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Nanoscale structuring of gallium‐based liquid metals has emerged as a promising approach for generating unique properties and functionalities in advanced materials and devices. However, their exceptionally high surface tension presents significant challenges for achieving surface nanostructuring using conventional fabrication techniques. Here, a hypergravity nanoimprinting method is introduced, which harnesses horizontal centrifugation to generate hypergravity fields that drive liquid gallium into nanoscale cavities on an elastic polymer stamp surface at subzero temperatures, where it solidifies and preserves imprinted features down to 100 nm lateral resolution. This surpasses previous limits of gallium patterning, enabling phenomena such as iridescent structural colors with a wide range of hues and high saturation. Numerical simulations reveal the intricate fluid dynamic behaviors and interfacial interactions during the imprinting process, providing valuable insights for process optimization and control. By synergistically combining advanced soft lithography techniques with the reversible solid‐liquid phase transition properties of liquid metals, hypergravity nanoimprinting offers a practical nanofabrication approach, facilitating the development of next‐generation nanoscale gallium devices with finely structured nanofeatures across diverse application domains, such as nanoelectronics and photonic metamaterials. [ABSTRACT FROM AUTHOR]

Electrochemical nanoimprinting (ECNI) is a microstructure fabrication technique that combines metal-assisted chemical etching (MaCE) with nanoimprint lithography. A significant advantage of ECNI over traditional MaCE is the reusability of the stamp and excellent pattern consistency. This work studies the effects of various etchant components on etching results, discussing the associative parameters separately. Experimental results demonstrate that ECNI successfully fabricates bi-layer microstructures with flat surface morphology, where the second layer has a feature size of 40 μ m and a depth of 12.5 μ m. These findings highlight ECNI's potential as a scalable method for producing complex multi-layer structures, positioning it as a promising solution for large-scale microfabrication of semiconductors. [ABSTRACT FROM AUTHOR]

The direct nanoimprinting of silver nanoparticles (Ag NPs) generated a plasmonic metallic nanostructure. The Ag NPs used in this study have been synthesized by a phase transfer method. The procedure comprised the utilisation of sodium borohydride to reduce silver nitrate in the presence of a stabilizing agent, which facilitated the transfer of the NPs from the aqueous phase to an organic phase, resulting in uniform and stable particles. The size and shape of the Ag NPs were characterized using electron microscopy, revealing spherical particles with an average diameter of 9 nm. The XRD examination revealed that the nanoparticles exhibit a high degree of crystallinity and possess a cubic geometric phase. The UV-visible absorption spectra demonstrate a significant level of homogeneity in the size. The silicon surface imprinted with Ag NPs exhibits hydrophobic behaviour towards water molecules. This approach allows for precise control of Ag NPs on the substrate, resulting in a robust and effective platform for future applications in sensor technology. Furthermore, the hydrophobic nature of the imprinted surface suggests potential applications in water-repellent coatings or self-cleaning materials. [ABSTRACT FROM AUTHOR]

Tunable filters are vital not only for dynamic display but also in the miniaturized spectral imaging system. Yet, the present tunable devices possess low optical throughput, bulky volume, slow response, or complex configuration. In this paper, the study proposed and experimentally demonstrated a compact tunable filter module based on metagratings combined with liquid crystals (LC). By the synergetic effect between the birefringent LC and the dichroic metagratings, the module possesses distinct transmissive features by electrically tuning the LC material, resulting from the polarization interference effect. A simple nanoimprinting method, which is suitable for the mass production of nanostructures is adopted for low‐cost fabrication. These unique features endow the present tunable filter module with low cost, high optical throughput, and compact volume. As a proof of concept, a multispectral imager is built with this filter based on a commercial microscope. Experimental results show the system response is five times higher in optical throughput across the whole visible region than the traditional liquid crystal tunable filter and the signal‐to‐noise ratio can be improved by 7 dB. Considering the feasibility of nanoimprinting, this module paves the way for spectral imaging in low‐light conditions and on‐site scenarios such as tongue diagnosis and food quality inspection. [ABSTRACT FROM AUTHOR]

We suggest a new method of making ultra-low blaze angle gratings for synchrotron application. The method is based on reduction of the blaze angle of a master grating by replication followed by a plasma etch. A master blazed grating with a relatively large blaze angle is fabricated by anisotropic wet etching of a Si single crystal substrate. The surface of the master grating is replicated by a polymer material on top of a quartz substrate by nanoimprinting and then transferred into quartz by a plasma etch. Then a 2nd nanoimprint step is applied to transfer the saw-tooth surface into a resist layer on top of a Si grating substrate. The plasma etch through the patterned resist layer provides transfer of the grooves into the Si substrate and results in reduction of the blaze angle due to the difference in etch rates of the resist and Si. We investigated the impact of the replication process on the groove shape, facet surface roughness, and diffraction efficiency of the fabricated 200 lines/mm low blaze angle grating.

As a new inorganic lead‐free perovskite, cesium copper iodide (CsCu2I3) has attracted wide attention in the field of photodetectors due to its non‐toxicity, good air and thermal stability, and excellent optoelectronic properties. However, the random growth and disordered distribution of CsCu2I3 crystals during their preparation results in poor crystal quality, seriously limiting their applications. Highly ordered CsCu2I3 crystal formation with high crystal quality for high‐performance photodetectors remains a major challenge. Here, an ingenious nanoimprinting technology is utilized to obtain high‐performance photodetectors based on highly aligned CsCu2I3 nanowires (NWs). Owing to the high crystal quality, the photodetector exhibits excellent responsivity of 12.35 A W−1 (310 nm) and 89.73 mA W−1 (365 nm), respectively, as well as good polarization light detection with a dichroism ratio of up to 2.28. Additionally, the device on a flexible substrate retains its initial level of performance even after being bent 2000 times. Remarkably, the device exhibits superior stability and maintains excellent performance after being placed in the natural environment for 1 month without any encapsulation. [ABSTRACT FROM AUTHOR]

