Monolithic Fabrication Research Articles

Analysis of occlusal clearance of crown preparations in a predoctoral clinical setting.

This study sought to assess the presence and location of inadequate tooth preparation performed by predoctoral dental students by scanning mounted casts submitted for monolithic zirconia crown fabrication METHODS: An intraoral scanner capable of volumetric measurements of crown preparations was used to analyze 56 crown preparations on mounted stone casts before submission to a lab for crown fabrication. The mounted casts were scanned individually and then a buccal bite was scanned to stitch the models together into virtual occlusion. The distance between the crown preparations and opposing dentition was displayed volumetrically, and the minimum clearance of each preparation was recorded for both the functional and non-functional cusps. Preparations were evaluated for adequate interocclusal clearance and comparisons were made using a Chi-square test with α=0.05 with respect to tooth location, functional versus nonfunctional cusp, and or single versus multi-unit preparation. Over 47% of mounted casts with crown preparations analyzed for the study exhibited a lack of occlusal clearance in at least one area. Functional cusps were more often under-reduced than non-functional (p<0.001). No other comparisons were statistically significant. The present study demonstrates a high percentage of under-reduced crown preparations in a predoctoral clinic and emphasizes the utility of quality control and analysis via digital scanning of crown preparations prior to crown fabrication.

Ceramics for Microelectromechanical Systems Applications: A Review

A comprehensive review of the application of different ceramics for MEMS devices is presented. Main ceramics materials used for MEMS systems and devices including alumina, zirconia, aluminum Nitride, Silicon Nitride, and LTCC are introduced. Conventional and new methods of fabricating each material are explained based on the literature, along with the advantages of the new approaches, mainly additive manufacturing, i.e., 3D-printing technologies. Various manufacturing processes with relevant sub-techniques are detailed and the ones that are more suitable to have an application for MEMS devices are highlighted with their properties. In the main body of this paper, each material with its application for MEMS is categorized and explained. The majority of works are within three main classifications, including the following: (i) using ceramics as a substrate for MEMS devices to be mounted or fabricated on top of it; (ii) ceramics are a part of the materials used for an MEMS device or a monolithic fabrication of MEMS and ceramics; and finally, (iii) using ceramics as packaging solution for MEMS devices. We elaborate on how ceramics may be superior substitutes over other materials when delicate MEMS-based systems need to be assembled or packaged by a simpler fabrication process as well as their advantages when they need to operate in harsh environments.

A fabrication strategy for millimeter-scale, self-sensing soft-rigid hybrid robots.

Soft robots typically involve manual assembly of core hardware components like actuators, sensors, and controllers. This increases fabrication time and reduces consistency, especially in small-scale soft robots. We present a scalable monolithic fabrication method for millimeter-scale soft-rigid hybrid robots, simplifying the integration of core hardware components. Actuation is provided by soft-foldable polytetrafluoroethylene film-based actuators powered by ionic fluid injection. The desired motion is encoded by integrating a mechanical controller, comprised of rigid-flexible materials. The robot's motion can be self-sensed using an ionic resistive sensor by detecting electrical resistance changes across its body. Our approach is demonstrated by fabricating three distinct soft-rigid hybrid robotic modules, each with unique degrees of freedom: translational, bending, and roto-translational motions. These modules connect to form a soft-rigid hybrid continuum robot with real-time shape-sensing capabilities. We showcase the robot's capabilities by performing object pick-and-place, needle steering and tissue puncturing, and optical fiber steering tasks.

Optimization of laser patterning process for eco-friendly tin-halide perovskite solar module – with a nanosecond green laser

The tin-based perovskite solar cells are promising future eco-friendly photovoltaic technology with increasing efficiency, which relies on fluorine-doped tin oxide (FTO) or indium tin oxide (ITO) as a transparent conducting oxide (TCO) for front contact. In the monolithic module fabrication process interconnections are executed by a series of three scribes with two different lasers 1064 nm and 532 nm. This study aims to simplify the interconnection process in tin-based perovskite solar modules by using a single visible laser source to perform all three scribes. The study uses an inverted device structure of Glass/TCO/ Poly(3,4-ethylenedioxythiophene): Polystyrene sulfonate (PEDOT: PSS)/Formamidinium-tin-iodide (FASnI3)/C60/Bathocuproine (BCP)/Ag and a 532 nm nanosecond pulsed laser source to pattern the ITO and FTO (P1 scribe), the PEDOT: PSS/FASnI3/C60/BCP stack (P2 scribe), and the PEDOT: PSS/FASnI3/C60/BCP/Ag (P3 scribe). The quality of the P1 scribe is assessed by examining the edges, completeness of film removal, cracking, film delamination, and elemental mapping using a stylus profiler, optical microscope, and energy dispersive x-ray spectroscopy. The P1 scribe is completely removed with line widths of 70 µm and 110 µm of ITO and FTO, respectively, without damage to the glass substrate. The profiles are steep, and the electrical isolation is greater than 40 MΩ. The same 532 nm laser is used for P2 and P3 scribes. The ablation of PEDOT: PSS during P2 and P3 scribe is studied by Raman spectroscopy. The results show that the use of a single 532 nm laser source can simplify the patterning process of monolithic tin-based perovskite solar modules, and potentially reduce production costs.

