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A method for active switching of plasmonic structures by surface oxide-stabilized silver deposition is presented. The longitudinal dipole mode in pairsof closely spaced gold nanodisks on ITO was switched by depositing andremoving a connecting layer of silver in solution. Optical properties werestudied using VIS-NIR extinction spectroscopy and confirmed by FDTDsimulations. Uniform dimensional growth by selective silver depositionbrought pairs of gold nanodisks of 73 nm average diameter and 11 nmaverage distance into electrical contact. The growth process was studied byspectroelectrochemical measurements, and uniformity and selectivity wereconfirmed by SEM and XPS analysis, respectively. Uniform deposition wasachieved by introduction of surface oxides on immobilized gold nanodisks,and selectivity by undervoltage deposition. Deposition of silver on disk pairscaused a blue-shift of the transverse dipole mode resonance of roughly 50 nm,and emergence of a new longitudinal mode with resonance around 960 nm.These results demonstrate the possibility for not only tuning of resonancepeak position, but also on-demand switching of an additional mode which canprovide materials with switchable optical properties.

Plasma focused ion beam microscopy (PFIB) is a recent nanofabrication technique that is suitable for site-specific atom probe sample preparation. Higher milling rates and fewer artifacts make it superior to Ga+ FIBs for the preparation of samples where large volumes of material must be removed, for example, when trying to avoid lift-out techniques. Transmission Kikuchi diffraction (TKD) is a method that has facilitated phase identification and crystallographic measurements in such electron transparent samples. We propose a procedure for preparing atom probe tomography (APT) tips from mechanically prepared ribbons by using PFIB. This is highly suitable for the preparation of atom probe tips of interfaces such as interphase boundaries from challenging materials where lift-out tips easily fracture. Our method, in combination with TKD, allows the positioning of regions of interest such as interfaces close to the apex of the tip. We showcase the efficacy of the proposed method in a case study on Alloy 718, where the interface between γ-matrix and δ-phase has not been yet extensively explored through APT due to preparation challenges. Results show depletion of γ″-precipitates near the γ/δ interface. A quantitative evaluation of the composition of phases in the bulk versus near the interface is achieved.

The present work exhibits a novel design of surface plasmon resonance (SPR) biosensor, which comprises CaF2 prism, TiO2, metal (Ag/Au), PtSe2, 2D materials (graphene/ transition metal dichalcogenides (MoS2/WS2)) and sensing medium, for point-of-care detection of various stages of malaria diseases. The transfer matrix method (TMM) is employed to examine the angular reflectivity of the proposed structure after judiciously optimizing the layer thicknesses and layer numbers. Phase interrogation technique is utilised to validate the position of occurrence of resonance angles. Additionally, the proposed SPR structure is designed using COMSOL Multiphysics, to assay the electric field intensity and electric field enhancement factor near the edge of 2D material-sensing layer interface. Simulation upshots revealed that the use of new class of 2D materials catapult the sensor performance to a new height compared to the traditional SPR configuration. A maximum sensitivity of 240.10°/RIU, quality factor of 78.46 RIU-1 and detection accuracy of 1.99 is attained for Ag-based SPR configuration with bilayer of WS2. Sensing parameters are compared with previously reported works to prove the superiority of the present research. Moreover, the real-time and label-free detection of malaria diseases makes the suggested sensor worth to fabricate as a SPR chip with the recent nanofabrication technologies.

Solid-state nanopores of on-demand dimensions and shapes can facilitate desired sensor functions. However, reproducible fabrication of arrayed nanopores of predefined dimensions remains challenging despite numerous techniques explored. Here, bowl-shaped nanopores combining properties of ultrathin membrane and tapering geometry are manufactured using a self-limiting process developed on the basis of standard silicon technology. The upper opening of the bowl-nanopores is 60–120 nm in diameter, and the bottom orifice reaches sub-5 nm. Current-voltage characteristics of the fabricated bowl-nanopores display insignificant rectification indicating weak ionic selectivity, in accordance to numerical simulations showing minor differences in electric field and ionic velocity upon the reversal of bias voltages. Simulations reveal, concomitantly, high-momentum electroosmotic flow downward along the concave nanopore sidewall. Collisions between the left and right tributaries over the bottom orifice drive the electroosmotic flow both up into the nanopore and down out of the nanopore through the orifice. The resultant asymmetry in electrophoretic–electroosmotic force is considered the cause responsible for the experimentally observed strong directionality in λ-DNA translocation with larger amplitude, longer duration, and higher frequencies for the downward movements from the upper opening than the upward ones from the orifice. Thus, the resourceful silicon nanofabrication technology is shown to enable nanopore designs toward enriching sensor applications. Stiftelsen Olle Engkvist

Nanolithography plays crucial roles in the miniaturization of dense integrated circuit, which extremely depends on innovative resist materials. Recently, metal-containing resists have been explored due to their higher short-wavelength photon absorption than traditional polymer resists. Herein, for the first time, the patterning performance of non-alkyl tin-oxo clusters has been evaluated. Meanwhile, the influence of structural characteristics on resolution and sensitivity has been investigated. To evaluate the surface ligand effect, three non-alkyl Sn10-oxo clusters with the same core were functionalized with pyrazole, 3-methylpyrazole and 4-methylpyrazole, respectively. Furthermore, another Sn14-oxo cluster with similar core configuration was also prepared using 4-methylpyrazole ligand to study the influence of Sn nuclearity. Spin-coating method was then applied to fabricate thin films of these non-alkyl tin-oxo clusters on Si substrate, which showed various thicknesses and roughnesses. More interestingly, electron beam lithography (EBL) patterning studies indicated that for the same Sn10 core, the 4-methylpyrazole-decorated clusters showed the best performance. As for the different cluster cores with the same 4-methylpyrazole ligand, the patterns of Sn10 with the higher ligand: Sn ratio are also better than those of Sn14. Finally, distinguishable 50 nm resolution was achieved by 4-methylpyrazole-decorated Sn10 at expose energy of 100 µC/cm2 which can be significantly improved by increasing expose energy to 1,000 µC/cm2 as confirmed by atomic force microscopy (AFM) images. This work not only opens the nanolithography applications of non-alkyl tin-oxo clusters, but also provides an effective structural methodology for improving their patterning performance in future.

