Fabrication Of Templates Research Articles

Magnetic force assisted thermal nanoimprint lithography (MF-TNIL) for cost-effective fabrication of 2D nanosquare array

The work presented here describes a simple, low-cost, and unconventional technique to fabricate a 2D nanosquare array using magnetic force assisted thermal nanoimprint lithography (MF-TNIL). The nanofabrication process involves two steps: (i) fabrication of a 2D nanosquare array template on a laminated plastic sheet via sequential thermal nanoimprinting of linear nanograting polydimethylsiloxane (PDMS) stamp, and (ii) reversal imprinting of template on UV curable polymer using soft UV-nanoimprint lithography. Without using an expensive nanofabrication tool, our proposed technique can fabricate nanosquare array over an area of 1 × 1 cm2 with individual nanosquare having a feature size of about 383 nm × 354 nm × 70 nm. We believe that our proposed MF-TNIL represents a promising nanofabrication technique that will allow fabricating various types of nanostructures for their applications in developing sensors, anti-reflective surfaces, self-cleaning surfaces, etc.

Pre – planned surgical Obturator prosthesis followed by a definitive ones: a requisite for rehabilitation- a case report.

Effective obturation of the maxillectomy defect is a challenging task for the maxillofacial prosthodontist. Multidisciplinary treatment planning is essential to achieve adequate retention and function for the prosthesis. The demand for maxillofacial prosthetic devices for the rehabilitation of patients with congenital or acquired (post-surgical, post-trauma) defects has intensified in recent years. Most of the difficulties can be overcome, to an extent, with the placement of an immediate surgical obturator. This clinical report describes the fabrication of a pre-planned surgical template (immediate surgical obturator) which uses patient’s original occlusion and tooth position, made prior to the surgical resection and inserted at the time of surgery, to provide the patient with the additional benefits of masticatory efficiency, aesthetics and psychological comfort during the healing period followed by a definitive soft liner bulb obturator to accommodate resected lesion post surgery. Keywords: Mucormycosis, surgical template, obturator, silicone based permanent denture soft liner.

Fabrication of PbBi4Ti4O15 microplatelets with different TiO2 reactants

Platelet PbBi4Ti4O15 (PBIT) microcrystals were fabricated by molten salt methods using different TiO2 crystal forms (anatase and rutile) as the reactants. The results showed that the pure PBIT phase can be obtained by using rutile as the reactant, while the PBIT and TiO2 phases coexisted when using anatase as the reactant. In comparison to anatase, the co-topping connection of rutile has better stability and accelerates the nucleation growth rate in a molten salt environment. Thus, PBIT microplatelets with the good crystallinity and plate-like morphology (aspect ratio of ~27) can be obtained when rutile is used as the reactant. Specifically, when using rutile as the reactant, a maximum d33∗ of ~153 pm/V can be obtained, which may potentially allow the fabrication of anisotropic perovskite templates for textured ceramics.

Generic Molding Platform for Simple, Low‐Cost Fabrication of Polymeric Microneedles

AbstractMicromolding technology is widely used for the fabrication of polymer microneedles for transdermal and intradermal drug delivery applications. Geometric features of microneedles in molding are solely determined by geometry of the master mold template. Fabrication of master mold template usually involves costly and cumbersome technologies due to small feature sizes typical of microneedles. In this research, a novel molding platform is designed that is fabricated using low‐cost and simple techniques with flexibility of producing large number of microneedle geometries. The proposed molding platform eliminates need for developing multiple mold templates for fabrication of various geometries of polymer microneedles. Utility of this molding platform is demonstrated in polylactic acid‐based solid thermoplastic microneedles and polyacrylic acid‐based dissolvable microneedles with various aspect ratio settings. Various microneedles fabricated at heights differing with resolution of as low as 100 µm are successfully achieved using specified settings in the molding platform. The suitability of fabricated microneedles for drug delivery applications is evaluated by in vitro and in vivo testing.