Design and fabrication of fluorous monoliths with tunable surface property for capillary liquid chromatography

Hierarchically porous monoliths with satisfactory properties have been employed in diverse fields, especially separation. In this study, pentafluorophenyl acrylate (PFPA), pentaerythritol tetraacrylate (PETA) and trimethylolpropane tris(3-mercaptopropionate) (TTMP) were selected as precursors to fabricate a novel monolithic column by thermally initiated polymerization in the presence of a binary porogenic system containing tetrahydrofuran and 1-propanol. The fabricated poly(PFPA-co-PETA-co-TTMP) monolithic column revealed excellent permeability and mechanical stability. Additionally, baseline separation of the mixture of small molecules can be achieved, involving alkylbenzene and fluorobenzene in chromatographic assessment, and the theoretical plate number is up to 60,500 plates/m for butylbenzene with a linear velocity of 0.14 mm/s. Tryptic digest of HeLa as an analyte was used to investigate the possibility of the poly(PFPA-co-PETA-co-TTMP) monolith in biological separation by cLC-MS/MS. Moreover, benefiting from the existence of pentafluorophenyl groups, the cucurbit[8]uril (CB[8]) could be modified on the prepared poly(PFPA-co-PETA-co-TTMP) monolith through host-guest interaction to obtain poly(PFPA-co-PETA-co-TTMP)-CB[8] monolith. It could be observed that significant changes in retention behavior of analytes appeared after immobilizing CB[8] on the monolith. It offered an innovative approach by utilizing host-guest interaction to fabricate monolithic columns with different chromatographic behaviors.

3D Printing of Customizable Transient Bioelectronics and Sensors

AbstractTransient electronics have emerged as a new category of devices that can degrade after their functional lifetime, offering tremendous potential as disposable sensors, actuators, wearables, and implants. Additive manufacturing methods represent a promising approach for patterning transient materials, yet examples of fully printed bioelectronic devices are scarce. This study introduces a fully digital 3D printing approach enabling the prototyping and customization of soft bioelectronics made of transient materials. The direct ink writing of poly(octamethylene maleate (anhydride) citrate) (POMaC) as an elastomeric matrix and of a shellac‐carbon ink as a conductor is investigated. Precise and repeatable deposition of both structural and conductive features is achieved by optimizing printing parameters, i.e., the dispense gap, printing speed, and inlet pressure. Multi‐material 3D printing enables the fabrication of functional transient devices. Notably, pressure and strain sensors are shown to operate in ranges relevant to implanted biomechanical monitoring. 3D‐printed transient electrodes are demonstrated to be comparable to state‐of‐the‐art devices in terms of impedance behavior. Finally, physical degradation of the materials is confirmed at physiological conditions. These fully digital additive manufacturing processes enable the monolithic fabrication of customizable transient bioelectronics with adaptable functions and geometries.

Tailoring microstructure and properties of porous mullite-based ceramics via sol-gel impregnation

Nanotechnology has been introduced into the refractory industry decades ago. However, there are still some peculiarities that hinder its routine application. Poor mechanical strength is one of them. Here we present the fabrication technique for mullite porous ceramics using a calcium-free colloidal binder system followed by secondary sol-gel impregnation intended for fabrication of large up-scaled monoliths. The primary foam was prepared via direct foaming of slurry containing colloidal silica, gelling agents, surfactant, silica fume, and different types of alumina. The foam mixture was cast, de-molded and dried using a cascade drying procedure. The investigation of mullitization that occurred during the high-temperature treatment was studied by XRD and TG-DTA analysis. The optimized sintering curve was then applied to obtain the highest mechanical properties. The resulting foam (with open porosity, volume density about 900 kg/m3 and mechanical strength about 10 MPa) was further processed by the impregnation step. The applied silica or combined silica/aluminum sol and unreacted alumina underwent secondary mullitization during following high-temperature treatment, which significantly enhanced the mechanical strength (up to 18 MPa). The secondary mullitization process was also investigated by HT-XRD and TG-DTA analysis. Foam microstructure was observed by an electron scanning microscope. Thermal conductivity of as-prepared ceramics foams varied from 0.3 to 0.4 W/m·K. The foam wall porosity evolution was studied by mercury intrusion porosimeter and estimated from image analysis.