In this work, the topographical effect of the scratching trajectory and the feed direction on the formation of lithographed lines on the (001) InP surface was investigated using an atomic force microscope (AFM) tip-based nanomachining approach. Nanoscratching tests were carried out using the sharp face of a diamond AFM tip in contact mode. From the topographic maps obtained by AFM, several morphological and fractal parameters were obtained and analyzed. Surface morphology presented a surface smoothing for surfaces with scratches produced in [011] and [001] directions. The height parameters confirmed this behavior because scratches in [001] direction exhibited lower roughness. Moreover, this scratch direction promoted the height distribution most symmetrical and platykurtic. The other morphological parameters revealed that this direction provided a more irregular surface (smaller Smc and Sxp ), peak distribution, denser and pointed, smaller portion of material in the core, less deep furrows, higher spatial frequency components, and high isotropy. Fractal parameters revealed that FRE90 has the highest spatial complexity, it is dominated by higher spatial frequencies, and has the lowest surface percolation. Furthermore, all samples exhibited high topographic uniformity.

Simple and efficient nanofabrication technology with low cost and high flexibility is indispensable for fundamental nanoscale research and prototyping. Lithography in the near field using the surface plasmon polariton (i.e. plasmonic lithography) provides a promising solution. The system with high stiffness passive nanogap control strategy on a high-speed rotating substrate is one of the most attractive high-throughput methods. However, a smaller and steadier plasmonic nanogap, new scheme of plasmonic lens, and parallel processing should be explored to achieve a new generation high resolution and reliable efficient nanofabrication. Herein, a parallel plasmonic direct-writing nanolithography system is established in which a novel plasmonic flying head is systematically designed to achieve around 15 nm minimum flying-height with high parallelism at the rotating speed of 8–18 m·s−1. A multi-stage metasurface-based polarization insensitive plasmonic lens is proposed to couple more power and realize a more confined spot compared with conventional plasmonic lenses. Parallel lithography of the nanostructures with the smallest (around 26 nm) linewidth is obtained with the prototyping system. The proposed system holds great potential for high- freedom nanofabrication with low cost, such as planar optical elements and nano-electromechanical systems.

The creation of biologically inspired artificial membranes on substrates with custom size and in close proximity to each other not only provides a platform to study biological processes in a simplified manner, but they also constitute building blocks for chemical or biological sensors integrated in microfluidic devices. Scanning probe lithography tools such as dip-pen nanolithography (DPN) have opened a new paradigm in this regard, although they possess some inherent drawbacks like the need to operate in air environment or the limited choice of lipids that can be patterned. In this work, we propose the use of the fluid force microscopy (FluidFM) technology to fabricate biomimetic membranes without losing the multiplexing capability of DPN but gaining flexibility in lipid inks and patterning environment. We shed light on the driving mechanisms of the FluidFM-mediated lithography processes in air and liquid. The obtained results should prompt the creation of more realistic biomimetic membranes with arbitrary complex phospholipid mixtures, cholesterol, and potential functional membrane proteins directly patterned in physiological environment.

Quantum dots (QDs) are semiconducting nanoparticles that exhibit unique fluorescent characteristics when excited by an ultraviolet light source. Owing to their highly saturated emissions, display panels using QDs as pixels have been presented. However, the complications of the nanofabrication procedure limit the industrial application of QDs. This study suggests a method to arrange high-aspect-ratio QD pixels by inducing both Laplace-pressure-driven capillary flow and thermally driven Marangoni flow. The evaporation of colloidal QDs induces a capillary flow that drives the QDs toward the inner tips of V-shaped structures. Additionally, the Marangoni flow arranges the gathered QDs at the tip; thus, they could form a high dune, overcoming the limitations of the existing capillary assembly method using evaporation. Using these phenomena, clover-shaped (assembly of V-shaped edges) templates were made to gather numerous QDs, and the clover with a 30° angle afforded the highest brightness among all the angle structures. Finally, by demonstrating a 100-cm2-sized QD microarray with high uniformity (98.6%), our method shows the feasibility of large-area fabrication, which has extensive application in manufacturing QD displays, anti-counterfeiting labels, and other QD-based optical devices.

Self-assembly of artificial opals has garnered significant interest as a facile nanofabrication technique capable of producing highly ordered structures for optical, electrochemical, biomolecular, and thermal applications. In these applications, the optimum opal particle diameter can vary by several orders of magnitude because the properties of the resultant structures depend strongly on the feature size. However, current opal fabrication techniques only produce high-quality structures over a limited range of sphere sizes or require complex processes and equipment. In this work, the rational and simple fabrication of polycrystalline opals with diameters between 500 nm and 10 μm was demonstrated using slope self-assembly of colloids suspended in ethanol-water. The role of the various process parameters was elucidated through a scaling-based model that accurately captures the variations of opal substrate coverage for spheres of size 2 μm or smaller. For spheres of 10 μm and larger, capillary forces were shown to play a key role in the process dynamics. Based on these insights, millimeter-scale monolayered opals were successfully fabricated, while centimeter-scale opals were possible with sparse sphere stacking or small uncovered areas. These insights provide a guide for the simple and fast fabrication of opals that can be used as optical coatings, templates for high power density electrodes, molecule templates, and high-performance thermo-fluidic devices.