Fabrication, structural and optical properties of a virtual GeSi template by Ge filling the porous Si prepared by EC etching

In this paper, a virtual GeSi template has been successfully fabricated by Ge filling the porous silicon (PSi) prepared by electrochemical etching (EC etching). The microstructure quality measured with cross-sectional scanning electron microscopy and photoluminescence spectra reveal that the PSi structure is fully filled with uniformly distributed Ge. Furthermore, Raman and X-ray diffraction results also show that the template has a typical GeSi feature, which originates from Ge interdiffusion with PSi during the Ge deposition. This design and structure can be expected to be useful as a template for Ge-related materials growth and device fabrication.

Endodontic Management of Canal Calcification in Maxillary Central Incisor Using 3D Prototyping Technique: A Case Report

Teeth with calcific metamorphosis pose a challenge to the endodontist in achieving proper access, identification, and debridement of the root canal. With the conventional technique, radiographs and bur orientation have dictated the access cavity preparation, which leads to the removal of more sound tooth structure and iatrogenic errors. To overcome these issues, the recent diagnostic imaging techniques such as cone beam computed tomography followed by three-dimensional fabrication of template have been proposed, which aid the clinician to accurately locate and negotiate the obliterated canal. The present case report describes the importance of conservative access cavity preparation with the use of the guided endodontic technique for the treatment of calcified canals in the maxillary central incisor.

Guided surgery in dental implantology

Dental implant surgery requires precise planning due to various anatomic limitations and restorative goals. The greatest challenges in the surgical and the prosthetic stages of dental implant surgery are due to diagnostic failure and poor case planning. With the advent of new technology surgical guides and templates can be fabricated which has made it possible to achieve more reliable agreement between the planned and final position of dental implants. These templates fabricated by sophisticated data acquisition methods and virtual planning software, seat directly on bone. They are preprogrammed with the individual depth and angulation during 3D computer simulation. It has improved preoperative planning reducing the surgical morbidity. This article reviews the concept of virtual planning and procedure of stereolithography for fabrication of surgical templates during implant planning and placement. Keywords: Dental implant, Guided implant surgery, Surgical guide, Rapid prototyping technology, Stereolithographic template, Radiographic template.

Reduction of surface roughness by modification of step-bunched aluminum nitride layers towards step-flow morphology

Conventional aluminum nitride (AlN) template fabrication techniques, like hydride vapour phase epitaxy or AlN growth on patterned sapphire substrates, usually lead to step-bunched template surfaces. The resulting macrosteps cause emission broadening or even multiple-peak characteristics of ultraviolet light-emitting diodes (UV LEDs) fabricated on such AlN templates. In order to reduce these macrosteps and to provide a smoother surface, even without the need of a thick AlN deposition, a two-layer growth procedure is reported here. A three-dimensional (3D) – twodimensional (2D) sequential growth initiates a significant modification of the previous AlN surface morphology and simultaneously limits the evolving tensile strain. A primarily step-bunched surface with a surface roughness root mean square of 1.8 nm is successfully reduced by the two-layer growth procedure down to 0.8 nm, without any film cracking. This distinct roughness reduction of more than 50% is achieved within an AlN thickness of only 1.3 µm. With a smoother surface, the electroluminescence characteristic of a UV LED structure is substantially improved. Instead of a double-peak emission, typical for LEDs grown on step-bunched templates, a single-peak emission and lower spectral width were achieved, indicating the high potential of the suggested two-layer technique for improving performance.

Hollow SiO2 microspheres with thiol-rich surfaces: The scalable templated fabrication and their application for toxic metal ions adsorption

In this study, the templated fabrication of hollow SiO2 microspheres with thiol-rich surfaces and their application as adsorbents for toxic metal ions were demonstrated. (Cyclohexane + TEOS)-in-water Pickering emulsion was first prepared employing detachable polyurethane-g-poly (N,N-dimethyl acrylamide) (PU-g-PDMA) copolymer micelles as emulsifiers. The subsequent Pickering emulsion interface directing sol-gel reaction of TEOS led to the formation of SiO2 microspheres. Hydrophobic PU cores of PU-g-PDMA copolymer emulsifier micelles were in-situ entrapped in the formed SiO2 layers, while hydrophilic PDMA shells were completely exposed on the surfaces of the SiO2 shells, forming polymer brush-like structure. The subsequent removal of PDMA shells through the cleavage of the reversible disulfide linkages between PU core and PDMA shells left a large number of thiol groups on the surfaces of hollow SiO2 microspheres. The resulting hollow SiO2 microspheres with thiol-rich surfaces, described as SiO2@SH in the text, demonstrated a promising recyclable adsorption for toxic metal ions. ~88% of adsorption capacity for Pb2+ has been maintained after four cycles of adsorption-desorption. The structure of hollow SiO2@SH microspheres was carefully characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy, respectively.

