to handle and process nanofibers, without sticking to them. Due to its morphology, the calamistrum has a reduced surface for contact with the nanofibers, which therefore reduces the adhesive forces. Three different types of structured surfaces were prepared: nanostructured surfaces (ripples), microstructured surfaces (lines), and a combination of micro- and nanostructured surfaces (lines superimposed with ripples). Polymer lines were created using UV mask lithography. Nanoripples, i.e., laser-induced periodic surface structures, were fabricated by exposure to a KrF* laser beam. Nanofibers were produced and deposited onto each sample by electrospinning. To quantify each samples’ adhesiveness, a peel-off test was used, and the results were plotted and compared against the control samples–a flat polymer film. Our results indicate that lines have a stronger influence on the adhesion reduction than the nanoripples: nanoripples reduce fiber adhesion by 7%, whereas the lines reduce it by 28%. The highest adhesion reduction of 33% is obtained for the polymer surfaces with a combination of both lines and nanoripples. Our results open new insights in the field of artificial nanofiber adhesion on micro- and nanopatterned surfaces, which are essential when designing tools for nanofiber handling.

Micro electro-mechanical systems (MEMS) combining sensing and microfluidics functionalities, as are common in Lab-on-Chip (LoC) devices, are increasingly based on polymers. Benefits of polymers include tunable material properties, the possibility of surface functionalization, compatibility with many micro and nano patterning techniques, and optical transparency. Often, additional materials, such as metals, ceramics, or silicon, are needed for functional or auxiliary purposes, e.g., as electrodes. Hybrid patterning and integration of material composites require an increasing range of fabrication approaches, which must often be newly developed or at least adapted and optimized. Here, a microfabrication process concept is developed that allows one to implement attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and electrochemistry on an LoC device. It is designed to spatially resolve chemical sensitivity and selectivity, which are instrumental for the detection of chemical distributions, e.g., during on-flow chemical and biological reaction chemistry. The processing sequence involves (i) direct-write and soft-contact UV lithography in SUEX dry resist and replication in polydimethylsiloxane (PDMS) elastomers as the fluidic structure; (ii) surface functionalization of PDMS with oxygen plasma, 3-aminopropyl-triethoxysilane (APTES), and a UV-curable glue (NOA 73) for bonding the fluidic structure to the substrate; (iii) double-sided patterning of silicon nitride-coated silicon wafers serving as the ATR-FTIR-active internal reflection element (IRE) on one side and the electrode-covered substrate for microfluidics on the back side with lift-off and sputter-based patterning of gold electrodes; and (iv) a custom-designed active vacuum positioning and alignment setup. Fluidic channels of 100 μm height and 600 μm width in 5 mm thick PDMS were fabricated on 2" and 4" demonstrators. Electrochemistry on-chip functionality was demonstrated by cyclic voltammetry (CV) of redox reactions involving iron cyanides in different oxidation states. Further, ATR-FTIR measurements of laminar co-flows of H2O and D2O demonstrated the chemical mapping capabilities of the modular fabrication concept of the LoC devices. [ABSTRACT FROM AUTHOR]

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]

Nano-fluidic devices have great potential in the applications of biology, chemistry, and medicine. However, their applications have been hampered by their expensive or complicated fabrication methods. We present a new and simple approach to fabricate low-cost two-dimensional (2D) nano-mold based on ultraviolet (UV) lithography and wet etching. The influence of UV lithography parameters on the width dimension of AZ5214 photoresist was investigated. With the optimized parameters of UV lithography, the width dimension of photoresist patterns had sharply decreased from microscale to nano-scale. At the same time, the influences of etching time on the over-etching amount of SiO2 film and nano-mold depth were also analyzed for further reducing the width of nano-mold. In addition, the effect of photoresist mesas deformation on the nano-mold fabrication was also studied for improving the quality of nano-mold. By the proposed method, trapezoid cross-sectional 2D nano-mold with different dimensions can be obtained for supporting varied applications. The minimum nano-mold arrays we fabricated are the ones with the dimensions of 115 nm in top edge, 284 nm in bottom edge, and 136 nm in depth. This method provides a low-cost way to fabricate high-quality and high-throughput 2D nano-mold. [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]

