We report on the development of a process chain for the conformal surface-structuring at sub-microscale of complex parts. More especially, the main objective was to manufacture functional microparts ...with engineered sidewall topographies. The solution proposed is based on the surface structuring of the sidewalls of resin molds used in the LIGA process (Lithography Galvanik Abformung). The surface structuring was achieved by depositing sub-micrometer particles prior to electroforming step. The length scale of the structures produced was controlled by the size of the particles deposited. The particle deposition process was monitored by using a quartz crystal microbalance and optimized on flat surfaces. It was successfully applied to produce structured nickel phosphorus LIGA parts. The structured surfaces produced were also used to create liquid infused surfaces, having low wetting hysteresis.
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Multimode polymer waveguides were created using epoxy resin materials. The fabrication process used non-contact photolithography, which is a simple and cost-effective method. During the experiments, ...a reliable and efficient developer was obtained. The samples were analyzed using scanning electron microscopy and the results showed that the ridge waveguides had a smooth surface and vertical sidewalls. The cross-section size was approximately 50 × 55 μm2. The waveguides had a transmission loss was about 0.08 dB/cm at a wavelength of 850 nm, which was measured using the cut-back method. Additionally, the waveguides were found to be stable in thermal and damp heat conditions.
•We present a developer for the production of epoxy resin optical waveguides in this paper.•We utilized a non-contact ultraviolet lithography method for the same.•We have also outlined a complete process for preparing the epoxy resin optical waveguide.•The performance of the sample was tested by conducting cut-back and aging tests.
Plasmonic nanostar‐dimers, decoupled from the substrate, have been fabricated by combining electron‐beam lithography and reactive‐ion etching techniques. The 3D architecture, the sharp tips of the ...nanostars and the sub‐10 nm gap size promote the formation of giant electric‐field in highly localized hot‐spots. The single/few molecule detection capability of the 3D nanostar‐dimers has been demonstrated by Surface‐Enhanced Raman Scattering.
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► Conventional lithography techniques and resist materials are discussed. ► Methods include optical lithography, electron beam- and ion beam-lithography. ► Unconventional ...high-resolution patterning technologies are reviewed. ► Discussed unconventional methods include printing, molding and embossing. ► Strengths, limitations and prospects of patterning technologies are treated.
This review provides a survey of lithography techniques and the resist materials employed with these techniques. The first part focuses on the conventional lithography methods used to fabricate complex micro- and nano-structured surfaces. In the second part, emphasis is placed on patterning with unconventional lithography techniques such as printing, molding, and embossing, and on their development into viable, high-resolution patterning technologies.
Theory predicts that periodic photonic nanostructures should outperform their random counterparts in trapping light in solar cells. However, the current certified world-record conversion efficiency ...for amorphous silicon thin-film solar cells, which strongly rely on light trapping, was achieved on the random pyramidal morphology of transparent zinc oxide electrodes. Based on insights from waveguide theory, we develop tailored periodic arrays of nanocavities on glass fabricated by nanosphere lithography, which enable a cell with a remarkable short-circuit current density of 17.1 mA/cm2 and a high initial efficiency of 10.9%. A direct comparison with a cell deposited on the random pyramidal morphology of state-of-the-art zinc oxide electrodes, replicated onto glass using nanoimprint lithography, demonstrates unambiguously that periodic structures rival random textures.
The investigation of the crossing of exogenous substances through the blood‐brain barrier (BBB) is object of intensive research in biomedicine, and one of the main obstacles for reliable in vitro ...evaluations is represented by the difficulties at the base of developing realistic models of the barrier, which could resemble as most accurately as possible the in vivo environment. Here, for the first time, a 1:1 scale, biomimetic, and biohybrid BBB model is proposed. Microtubes inspired to the brain capillaries were fabricated through two‐photon lithography and used as scaffolds for the co‐culturing of endothelial‐like bEnd.3 and U87 glioblastoma cells. The constructs show the maturation of tight junctions, good performances in terms of hindering dextran diffusion through the barrier, and a satisfactory trans‐endothelial electrical resistance. Moreover, a mathematical model is developed, which assists in both the design of the 3D microfluidic chip and its characterization. Overall, these results show the effective formation of a bioinspired cellular barrier based on microtubes reproducing brain microcapillaries to scale. This system will be exploited as a realistic in vitro model for the investigation of BBB crossing of nanomaterials and drugs, envisaging therapeutic and diagnostic applications for several brain pathologies, including brain cancer.