In-Plane Direct-Write Assembly of Iridescent Colloidal Crystals.

Materials made by directed self-assembly of colloids can exhibit a rich spectrum of optical phenomena, including photonic bandgaps, coherent scattering, collective plasmonic resonance, and wave guiding. The assembly of colloidal particles with spatial selectivity is critical for studying these phenomena and for practical device fabrication. While there are well-established techniques for patterning colloidal crystals, these often require multiple steps including the fabrication of a physical template for masking, etching, stamping, or directing dewetting. Here, the direct-writing of colloidal suspensions is presented as a technique for fabrication of iridescent colloidal crystals in arbitrary 2D patterns. Leveraging the principles of convective assembly, the process can be optimized for high writing speeds (≈600 µm s-1 ) at mild process temperature (30 °C) while maintaining long-range (cm-scale) order in the colloidal crystals. The crystals exhibit structural color by grating diffraction, and analysis of diffraction allows particle size, relative grain size, and grain orientation to be deduced. The effect of write trajectory on particle ordering is discussed and insights for developing 3D printing techniques for colloidal crystals via layer-wise printing and sintering are provided.

Fabrication of a GaN template with an air tunnel in a patterned sapphire substrate using carbonization with a photoresist mask

We successfully fabricated a template with an air tunnel between a patterned sapphire substrate (PSS) and GaN using a photoresist mask. The photoresist mask was subjected to plasma etching to induce the growth of the GaN nucleus at the top of the mask by exposing only the top of the PSS lens to the mask height. The carbon profile of the photoresist mask was checked by secondary ion mass spectrometry to detect the presence or absence of carbon in the GaN template during the process. In order to confirm the carbon’s effect on the epitaxially grown GaN template, the XRD was confirmed by the pole figure and the rocking curve. In order to confirm the change of the energy level of GaN by forming a trap in the energy band by carbon, we confirmed the effect of the carbon by comparing the degree of pure GaN.

Metalorganic chemical vapor deposition of aluminum nitride on vertical surfaces

Metalorganic chemical vapor deposited (MOCVD) aluminum nitride (AlN) on vertical sidewalls can be used to implement piezoelectric in-plane actuation and sensing in microelectromechanical system (MEMS) sensors. The AlN films should optimally cover conformally the sidewalls and have good crystal quality with c-axis oriented microstructure for optimal piezoelectric properties. Previous MOCVD AlN research has focused on using AlN as a buffer layer for other III-nitrides and so far, AlN growth has not been studied on large vertical surfaces. In this study, AlN thin films were grown using MOCVD on vertical sidewalls of fabricated templates and the conformality and crystal quality was characterized. The growth template fabrication was optimized with respect to surface roughness, the conformal coverage was analyzed by measuring the thickness profiles of the films, and the crystal quality was investigated using in-plane XRD and TEM. The AlN films have good crystal quality (FWHM 1.70°–3.44°) and c-axis orientation on vertical Si(1 1 1) sidewalls. However, the thicknesses of the films reduce approximately at a rate of 0.8–1.2 nm/μm down the sidewall. Lowering the reactor pressure improved the conformal coverage while changing the growth mode from columnar to step-flow, which also improved the film morphology.