The development of nanotechnology and nanoscience is largely dependent upon nanopatterning and nanofabrication and it is commonly achieved by photolithography which has been evolved is last decade so that 90 nm and even 65 nm line-width can be achieved in the semiconductor industry i.e. digital manufacturing sector in recent times. Laser-assisted nanoimprint lithography is a process in which polymer is melted by a single excimer laser pulse followed by imprinted by a mould made of fused quartz. Present research work is focused on silicon materials and utilized a single KrF excimer laser pulse (248 nm wavelength and 30 ns pulse duration) as the heating source. Mathematical modelling is carried out on the basis of hybrid application of Duhamel's application and finite integral transform approach. The thermal field is investigated in both mould and substrate surface for different nanoscale process parameters. For the first time, most updated heat transfer model is employed in this arena as dual-phase-lag heat conduction model is universally accepted for application in microscale and nanoscale structures. The research outcome is successfully validated with the published research papers and the importance of multi-dimensional modelling in the arena of nanofabrication has been demonstrated. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance is an effect widely used for biosensing. Biosensors based on this effect operate in different configurations, including the use of diffraction gratings as couplers. Gratings are highly tunable and are easy to integrate into a fluidic system due to their planar configuration. We discuss the optimization of plasmonic grating couplers for use in a specific sensor configuration based on the optical switch. These gratings present a sinusoidal profile with a high depth/period ratio. Their interaction with a p-polarized light beam results in two significant diffracted orders (the 0th and the −1st), which enable differential measurements cancelling noise due to common fluctuations. The gratings are fabricated by combining laser interference lithography with nanoimprinting in a process that is aligned with the challenges of low-cost mass production. The effects of different grating parameters such as the period, depth and profile are theoretically and experimentally investigated. [ABSTRACT FROM AUTHOR]

Fused filament fabrication, commonly referred to as 3D printing, is an additive manufacturing method finding plenty of applications nowadays. In contrast, polymer nanopatterning by nanolithographic techniques plays an important role in obtaining functional surfaces and coatings for applications in different fields including micro‐ and nanoelectronics. In spite of their relevance, additive manufacturing and polymer nanolithography have not found yet a common niche to be developed. Although both approaches are oriented to achieve different types of objects, it is shown that the confluence of both technologies can be desirable and potentially convenient. Herein, it is demonstrated that by employing conventional 3D printing, it is possible to fabricate nanostructured polymer surfaces in a relatively simple way by using similar approaches as those used in nanoimprint lithography but without the need for clean room conditions. To do that, a printed‐assisted nanoimprint lithography concept (3DPrANIL) has been tested for different types of polymer and silicon templates. It is demonstrated that a polymeric nanostructured hydrophilic template can be replicated accurately on another polymer rendering a nanostructured surface with enhanced hydrophobicity. The results support 3DPrANIL as novel method to obtain micro‐ and nanostructured surfaces with different functionalities like iridescence and hydrophobicity. [ABSTRACT FROM AUTHOR]

Polysiloxane antireflective structures composed of tapered nanopillar arrays were prepared by nanoimprinting using anodic porous alumina molds with tapered pores. Because polysiloxane is a heat-resistant material, the resulting tapered nanopillar array structures were maintained even after heat treatment at 200 °C. In addition, no significant changes in antireflection properties were observed before and after heat treatment at 200 °C. These results indicate that the polysiloxane nanopillar arrays obtained in this study can be applied as heat-resistance antireflection structures. [ABSTRACT FROM AUTHOR]

Abstract Plasmonic nanometasurfaces/nanostructures possess strong electromagnetic field enhancement caused by resonant oscillations of free electrons, and has been extensively applied in biosensing, nanophotonic and photocatalysis. However, fabrication of uniform nanostructured metasurfaces by conventional methods is complicated and costly, which mitigates a wide‐spread use of this technique in ubiquitous applications. Here, we present a facile and scalable method to fabricate an active nanotrench plasmonic gold substrate. The surface comprises sub‐10 nm plasmonic nanogaps and their formation is assisted by a pre‐fabrication of nano‐imprinted polymer nano‐well arrays. The plasmonic metasurface is optimized to maximize the density of the nano‐trenches by tuning the substrate material, imprinting procedure and film deposition. We show that the surface Raman enhancement due to plasmonic resonances correlates well with trench density and reach a meritorious enhancement factor of EF > 105 over large surfaces. We further show that the electric field strength at the nanotrench features are well explained by finite element method simulations using COMSOL Multiphysics. The plasmonic substrate is transparent in the visible spectrum and conductive. In combination with a scalable bottom‐up fabrication the plasmonic metasurface opens up for a wider use of the sensitive and reliable SERS substrate in applications such as portable sensing devices and for future internet of things.

The proposed work aims to develop a sensitive surface-enhanced Raman spectroscopy (SERS) nano-biosensor. The inverted nano pyramid array on silicon substrate fabricated using electron beam lithography (EBL) was utilised as a master template and the mold was later replicated via nanoimprinting process to prepare gold-coated polymer nanopyramid three-dimensional (3D) SERS substrate. The fast and versatile replication process using nanoimprinting lithography (NIL) can produce polymer nanopyramids in a low-cost and reproducible fashion. Also, the proposed fabrication protocol can be easily upscale for large scale fabrication. The intense electric field confinement at nanotips and four edges of gold-coated polymer nanopyramid enhanced the Raman signal of probe molecules, i.e., Rhodamine 6G with a limit of detection down to 3.277 × 10−9 M was achieved. This work also underlines the efficiency of gold-coated polymer nanopyramid arrays in the spectral detection of hemoglobin proteins at low concentrations. The Raman signal enhancement mechanism was further studied through the electromagnetic simulation using COMSOL Multiphysics. In addition, bending test experiments were performed to understand the effect of flexibility on SERS signal response. The fabricated gold-coated polymer nanopyramids arrays could pave the way for the development of low-cost SERS platforms for the detection of hazardous biological and chemical compounds at ultra-low concentrations in practical applications. [ABSTRACT FROM AUTHOR]