A 3D, real‐scale, and biomimetic model of the blood‐brain barrier (BBB) is proposed. Taking advantage of the two‐photon lithography technique, an in vitro biohybrid dynamic BBB model is developed and fully characterized, aiming at obtaining a realistic tool for the testing of drug targeting and delivery at the level of the central nervous system.
Since 2019, EUV lithography with a wavelength of 13.5 nm has been used for the mass production of 7 nm+ node semiconductor logic devices, and pattern processing of 16-nm-half pitch and below is also ...possible. According to IRDS, further miniaturization is still required by 2037. In EUVL, the most important issue is the development of resists with high sensitivity, high resolution, and low line-width roughness, simultaneously. At the NewSUBARU synchrotron light facility, the exposure tool on EUV interference lithography was developed to replicate EUV resist patterns, which can evaluate the resolution and line-width roughness performance. In this study, it is reported that the current results and status of this tool, especially on the improvement of the exposure shot numbers with a new grating holder and exposure-process automation by developing specific software program. As a result, the exposure shot numbers were improved to 48 shots, which were more than three times larger than those of the previous condition.
Developing high-throughput nanopatterning techniques that also allow for precise control over the dimensions of the fabricated features is essential for the study of cell-nanopattern interactions. ...Here, we developed a process that fulfills both of these criteria. Firstly, we used electron-beam lithography (EBL) to fabricate precisely controlled arrays of submicron pillars with varying values of interspacing on a large area of fused silica. Two types of etching procedures with two different systems were developed to etch the fused silica and create the final desired height. We then studied the interactions of preosteoblasts (MC3T3-E1) with these pillars. Varying interspacing was observed to significantly affect the morphological characteristics of the cell, the organization of actin fibers, and the formation of focal adhesions. The expression of osteopontin (OPN) significantly increased on the patterns, indicating the potential of the pillars for inducing osteogenic differentiation. The EBL pillars were thereafter used as master molds in two subsequent processing steps, namely soft lithography and thermal nanoimprint lithography for high-fidelity replication of the pillars on the substrates of interest. The molding parameters were optimized to maximize the fidelity of the generated patterns and minimize the wear and tear of the master mold. Comparing the replicated feature with those present on the original mold confirmed that the geometry and dimensions of the replicated pillars closely resemble those of the original ones. The method proposed in this study, therefore, enables the precise fabrication of submicron- and nanopatterns on a wide variety of materials that are relevant for systematic cell studies.
Submicron pillars with specific dimensions on the bone implants have been proven to be effective in controlling cell behaviors. Nowadays, numerous methods have been proposed to produce bio-instructive submicron-topographies. However, most of these techniques are suffering from being low-throughput, low-precision, and expensive. Here, we developed a high-throughput nanopatterning technique that allows for control over the dimensions of the features for the study of cell-nanotopography interactions. Assessing the adaptation of preosteoblast cells showed the potential of the pillars for inducing osteogenic differentiation. Afterward, the pillars were used for high-fidelity replication of the bio-instructive features on the substrates of interest. The results show the advantages of nanoimprint lithography as a unique technique for the patterning of large areas of bio-instructive surfaces.
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A moth‐eye nanostructured mp‐TiO2 film using conventional lithography, nano‐imprinting and polydimethyl‐siloxane (PDMS) stamping methods is demonstrated for the first time. Power conversion ...efficiency of the moth‐eye patterned perovskite solar cell is improved by ≈11%, which mainly results from increasing light harvesting efficiency by structural optical property.
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