Single-shot grating-based phase-contrast imaging techniques offer additional contrast modalities based on the refraction and scattering of X-rays in a robust and versatile configuration. The utilization of a single optical element is possible in such methods, allowing the shortening of the acquisition time and increasing flux efficiency. One of the ways to upgrade single-shot imaging techniques is to utilize customized optical components, such as two-dimensional (2D) X-ray gratings. In this contribution, we present the achievements in the development of 2D gratings with UV lithography and gold electroplating. Absorption gratings represented by periodic free-standing gold pillars with lateral structure sizes from 5 μm to 25 μm and heights from 5 μm to 28 μm have shown a high degree of periodicity and defect-free patterns. Grating performance was tested in a radiographic setup using a self-developed quality assessment algorithm based on the intensity distribution histograms. The algorithm allows the final user to estimate the suitability of a specific grating to be used in a particular setup. [ABSTRACT FROM AUTHOR]

In multigigahertz integrated circuit design, the extra delay and power losses due to surface roughness in copper (Cu) interconnects is more evident than ever before and needs utmost consideration. This paper reports novel closed-form expressions for parameter extraction in chip-to-chip Cu interconnects at several gigahertz frequency ranges considering experimentally measured fractal surface roughness. Backplane (BP) and printed circuit board (PCB) links are considered here to study the effect of surface roughness in chip-to-chip Cu interconnects. Our proposed model is verified with experimental characterization performed on fabricated interconnects structures as well as simulation data obtained using full-wave electromagnetic field solvers, i.e., HFSS and Q3D extractor, that show excellent accuracy. Our analysis, for the first time, quantitatively proves the penalty incurred due to surface roughness in chip-to-chip interconnects using experimental measured realistic surface profiles. We observe that surface roughness strongly affects the interconnect performance metrics, i.e., delay, energy-delay product, and bandwidth density of BP and PCB chip-to-chip interconnects at higher frequency regimes. At 100 GHz and 50 cm length, BP interconnects with all four rough surfaces exhibit $2.6\times $ and $2.8\times $ higher delay and energy budget, respectively, when compared to interconnects with smooth surfaces. Similarly, PCB interconnects in the worst case exhibit $2.5\times $ and $2.6\times $ higher delay and energy budget, respectively, due to surface roughness. We also present computational overhead for simulating BP and PCB interconnects with rough surfaces. The simulation time, physical memory, matrix size, and number of tetrahedrons increase by several times due to surface roughness. Finally, we present eye diagrams at 10- and 15-Gb/s data rates that show 53.4% and 40% penalty on eye height and signal-to-noise ratio, 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]

Microfluidics-based lab-on-a-chips have many advantages, one of which is to provide physiologically relevant settings for cell biology experiments. Thus there is an ever increasing interest in their fabrication. Our goal is to construct three dimensional (3D) Controlled in vitro Microenvironments (CivMs) that mimic the in vivo microenvironments. Here, we present our optimized fabrication method that works for various lab-on-a-chip designs with a wide range of dimensions. The most crucial points are: • While using one type of SU-8 photoresist (SU-2075), fine tuning of ramp, dwell time, spin speed, durations of soft bake, UV exposure and development allows fabrication of SU-8 masters with various heights from 40 to 600 μm. • Molding PDMS (polydimethylsiloxane) at room temperature for at least two days instead of baking at higher temperatures prevents not only tears and bubbles in PDMS stamps but also cracks in the SU-8 master. • 3D nature of the CivMs is ensured by keeping the devices inverted during gel polymerization.

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]

In this work, an engineered hydrogel system with a 2D and 3D tunable cross-linking degree is presented. A precise chemical design by the introduction of cross-linkable units, having reaction orthogonality, allows to control the network formation both in time and space and to selectively alter the hydrogel physical properties. Hydrogel chemistry has been tailored in order to produce spatially controlled stiffness changes and drive cell morphology through mechanical cues. Elastic modulus rises by more than double after photocross-linking, as shown by atomic force microscopy measurements. Biological response is also analyzed and stiffness-dependent cell spreading and proliferation are verified. Different pattern geometries are successfully realized by UV lithography, allowing 2D cross-linking modulation. Furthermore, 3D mechanical tuning at micro- and submicrometer scale by two-photon polymerization makes this system a biologically relevant matrix to study cell functions and tissue development. [ABSTRACT FROM AUTHOR]

Single-shot grating-based phase-contrast imaging techniques offer additional contrast modalities based on the refraction and scattering of X-rays in a robust and versatile configuration. The utilization of a single optical element is possible in such methods, allowing the shortening of the acquisition time and increasing flux efficiency. One of the ways to upgrade single-shot imaging techniques is to utilize customized optical components, such as two-dimensional (2D) X-ray gratings. In this contribution, we present the achievements in the development of 2D gratings with UV lithography and gold electroplating. Absorption gratings represented by periodic free-standing gold pillars with lateral structure sizes from 5 µm to 25 µm and heights from 5 µm to 28 µm have shown a high degree of periodicity and defect-free patterns. Grating performance was tested in a radiographic setup using a self-developed quality assessment algorithm based on the intensity distribution histograms. The algorithm allows the final user to estimate the suitability of a specific grating to be used in a particular setup.

