Array Template Research Articles

Efficient fabrication of large-scale chalcogenide glass microlens arrays via precision molding method

Infrared microlens arrays (IR MLAs) are crucial for infrared imaging, target detection, and night vision, but creating high-quality large-scale IR MLAs is costly and challenging. This study presents a precision molding method to produce 500 × 500 microlenses on chalcogenide glass. The method involves creating concave silica molds with femtosecond laser-assisted chemical etching, which are then used to press convex MLAs onto the chalcogenide glass surface. By using single-pulse direct writing technology, a microlens array template containing 500 × 500 microlenses can be completed within 25 min. Meanwhile, the chemical etching method offers a highly efficient and low-cost way to prepare mold. The resulting MLAs exhibited smooth surfaces, uniform structures, and good imaging and focusing capabilities, indicating the effectiveness of this approach for large-scale MLA patterning and batch production.

Template-Oriented-Assembly microsphere lithography for multi-type SiC microlens arrays

Silicon carbide (SiC) microlens arrays (MLAs) with a defined layout are used as an optical homogenizer in extremely high-temperature environments due to their excellent physicochemical properties. In this paper, a novel template-oriented-assembly microsphere lithography (TMSL) method is proposed to fabricate SiC MLA. Firstly, the metal micropyramid array (MPA) template was designed and fabricated by ultraprecision cutting and then converted to a polydimethylsiloxane (PDMS) surface. After that, the microspheres were assembled into a monolayer on the inverted MPA of PDMS. Subsequently, the microsphere array monolayer (MSM) was used as the stamper in the hot embossing process to create the photoresist MLA mask. Finally, the patterns on the photoresist mask were transferred to the SiC substrate by inductively coupled plasma (ICP) etching. The layout of lens units was determined by the MPA template and the positioning accuracy of MLA unit is mainly influenced by the form error in MPA mold manufacturing process. The transfer mechanism from the metal MPA template to SiC MLA was studied, and the transfer characteristics of theoretical analyses and experimental results were compared, confirming the feasibility and advantages of the TMSL method.

Capillary Manganese Halide Needle-Like Array Scintillator with Isolated Light Crosstalk for Micro-X-Ray Imaging.

The exacerbation of inherent light scattering with increasing scintillator thickness poses a major challenge for balancing the thickness-dependent spatial resolution and scintillation brightness in X-ray imaging scintillators. Herein, a thick pixelated needle-like array scintillator capable of micrometer resolution is fabricated via waveguide structure engineering. Specifically, this involves integrating a straightforward low-temperature melting process of manganese halide with an aluminum-clad capillary template. In this waveguide structure, the oriented scintillation photons propagate along the well-aligned scintillator and are confined within individual pixels by the aluminum reflective cladding, as substantiated from the comprehensive analysis including laser diffraction experiments. Consequently, thanks to isolated light-crosstalk channels and robust light output due to increased thickness, ultrahigh spatial resolutions of 60.8 and 51.7 lp mm-1 at a modulation transfer function (MTF) of 0.2 are achieved on 0.5mm and even 1mm thick scintillators, respectively, which both exceed the pore diameter of the capillary arrays' template (Φ = 10µm). As far as it is known, these micrometer resolutions are among the highest reported metal halide scintillators and are never demonstrated on such thick scintillators. Here an avenue is presented to the demand for thick scintillators in high-resolution X-ray imaging across diverse scientific and practical fields.

Preparation and performance of a CsI scintillation screen with a double-period structure based on an oxidized silicon micropore array template.