Controlled etching of silica nanospheres monolayer for template application: A systematic study

Monolayers of silica nanospheres (SNs), via self- or guided-assembly has been extensively used for template fabrication in thin films, employed in the areas of plasmonics, photonic crystals, and solar cells. We report on a versatile, rapid, and controllable process to obtain non-close-packed structure by restructuring the SNs geometry at two-particle level. A geometrical model has been proposed to quantify parameters that control the final morphology of the monolayer. SNs of different sizes (viz. 140 nm, 170 nm, and 220 nm) were self-assembled as a close-packed monolayer on a silicon substrate using a three-step spin coating method and then sintered at 950 °C before being exposed to an etchant. We investigate the dependence of particle radius, neck (formed due to sintering) parameters and distance between the SNs, on etching time and etchant concentration. The intermediate and final morphology of the restructured monolayer is used as a template to grow silicon nanowires using metal-assisted chemical etching. We provide quantitative estimates of the parameters pertaining to the restructuring of the monolayer of SNs, which can be used as tunable templates for the growth of nanowires. The optimized process can be scaled-up for industrial application because of its faster and controllable rate of production.

Facile template fabrication of Fe-Mn mixed oxides with hollow microsphere structure for efficient and stable catalytic oxidation of 1,2-dichlorobenzene

A series of novel Fe-Mn mixed oxide hollow microspheres are synthesized by a hard template approach and used for catalytic oxidation of 1,2-dichlorobenzene (DCB). The obtained materials are characterized by FAAS, XRD, N2 sorption, SEM, TEM, in situ FT-IR and XPS techniques. The results show that the proportions of Fe/Mn can make great influence on the physicochemical properties of Fe-Mn mixed oxides, and thus, affecting their catalytic performances in DCB oxidation. In particular, the FeMn20 catalyst (molar ratio Mn/(Fe + Mn) ≈ 20%) exhibits the highest catalytic performance (i.e., high catalytic activity and CO2 selectivity, long-term stability and good water-resistant ability). In situ FT-IR measurements and XPS results reveal that the FeMn20 catalyst shows almost no obvious carbon deposition after long-term testing. The excellent catalytic performance of FeMn20 catalyst is attributed to the combined effects of several factors such as small crystallite size, hierarchical porous structure and high surface active oxygen concentration. It is reasonable for us to believe that such Fe-Mn mixed oxide hollow microspheres represent a very promising catalyst system for total catalytic oxidation of chlorinated volatile organic pollutants.

Bio-oil derived hierarchical porous hard carbon from rubber wood sawdust via a template fabrication process as highly stable anode for sodium-ion batteries

Novel rational design of hierarchical porous hard carbon as anode material for Na-ion storage is successfully prepared from rubber-wood sawdust via a ZnO-based hard template method. The as-synthesized hard carbon reveals a high specific surface area (820 m2 g−1) with the hierarchical porous structure. In order to overcome poor initial coulombic efficiency in the first cycle, we use environmental-friendly water-based carboxymethyl cellulose with styrene butadiene rubber (CMC/SBR) binder instead of organic-based poly (vinylidene fluoride) (PVDF). The CMC/SBR binder delivers a reversible specific capacity of 275 mAh/g and maintains 192 mAh/g over 500 cycles at 100 mA/g. Moreover, PVDF binder exhibits a reversible capacity of 217 mAh/g and over the 500 cycles maintains 123 mAh/g. The Na-ion storage capacity contributes from the adsorption-intercalation mechanism of Na+ ions into the prepared hard carbon for both electrodes. The contribution of surface capacitive for CMC-SBR sample is higher than that of PVDF binder, which demonstrates the enhanced capacity, high rate capability, and excellent cycle stability. This report confers a promising manner of a cost-effective method and eco-friendly abundant resource from bio-waste recycles to utilize the advanced sustainable clean green energy storage for future grid storage applications.

Femtosecond laser fabrication of 3D templates for mass production of artificial compound eyes

Compound eyes are unique optical imaging systems that consist of numerous separate light-sensitive units (ommatidia). Attempts have been made to produce artificial compound eyes via advanced 3D nanotechnologies. Among them, femtosecond laser direct writing (FsLDW) technology has emerged as an effective strategy due to its distinct advantages in 3D designable and high precision fabrication capability. However, the point-by-point scanning process results in a very low fabrication efficiency, limiting the practical applications of the FsLDW technology. To solve this problem, we propose a high-efficiency method for the mass production of 3D artificial compound eyes using a photopolymer template fabricated by FsLDW. The resultant 3D SU-8 compound eye templates could be used to replicate polydimethylsiloxane (PDMS) compound eyes many times (over 50 times) with a highly improved efficiency (nearly 20 times higher than the efficiency of direct fabrication using the point-by-point FsLDW). The PDMS replicas showed good focusing and imaging performances. We anticipate that this method may serve as an enabler for the mass production of 3D artificial compound eyes and promote their practical applications in the near future.