Metamaterial absorbers are photonic structures composed of an array of sub-wavelength metallic patterns. Results in literature are usually based on structures of nominal dimensions, despite the significant effect of fabrication tolerances on performance. This research aims to identify the main sources of uncertainty and to investigate their effect, notably that of an irregular surface quality (i.e., roughness) of the thin metallic layer and the lithography related variations in size and shape. The effect of the shape and positioning of the resonance peak was investigated and validated using mid-infrared metamaterial absorbers. This sensitivity analysis is essential to the batch fabrication of metamaterial absorbers for MEMS applications.

Contact exposure is expected to occur in conventional lithography, and can be a source of process deviations (such as shrinking and distortion of templates) during reactive ion etching and inductively coupled plasma etching, as these deviations are induced by ion bombardment. This typically results in undesired sidewall effects, such as lower sidewall angles. Here we report a novel hanging bowlshaped lithography mask that can effectively minimize sidewall effects in lithography applications. As a test case, standard silicon carbide pillars with vertical sidewalls are fabricated using this mask. The mask could be used for fabrication of high-aspect-ratio structures with ultra-violet lithography. [ABSTRACT FROM AUTHOR]

A synthetic route is demonstrated to build purely polymeric nanostructured multilayer coatings, adaptable to arbitrary surfaces, and capable of efficiently blocking by reflection a targeted and tunable ultraviolet (UV) range. Reflection properties are determined by optical interference between UV light beams reflected at the interfaces between polystyrene layers of different porosity and hence refractive index. As no dopant absorber intervenes in the shielding effect, polymer degradation effects are prevented. Alternated porosity results from the modulation of photochemical effects at the few tens of nanometers length scale, combined with the collective osmotic shock induced during the processing of the precursor diblock copolymer film. Experimental evidence of the application of this method to coat rough surfaces with smooth and conformal UV protecting films is provided. [ABSTRACT FROM AUTHOR]

In order to produce disposable microneedles for blood-collection devices in smart homecare monitoring systems, we have developed a simple low-cost scalable process for mass fabrication of sharp-tipped microneedle arrays. The key feature in this process is a design of computer numerical control-machined aluminum sample (CAS). The inclined sidewalls on the CAS enable microfabricated traditional-shaped microneedles (TMNs) to be produced in the desired shape. This process provides significant advantages over other methods that use inclined lithography or anisotropic wet etching. TMNs with a length of 1510 \mu \textm , a hollow diameter of 120 \mu \textm , and the tip radius of 16 \mu \textm were successfully fabricated. Theoretical study and practical measurements of fracture force verified the improved mechanical strength of TMNs for safe skin insertion. In addition, the penetration tests on cadaver pork skin demonstrated that the TMNs could pierce the pork skin without breaking, and create the transport conduits through microneedle lumens. [2014-0361] [ABSTRACT FROM PUBLISHER]

Diamond-like carbon (DLC) coating is becoming a promising protective coating layers due to its superior properties. In this study, instead of protective coating, DLC film was applied as the only component for micropattern then etched with lithography and lift-off process selectively. Furthermore, DLC film has been fabricated on aluminum roll mold. Then UV curing resin was applied to form the pattern on the polyethylene terephthalate (PET) film. The dimension and formation of the DLC micropattern on roll mold were analyzed. Moreover, the Raman spectroscopic of nitrogen-doped DLC film was analyzed. [ABSTRACT FROM AUTHOR]

In this paper, we report a multianode paper-based microbial fuel cell (MFC) capable of generating a power density of 28.4 μW/cm2. This MFC features: 1) flexible multilayered carbon cloth anodes for bacterial attachment and 2) paper reservoirs for holding the anolyte and catholyte for an extended period of time. The hydrophobic barriers in the anodes and paper-based reservoirs were patterned by impregnating and selectively polymerizing photoresist through UV lithography. Upon inoculum/catholyte introduction, a current of 211 μA/cm2 was immediately generated. By using the multianode MFC, the power and current densities increased by 5× and 3×, respectively, compared with a single anode one. The paper-based MFC is expected to be a simple and easy-to-use power source for single-use diagnostic biosensors because even sewage or soiled water in a puddle can become an excellent source for operating MFCs and harvesting electricity through bacterial metabolism. [ABSTRACT FROM PUBLISHER]