Nanolenses are gaining importance in nanotechnology, but their challenging fabrication is thwarting their wider adoption. Of particular challenge is facile control of the lens' curvature. In this work, we demonstrate a new nanoimprinting technique capable of realizing polymeric nanolenses in which the nanolens' curvature is optically controlled by the ultraviolet (UV) dose at the pre-curing step. Our results reveal a regime in which the nanolens' height changes linearly with the UV dose. Computational modeling further uncovers that the polymer undergoes highly nonlinear dynamics during the UV-controlled nanoimprinting process. Both the technique and the process model will greatly advance nanoscale science and manufacturing technology. [ABSTRACT FROM AUTHOR]

In this work, the fabrication of the nanoimprinted titanium dioxide (TiO 2) gratings via thermal nanoimprinting lithography method (T-NIL) and its visible light response are studied. A polydimethylsiloxane (PDMS) primary mould, which in turn made via pattern transfer of micro/nano tracks present in the optical discs is used in T-NIL process. A transparent TiO 2 film on a FTO substrate was subjected to pattern transfer from the PDMS mould. The imprinted TiO 2 was post annealed to obtain anatase phase. The optical properties and photo response behaviour of plain and nanoimprinted TiO 2 films were measured and compared. Raman spectroscopy measurements indicated the surface enhanced Raman scattering in imprinted samples. The imprinted TiO 2 showed reduced reflectance compared to plain TiO 2 films due to the increased light path length because of multiple reflections leading to in coupling of light. Photo response was observed under visible light illumination conditions, wherein imprinted TiO 2 films showed appreciable photocurrent, which is otherwise very minimal in plain TiO 2. The visible light photosensing in imprinted TiO 2 occur due to the oxygen adsorption-desorption during the post deposition annealing and under illumination respectively. This work makes use of low-cost PDMS primary mould and T-NIL at favourable temperature and pressure conditions with a promising outlook for fabricating imprinted TiO 2 with photo sensing ability and adaptability for large area upscaling. [Display omitted] • TiO 2 nanogratings fabricated via thermal nanoimprinting lithography process exhibit visible light photoresponse. • It is due to oxygen adsorption-desorption during post deposition annealing and light illumination respectively. • Nanoimprinting PDMS mold prepared using optical discs demonstrates the prospect of economical large area scalability. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance is an effect widely used for biosensing. Biosensors based on this effect operate in different configurations, including the use of diffraction gratings as couplers. Gratings are highly tunable and are easy to integrate into a fluidic system due to their planar configuration. We discuss the optimization of plasmonic grating couplers for use in a specific sensor configuration based on the optical switch. These gratings present a sinusoidal profile with a high depth/period ratio. Their interaction with a p-polarized light beam results in two significant diffracted orders (the 0th and the −1st), which enable differential measurements cancelling noise due to common fluctuations. The gratings are fabricated by combining laser interference lithography with nanoimprinting in a process that is aligned with the challenges of low-cost mass production. The effects of different grating parameters such as the period, depth and profile are theoretically and experimentally investigated.

Nanoimprinting lithography (NIL) technique is widely utilized for nanostructure engineering of soft materials. Owing to the soft organic/inorganic hybrid nature, the optical and crystallographic properties of halide perovskites (HPs) are improved by the NIL process. However, the wide application of NIL into various HPs has lagged. Herein, a defect‐free nanopatterned‐(FAPbI3)0.85(MAPbBr3)0.15 (NP‐FAMA) film is successfully developed via optimized NIL. As surface energy is a key parameter to be controlled for accomplishing NIL process, trichloro(1H,1H,2H,2H‐perfluorooctyl)silane (CF3(CF2)5CH2CH2SiCl3) treatment on polymeric mold, which prevents the peeling‐off problem. Along with surface morphology modification, NP‐FAMA exhibits enhanced crystallographic and photophysical properties. The photoresponsivity of NP‐FAMA‐based photodetectors outperforms bare (b‐) FAMA‐based devices. Surprisingly, the external quantum efficiency (EQE) of the NP‐FAMA‐based devices dramatically increases to 225%, photomultiplication (PM), under 1 nW illumination without any charge‐injecting materials. To clarify these PM phenomena, the trap‐assisted PM mechanism is suggested as a model system for promoting photocurrent generation of HPs that is supported by PL analysis. [ABSTRACT FROM AUTHOR]

We present the fabrication of three-dimensional inlets with gradually decreasing widths and depths and with nanopillars on the slope, all defined in just one lithography step. In addition, as an application, we show how these micro- and nanostructures can be used for micro- and nanofluidics and lab-on-a-chip devices to facilitate the flow and analyze single molecules of DNA. For the fabrication of 3D inlets in a single layer process, dose-modulated electron beam lithography was used, producing depths between 750 nm and 50 nm along a 30 μm long inlet, which is additionally structured with nanometer-scale pillars randomly distributed on top, as a result of incomplete exposure and underdevelopment of the resist. The fabrication conditions affect the slope of the inlet, the nanopillar density and coverage. The key parameters are the dose used for the electron beam exposure and the development conditions, like the developer’s dilution, stirring and development time. The 3D inlets with nanostructured pillars were integrated into fluidic devices, acting as a transition between micro and nanofluidic structures for pre-stretching and unfolding DNA molecules, avoiding the intrusion of folded molecules and clogging the analysis channel. After patterning these structures in silicon, they can be replicated in polymer by UV nanoimprinting. We show here how the inlets with pillars slow down the molecules before they enter the nanochannels, resulting in a 3-fold decrease in speed, which would translate to an improvement in the resolution for DNA optical mapping. [ABSTRACT FROM AUTHOR]