Nanomaterial-based optical techniques for biomarker detection have garnered tremendous attention from the nanofabrication community due to their high precision and enhanced limit of detection (LoD) features. These nanomaterials are highly responsive to local refractive index (RI) fluctuations, and their RI unit sensitivity can be tuned by varying the chemical composition, geometry, and dimensions of the utilized nanostructures. To improve the sensitivity and LoD values of these nanomaterials, it is common to increase both dimensions and aspect ratios of the fabricated nanostructures. However, limited by the complexity, prolonged duration, and elevated costs of the available nanofabrication techniques, mass production of these nanostructures remains challenging. To address not only high accuracy, but also speed and production effectiveness in these nanostructures' fabrication, our work reports, for the first time, a fast, high-throughput, and cost-effective nanofabrication protocol for routine manufacturing of polymer-based nanostructures with high sensitivity and calculated LoD in the pM range by utilizing anodized aluminum oxide (AAO) membranes as templates. Specifically, our developed platform consists of arrays of nearly uniform polystyrene nanopillars with an average diameter of ∼185 nm and aspect ratio of ∼11. We demonstrate that these nanostructures can be produced at a high speed and a notably low price, and that they can be efficiently applied for biosensing purposes after being coated with aluminum-doped silver (Ag/Al) thin films. Our platform successfully detected very low concentrations of human C-reactive protein (hCRP) and SARS-CoV-2 spike protein biomarkers in human plasma samples with LoDs of 11 and 5 pM, respectively. These results open new opportunities for day-to-day fabrication of high aspect ratio arrays of nanopillars that can be used as a base for nanoplasmonic sensors with competitive LoD values. This, in turn, contributes to the development of point-of-care devices and further improvement of the existing nanofabrication techniques, thereby enriching the fields of pharmacology, clinical analysis, and diagnostics.

This paper presents a detailed computational protocol for the atomistic simulation of formation and growth of metal-containing nanostructures during focused electron beam-induced deposition (FEBID). The protocol is based upon irradiation-driven molecular dynamics (IDMD), a novel and general methodology for computer simulations of irradiation-driven transformations of complex molecular systems by means of the advanced software packages MBN Explorer and MBN Studio. Atomistic simulations performed following the formulated protocol provide valuable insights into the fundamental mechanisms of electron-induced precursor fragmentation and the related mechanism of nanostructure formation and growth using FEBID, which are essential for the further advancement of FEBID-based nanofabrication. The developed computational methodology is general and applicable to different precursor molecules, substrate types, and irradiation regimes. The methodology can also be adjusted to simulate the nanostructure formation by other nanofabrication techniques using electron beams, such as direct electron beam lithography. In the present study, the methodology is applied to the IDMD simulation of the FEBID of Pt(PF3)4, a widely studied precursor molecule, on a SiO2 surface. The simulations reveal the processes driving the initial phase of nanostructure formation during FEBID, including the nucleation of Pt atoms and the formation of small metal clusters on the surface, followed by their aggregation and the formation of dendritic platinum nanostructures. The analysis of the simulation results provides spatially resolved relative metal content, height, and growth rate of the deposits, which represents valuable reference data for the experimental characterization of the nanostructures grown by FEBID.

Tin oxides (SnO2) have been widely utilized in electronics, nanolithography, and catalysis. As the atomically precise models of SnO2, tin-oxo clusters (TOCs) not only provide opportunities for mech...

We develop a solution-processable, Ag-sandwiched carbon-nanotube-coated, durable (SAND) architecture that enables power-efficient and highly consistent cyclic heating up to 400 °C at 6 V with neither structural degradation nor substrate breakage. The Ag/CNT/Ag-stacked SAND structure, comprising an airbrushed carbon nanotube (CNT) network layer sandwiched by the Ag layers reduced with ionic Ag ink coatings, can be created by a facile and scalable all-solution-processable fabrication protocol without resorting to vacuum-assisted nanofabrication. Through a systematic comparison with Ag-only and CNT/Ag- or Ag/CNT-bilayered structures, we show that the SAND architecture can improve the joule-heating efficiency and uniformity, and more importantly, the anti-breaking durability to overcome the thermal expansion discrepancy against the underlying substrate. This is analytically interpreted through a thermal stress-induced substrate breaking mechanism, where the increasing difference in the thermal expansion between the substrate and coated layers upon heating can be effectively suppressed within the SAND architecture. Readily applicable to more scalable, diverse substrates ranging from brittle glass to large-area polymer films, the SAND architecture can be utilized in the flexible and reliable anti-failure heating devices required in such applications as machine and vehicle components, sensor systems, and safety and warm-up gears.

As one of the most widely used nanofabrication methods, the atomic force microscopy (AFM) tip-based nanomachining technique offers important advantages, including nanoscale manipulation accuracy, low maintenance cost, and flexible experimental operation. This technique has been applied to one-, two-, and even three-dimensional nanomachining patterns on thin films made of polymers, metals, and two-dimensional materials. These structures are widely used in the fields of nanooptics, nanoelectronics, data storage, super lubrication, and so forth. Moreover, they are believed to have a wide application in other fields, and their possible industrialization may be realized in the future. In this work, the current state of the research into the use of the AFM tip-based nanomachining method in thin-film machining is presented. First, the state of the structures machined on thin films is reviewed according to the type of thin-film materials (i.e., polymers, metals, and two-dimensional materials). Second, the related applications of tip-based nanomachining to film machining are presented. Finally, the current situation of this area and its potential development direction are discussed. This review is expected to enrich the understanding of the research status of the use of the tip-based nanomachining method in thin-film machining and ultimately broaden its application.