Ultrathin, solvent-resistant dielectric for monolithic fabrication of low-power, intrinsically stretchable active-matrix electronic skin

Ultrathin, solvent-resistant dielectric for monolithic fabrication of low-power, intrinsically stretchable active-matrix electronic skin

β‐Ketoenamine‐Linked Covalent Organic Frameworks Synthesized via Gel‐to‐Gel Monomer Exchange Reaction: From Aerogel Monoliths to Electrodes for Supercapacitors

AbstractCovalent organic frameworks (COFs) possess intrinsic nanoscale pores, limiting mass transport and impacting their utility in many applications, such as catalysis, supercapacitors, and gas storage, demanding efficient diffusion throughout the material. Hierarchical porous structures, integrating larger macropores with inherent micro‐/meso‐pores, facilitate rapid mass transport. Recently, the fabrication of aerogel monoliths is reported exclusively from imine‐linked COFs, offering flexibility in aerogel composition. However, challenges in synthesizing robust β‐ketoenamine‐based COFs with comparable surface areas prompted innovative synthetic approaches. Leveraging the dynamic nature of COF bonds, in this work efficient monomer exchange from imine to partially β‐ketoenamine‐linked COFs within the gel phase is demonstrated. These aerogels can be transformed into electrodes using the compression technique. The new flexible electrodes‐based β‐ketoenamine‐linked COF composites with C super P exhibit superior durability and redox activity. Through supercapacitor assembly, the β‐ketoenamine‐linked COF electrodes outperform their imine‐based counterparts, showcasing enhanced capacitance (88 mF cm−2) and stability at high current densities (2.0 mA cm−2). These findings underscore the promise of β‐ketoenamine‐linked COFs for pseudocapacitor energy storage applications.

Control of Pore Sizes in Epoxy Monoliths and Applications as Sheet-Type Adhesives in Combination with Conventional Epoxy and Acrylic Adhesives.

Materials with monolithic structures, such as epoxy monoliths, are used for a variety of applications, such as for column fillers in gas chromatography and HPLC, for separators in lithium-ion batteries, and for precursor polymers for monolith adhesion. In this study, we investigated the fabrication of epoxy monoliths using 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (TETRAD-C) as the tetrafunctional epoxy and 4,4'-methylenebis(cyclohexylamine) (BACM) as the amine curing agent to control pore diameters using polyethylene glycols (PEGs) of differing molecular weights as the porogenic agents. We fabricated an epoxy monolith with micron-order pores and high strength levels, and which is suitable for the precursors of composite materials in cases where smaller PEGs are used. We discussed the effects of the porous structures of monoliths on their physical properties, such as tensile strength, elongation, elastic modulus, and glass transition temperatures. For example, epoxy monoliths prepared in the presence of PEGs exhibited an elastic modulus less than 1 GPa at room temperature and Tg values of 175-187 °C, while the epoxy bulk thermoset produced without any porogenic solvent showed a high elastic modulus as 1.8 GPa, which was maintained at high temperatures, and a high Tg of 223 °C. In addition, the unique adhesion characteristics of epoxy monolith sheets are revealed as a result of the combinations made with commercial epoxy and acrylic adhesives. Epoxy monoliths that are combined with conventional adhesives can function as sheet-type adhesives purposed with avoiding problems when only liquid-type adhesives are used.

Multimodule microwave assembly for fast readout and charge-noise characterization of silicon quantum dots

Fast measurements of quantum devices is useful in areas such as quantum sensing, quantum computing, and nanodevice quality analysis. Here, we develop a superconductor-semiconductor multimodule microwave assembly to demonstrate charge-state readout at the state of the art. The assembly consist of a superconducting readout resonator interfaced to a silicon-on-insulator (SOI) chiplet containing quantum dots (QDs) in a high-κ nanowire transistor. The superconducting chiplet contains resonant and coupling elements as well as LC filters that, when interfaced with the silicon chip, result in a resonant frequency f=2.12 GHz, a loaded quality factor Q=850, and a resonator impedance Z=470Ω. Combined with the large gate lever arms of SOI technology, we achieve a minimum integration time for single and double QD transitions of 2.77 and 13.5 ns, respectively. We utilize the assembly to measure charge noise over 9 decades of frequency up to 500 kHz and find a 1/f dependence across the whole frequency spectrum as well as a charge-noise level of 4μeV/Hz at 1 Hz. The modular microwave circuitry presented here can be directly utilized in conjunction with other quantum devices to improve the readout performance as well as enable large bandwidth noise spectroscopy, all without the complexity of superconductor-semiconductor monolithic fabrication. Published by the American Physical Society 2024