Plasmonic nanometasurfaces/nanostructures possess strong electromagnetic field enhancement caused by resonant oscillations of free electrons, and has been extensively applied in biosensing, nanophotonic and photocatalysis. However, fabrication of uniform nanostructured metasurfaces by conventional methods is complicated and costly, which mitigates a wide‐spread use of this technique in ubiquitous applications. Here, we present a facile and scalable method to fabricate an active nanotrench plasmonic gold substrate. The surface comprises sub‐10 nm plasmonic nanogaps and their formation is assisted by a pre‐fabrication of nano‐imprinted polymer nano‐well arrays. The plasmonic metasurface is optimized to maximize the density of the nano‐trenches by tuning the substrate material, imprinting procedure and film deposition. We show that the surface Raman enhancement due to plasmonic resonances correlates well with trench density and reach a meritorious enhancement factor of EF > 105 over large surfaces. We further show that the electric field strength at the nanotrench features are well explained by finite element method simulations using COMSOL Multiphysics. The plasmonic substrate is transparent in the visible spectrum and conductive. In combination with a scalable bottom‐up fabrication the plasmonic metasurface opens up for a wider use of the sensitive and reliable SERS substrate in applications such as portable sensing devices and for future internet of things. [ABSTRACT FROM AUTHOR]

Scratch recovery of micro-nano-patterned polymer surfaces extends the service life of products that require tunable surface properties and contributes to more sustainable development. Scratch recovery has been widely studied in bulk and 4D-printed polymers via intrinsic self-healing mechanisms. Existing studies on self-healing of micro/nano-scale polymeric surfaces are limited to the recovery of controlled tensile or compressive strain. Scratch recovery requires material transport to close the gap created by a scratch. Here, for the first time, scratch recovery of thermally nanoimprinted polymer surfaces in a heterogeneous polymer is reported. A blend of Polyurethane (TPU) and poly(caprolactone) (PCL) with selectively crosslinked TPU imparts shape-memory properties, and the uncrosslinked PCL retains chain mobility for molecular diffusion during scratch recovery. Scratch recovery of nanoimprinted micro-pillars has been achieved spontaneously and completely by heat and without any pressure input. The healing temperature is determined to be the melting point of PCL at 60 °C. Rapid recovery is also achieved at 60 s with complete closure of scratch width of 5 µm and topography recovery of the nanoimprinted micro-pillars., (© 2024 Wiley‐VCH GmbH.)

Perovskite nanocrystals (PNCs) are attractive emissive materials for developing compact lasers. However, manipulation of PNC laser directionality has been difficult, which limits their usage in photonic devices that require on-demand tunability. Here we demonstrate PNC metasurface lasers with engineered emission angles. We fabricated millimeter-scale CsPbBr 3 PNC metasurfaces using an all-solution-processing technique based on soft nanoimprinting lithography. By designing band-edge photonic modes at the high-symmetry X point of the reciprocal lattice, we achieved four linearly polarized lasing beams along a polar angle of ∼30° under optical pumping. The device architecture further allows tuning of the lasing emission angles to 0° and ∼50°, respectively, by adjusting the PNC thickness to shift other high-symmetry points (Γ and M) to the PNC emission wavelength range. Our laser design strategies offer prospects for applications in directional optical antennas and detectors, 3D laser projection displays, and multichannel visible light communication.

Nanoimprinting large-area structures, especially high-density features like meta lenses, poses challenges in achieving defect-free nanopatterns. Conventional high-resolution molds for nanoimprinting are often expensive, typically constructed from inorganic materials such as silicon, nickel (Ni), or quartz. Unfortunately, replicated nanostructures frequently suffer from breakage or a lack of definition during demolding due to the high adhesion and friction at the polymer-mold interface. Moreover, mold degradation after a limited number of imprinting cycles, attributed to contamination and damaged features, is a common issue. In this study, a disruptive approach is presented to address these challenges by successfully developing an anti-sticking nanocomposite mold. This nanocomposite mold is created through the co-deposition of nickel atoms and low surface tension polytetrafluoroethylene (PTFE) nanoparticles via electroforming. The incorporation of PTFE enhances the ease of polymer release from the mold. The resulting Ni-PTFE nanocomposite mold exhibits exceptional lubrication properties and a significantly reduced surface energy. This robust nanocomposite mold proves effective in imprinting fine, densely packed nanostructures down to 100 nm using thermal nanoimprinting for at least 20 cycles. Additionally, UV nanoimprint lithography (UV-NIL) is successfully performed with this nanocomposite mold. This work introduces a novel and cost-effective approach to reusable high-resolution molds, ensuring defect-reduction production in nanoimprinting., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

The anti-reflection film can effectively reduce the surface reflectivity of solar photovoltaics, increase the transmittance of light, and improve the photoelectric conversion efficiency. The high refractive index coating is an important part of the anti-reflection film. However, the traditional metal oxide coating has poor stability and complicated processes. To address this issue, we prepared two organic high refractive index (HRI) photopolymers by modifying epoxy acrylic acid with 4,4′-thiodibenzenethiol, which can be surface patterned by nanoimprinting to prepare antireflection coatings. As a result, two modified photopolymers with high refractive index (n > 1.63), high optical transmittance (T > 95%), and thermal stability (Tg > 100 °C) are obtained after curing. In particular, the diphenyl sulfide photopolymer modified by ethyl isocyanate acrylate has a refractive index up to 1.667 cured by UV light. Our work confirms that the organic HRI photopolymer can be obtained by introducing high molar refractive index groups, with potential to be applied as a PV cell power conversion efficiency material. [ABSTRACT FROM AUTHOR]