A structured double-period CsI scintillation screen was successfully developed to improve its detection efficiency based on an oxidized silicon micropore array template with a period value on the order of micro-scale. The structure comprises a main structure along with a sub-structure. The main structure with a period of 8 µm was arranged in a square array consisting of square columnar scintillator units. The micropore walls between the main structure units were purposely fabricated from a SiO2-Si-SiO2 layered structure. The pore walls in commonly used single-structure with a period of 4 µm use the same layered structure composition to obtain a fair comparison. The thickness of both Si and the SiO2 layers was around 0.4 µm. The unique feature of the double structure lies in the even separation of each unit within the main structure into four square columnar scintillator sub-units. These four sub-units within each sub-structure were isolated solely by SiO2 layers with a thickness of approximately 0.8 µm. As a result, the X-ray-induced optical luminescence intensity of the double-structure screen exhibited a 31% increase compared to the corresponding single-structure scintillation screen. In X-ray imaging, a spatial resolution of 109 lp/mm was achieved, which closely matched the results obtained with the single-structure CsI screen. Furthermore, the detective quantum efficiency also displayed a notable improvement.

Scalable decoration of Au nanoparticles on Al nanoconcavity arrays for highly enhanced SERS detection

High sensitivity surface-enhanced Raman spectroscopy (SERS) detection platforms are developed based on Al nanoconcavity array templates with Au nanoparticles assembled via sputtering and thermal treatment.

Ultrahigh sensitive SERS film of silver nanorods grown on nanohole array template by oblique angle deposition

To develop a highly sensitive silver nanorod (AgNR) array SERS film, anodic aluminum oxide (AAO) nanohole array templates were employed as seed substrates for oblique angle deposition (O.A.D.) by thermal evaporation. By pore broadening process, precise hole arrays of various diameters were fabricated from preliminarily prepared nanoholes of 30 nm diameter comprising equilateral triangle unit cells whose side length is 100 nm. Aligned silver nanorods of ∼1 μm length were fabricated on the several kinds of seed templates. The optical properties of the AgNR films were measured using thiophenol self-assembled monolayers on the film surfaces and a micro-Raman spectrometer employing a 785 nm pump laser. Out of the AgNR array samples, the AgNR array deposited on an 80-nm hole array substrate showed the highest SERS activity. The highest surface enhancement factor (E.F.) of Raman signal measured in this experiment was ∼7·107, which is ∼7 times higher than that of the AgNR array fabricated on a flat substrate. The main role of the nanopore array substrate was found to decrease the density of the grown nanorods, which is the key parameter determining the E.F. values of the AgNR arrays. From this and previous works, the optimum nanorod density is anticipated to be 8–9 rods/μm2, where E.F. of > 109 could be obtained. The nanorod density of the optimum AgNR array in this experiment was ∼10/μm2. The origin of the key role conducted by the nanorod density cannot be explained by hot spot effect and waits for understanding in the future studies. The ultrahigh sensitive AgNR array SERS film obtained in this work can be a very powerful medium for various chemical and biological sensors.

Wearable electrochemical sensor based on bimetallic MOF coated CNT/PDMS film electrode via a dual-stamping method for real-time sweat glucose analysis

Non-invasive wearable sweat glucose sensors are expected to be highly desirable for personalized diabetes management. Therefore, developing facile, convenient, and scalable manufacturing method of such wearable sensors is urgently needed. Herein, we report a simple and low-cost stamping-vacuum filtration dry transfer (SVFDT) method for construction of a wearable sweat glucose electrochemical sensor. In this patch, a three-electrode array template was made by using a polyvinyl chloride (PVC) stamp, followed by the preparation of multiwalled carbon nanotubes (MWCNTs)/polydimethylsiloxane (PDMS) (MP) film electrode using the vacuum-filtration dry transfer method. In addition, for further enhancing the conductivity of the electrode, another similar stamp with a raised surface dipping carbon nanotubes (CNTs) conductive coating was stamped on the surface of the MP electrode to obtain CNTs/MWCNTs/PDMS (CMP) electrode. CMP electrode was modified with the enzyme-like Ni-Co metal-organic framework (MOF) material which showed good electro-catalytic activity and achieved high sensitivity for glucose detection with a low detection limit of 6.78 μM and a wide linear range of 20 μM - 1.1 mM. More importantly, the Ni-Co MOF modified CMP (NCMP) electrode also displayed high stability under stretching and bending conditions. Finally, the sweat absorbent cloth was combined with the NCMP film electrode to form a wearable flexible electrochemical sensor patch, which could adhere to the skin to enrich sweat and realize real-time detection of sweat glucose with high accuracy. This SVFDT method can also be applied to the fabrication of other electronic devices.