This article thanks to recent advancements in nanofabrication and 3-D packaging, typical Internet of Things devices can now be wirelessly controlled using millimeter-scale sensors known as Internet of Tiny Things devices. Since these low-power devices may be exposed to low and indirect solar irradiation, we demonstrate a novel mesosuperstructured solar cell (MSSC) that allows low flux light to be harvested from both its top and bottom sides. Our cell is based on either a dye-sensitized solar cell (DSSC) or a perovskite solar cell (PSC). The active layer in the proposed MSSCs was tuned to allow semitransparent behavior. Moreover, we developed an experimentally validated model that enables optimization of the active layer thickness for different semitransparent MSSC applications. In MSSCs, such optimization is necessary to balance the tradeoff between transparency and efficiency for various active layer thicknesses. Fabricated DSSCs and PSCs cells were used to validate the simulation results. The fabricated DSSC achieved a harvesting ratio of 1:10 with a conversion efficiency of around 2% at one Sun. We demonstrate that the optimum thickness of the mesoporous TiO 2 active layer in DSSCs was 800 nm, enabling a maximum power density of 7 mW/cm 2 .

Advances in femtosecond laser-material interaction facilitate the extension of maskless optical processing to the high efficiency and deep-subwavelength scale. Here, a hybrid plasmon lithography technique has been demonstrated by irradiating near-infrared femtosecond laser pulses onto the Si material coated with thin Cr films in a vacuum chamber, and superior nanograting structures are found to deeply penetrate through the thin Cr film into the underlying Si substrate. In stark contrast to the common ripple structures formed on the Si surface, the Cr-layer mediated Si nanograting structures not only exhibit the spatially super-regular arrangements with a deep-subwavelength period of 355 nm but also present the nonsinusoidal sharp-edged groove geometry with a large depth-to-width aspect ratio of 2.1. Theoretical analyses and calculations reveal that the anomalous structure characterizations are physically ascribed to the excitation of dual-interface coupled plasmons in the thin metal layer, which possess the squeezed spatial wavelength and the periodic columnar intensity distributions. Moreover, the further deepening of periodic nanostructures into the Si substrate is also elucidated by the simulation of electric field enhancements at the bottom of shallow grooves under irradiation of subsequent laser pulses. In combination with a wet etching process, the Si nanograting structures can be modified into the smooth and narrow-mouthed V-profiles, whose optical measurements show a near omnidirectional antireflection especially in the visible range of 565–750 nm, which is expected for the design of advanced photonic devices.

The high-efficiency processing and the high geometrical precision requirements on the transparent hard-brittle optoelectrical materials are attractive to the modern industrial’s interest. Laser-induced related ablation/etching technology is proved to be effective processing for micro/nanofabrication of the transparent hard and brittle materials, due to its unique advantages of mechanical micro-machining with controllable thermal damage. There are some influencing factors like laser duration, target-to-substrate distance (work distance), target materials (absorption resolution), laser fluence, and circumstance (pressure, air, resolution) which were discussed in this review. The processing qualities in various methods were compared and described in this review. The new development of laser-induced related ablation/etching and related advanced technologies is introduced at the end of this review.

Metal-Insulator-Metal (MIM) structures possess a number of shortcomings which include optical loss, tenability, nanofabrication challenges, chemical instability, incompatible manufacturing process etc. To overcome these shortcomings, plasmonic properties of heavily n-doped silicon are studied and found to be similar to those of conventional plasmonic metals like gold or silver. A plasmonic refractive index sensor using n-doped silicon instead of metal is designed and analyzed numerically using Finite Element Method (FEM). A maximum sensitivity of 4900 nm/RIU, which is higher than most of the MIM plasmonic refractive index (RI) sensors proposed to date, is obtained here. The RI sensor reported here, provides a significant improvement in the sensitivity of the device along with its compatibility with traditional nanoelectronics.

A new nanofabrication method for construction of complex superlattice structure with versatile super-periodicity is developed using the moiré fringe of anodized aluminium oxide (AAO) membranes. Two ultrathin AAO membranes with long-range order holes are stacked to form 2D moiré nanopatterns. Both rotational symmetry and the periodicity of the holes are modified by the relative spatial displacement between the superimposing layers. Using the membranes as metal evaporation masks, a wide assortment of complex Al nanostructures are fabricated by varying the misorientation angle of the two ultrathin AAO membranes. Highly ordered Al nanoparticles with different sizes, shapes, orientations, and arrangements on substrates are achieved, which are expected to give abundant surface plasmon mode.

Multi-material and multilayered micro- and nanostructures are prominently featured in nature and engineering and are recognized by their remarkable properties. Unfortunately, the fabrication of micro- and nanostructured materials through conventional processes is challenging and costly. Herein, we introduce a high-throughput, continuous, and versatile strategy for the fabrication of polymer fibers with complex multilayered nanostructures. Chaotic electrospinning (ChE) is based on the coupling of continuous chaotic printing (CCP) and electrospinning, which produces fibers with an internal multi-material microstructure. When a CCP printhead is used as an electrospinning nozzle, the diameter of the fibers is further scaled down by 3 orders of magnitude while preserving their internal structure. ChE enables the use of various polymer inks for the creation of nanofibers with a customizable number of internal nanolayers. Our results showcase the versatility and tunability of ChE to fabricate multilayered structures at the nanoscale at high throughput. We apply ChE to the synthesis of unique carbon textile electrodes composed of nanofibers with striations carved into their surface at regular intervals. These striated carbon electrodes with high surface areas exhibit 3- to 4-fold increases in specific capacitance compared to regular carbon nanofibers; ChE holds great promise for the cost-effective fabrication of electrodes for supercapacitors and other applications.