A wide variety of environmental factors including physical and biochemical signals are responsible for stem cell behavior and function. In particular, matrix elasticity and cell shape have been shown to determine stem cell function, yet little is known about the interplay between how these physical cues control cell differentiation. For the first time, by using ultraviolet (UV) lithography to pattern poly(ethylene) glycol (PEG) hydrogels, it is possible to manufacture microenvironments capable of parsing the effects of matrix elasticity, cell shape, and cell size in order to explore the relationship between matrix elasticity and cell shape in mesenchymal stem cell (MSC) lineage commitment. These data show that cells cultured on 1000 μm2 circles, squares, and rectangles are primarily adipogenic lineage regardless of matrix elasticity, while cells cultured on 2500 and 5000 μm2 shapes more heavily depend on shape and elasticity for lineage specification. It is further characterized how modifying the cell cytoskeleton through pharmacological inhibitors can modify cell behavior. By showing MSC lineage commitment relationships due to physical signals, this study highlights the importance of cell shape and matrix elasticity in further understanding stem cell behavior for future tissue engineering strategies. [ABSTRACT FROM AUTHOR]

Drug delivery through micromachined needles is an attractive alternative to intramuscular and subdermal injection by hypodermic needles, due to the potential for reduced pain caused by the micro-sized needles. In this paper, a polymer-based fabrication process using UV lithography into micromolds is developed, allowing the fabrication of microneedle (MN) shafts, tips, lumens, and substrate baseplate using lithography. Using UV lithography into micromolds allows complex three-dimensional structures to be defined, since both mask patterns and mold topography are available to define the structures. A hollow MN array and baseplate, in which the needle lumens extend through the thickness of the baseplate, are demonstrated. Fabricated SU-8 MNs are 825 \mum in height and 400 \mum in width, with a pyramidal tip; the needle lumen, 120 \mum in diameter, intersects with one of the faces of the pyramidal tip. Mechanical characterization of the fabricated MNs shows that the fracture force of a single needle against a rigid surface is 12.0 N. The insertion force of a single needle into porcine skin is empirically determined to be 2.4 N. The fracture force of the needle against porcine skin is observed to be in excess of 90 N. \hfill[2012\-0359] [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]

In this paper, we present our results from process development and characterization of optical oxygen sensors that are patterned by traditional UV lithography. An oxygen sensitive luminescent probe, platinum octaethylporphyrin, was encapsulated in commercially purchased photoresist (AZ5214) to form uniform thin sensor films on fused silica substrates. Plasticizer ethoxylated trimethylolpropane triacrylate (SR454) was added to the dye-photoresist sensor mixtures to improve the oxygen sensitivity. The optimum sensor mixture composition that can be patterned with maximum sensitivity was identified. The microfabrication process conditions, cell adherence and oxygen sensitivity results from patterned structures were characterized in detail. Down to 3 μm features have been fabricated on fused silica substrates using the developed techniques. The result implies that the developed methods can provide a feasible way to miniaturize the optical sensor system for single cell analysis with precise control of sensor volume and response. [ABSTRACT FROM PUBLISHER]

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]

A positive tone resist for UV and X-ray lithography synthesized starting from an organically modified silicon alkoxide, bis(triethoxysilyl)benzene, through the sol-gel method, either in basic or in acid catalysis, is presented. Being directly photo-processable, the sol-gel system combines the opportunity to avoid the use of a sacrificial layer in the fabrication process, with the possibility to fit electro-optical and structural properties of the final device material to specific requirements. In addition, the positive tone behaviour allows to preserve the organic functionality of the system after irradiation. A study of the optical and structural modifications induced on the resist by irradiation has been carried out by FT-IR spectroscopy, UV-vis spectroscopy and spectroscopic ellipsometry. An interpretation of the mechanisms leading to exposed cross-linked film development is given. Experiments have demonstrated the possibility of obtaining structures on films with lateral dimensions spanning from the micron scale up to less than a hundred nm, opening the way to a possible exploitation of such positive tone functional system in the field of miniaturized sensors. [ABSTRACT FROM AUTHOR]