We demonstrate the potential of thermoresponsive poly N‐(isopropylacrylamide) (PNIPAM) based surfaces in achieving a low‐energy approach to modulate surface wetting for applications such as fog harvesting and anti‐fogging. Alternative to grafting methods, we use a two‐step approach for tuning the response amplitude. First, we blend PNIPAM with a chemically non‐reactive poly (vinylidene fluoride), PVDF (1/3, 1/1, 3/1 by weight). Second, thermal nanoimprint lithography is used to create micro (3, 5, 10, and 20 μm) and nano‐scale (100 and 200 nm) pillars. Nano‐patterned surfaces show a response amplitude of ~30°–50° compared to ~15°–30°, observed for the micro‐patterned surface. X‐ray photo‐electron spectroscopy and energy dispersive X‐ray analysis confirms the reduction of polyvinylidene fluoride phase domains and enrichment of PNIPAM on the nano‐patterned surface. A real‐time dynamic mist condensation study showed that the nano‐patterned blend exhibited a lower temperature range (34/41°C) for on/off (wetting/drying) state compared to an unpatterned blend (37/50°C). [ABSTRACT FROM AUTHOR]

Reducing the contact resistance between active materials and current collectors is of engineering importance for improving capacitive energy storage. 3D current collectors have shown extraordinary promise for reducing the contact resistance, however, there is a major obstacle of being bulky or inefficient fabrication before they become viable in practice. Here a roll‐to‐roll nanoimprinting method is demonstrated to deform flat aluminum foils into 3D current collectors with hierarchical microstructures by combining soft matter‐enhanced plastic deformation and template‐confined local surface nanocracks. The generated 3D current collectors are inserted by and interlocked with active electrode materials such as activated carbon, decreasing the contact resistance by at least one order of magnitude and quadrupling the specific capacitance at high current density of 30 A g–1 for commercial‐level mass loading of 5 mg cm–2. The 3D current collectors are so compact that they have a low volume percentage of 7.8% in the entire electrode film, resulting in energy and power density of 29.1 Wh L–1 and 12.8 kW L–1, respectively, for stack cells in organic electrolyte. Furthermore, roll‐to‐roll nanoimprinting of metal microstructures is low‐cost, high‐throughput, and can be extended to other systems that involve the microstructured metal interface, such as batteries and thermal management. [ABSTRACT FROM AUTHOR]

Ordered metallic nanostructures, due to their superior electronic and photonic properties, have played a vital role in wide range of applications, such as metamaterials, plasmonic sensing, electrocatalysis, and energy devices. However, traditional fabrication strategies based on bottom‐up self‐assembly and top‐down lithography are either poor in uniformity or time‐consuming with low scalability. Here, a robust and cost‐effective approach for the fabrication of highly ordered metallic pillars arrays in centimeter scale is presented. This is realized by superplastic nanomolding of metals with highly ordered anodic aluminum oxide templates which are fabricated by the prepatterning of aluminum sheets with bulk metallic glass (BMG) mold, followed by anodizing. The nanopatterning process is rationalized with finite element simulation to avoid the damage of BMG mold. Finally, it is shown that the molded metallic sub‐micrometer pillars arrays can be used for the surface‐enhanced Raman scattering (SERS) with enhancement factor of ≈106. It is found that the SERS performance is influenced by the specific surface area of the pillars in addition to the near‐field intensity. This simple and cost‐effective method not only opens new opportunities for rapid prototyping of large‐scale ordered metallic nanostructures for various applications but also provides guidance for the quantitative analysis on sub‐micrometer scale. [ABSTRACT FROM AUTHOR]

Roll-to-plate nanoimprinting with flexible stamps is a fabrication method to pattern large-area substrates with micro- and nanotextures. The imprint consists of the preferred texture on top of a residual layer, of which the thickness and uniformity is critical for many applications. In this work, a numerical model is developed to predict the residual layer thickness (RLT) as a function of the imprint parameters. The model is based on elastohydrodynamic lubrication (EHL) theory, which combines lubrication theory for the pressure build-up in the resin film, with linear elasticity theory for the elastic deformation of the roller material. The model is extended with inextensible cylindrical shell theory to capture the effect of the flexible stamp, which is treated as a tensioned web. The results show that an increase in the tension of the web increases the effective stiffness of the roller, resulting in a reduction in the RLT. The numerical results are validated with layer height measurements from flat layer imprints. It is shown that the simulated minimum layer height corresponds very well with the experimental results for a wide range of resin viscosities, imprint velocities, and imprint loads. [ABSTRACT FROM AUTHOR]

Abstract The low-dimensional, highly anisotropic geometries, and superior mechanical properties of one-dimensional (1D) nanomaterials allow the exquisite strain engineering with a broad tunability inaccessible to bulk or thin-film materials. Such capability enables unprecedented possibilities for probing intriguing physics and materials science in the 1D limit. Among the techniques for introducing controlled strains in 1D materials, nanoimprinting with embossed substrates attracts increased attention due to its capability to parallelly form nanomaterials into wrinkled structures with controlled periodicities, amplitudes, orientations at large scale with nanoscale resolutions. Here, we systematically investigated the strain-engineered anisotropic optical properties in Te nanowires through introducing a controlled strain field using a resist-free thermally assisted nanoimprinting process. The magnitude of induced strains can be tuned by adjusting the imprinting pressure, the nanowire diameter, and the patterns on the substrates. The observed Raman spectra from the chiral-chain lattice of 1D Te reveal the strong lattice vibration response under the strain. Our results suggest the potential of 1D Te as a promising candidate for flexible electronics, deformable optoelectronics, and wearable sensors. The experimental platform can also enable the exquisite mechanical control in other nanomaterials using substrate-induced, on-demand, and controlled strains.

Surface nanopatterning of semiconductor optoelectronic devices is a powerful way to improve their quality and performance. However, photoelectric devices’ inherent stress sensitivity and inevitable warpage pose a huge challenge on fabricating nanostructures large-scale. Electric-driven flexible-roller nanoimprint lithography for nanopatterning the optoelectronic wafer is proposed in this study. The flexible nanoimprint template twining around a roller is continuously released and recovered, controlled by the roller’s simple motion. The electric field applied to the template and substrate provides the driving force. The contact line of the template and the substrate gradually moves with the roller to enable scanning and adapting to the entire warped substrate, under the electric field. In addition, the driving force generated from electric field is applied to the surface of substrate, so that the substrate is free from external pressure. Furthermore, liquid resist completely fills in microcavities on the template by powerful electric field force, to ensure the fidelity of the nanostructures. The proposed nanoimprint technology is validated on the prototype. Finally, nano-grating structures are fabricated on a gallium nitride light-emitting diode chip adopting the solution, achieving polarization of the light source.