Although immunofluorescence assays have been used for decades, they are not traditionally capable of quantifying biomarkers at ng/ml levels. Plasmonic enhancement of fluorescence using metallic surface nanostructures has exhibited potential in amplifying the fluorescence signal, which could reduce limits of detection and increase sensitivity. However, current methods for fabricating metallic nanostructures, such as e-beam nanolithography, colloidal lithography, and colloidal self-assembly, require complicated processes and have various drawbacks. In this work, we describe a nanostructure fabrication process we have developed based on the dewetting of thin silver films by rapid thermal annealing, which is suitable for large areas. The nanostructures were then coated with a thin silica film to protect them and also to control the distance between the metallic surface and fluorophores, an important parameter when tuning metal enhancement of fluorescence. Antibody-antigen immunoassays utilizing immunoglobulin G were applied to evaluate the fluorescence enhancement from these nanostructures. A nearly 19-fold increase in the fluorescence intensity was achieved with an optimized structure. Calibration of the resulting plasmonically enhanced immunofluorescence sensor showed that it is nearly 13 times more sensitive than the non-enhanced version and was capable of quantification of a biomarker at ~ 1 ng/ml levels. A model nanostructure was constructed for which finite difference time domain simulations were in good agreement with experimental results, allowing for optimization of process conditions for the further generation of nanostructures.

Developing an efficient and versatile process to transform a single linear polymer chain into a shape-defined nanoobject is a major challenge in the fields of chemistry and nanotechnology to replicate sophisticated biological functions of proteins and nucleic acids in a synthetic polymer system. In this study, we performed one-shot intrablock crosslinking of linear block copolymers (BCPs) to realize single-chain nanoparticles (SCNPs) with two chemically compartmentalized domains (i.e., Janus-shaped SCNPs). Detailed structural characterizations of the Janus-shaped SCNP composed of polystyrene- block -poly(glycolic acid) revealed its compactly folded conformation and compartmentalized block localization, similar to the self-folded tertiary structures of natural proteins. Versatility of the one-shot intrablock crosslinking was demonstrated using several different BCP precursors. We further discovered the excellent self-assembling behavior of the Janus-shaped SCNP to produce miniscule microphase-separated structures, representing the significant potential of the presented compartmentalization protocol, for developing biomimetic synthetic-systems, as well as for industrial nanofabrication applications.

The growing demands of supramolecular hyperbranched polymers integrating noncovalent interaction and unique topological structure merits had received considerable interest in the fabrication of novel materials for advanced applications. Herein, we prepared A2B6-type POSS-containing supramolecular hyperbranched polymers with multiple morphologies including lamellar-like, branched, hollow, core-shell and porous spherical structures through regulating self-assembling monomer concentrations and solvent polarities. The incorporation of appropriate emulative guest molecules would further trigger morphological transformations (such as vesicles and spherical micelles) by synergistic effects of unique POSS aggregation ability, supramolecular complexations and hydrophilic-hydrophobic interactions. Thus, this facile and universal strategy may enable a modular nanofabrication of supramolecular hyperbranched polymers with diversiform topological structure and sophisticated multifunctionality for their potential applications.

Dip-pen nanolithography is an emerging and attractive surface modification technique that has the capacity to directly and controllably write micro/nano-array patterns on diverse substrates. The superior throughput, resolution, and registration enable DPN an outstanding candidate for biological detection from the molecular level to the cellular level. Herein, we overview the technological evolution of DPN in terms of its advanced derivatives and DPN-enabled versatile sensing patterns featuring multiple compositions and structures for biosensing. Benefitting from uniform, reproducible, and large-area array patterns, DPN-based biosensors have shown high sensitivity, excellent selectivity, and fast response in target analyte detection and specific cellular recognition. We anticipate that DPN-based technologies could offer great potential opportunities to fabricate multiplexed, programmable, and commercial array-based sensing biochips.

Direct optical polymer patterning As a platform for electronic devices, polymeric materials offer the advantages of intrinsic flexibility and stretchability relative to hard material devices. However, unlike materials such as silicon, there are few tools for large-scale patterning of monolithic devices. Zheng et al. developed an optical lithography technique for the high-throughput fabrication of transistor circuitry on stretchable substrates. In this method, ultraviolet light is used to control the local solubility of the polymer, which makes it possible to fabricate transistors on the micrometer scale. These devices can be made with high yield and excellent uniformity without compromising their electronic and mechanical characteristics. Science , abh3551, this issue p. 88

The helium ion microscope has emerged as a multifaceted instrument enabling a broad range of applications beyond imaging in which the finely focused helium ion beam is used for a variety of defect engineering, ion implantation, and nanofabrication tasks. Operation of the ion source with neon has extended the reach of this technology even further. This paper reviews the materials modification research that has been enabled by the helium ion microscope since its commercialization in 2007, ranging from fundamental studies of beam–sample effects, to the prototyping of new devices with features in the sub-10 nm domain.