In this review hybrid organic-inorganic (HOI) resists as emerging materials alternative to organic polymers for micro and nanolithography are presented and discussed. In particular, results on sol-gel materials belonging to 3-glycidoxypropyltrimethoxysilane based HOI are presented and reviewed, highlighting as various lithographic techniques can be used to pattern their surface and showing examples of micro- and nano-patterned structures achieved with radiation assisted lithography (UV, X-rays and electron beam) or imprint techniques. It will be demonstrated the particular versatility shown by some of these materials, that in some case can be processed with all the lithographic methods herein considered, without any significant modification of their main composition and synthesis procedure. Moreover, results about the investigation of interaction between radiation and HOI materials and thermal treatment will be discussed, as well as possible synthesis strategies and composition modification developed in order to improve efficiency of curing, tailor HOI properties to specific needs (optical properties, resist composition, mechanical stability, etc.) and explore innovative and non conventional patterning techniques. The reported results highlight as these novel materials, thanks to their solution processability and higher performances respect to commercial polymeric resists, allow to use the above mentioned lithographic techniques in a direct patterning process, strongly simplifying conventional technique and reducing their processing time and costs. [ABSTRACT FROM AUTHOR]

Magnetostatic coupling in arrays of closely spaced magnetic elements is becoming an important issue in the path to the fabrication of spintronic devices. Dense chains of rounded-corners rectangular particles (dots) of lateral size 1025 × 450 nm, with interdot spacing variable in the range between 55 and 700 nm, have been patterned by deep UV lithography, followed by the lift-off of two permalloy films of thickness 20 and 40 nm. Magneto-optical Kerr effect (MOKE) and magnetic force microscopy (MFM) experiments, together with micromagnetic simulations, were performed to study the dependence of the magnetization configuration on the dipolar coupling. Both MOKE measurements and MFM images clearly show that, at remanence, the magnetic state of isolated particles of thickness 20 nm takes the form of a distorted single domain (C-state or S-State configurations). Instead, when the particle thickness is double (40 nm), closure states characterized by one, two or three vortices occur at remanence. However, when the 40 nm thick dots are placed in chains along the easy axis (head to tail), as the separation is progressively reduced, the single domain state is stabilized at remanence. On the other hand, when the 40 nm thick particles are placed side by side in chains the effect of dipolar interactions is to favour the nucleation of vortex states. For small inter-element separation, there is only one vortex per particle and it has the same chirality in adjacent particles, due to the dipolar interaction. Different from this, for the 20 nm thick samples and sub-100 nm separation, adjacent particles are single-domain but with antiparallel magnetization in neighbour elements, like in an artificial antiferromagnet. [ABSTRACT FROM AUTHOR]

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]

This paper reports on a novel and simple 3-D fabrication technique of microstructures embedded in a single-layer negative resist. The proposed technique allows one the fabrication of an embedded microstructure with a single exposure and the subsequent development process. The unique feature of the proposed fabrication technique is the development method which enables the rapid fabrication of polymer-based microfluidic systems with relatively large areas but with micrometer-sized features. For example, features of microchannels, on the order of 100 \mu\m in width and 50 mm in length, sufficient for microfluidic systems, were successfully fabricated with a relatively short (< 20 min) development time. These features are realized by the interesting physical response of the top-membrane to the developer; the developer permeates through the top-membrane region made of semi-cross-linked photoresist, and the permeated developer dissolves the uncross-linked photoresist at the same time. As a step toward the practical use of the proposed development method, process parameter sets (exposure dose, postexposure bake (PEB) time, and temperature) related to the cross-linking reaction of the top-membrane region were investigated by employing the cross-linking reaction model describing the chemical reaction during the UV exposure and the PEB. Through a series of experiments, 1) a criterion of process parameter sets for the fabrication of centimeter-long embedded microchannels was obtained, and 2) the applicability to polymer-based microfluidic systems was successfully demonstrated.\hfill[2010-0029] [ABSTRACT FROM PUBLISHER]

Abstract: Materials with chemical micropatterned surface have broad applications in many fields. In this article, we report a simple one-step UV lithography method to activate inert hydrocarbon monolayers for spontaneous formation of water and covalently immobilized protein micropatterns on the surface. Two types of hydrocarbon monolayers including octadecyltrichlorosilane (OTS) on silicon oxide and 1-hexadecene on hydrogen-terminated silicon were studied. It was found that after UV modifications, water can form micropatterns spontaneously on both surfaces. Furthermore, when protein solutions were used, covalently immobilized protein micropatterns can be formed. Our XPS results and controlled reducing experiments showed that UV exposure transformed inert monolayers into active surfaces with aldehyde groups, which are responsible for the covalent immobilization of proteins. The method reported herein can be applied under ambient conditions without having a high vacuum system. It can also be extended to pattern other biomolecules bearing amine groups. [Copyright &y& Elsevier]