The present review provide a brief overview of the basic aspects of molecular imprinting technology covering template molecules, functional monomers, crosslinking agents, initiators, characterization methods and application by emphasizing on the novel polymer materials. Compare to other reviews, various aspects of computational designing of imprinted polymers, carbon based nano-imprinting and stimuli-responsive imprinted polymers are highlighted here in the present review. This review comprises a critical account of the most recent developments in the field of molecular imprinting. It is directed towards a broad spectrum of readers like separation science, polymer material, synthetic, analytical and bioorganic chemists who make use of computational aspects and photoresponsive materials for specific purpose.

Nanolenses are gaining importance in nanotechnology, but their challenging fabrication is thwarting their wider adoption. Of particular challenge is facile control of the lens’ curvature. In this work, we demonstrate a new nanoimprinting technique capable of realizing polymeric nanolenses in which the nanolens’ curvature is optically controlled by the ultraviolet (UV) dose at the pre-curing step. Our results reveal a regime in which the nanolens’ height changes linearly with the UV dose. Computational modeling further uncovers that the polymer undergoes highly nonlinear dynamics during the UV-controlled nanoimprinting process. Both the technique and the process model will greatly advance nanoscale science and manufacturing technology.

Deposition of nanoparticles on a substrate in a controlled manner leads to the formation of multifunctional surfaces and therefore devices. Electrostatic forces can be utilized to manipulate different types of materials such as magnetic, insulating, conducting, semiconducting, organic and inorganic, without altering the chemistry of the surface. However, simultaneous and successive electrophoretic deposition (EPD) methods are not fully utilized for nanoparticles with different characteristics. In this work, electrostatic forces are applied to direct and position charged nanoparticles suspended in aqueous dispersions on desired areas of the surface. Assemblies of particles are obtained by electrostatic attraction generated by gold electrodes of sizes from 500 nm to 50 µm that are fabricated by thermal evaporation. Different types of charged nanoparticles were simultaneously attracted towards different locations of the surface by means of EPD; as a result, alternating nanoparticle patterns and particle deposition on the same designated areas for forming composite areas are obtained. Assemblies formed from positively charged silver nanoparticles and negatively charged fluorescent latex and silica nanoparticles are demonstrated. The position of metallic-, polymeric- and inorganic-based nanoparticles is controlled by the design of electrode geometry. [ABSTRACT FROM AUTHOR]

Perovskite (PVK) photodetectors (PDs) have emerged as highly‐efficient versatile optoelectrical devices due to their highly efficient and simple solution‐processable preparation method. Meanwhile, optical structures offer an efficient and facile strategy to improve the light‐harvesting performance of devices and introduce extra optical activity such as polarization sensitivity. Here, an efficient moiré perovskite photodetector with a stacked dual shallow grating structure is designed and fabricated, and sensitive digital polarization imaging is realized. The moiré PVK presents superior ability in light harvesting through the synergistic effects of feedback reflection, diffraction, and excitation of waveguide modes in the dual grating structure. Additionally, the highly crystalline PVK is fabricated through the imprint lithography process. Consequently, excellent device performance is achieved by taking advantage of highly‐efficient light‐harvesting and the good electrical properties of large grain PVK crystals. The responsivity (R) and detectivity (D*) of the moiré PVK PD are up to 15.62 A W and 5.58 × 1013 Jones, which are 6.7 and 7.8 times larger than that of the flat perovskite photodetector, respectively. The on/off ratio reaches 2.7 × 104. The nanograting array introduces good polarization sensitivity to the moiré PVK PD achieving a peak‐to‐valley ratio of 1.58. Excellent polarization images are obtained using a 576 pixel sensor array. [ABSTRACT FROM AUTHOR]

Laser shock imprinting (LSI) is an emerging method for creating sub-micrometer and nanoscale reliefs on thin metal foils. This report proposes using underwater shockwaves, generated by detonating an explosive charge, for high-quality imprinting as an alternative to LSI. The nanoscale relief of a polycarbonate mold with 740 nm periodic grooves was replicated on an Al foil using an underwater shockwave. Underwater detonation of a high explosive creates a shockwave with pressure ≥ 1 GPa that lasts for more than 100 ns, significantly longer than that for LSI. This provides a relief depth equal to 90% of the depth of the grooves on the mold. This mold filling efficiency is the best achieved by shock imprinting reported to date. In addition, underwater shockwaves can be used for imprinting over a large area in a single shot. Furthermore, the thickness of the Al foil can be increased in comparison to that for LSI. Using a simplified 1-D model of foil acceleration, we showed that increasing the foil thickness decreases the imprinting accuracy. This study paves new ways for large-area manufacturing of micro/nanopatterns on metals that would be especially beneficial for future applications in the fields of plasmonics and metasurfaces.

The anti-reflection film can effectively reduce the surface reflectivity of solar photovoltaics, increase the transmittance of light, and improve the photoelectric conversion efficiency. The high refractive index coating is an important part of the anti-reflection film. However, the traditional metal oxide coating has poor stability and complicated processes. To address this issue, we prepared two organic high refractive index (HRI) photopolymers by modifying epoxy acrylic acid with 4,4′-thiodibenzenethiol, which can be surface patterned by nanoimprinting to prepare antireflection coatings. As a result, two modified photopolymers with high refractive index (n > 1.63), high optical transmittance (T > 95%), and thermal stability (Tg > 100 °C) are obtained after curing. In particular, the diphenyl sulfide photopolymer modified by ethyl isocyanate acrylate has a refractive index up to 1.667 cured by UV light. Our work confirms that the organic HRI photopolymer can be obtained by introducing high molar refractive index groups, with potential to be applied as a PV cell power conversion efficiency material.