Structured hydrogel sheets offer the potential to mimic the mechanics and morphology of native cell environments in vitro; however, controlling the morphology of such sheets across multiple length scales to give cells consistent multi-dimensional cues remains challenging. Here, we demonstrate a simple two-step process based on sequential electrospinning and thermal wrinkling to create nanocomposite poly(oligoethylene glycol methacrylate)/cellulose nanocrystal hydrogel sheets with a highly tunable multi-scale wrinkled (micro) and fibrous (nano) morphology. By varying the time of electrospinning, rotation speed of the collector, and geometry of the thermal wrinkling process, the hydrogel nanofiber density, fiber alignment, and wrinkle geometry (biaxial or uniaxial) can be independently controlled. Adhered C2C12 mouse myoblast muscle cells display a random orientation on biaxially wrinkled sheets but an extended morphology (directed preferentially along the wrinkles) on uniaxially wrinkled sheets. While the nanofiber orientation had a smaller effect on cell alignment, parallel nanofibers promoted improved cell alignment along the wrinkle direction while perpendicular nanofibers disrupted alignment. The highly tunable structures demonstrated are some of the most complex morphologies engineered into hydrogels to-date without requiring intensive micro/nanofabrication approaches and offer the potential to precisely regulate cell-substrate interactions in a “2.5D” environment (i.e. a surface with both micro- and nano-structured topographies) for in vitro cell screening or in vivo tissue regeneration. Statement of significance While structured hydrogels can mimic the morphology of natural tissues, controlling this morphology over multiple length scales remains challenging. Furthermore, the incorporation of secondary morphologies within individual hydrogels via simple manufacturing techniques would represent a significant advancement in the field of structured biomaterials and an opportunity to study complex cell-biomaterial interactions. Herein, we leverage a two-step process based on electrospinning and thermal wrinkling to prepare structured hydrogels with microscale wrinkles and nanoscale fibers. Fiber orientation/density and wrinkle geometry can be independently controlled during the electrospinning and thermal wrinkling processes respectively, demonstrating the flexibility of this technique for creating well-defined multiscale hydrogel structures. Finally, we show that while wrinkle geometry is the major determinant of cell alignment, nanofiber orientation also plays a role in this process.

Antireflection (AR) silicon and glass surfaces are necessarily required for solar cells, because a reflective silicon solar cell with a glass covering will reflect a percentage of sunlight. In this work, we demonstrate a universal and scalable net-shape nanofabrication method for broadband nanostructured AR surface on transparent glass, intended for solar cell applications. Moth eye-like glass nanopillars with various diameters were successfully fabricated by a combination of precision hot embossing and ultrasonic vibration demolding process. The morphologies of nanopillars were detected to characterize different profiles formed by glass flow at elevated temperatures. Facile optical experiments were designed and conducted to measure the AR performance at varying wavelengths and angle of incidences and the proposed nanostructures exhibit excellent AR property. Additionally, a feasible optical modeling is developed and compared with the measurement to evaluate the theoretical optical behaviors of glass nanostructures based on their embossed shapes. The inexpensive and environmental hot embossing method with ultrasonic vibration demolding is expected to create AR glass nanostructured surfaces for widespread applications such as solar cells, displays and laser systems.

Nanofabrication schemes usually suffer challenges in direct growth on complex nanostructured substrates. We provide a new technology that allows for the convenient, selective growth of complex nanostructures directly on three-dimensional (3D) homogeneous semiconductor substrates. The nature of the selectivity is derived from surface states modulated electrochemical deposition. Metals, metal oxides, and compound semiconductor structures can be prepared with high fidelity over a wide scale range from tens of nanometers to hundreds of microns. The utility of the process for photoelectrochemical applications is demonstrated by selectively decorating the sidewalls and tips of silicon microwires with cuprous oxide and cobalt oxides catalysts, respectively. Our findings indicate a new selective fabrication concept applied for homogeneous 3D semiconductor substrates, which is of high promise in community of photoelectronics, photoelectrochemistry, photonics, microelectronics, etc.

Conventional photolithography, due to its scalability, robustness, and straightforward processes, has been widely applied to micro- and nanostructure manufacturing in electronics, optics, and biology. However, optical diffraction limits the ultimate resolution of conventional photolithography, which hinders its potential in nanoscale patterning for broader applications. Here, we introduce a derivative of conventional photolithography for nanoscale patterning called dual-layer photolithography (DLPL), which is based on the controlled exposure and development of overlapping positive and negative photoresists. In a typical experiment, substrates are sequentially coated by two layers of photoresists (both positive and negative). Then, we purposefully control the exposure time to generate slightly larger features in the positive photoresist than those in the negative photoresist. After development, their overlapping areas become the final features, which outline the original features. We demonstrate line widths down to 300 nm here, which can be readily improved with more precise control. By adjusting the lithography parameters and material deposition, the feature sizes, shapes (e.g., rings, numbers, letters), line widths (300-900 nm), and materials (e.g., SiO2, Cr, and Ag) of these features can be independently controlled. Combined with anisotropic etching, more complex three-dimensional nanostructures can be fabricated as well, as we demonstrate here with Si. We further fabricate photodetectors as an example application to show that these nanostructures fabricated by DLPL can be used to promote light-trapping MAPbI3 perovskite films to achieve good photoelectric properties. This strategy is not limited to ultraviolet photolithography and may also be incorporated into other energetic beam-based lithographic approaches, including deep and extreme ultraviolet photolithographies and electron beam lithography, to enhance their resolution.

Considering that the periodic photonic nanostructures are commonly realized by expensive nanofabrication processes and the tunability of structure parameters is limited and complicated, we demonstrate a solution-processed upside-down molding method to fabricate photonic resonators on perovskites with a pattern geometry controllable to a certain extent. This upside-down approach not only reveals the effect of capillary force during the imprinting but also can control the waveguide layer thickness due to the inversion of the perovskite membranes.

The outcomes of the study of plant surfaces, such as rice leaves or bamboo leaves, have led to extensive efforts being devoted to fabricating anisotropic arrays of micro/nanoscale features for exploring anisotropic droplet spreading. Nonetheless, precise engineering of the density and continuity of three-phase contact lines for anisotropic wetting remains a significant challenge without resorting to chemical modifications and costly procedures. In this work, we investigated secondary electrohydrodynamic instability in polymer films for producing secondary nanosized patterns between the micrometer-sized grooves by controlling the timescale parameter, 1/τm (>10-4 s-1). We experimentally demonstrated facile morphological control of anisotropic wettability without the use of any chemical modifications. Thus, anisotropic hydrophilic surfaces fabricated by the secondary phase instability of polymer films are advantageous for both droplet condensation and removal, thereby outperforming the water collection efficiency of conventional (isotropic) hydrophilic surfaces in water harvesting applications (∼200 mg·cm-2·h-1) with excellent durability.