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]

Fabrication and optical characterization of single-mode polymeric embedded waveguides are performed. A specific material combination (SU-8 2005 as core and the modified SU-8 mr-L 6050XP as cladding) is chosen in order to obtain a small refractive index difference for single-mode propagation combined with the conventional fabrication method UV lithography to facilitate the integration of different types of optical detection methods on lab-on-a-chip systems. We analyze the behavior of the refractive index and carefully observe how the value of the refractive index can be tailored during processing. We show that we can fabricate waveguides with an index difference in the order of 10-3 , where both the core material and the cladding material are based on SU-8. The refractive index measurements are performed on thin polymeric films, while further optical characterizations are performed on waveguides with a height of 4.5 mum. We study the mode profiles of these waveguides and confirm that only the fundamental mode is excited. We also study the absorption spectra of the material in the wavelength range 800-1600 nm combined with cut-back measurements. We find that the waveguides have a propagation loss of 0.2-3 dB/cm in this wavelength range [ABSTRACT FROM PUBLISHER]

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]

This paper describes the fabrication and characterization of optical/electrical printed circuit boards (O/E-PCB) with embedded multimodal step index (MM-SI) waveguides and integrated out-of-plane micromirrors (IMMs) for three-dimensional (3-D) optical interconnects. Optical circuitry is built up on PCBs using UV lithography; 45° input/output (I/O) couplers are fabricated by inclined exposure. Commercial polymers are used as optical core and cladding materials. Critical mirror properties of angle, surface quality, reflectivity, and coupling efficiency are characterized experimentally and theoretically. Optical and scanning electron microscopy, white light interferometry, and fiber scanning method are used in the investigations. Sloping profiles measured as a function of the incident light showed the attainment of mirror angles of α=36°-45° with ±2° consistency. Near-field optical imaging with a white light source showed that out-of-plane beam turning was achieved. Topography investigations revealed a rectilinear negative tapering shape regardless of the incoming beam angle or type of substrate. However, higher substrate reflectancy was observed to lower the mirror angle. The average propagation loss measured for 10-cm-long waveguides at λ=850 nm by the cut-back method was 0.60 dB/cm; the excess loss calculated for the mirror coupling was 1.8-2.3 dB. The results showed that the IMMs can be incorporated in O/E-PCBs to couple light in and out of planar waveguides. Furthermore, the presented results indicate that optical waveguides with integrated micromirrors for optical 3-D wiring can be produced compatible with volume manufacturing techniques. [ABSTRACT FROM PUBLISHER]

In this paper, the impact of the Si nanocrystals technological fluctuations on the programming window dispersion of multi nanocrystals memory is thoroughly investigated. Technological dispersions of different nanocrystals populations, directly measured by high-resolution transmission electron microscopy, are used as starting points for the modeling of the device characteristics. Numerical Monte Carlo simulations as well as an original compact modeling, based on the compound distributions (CD) statistics, are here presented. Exact analytical results (CD model), approximated analytical results (CD+Central Limit Theorem model) and numerical results (numerical convolution) are deeply discussed. Finally, the good agreement between our simulations and experimental data of ultrascaled nanocrystal devices, made by conventional UV lithography or by e-beam lithography, definitively confirms the validity of our theoretical approach. [ABSTRACT FROM PUBLISHER]

We report the synthesis and optical properties (refractive index and absorption) of a class of highly fluorinated, photosensitive ormosils, and investigate their refractive index, absorption and UV-imprinting properties to assess them for optical waveguide applications. [ABSTRACT FROM AUTHOR]

A novel laser-assisted chip bumping technique is presented in which bumps are fabricated on a carrier and subsequently transferred onto silicon chips by a laser-driven release process. Copper bumps with gold bonding layers and intermediate nickel barriers are fabricated on quartz wafers with pre-deposited polyimide layers, using UV lithography and electroplating. The bumps are thermosonically bonded to their respective chips and then released from the carrier by laser machining of the polyimide layer, using light incident through the carrier. Bumps of 60 to 85 μm diameter and 50 μm height at a pitch of 127 μm have been fabricated in peripheral arrays. Parallel bonding and subsequent transfer of arrays of 28 bumps onto test chips have been successfully demonstrated. Individual bump shear tests have been performed on a sample of 13 test chips, showing an average bond strength of 26 gf per bump [ABSTRACT FROM PUBLISHER]

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]