Structured Cs3Cu2I5 scintillation screen based on oxidized silicon micropore array template for high-resolution X-ray imaging

Improving the spatial resolution of X-ray imaging is one of the main directions of scintillation screen research. Herein, a structured Cs3Cu2I5 scintillation screen based on oxidized silicon micropore array template was developed. A feasible method was explored to solve the problems such as the preparation of oxidized silicon micropore array template with micron-period structure and the compact filling of Cs3Cu2I5 scintillator into the template. The X-ray imaging resolution using the structured Cs3Cu2I5 scintillation screen reaches 113 lp/mm attributing to the light guide and optical isolation of the template pore walls. The results of detective quantum efficiency, the X-ray imaging photographs of a micro-resolution plate and a small zebrafish show that the image quality using the structured screen is excellent. Meanwhile, the developed Cs3Cu2I5 scintillation screen exhibits good radiation resistance, which can keep the light output basically unchanged when the radiation dose is up to 43.2 Gy. The screen also exhibits good luminescence stability compared to Cs3Cu2I5 itself due to the protection of the template. These indicate that the structured Cs3Cu2I5 scintillation screen has a good application prospect in high-resolution X-ray imaging.

Optimization of SiO2 reflective layer thickness for improving the performance of structured CsI scintillation screen based on oxidized Si micropore array template in X-ray imaging.

Structured scintillation screen based on oxidized Si micropore array template can effectively improve the spatial resolution of X-ray imaging. The purpose of this study is to investigate the effect of SiO2 layer thickness on the light guide and X-ray imaging performance of CsI scintillation screen when the structural period is as small as microns. Cylindrical micropores with a period of 4.3 µm, an average diameter of 3.3 µm and a depth of about 40 µm were prepared in Si wafers. SiO2 layer was formed on the pore walls after thermal oxidation. Increasing SiO2 layer thickness would be beneficial to the propagation of scintillation light along the cylindrical channels. What was not previously anticipated was that the pore size gradually shrank as the SiO2 layer thickened. The pore shrinkage would reduce the filling rate of CsI in the templates and thus would reduce the production of scintillation light. The structured CsI scintillation screens with different SiO2 layer thicknesses were fabricated by filling CsI scintillator into the oxidized silicon micropore array template. The morphology, crystallinity, X-ray excited optical luminescence, and X-ray imaging performance of the screens were studied. The results show that the spatial resolutions of X-ray images measured using the structured CsI scintillation screens with different SiO2 layer thicknesses are close to each other, and they are all about 110 lp/mm. However, the X-ray excited optical luminescence of the screen and detective quantum efficiency of X-ray imaging vary with the thickness of the SiO2 layer. The optimal thickness is about 350 nm.

Bioinspired optical and electrical dual-responsive heart-on-a-chip for hormone testing

Heart-on-chips have emerged as a powerful tool to promote the paradigm innovation in cardiac pathological research and drug development. Attempts are focused on improving microphysiological visuals, enhancing bionic characteristics, as well as expanding their biomedical applications. Herein, inspired by the bright feathers of peacock, we present a novel optical and electrical dual-responsive heart-on-a-chip based on cardiomyocytes hybrid bright MXene structural color hydrogels for hormone toxicity evaluation. Such hydrogels with inverse opal nanostructure are generated by using pregel to replicate MXene-decorated colloidal photonic crystal (PhC) array templates. The attendant MXene in the hydrogels could not only enhance the saturation of structural color, but also ensure the composite hydrogel with excellent electroconductivity to facilitate the synergetic beating of their surface cultured cardiomyocytes. In this case, the hydrogels would undergo a synchronous deformation and generate shift in corresponding photonic band gap and structural color, which could be employed as visual signal for self-reporting of the cardiomyocyte mechanics. Based on these features, we demonstrated the practical value of the optical and electrical dual-responsive structural color MXene hydrogels constructed heart-on-a-chip in hormone toxicity testing. These results indicated that the proposed heart-on-a-chip might find broad prospects in drug screening, biological research, and so on.