Roll-to-plate nanoimprinting with flexible stamps is a fabrication method to pattern large-area substrates with micro- and nanotextures. The imprint consists of the preferred texture on top of a residual layer, of which the thickness and uniformity is critical for many applications. In this work, a numerical model is developed to predict the residual layer thickness (RLT) as a function of the imprint parameters. The model is based on elastohydrodynamic lubrication (EHL) theory, which combines lubrication theory for the pressure build-up in the resin film, with linear elasticity theory for the elastic deformation of the roller material. The model is extended with inextensible cylindrical shell theory to capture the effect of the flexible stamp, which is treated as a tensioned web. The results show that an increase in the tension of the web increases the effective stiffness of the roller, resulting in a reduction in the RLT. The numerical results are validated with layer height measurements from flat layer imprints. It is shown that the simulated minimum layer height corresponds very well with the experimental results for a wide range of resin viscosities, imprint velocities, and imprint loads.

The combination of light‐emitting diodes (LEDs) and rare earth (RE) phosphors as color‐converting layers comprises the basis of solid‐state lighting. Indeed, most LED lamps include a photoluminescent coating made of phosphor material, i.e., crystalline matrix suitably doped with RE elements, to produce white light from a blue or ultraviolet LED chip. Transparent phosphor‐based films constitute starting materials for new refined emitters that allow different photonic designs to be implemented. Among the different photonic strategies typically employed to tune or enhance emission, surface texturing has proved its versatility and feasibility in a wide range of materials and devices. However, most of the nanofabrication techniques cannot be applied to RE phosphors directly because of their chemical stability or because of their cost. The first monolithic patterned structure of down‐shifting nanophosphors with square arrays of nanoholes with different lattice parameters is reported in this study. It is shown that a low‐cost soft‐nanolithography procedure can be applied to red‐emitting nanophosphors (GdVO4:Eu3+ nanocrystals) to tune their emission properties, attaining a twofold directional enhancement of the emitted light at predesigned emission wavelengths in specific directions. [ABSTRACT FROM AUTHOR]

Polarized light detection can effectively identify the difference between the polarization information on the target and the background, which is of great significance for detection in complex natural environments and/or extreme weather. Generally, polarized light detection inevitably relies on anisotropic structures of photodetector devices, while organic-inorganic hybrid perovskites are ideal for anisotropic patterning due to their simple and efficient preparation by solution method. Compared to patterned thin films, patterned arrays of aligned one-dimensional (1D) perovskite nanowires (PNWAs) have fewer grain boundaries and lower defect densities, making them well suited for high-performance polarization-sensitive photodetectors. Here, we fabricated PNWAs crystallographically aligned with variable line widths and alignment densities employing CD-ROM and DVD-ROM grating pattern template-confined growth (TCG) methods. The photodetectors constructed from MAPbI 3 PNWAs achieved responsivity of 35.01 A/W, detectivity of 6.85 × 10 13 Jones, and fast response with a rise time of 172 μs and fall time of 114 μs. They were successfully applied to high-performance polarization detection with a polarization ratio of 1.81, potentially applicable in polarized light detection systems.

In the last decade, a new technique has been developed for the nanoimprinting of thin-metal foils using laser-induced shock waves. Recent studies have proposed replacing metal or silicone molds with inexpensive polymer molds for nanoimprinting. In addition, explosive-derived shock waves provide deeper imprinting than molds, greatly simplifying the application of this technology for mass production. In this study, we focused on explosive-derived shock waves, which persist longer than laser-induced shock waves. A numerical analysis and a set of simplified molding experiments were conducted to identify the cause of the deep imprint. Our numerical analysis has accurately simulated the pressure history and deformation behavior of the workpiece and the mold. Whereas a high pressure immediately deforms the polymer mold, a sustained pressure gradually increases the molding depth of the workpiece. Therefore, the duration of the pressure can be one of the conditions to control the impact imprint phenomenon.

Metal nanostructures offer exciting ways to manage light at the nanoscale exploited in fields such as imaging, sensing, energy conversion, and information processing. The optical response of the metallic architectures can be engineered to exhibit photonic properties that span from plasmon resonances to more complex phenomena such as negative refractive index, optical chirality, artificial magnetism, and more. However, the latter optical properties are only observed in intricate architectures, which are highly demanding in terms of nanofabrication and hence less scalable and far away from device implementation. Here, a series of metasurfaces covering centimeter areas and operating in the visible spectrum are presented, which are produced from the combination of nanoimprinting lithography and oblique angle metal evaporation. The potential of this scalable approach is illustrated by easily fabricating metasurfaces engineered to exhibit artificial optical magnetism, tunable linear polarization dependent response, chirality with g‐factor of 0.2, and photoluminescence enhancement of 20 times over a 9 mm2 area. [ABSTRACT FROM AUTHOR]

Negative index metamaterials have revolutionized the field of photonics because of their unconventional electromagnetic properties absent in naturally occurring materials. It remains a challenge however, to achieve strong negative refractive index at optical frequencies over large areas in a device compatible fashion. In this work, a scalable method for the straightforward production of fishnet‐like negative index metamaterials combining soft nanoimprinting and electrodeposition is reported. In four simple steps, 2D arrays of pillars surrounded by metal–insulator–metal stacks made of gold and air gaps are created. The proper design of the geometrical features leads to negative indices from the visible to the near infrared, with values from ‐1.2 at 700 nm to ‐2.8 at 910 nm. The metamaterials are prepared on transparent conductive electrodes hence ready for device implementation. In addition, the nanostructures display high optical quality, which is corroborated with numerical simulations under normal and oblique incidence. As a proof of concept, the accessibility to the porosity of the metamaterial by studying the spectral changes produced when infiltrating different liquids through the metallic layers is demonstrated. The resonant wavelength increasing with the refractive index of the media makes the metamaterials potential platforms for both negative index structures and optical sensors. [ABSTRACT FROM AUTHOR]