Grating nanostructures play a crucial role for their application in plasmonic sensors. A comprehensive review on grating nanostructure based plasmonic sensor is presented in this article. The structural developments and sensing performance enhancements in last two decades are focused upon. Surface plasmon resonance (SPR) and localized SPR (LSPR) sensors have gained much popularity and are still flourishing due to advancements in nanofabrication technology. Refractive index change and field enhancement are the two phenomena that are responsible for qualitative and quantitative detection and analysis of a variety of samples. The future scenario and possibilities regarding the advancements in grating plasmonic sensors have also been discussed.

Soft lithography is one of the most promising nanofabrication technologies for scalable nanomanufacturing. It uses flexible molds or stamps to fabricate extremely high-resolution nanopatterns in a low cost and rapid fashion on both flat and curved surfaces. Although two-dimensional soft lithography has been widely investigated and applied for some applications, there is a lack of quantitative research on using nanometer scale 3D patterns fabricated by atomic force microscope (AFM) for 3D soft lithography. In this paper, we demonstrated the effectiveness of ultrasonic vibration assisted AFM-based nanomachining in fabricating 3D master nanotemplates for 3D soft lithography. We successfully applied Polydimethylsiloxane (PDMS) daughter molds, casted from a nanometer scale 3D master template, using a soft lithography technique solvent-assisted micromolding. In addition, we investigated the quality and reusability of the master nanotemplates, and the quality of the PDMS patterns by quantifying the volume differences using an automatic imaging registration algorithm. Results show that there are zero or little PDMS residuals in the polymethyl methacrylate (PMMA) master nanotemplate with a simple contour for the first and second daughter mold casting, but 7% residuals for the third casting. And a more complex master nanotemplate shows slightly higher residual levels.

In the increasing demands for exotic device development in the fields of electronics, optoelectronics, sensors, energy, integrated circuits, and quantum technologies, 2D heterostructures can offer tremendous possibilities to sustain Moore’s law. Despite considerable efforts in integrating distinct 2D materials, incomplete understanding of the role of native defects, poor mobility, stability, and low quantum yield poses many challenges for the overall performance of most heterostructure-based devices. In this review, we explore the recent development in the synthesis, strategies for interface modulation, structure–property optimization, and nanofabrication technologies of 2D lateral assembly. Specifically, chemical vapor deposition (CVD) methods and adopting phase and doping engineering for the reliable development of lateral heterostructures are explored in detail. The traditional phase engineering is extrapolated to understand the role of metal/2D semiconductors contact interface, essentially bridging metallic 2D materials as contacts to traditional metal electrodes. The applications of these integrated 2D lateral heterostructures as an active component of many optoelectronics including p-n junction diodes, high-performance transistors, LED, photosensors, and photovoltaics are highlighted. Moreover, we underline the challenges and outlooks to increase the library of 2D lateral geometry in high phase purity and excellent controllability.

Quasi-three-dimensionally designed metal-dielectric hybrid nanoantennas have provided a unique capability to control light at the nanoscale beyond the diffraction limit, which has enabled powerful optical manipulation techniques. However, the fabrication of these nanoantennas has largely relied on the use of nanolithography techniques that are time- and cost-consuming, impeding their application in wide-ranging use. Herein, we report a versatile methodology enabling the repetitive replication of these nanoantennas from their silicon molds with tailored optical features for infrared bandpass filtering. Comprehensive experimental and computational analyses revealed the underlying mechanism of this methodology and also provided a technical guideline for pragmatic translation into infrared filters in multispectral imaging.

Shear alignment of the block copolymer (BCP) thin film is one of the promising directed self-assembly (DSA) methodologies for the unidirectional alignment of sub-10 nm microdomains of BCPs for next-generation nanolithography and nanowire-grid polarizers. However, because of the differences in the surface/interfacial energies at the top surface/bottom interface, the shear-induced ordering of BCP nanopatterns has been restricted to BCPs with spherical and cylindrical nanopatterns and cannot be realized for high-aspect-ratio perpendicular lamellar structures, which is essential for practical application to semiconductor pattern processes. It is still a difficult challenge to fabricate the unidirectional alignment in a short time over a large area. In this study, we propose an approach for combining the shear-rolling process with the filtered plasma treatment of BCP films for the fabrication of unidirectionally aligned and perpendicularly oriented lamellar nanostructures. This approach enables fabrication within 1 min on a 4 in scale. We treated filtered plasma on the BCP film for perpendicular orientation and executed the hot-rolling process with different roller and stage speeds. Large-scale shear was generated only at the location where the BCP film was in contact with both the roller and stage, effectively applying shear stress to a large area of the BCP film within a short time. The repeated application of this shear-rolling process can achieve a higher level of unidirectional alignment. Our aligned BCP vertical lamellae were used to fabricate a high-aspect-ratio sub-10-nm-wide metallic nanowire array via dry/wet processes. In addition, shear-rolling with chemoepitaxy patterns can achieve higher orientational order and lower defectivity.

Different aspects of electron-beam damage are summarized, together with some quantitative evaluation. TEM and STEM are compared in terms of information-to-damage ratio. Electron-beam fabrication is briefly considered in terms of resolution and writing speed.