Virtual Surgical Planning Assisted Management for Cleft-Related Maxillary Hypoplasia.

Maxillary hypoplasia is a common developmental deformity affecting patients with cleft lip and palate. Various surgical techniques including conventional orthognathic surgery, total maxillary distraction osteogenesis, and anterior maxillary segmental distraction have been applied to address the deformity. With the evolution of 3D computed tomography imaging, the visualization of skeletal complexities in different perspectives is greatly enhanced and comprehensive surgical planning is achieved. Intraoperative efficiency is also improved with the fabrication of 3D-printed templates. The study aims to present different surgical techniques with virtual surgical planning (VSP) and 3D-printed surgical templates and the solution of representative cases. From January 2014 to January 2019, VSP was transferred to actual surgery or distraction precisely in 80 adult patients with cleft-related maxillary hypoplasia. The accuracy was analyzed and the relapse was also estimated and observed in 18 patients after 1-year follow-up. Based on our experience, VSP provides a more reliable and effective option to conventional model surgery. It facilitates the preoperative planning and accurately transfers the virtual plan to correct the cleft-related maxillary hypoplasia.

An Easy Approach for the Fabrication of Surgical Template for Placement of Mini-implant

The success of dental implant depends on meticulous treatment planning. Restorative problems are often common with improper placement of implants, especially where the alveolar bone quantity is compromised. The accuracy needed in placement of the mini-implant is even more. Hence, the use of a surgical guide becomes essential. Various authors have suggested techniques for the fabrication of surgical and radiographic stents. These techniques make use of different materials in fabrication of stent. This article presents a simple technique for the fabrication of a surgical guide for the placement of mini-implants using simple readily available materials. The technique can be modified to be used for regular diameter implants.

CTAB-assisted fabrication of well-shaped PDA-based colloidosomes

Colloidosomes have gained intensive attention in the past years due to their substantial applications in wide scopes involving encapsulation, catalysis, and drug delivery, etc. In this study, we depicted the templated fabrication of well-shaped colloidosomes with tunable shell thickness by Pickering emulsion at a mild condition. To this end, toluene-in-water Pickering emulsion stabilized by cetyltrimethylammonium bromide (CTAB)–modified polydopamine (PDA) nanoparticles (PDA@CTAB) was prepared. After the covalent cross-linking of PDA nanoparticles assembled on the surface of an oil droplet through chemical reactions occurring in toluene phase, exclusive intra-colloidosomes were afforded. The shell thickness of colloidsomes could be roughly tuned by the adjustment of the amount of the reactive monomers in the oil phase. Our investigations revealed that CTAB was critical for the successful fabrication of well-shaped colloidosomes. Otherwise, only irregular structures were obtained if pristine PDA–stabilized Pickering emulsion was applied. The current strategy could enable hydrophobic cargo, such as 10-hydroxycamptothecin to be encapsulated while colloidosomes were created. The release behavior of the encapsulated cargoes was also investigated.

Progress in Nanoporous Templates: Beyond Anodic Aluminum Oxide and Towards Functional Complex Materials.

Successful synthesis of ordered porous, multi-component complex materials requires a series of coordinated processes, typically including fabrication of a master template, deposition of materials within the pores to form a negative structure, and a third deposition or etching process to create the final, functional template. Translating the utility and the simplicity of the ordered nanoporous geometry of binary oxide templates to those comprising complex functional oxides used in energy, electronic, and biology applications has been met with numerous critical challenges. This review surveys the current state of commonly used complex material nanoporous template synthesis techniques derived from the base anodic aluminum oxide (AAO) geometry.