Nanorod array-induced growth of high-quality Sb2Se3 absorber layers for efficient planar solar cells

Antimony selenide (Sb2Se3) has been applied extensively in the field of optoelectronics because of its excellent material and photoelectric properties, as well as its potential low cost effectiveness. Owing to its unique quasi-one-dimensional structure, the preparation of an Sb2Se3 absorption layer with high crystallization quality and standing preferred orientation is crucial for constructing high-performance Sb2Se3 devices. Herein, we reported a new method for the subsequent epitaxial growths of Sb2Se3 thin films with high crystallization and preferred standing orientations using the Sb2Se3 nanorod array as growth template on the Mo substrate and summarized the growth mechanism of the nanorod arrays. High crystal quality and crystal orientation can be easily controlled, carrier recombination is reduced, charge transport is enhanced, and the performance of Sb2Se3 device is improved significantly. As high as 6.3 % power-to-efficiency with a fill factor of 62 % has been achieved for the champion device. This general-purpose nanorod array template growth film provides an effective reference for the growth control of other low latitude crystal films.

Growth of GaN Hexagonal Arrays on Partially Crystallized Sapphire Nanomembranes for Micro-Light-Emitting Diodes

100-nm-thick hexagonal fully and partially crystallized sapphire nanomembrane arrays were demonstrated as growth templates for hexagonal micro-sized GaN arrays for micro-light-emitting diodes (LEDs). By simply controlling the thermal treatment time for crystallization of the amorphous membrane, the partially crystallized nanomembrane which has both single- and polycrystalline alumina on the top surface was fabricated. The unique crystalline structures contributed to unique growth behavior which contains selective and lateral overgrowth of GaN, compared to that of GaN on fully crystallized sapphire nanomembranes, leading to superior structural and optical properties of GaN. Threading dislocation densities were reduced by 75% and 1.29 times higher integrated photoluminescence intensity was achieved compared to GaN on the fully crystallized sapphire nanomembranes. Stress in GaN was also fully relaxed due to the ultrathin membrane structure as a compliant substrate. The superior properties of GaN as well as the truncated inverted pyramid structure are expected to improve the performance of micro-LED devices. Hexagonal partially crystallized sapphire nanomembrane technology also provided advances in the fundamental study of epitaxial growth of GaN-based materials.

A Novel Non-Enzymatic Sensor Prepared by ZnO Nanoneedle Arrays Template for High Performance of Glucose Sensing

In this study, we prepared a gold film covered with dense particles and honeycomb-like holes using a sacrificial template of ZnO nanoneedle arrays and integrated it into a non-enzymatic glucose sensor. The template was characterized by transmission electron microscope (TEM) and scanning electron microscopy (SEM). This is an effective and novel method because the three-dimensional microstructure appeared on its surface when the zinc plate was heated directly. Moreover, seperate steps were not required to modify the electrode. Due to a large specific surface area (Rf = 27.8) and more active sites, the glod film showed a good electrochemical catalytic behavior. The surface morphology and elements of working electrode were characterized by SEM and energy dispersive spectroscopy (EDS). The sensor showed a wide linear range of 0.1–11.0 mM, a high sensitivity of 514.41 μAcm−2 mM−1, and a low detection limit of 2.31 μM. It also can distinguish small changes in glucose concentration (10 or 20 μM). Moreover, The sensor displayed good repeatability, stability and selectivity. Ascorbic acid (AA) and uric acid (UA) had low interference when it detected glucose. Fianlly, a sensor with outstanding performancces, easy preparation was manufactured in this work. It has promising prospects.