Area-selective atomic layer deposition is a key technology for modern microelectronics as it eliminates alignment errors inherent to conventional approaches by enabling material deposition only in specific areas. Typically, the selectivity originates from surface modifications of the substrate that allow or block precursor adsorption. The control of the deposition process currently remains a major challenge as the selectivity of the no-growth areas is lost quickly. Here, we show that surface modifications of the substrate strongly manipulate surface diffusion. The selective deposition of TiO

Three-dimensional (3D) nanoarchitectures have offered unprecedented material performances in diverse applications like energy storages, catalysts, electronic, mechanical, and photonic devices. These outstanding performances are attributed to unusual material properties at the nanoscale, enormous surface areas, a geometrical uniqueness, and comparable feature sizes with optical wavelengths. For the practical use of the unusual nanoscale properties, there have been developments for macroscale fabrications of the 3D nanoarchitectures with process areas over centimeter scales. Among the many fabrication methods for 3D structures at the nanoscale, proximity-field nanopatterning (PnP) is one of the promising techniques that generates 3D optical holographic images and transforms them into material structures through a lithographic process. Using conformal and transparent phase masks as a key factor, the PnP process has advantages in terms of stability, uniformity, and reproducibility for 3D nanostructures with periods from 300 nm to several micrometers. Other merits of realizing precise 3D features with sub-100 nm and rapid processes are attributed to the interference of coherent light diffracted by phase masks. In this review, to report the overall progress of PnP from 2003, we present a comprehensive understanding of PnP, including its brief history, the fundamental principles, symmetry control of 3D nanoarchitectures, material issues for the phase masks, and the process area expansion to the wafer-scale for the target applications. Finally, technical challenges and prospects are discussed for further development and practical applications of the PnP technique.

Metals were for decades perceived as devoid of interesting optical properties that could be harnessed for optical components and devices. However, with the development of accurate nanofabrication techniques and precise control over architectural parameters, metals can be structured and characterized on the nanoscale. Metallic plasmonic nanomaterials exhibit a number of unique structural and optical properties, which offer the potential for developing new types of plasmonic devices. Here, we demonstrate a low-loss broadband polarizer based on a hybrid plasmonic fiber structure using metals as polarization-selective absorption materials. The polarization mechanism, design, fabrication, and characteristics of the plasmonic polarizers are investigated theoretically, numerically, and experimentally. The theoretical analysis predicts that the polarization-selective absorption with insensitivity to wavelength enables hybrid plasmonic fibers to function as broadband polarizers. Numerical simulations give the comparison of the polarization-selective absorption of various metallic nanomaterials (Ag, Au, In, Al, Cr) and show that aluminum is regarded as the optimum absorption material for the plasmonic polarizer. Experimental results show that through precise control over geometrical parameters, this device is capable of offering a high polarization extinction ratio (PER) of over 40 dB and a low insertion loss (IL) of less than 1.3 dB in the wavelength region of 810.1-870.0 nm. Compared with commercial birefringent-crystal-fiber polarizers, the plasmonic fiber polarizer has a better PER and IL bandwidth. These merits, combined with a compact and robust configuration, enable the plasmonic polarizer to have great potential in a broad range of applications.

Janus membrane with opposite wettability on its two sides has witnessed an explosion of interest in the field of liquid spontaneous and directional transport for their promising prospect. The advances in fabrication technology and natural bionics have brought remarkable progress for the development of Janus materials. Among the exciting progress, the micro/nanofabrication technique of electrospinning shows advantages in constructing thin porous fibrous membrane materials with controllable surface wettability and hierarchical structures. Here, a brief review of bioinspired Janus membrane for unidirectional liquid penetration fabricated by electrospinning is presented, and the underlying scientific mechanism is discussed with an emphasis on the materials design involving asymmetric surface wettability and micro-topology structure. An overview of recent emerging applications is also reviewed, with special attentions to liquid separation, water collection, distillation, and smart textile, etc. As researchers keep to develop more efficient strategies on designing new Janus membrane with higher performances, it has become increasingly important to understand the mechanism of liquid moving dynamics at the asymmetric interface in order to better recognize the scientific limitations currently hindering the field development. At last, the challenges currently faced and possible strategies on developing new Janus membranes for optimization and engineering in the future are proposed.

Densely packed high-aspect-ratio (HAR) nanostructures are the core elements of future microelectronics components. Manufacturing these nanostructures for device applications requires multiple fabri...

In this work, we demonstrate a process having the capability to realize single-digit nanometer lithography using single heavy ions. By adopting 2.15 GeV 86Kr26+ ions as the exposure source and hydrogen silsesquioxane (HSQ) as a negative-tone inorganic resist, ultrahigh-aspect-ratio nanofilaments with sub-5 nm feature size, following the trajectory of single heavy ions, were reliably obtained. Control experiments and simulation analysis indicate that the high-resolution capabilities of both HSQ resist and the heavy ions contribute the sub-5 nm fabrication result. Our work on the one hand provides a robust evidence that single heavy ions have the potential for single-digit nanometer lithography and on the other hand proves the capability of inorganic resists for reliable sub-5 nm patterning. Along with the further development of heavy-ion technology, their ultimate patterning resolution is supposed to be more accessible for device prototyping and resist evaluation at the single-digit nanometer scale.

Background and Introduction: Metal oxides (MOs) have been extensively used in a large range of engineering and medical applications. Methods: FeCo nanoparticles (NPs) were successfully synthesized by the solgel method in the presence of a powerful reducing agent-sodium borohydride (NaBH4). The structure, morphology, and optical properties of NPs were analyzed by X-ray diffraction (XRD), field effect scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) at room temperature. Results: The XRD spectrum showed the body center cubic (BCC) structure of the samples after heat treatment at 500 °C. The SEM analysis exhibited that the particle size of as-synthesized and annealed samples was approximately 40 nm and 22 nm, respectively. Conclusion: The TEM investigations showed the rod-shaped sample of annealed NPs. The optical studies of the FTIR analysis revealed the starching bound of Fe-Co at the frequencies of 673 cm-1, 598 cm-1, and 478 cm-1.