Directly linearly polarized light emission from organic light‐emitting diodes (OLEDs), as an important functional expansion, is an intriguing and attractive research topic due to its increasing importance in various applications. Until now, however, the limited efficiency and inadequate polarization ratio constitute two major hurdles for real application. In this work, high‐efficiency linearly polarized white OLEDs with an ultrahigh polarization ratio are achieved by using integrated dielectric/metal nanograting and nanorelief speckle image holography metasurfaces. In the devices, the integrated grating behave as a polarizer to select the transverse magnetic wave (TM) component and simultaneously reflect the transverse electric wave (TE) counterpart over the whole emission spectrum, while the metasurfaces gather the otherwise waste TE‐polarized light reflected by the grating and transform it into reusable TM‐polarized light. This synergistic energy‐light recycling system leads to dramatically boosted device efficiency and polarization ratio, i.e., a power efficiency 21.4 lm W−1 (@ 1000 cd m−2), and an extinction ratio of 17.8 dB (@ V = 5 V) for the polarized white OLEDs. The presented paradigm for simultaneous polarization controlling and efficiency boosting in white OLEDs is expected to advance the OLED techniques in device reconfigurability for future multifunctional applications. [ABSTRACT FROM AUTHOR]

The ongoing revolution of human–robot interactions and electronic skins has created new requirements for tactile sensors, including good mechanical flexibility, high sensitivity, and the availability of distributed pixels for detecting force distribution. Here, a highly sensitive flexible sensor array based on piezoelectricity‐enhanced vertically aligned P(VDF‐TrFE) micropillars is developed for dynamic tactile sensing. The core piezoelectric sensing micropillars are fabricated using a straightforward and scalable nanoimprinting technology and then sandwiched between a pair of cross electrode arrays to construct multiplexed sensor arrays. Due to the proposed structural design and nanoimprinting methodology, the sensor pixels exhibit uniform output generation, robust output stability, and scalable fabrication ability. In addition, taking advantage of the high compressibility and enhanced strain of the piezoelectric micropillars compared to planar films, the microstructured sensors show an enhanced sensitivity of 228.2 mV N−1 and a highly linear response to loads. By integrating the flexible sensor with a portable signal processing circuit, a complete tactile sensing system is successfully developed to provide clear intuitive user interfaces. The good flexibility and robust stability of the sensor arrays enable them to be attached onto curved surface for real‐time tracking of dynamic force and imaging the force distribution. [ABSTRACT FROM AUTHOR]

The effects of alloy composition, cavity aspect ratio, and temperature on the pattern transfer mechanism and mechanics of ZrCu metallic glass (MG) films under a nanoimprinting process are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The simulation results show that the glass transition temperature of ZrCu MGs increases with increasing Zr content. Imprinting at higher temperatures or with a higher cavity aspect ratio shortens filling time. Shear origin zones are more concentrated for imprinting at lower imprint temperatures or a higher cavity aspect ratio. The loading force increases with increasing cavity aspect ratio and decreasing Zr content. The springback ratio of a pattern increases with increasing cavity aspect ratio and decreasing Zr contare the film heights including and ent. For imprinting with a high cavity aspect ratio, the pattern width has much more springback than that of the pattern height. The sharpness of patterns significantly decreases with increasing unloading temperature. [ABSTRACT FROM AUTHOR]

Highlights: Exquisite strain engineering in 1D chiral semiconductor. Facile nanoimprinting induced tensile strain in Te nanowire. Intriguing and tunable optical properties of 1D Te nanowire by strain engineering.The low-dimensional, highly anisotropic geometries, and superior mechanical properties of one-dimensional (1D) nanomaterials allow the exquisite strain engineering with a broad tunability inaccessible to bulk or thin-film materials. Such capability enables unprecedented possibilities for probing intriguing physics and materials science in the 1D limit. Among the techniques for introducing controlled strains in 1D materials, nanoimprinting with embossed substrates attracts increased attention due to its capability to parallelly form nanomaterials into wrinkled structures with controlled periodicities, amplitudes, orientations at large scale with nanoscale resolutions. Here, we systematically investigated the strain-engineered anisotropic optical properties in Te nanowires through introducing a controlled strain field using a resist-free thermally assisted nanoimprinting process. The magnitude of induced strains can be tuned by adjusting the imprinting pressure, the nanowire diameter, and the patterns on the substrates. The observed Raman spectra from the chiral-chain lattice of 1D Te reveal the strong lattice vibration response under the strain. Our results suggest the potential of 1D Te as a promising candidate for flexible electronics, deformable optoelectronics, and wearable sensors. The experimental platform can also enable the exquisite mechanical control in other nanomaterials using substrate-induced, on-demand, and controlled strains. [ABSTRACT FROM AUTHOR]

An array of nano-scale protrusions, called the nipple array, is found on the body surface of various invertebrates, and this structure is believed to decrease light reflectance and water wettability on the surface in the terrestrial environment. However, its potential functions have not been well studied in aquatic environments. Clavelina spp. are colonial ascidians that have the nipple array on their integumentary matrix (i.e. tunic). We examined the physical properties on the surface of the tunic of C. cyclus and C. obesa , such as hardness, wettability and refractive indices, to evaluate the functional importance of this structure. The tunic cuticle of both species was covered with the nipple array, and the cuticle of C. cyclus was bent into folds forming parallel plications. The Clavelina tunic was very soft and had high bubble- and oil-repellency. The refractive-index deviation between the tunic and seawater was 0.07–0.095 for 589-nm light (D-line). Rigorous coupled wave analysis (RCWA) showed that the nipple array slightly reduced reflectance on the surface and the parallel plications reduced the reflectance still more. The nanoimprinted plates imitating the parallel plications have higher bubble repellency and lower reflectance than the flat plates. These findings support the functional importance of the plications as well as the nipple array. [ABSTRACT FROM AUTHOR]