Non-gelated polymeric photonic crystal films

A rapid curing method for the preparation of colloidal photonic crystal films is presented. Firstly, a colloidal crystal array template was prepared by self-assembly of nanospheres, and then a dilute polymer solution was poured into the gap of the template. Then the composite photonic film was obtained as the polymer solution was cured. Such films have good properties in mechanical strength, anti pH interference, rapid solvent response and are easy to preserve. The films show good linear response to ethanol aqueous solutions of different concentrations, and the response equilibrium takes less than 20 s. The films also show long-term stability and reusability, and further functionalization can make the films multi-sensitive.

Hollow Nanowire Constructed by NiCo Doped RuO2 Nanoparticles for Robust Hydrogen Evolution at High-Current-Density.

Large-current-density electrocatalytic water splitting is essential for industrial hydrogen production, but it is currently hindered by lacking active and robust hydrogen evolution reaction (HER) catalysts. Herein, a novel electrode of hollow nanowire arrays constructed by NiCo modified RuO2 nanoparticles on Ni foam (NiCo@RuO2 HNAs/NF) for high-performance HER was reported. Such efficient electrode was fabricated by ion exchange with NF-supported Ni modified cobalt carbonate hydroxide nanowire arrays template (Ni@CoCH NAs/NF). The formed NiCo@RuO2 HNAs/NF only needed overpotentials of 148.5 and 236.1 mV to deliver 500 and 1000 mA cm-2 , respectively, along with excellent stability at the high-current-density for 300 h. Such remarkable HER performance was mainly attributed to the hollow structure with high surface area, hydrophilic feature, and NiCo@RuO2 with optimized hydrogen evolution kinetics. After coupling with anodic Ni@CoCH NAs/NF, our electrolyzer outperformed Pt/C-IrO2 and most other Ru-based electrolyzers. This work provides a promising Pt alternative catalyst for profitable H2 production.

A Novel Fabrication of Single Electron Transistor from Patterned Gold Nanoparticle Array Template-Prepared by Polystyrene Nanospheres.

In this paper, polystyrene microspheres were firstly prepared by seeded emulsion polymerization, and the uniform monolayer of polystyrene microspheres was prepared on the substrate by the dipping method. Then, polystyrene monolayer film was used as a mask and a low dimensional array structure of gold was prepared by bottom-up self-assembly process. After that, the method of solution etching and annealing was used, and the gold nanoparticle array was post-processed. As a result, gold nanoparticles were recrystallized, with an average diameter of about 50 nm. Subsequently, the semiconductor process was adopted, with focused ion beams induced deposition and electron beam evaporation, and single electron transistors were fabricated, based on self-assembled gold nanoparticles. Finally, the devices were fixed in a liquid helium cryostat and Coulomb blockade was observed at 320 mK. It is a novel fabrication of a single electron transistor based on gold nanoparticle array template and prepared with polystyrene nanospheres.

Spontaneous Formation of Oriented Lateral Wrinkles Assisted by Shrinkage Controlled Cracking

AbstractOriented wrinkled surfaces play a vital role in the preparation of functional components. However, existing methods for the fabrication of oriented wrinkle patterns are often limited by specific equipment (e.g., high vacuum systems) and cumbersome processes. In this study, an approach utilizing shrinkage controlled cracking method is proposed to introduce prefabricated topographic patterns on flat semi‐crosslinked polydimethylsiloxane (Semi‐PDMS) substrate for modulating anisotropic release of the interlaminar lateral stresses, where the crosslinking‐induced volumetric shrinkage from the Semi‐PDMS substrate provides the driving force for developing and stabilizing oriented surface wrinkle formation; followed by thickening polydopamine (PDA) capping layer to increase the orientation degree of wrinkles. Moreover, the evolutionary mechanism of oriented wrinkles on the PDA/Semi‐PDMS composite surface are demonstrated. The materials used in the reported method are low cost and environmentally friendly, and the preparation process is simple and green without the need for extreme conditions or strong solvents, which can be scaled up to large‐scale fabrication. According to the biocompatibility, high stability, and reactivity of polydopamine, the prepared oriented wrinkles may find potential applications in electronic skin, enhancement of cell alignment, flexible and stretchable electronics, and as structured templates for surface arrays.

