Search Results (6)

This article proposes a novel transparent conductive film structure to solve the problem of electrostatic accumulation in traditional nanoimprint lithography processes. This structure is formed by spin-coating a layer of silver nanowire (AgNWs) transparent conductive films on a graphic substrate, followed by coating a layer of polydimethylsiloxane (PDMS) on the surface of the film. After the PDMS is cured, it is peeled off from the substrate to form a free-standing elastic three-dimensional structured surface. These transparent conductive films are not only designed to mitigate static electricity generated during the nanoimprint lithography process, but also have excellent UV transparency, with a 325 nm UV transmittance of up to 90%. At the same time, it exhibits good conductivity with a sheet resistance of 20 Ω/sq. In addition, the films have excellent elasticity and can maintain stable conductivity during repeated stretching, providing a novel solution for flexible optoelectronic devices and nanoimprint technology. Full article

Directed cell migration is crucial for numerous biological processes, including tissue regeneration and cancer metastasis. However, conventional symmetrical micropatterns typically result in bidirectional cell migration guidance instead of unidirectional guidance. In this study, polydimethylsiloxane (PDMS)-based platforms with asymmetrical arrowhead micropatterns, nanopillars, and selective fibronectin coating were developed to enhance unidirectional cell migration. The platforms were fabricated using nanoimprint lithography and PDMS replication techniques, allowing for precise control over surface topography and biochemical modification. The MC3T3 osteoblastic cells cultured on these platforms demonstrated significantly enhanced directional migration, characterized by increased displacement, and directional alignment with micropattern orientation compared to symmetrical patterns. Quantitative analyses revealed that asymmetrical arrowheads combined with nanopillars induced more focal adhesions and F-actin polarization at cell front regions, supporting the observed unidirectional cell migration enhancement. These results confirm that integrating micropattern asymmetry, nanoscale features, and biochemical functionalization synergistically promotes unidirectional cell migration. The developed platforms offer valuable insights and practical strategies for designing advanced biomaterials capable of precise spatial cell guidance that can be applied to the designs of organ-on-a-chip systems. Full article

Nanostructures with sufficiently large areas are necessary for the development of practical devices. Current efforts to fabricate large-area nanostructures using step-and-repeat nanoimprint lithography, however, result in either wide seams or low efficiency due to ultraviolet light leakage and the overflow of imprint resin. In this study, we propose an efficient method for large-area nanostructure fabrication using step-and-repeat nanoimprint lithography with a composite mold. The composite mold consists of a quartz support layer, a soft polydimethylsiloxane buffer layer, and multiple intermediate polymer stamps arranged in a cross pattern. The distance between the adjacent stamp pattern areas is equal to the width of the pattern area. This design combines the high imprinting precision of hard molds with the uniform large-area imprinting offered by soft molds. In this experiment, we utilized a composite mold consisting of three sub-molds combined with a cross-nanoimprint strategy to create large-area nanostructures measuring 5 mm × 30 mm on a silicon substrate, with the minimum linewidth of the structure being 100 nm. Compared with traditional step-and-flash nanoimprint lithography, the present method enhances manufacturing efficiency and generates large-area patterns with seam errors only at the micron level. This research could help advance micro–nano optics, flexible electronics, optical communication, and biomedicine studies. Full article

In this paper, three types of optical textured glass substrates were prepared at the glass/transparent conductive oxide interface using polydimethylsiloxane nanoimprint lithography to increase the conversion efficiency of dye-sensitized solar cells (DSSCs). There were three types of textures: nanotexture, microtexture, and micro/nano double texture. In terms of optical characteristics, it was confirmed that the reflectance of all of the textured glass substrates was lower than that of flat glass in the mean value of the 400–800 nm wavelength band. Further, the diffuse transmittance was higher than that of flat glass for all of the textured glass substrates, and the D-Tx was particularly high. DSSCs were fabricated using N749 and N719 dyes; their size was 6 mm². The conversion efficiencies of the N749 DSSCs were improved by 11% for the N-Tx (η of 2.41%) and 10% for the D-Tx (η of 2.38%) compared with flat glass (η of 2.17%) DSSCs. On the other hand, the M-Tx did not improve it. The conversion efficiencies of the N719 DSSCs with textured glass substrates were improved by 7.5% for the M-Tx (η of 2.74%), 18% for the N-Tx (η of 3.01%), and 26% for the D-Tx (η of 3.22%) compared with flat glass (η of 2.55%) DSSCs. Full article

Bio-inspired surfaces with superamphiphobic properties are well known as effective candidates for antifouling technology. However, the limitation of large-area mastering, patterning and pattern collapsing upon physical contact are the bottleneck for practical utilization in marine and medical applications. In this study, a roll-to-plate nanoimprint lithography (R2P NIL) process using Morphotonics’ automated Portis NIL600 tool was used to replicate high aspect ratio (5.0) micro-structures via reusable intermediate flexible stamps that were fabricated from silicon master molds. Two types of Morphotonics’ in-house UV-curable resins were used to replicate a micro-pillar (PIL) and circular rings with eight stripe supporters (C-RESS) micro-structure onto polycarbonate (PC) and polyethylene terephthalate (PET) foil substrates. The pattern quality and surface wettability was compared to a conventional polydimethylsiloxane (PDMS) soft lithography process. It was found that the heights of the R2P NIL replicated PIL and C-RESS patterns deviated less than 6% and 5% from the pattern design, respectively. Moreover, the surface wettability of the imprinted PIL and C-RESS patterns was found to be superhydro- and oleophobic and hydro- and oleophobic, respectively, with good robustness for the C-RESS micro-structure. Therefore, the R2P NIL process is expected to be a promising method to fabricate robust C-RESS micro-structures for large-scale anti-biofouling application. Full article

Among soft lithography techniques, Thermal Nanoimprint Lithography (NIL) is a high-throughput and low-cost process that can be applied to a broad range of thermoplastic materials. By simply applying the appropriate pressure and temperature combination, it is possible to transfer a pattern from a mold surface to the chosen material. Usually, high-resolution and large-area NIL molds are difficult to fabricate and expensive. Furthermore, they are typically made of silicon or other hard materials such as nickel or quartz for preserving their functionality. Nonetheless, after a large number of imprinting cycles, they undergo degradation and become unusable. In this paper, we introduce and characterize an innovative two-step NIL process based on the use of a perfluoropolyether (PFPE) intermediate mold to replicate sub-100 nm features from a silicon mold to the final thermoplastic material. We compare PFPE elastomeric molds with molds made of the standard polydimethylsiloxane (PDMS) elastomer, which demonstrates better resolution and fidelity of the replica process. By using PFPE intermediate molds, the nanostructured masters are preserved and the throughput of the process is significantly enhanced. Full article