Influence of the thickness of a SiO2 reflective layer on the performance of a structured CsI(Tl) scintillation screen based on an oxidized Si micropore array template in X-ray imaging.

To obtain better light guidance and optical isolation effects under a limited microcolumn wall thickness, the influence of the thickness of a SiO2 reflective layer on the performance of a structured CsI(Tl) scintillation screen based on an oxidized Si micropore array template in X-ray imaging was simulated. The results show that the SiO2 reflective layer should maintain a certain thickness to achieve good light-guide performance. However, if the template is entirely composed of SiO2, the light isolation performance of the microcolumn wall will be slightly worse. The results provide a basis for optimizing the thickness of SiO2 reflective layer.

Influence of Si wall thickness of CsI(Tl) micro-square-frustums on the performance of the structured CsI(Tl) scintillation screen in X-ray imaging

To improve the detection efficiency of the structured scintillation screen with CsI(Tl) micro-square-frustums based on oxidized Si micropore array template in the case of a period as small as microns, the influence of Si wall thickness of the CsI(Tl) micro-square-frustums on the performance of the structured screen in X-ray imaging was investigated. The results show that when CsI(Tl) at the bottom of the screen is structured, the detective quantum efficiency (DQE) improves at almost all spatial frequency as the top thickness of the Si wall tSi decreases. However, when CsI (Tl) at the bottom of the screen is not structured, the DQE becomes better at low-frequency and worse at high-frequency as tSi decreases. The results can provide guidance for optimizing tSi according to the comprehensive requirements of detection efficiency and spatial resolution in X-ray imaging.

Detonated growth and functionalization of iron (III) oxyhydroxide nanorod array templates via microwave-assisted synthesis for photoelectrochemical water splitting

In this study, we describe for the first time the detonated ultrafast growth and functionalization of Iron (III) oxyhydroxide (FeOOH) nanorod array templates on a fluorine-doped tin oxide (FTO) substrate using a specially designed microwave-assisted cost-effective synthesis route. The rapid recrystallization and polycondensation in microwave-assisted synthesis (MAS) led to the controlled growth of ferric-hydroxide Fe(OH)3 from the iron-hydroxo complex Fe(H2O)3(OH)3 formed from hydrolyzed FeCl3. Further, the dependence of a number of MAS cycles on the growth and evolution of β-FeOOH nanorod array templated photoanode was examined by high-resolution scanning electron microscopy. The formation mechanism with morphology-controlled FeOOH nanostructure was well discussed and verified. Further, high-temperature quenching (HTQ) transformed MAS akaganeite into hematite, and Sn4+ diffused from FTO substrate. Due to the synergistic impact of MAS growth and Sn4+ diffusion in the α-Fe2O3 nanostructure, the optimum FTO/Fe2O3-1 photoanode achieved the highest photocurrent density (0.854 mA cm−2 at 1.23 V vs. RHE) related with other studied samples. The charge-transfer mechanisms in microwave-assisted Sn4+-diffused α-Fe2O3 nanostructure photoanodes are also investigated. Additionally, the surface-modified FTO/Fe2O3-1 photoanode exhibited the 91 and 180 μmol of oxygen and hydrogen evolution during photoelectrochemical water splitting, respectively. This work opens a sustainable and feasible strategy for designing and regulating high-efficient novel functional photoanode materials for water splitting.