3D-printed photocatalytic scaffolds of BiVO4 by direct ink writing for acetaminophen mineralization

A novel methodology to obtain 3D printable BiVO4 precursor scaffolds (3DM-BiVO4) via robocasting, showing excellent periodicity, shape retention, and mechanical stability, is disclosed for the first time. The ceramic pastes (solids at 70 wt.-%) comprised of BiVO4 precursor, SiO2NPs, and a solution of deionized water: ethylene glycol (volume ratio 1:2, DI water: EG) exhibited enhanced rheology for the 3D printing of self-supported structures (3DM-BiVO4). The thermal treatment induced a monoclinic scheelite phase, and the ethylene glycol contributed to achieving a unique square flake-like particle morphology. 3DM-BiVO4 scaffolds were used as reusable monolithic photocatalysts, showing 72% acetaminophen mineralization at 240 min and pH = 9. This innovative approach opens avenues for designing 3D printable ceramic pastes, offering potential applications in tailoring-made monolithic photocatalyst fabrication by using SiO2NPs as an inorganic binder.

Structural design and particle size examination on NiO-CeO2 catalysts supported on 3D-printed carbon monoliths for CO2 methanation

3D-printed high-surface carbon monoliths have been fabricated and tested as catalyst supports of CO2 methanation active phases (NiO-CeO2, 12 wt% Ni). The carbon carriers show a developed microporosity and good adherence to the catalytic phases of NiO-CeO2, showing great stability and cyclability. Two monolith designs were used: a conventional parallel-channeled structure (honeycomb) and a complex 3D network of non-linear channels built upon interconnected circular sections (circles), where flow turbulences along the reactant gas path are spurred. The effect of the active phases particle size on the catalyst distribution and the overall performance has been assessed by comparing NiO-CeO2 nanoparticles of 7 nm average (Np), with a reference counterpart of uncontrolled structure (Ref). The improved radial gases diffusion in the circles monolith design is confirmed, and nanoparticles show enhanced CO2 methanation activity than the uncontrolled-size active phase at low temperatures (< 300 ºC). On the contrary, the Ref catalysts achieve higher CH4 production at higher temperatures, where the reaction kinetics is controlled by mass transfer limitations (T > 300 ºC). SEM and Hg porosimetry evidence that nanoparticles are deposited at deeper penetration through the narrow micropores of the carbon matrix of the monolithic supports, which tend to accumulate on the channels surface remaining more accessible to the reactant molecules. Altogether, this study examines the impact of the channel tortuosity and the active phase sizing on the CO2 methanation activity, serving as ground knowledge for the further rational and scalable fabrication of carbon monolith for catalytic applications.

Monolithic Fabrication of Metal‐Free On‐Paper Self‐Charging Power Systems

AbstractSelf‐charging power systems (SCPSs) are envisioned as promising solutions for emerging electronics to mitigate the increasing global concern about battery waste. However, present SCPSs suffer from large form factors, unscalable fabrication, and material complexity. Herein, a type of highly stable, eco‐friendly conductive inks based on poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are developed for direct ink writing of multiple components in the SCPSs, including electrodes for miniaturized spacer‐free triboelectric nanogenerators (TENGs) and microsupercapacitors (MSCs), and interconnects. The principle of “one ink, multiple functions” enables to almost fully print the entire SCPSs on the same paper substrate in a monolithic manner without post‐integration. The monolithic fabrication significantly improves the upscaling capability for manufacturing and reduces the form factor of the entire SCPSs (a small footprint area of ≈2 cm × 3 cm and thickness of ≈1 mm). After pressing/releasing the TENGs for ≈79000 cycles, the 3‐cell series‐connected MSC array can be charged to 1.6 V while the 6‐cell array to 3.0 V. On‐paper SCPSs are promising to serve as lightweight, thin, sustainable, and low‐cost power supplies.

Millimeter-wave 3D-printed filtering power divider with high frequency selectivity and enhanced heat dispersion

In this paper, a 3D-printed filtering power divider with high frequency selectivity and enhanced heat dispersion is proposed in the Ka-band. Based on filter synthesis theory, a meticulous design is implemented for 32 rectangular resonators and their adjacent inductive irises, enabling the simultaneous realization of a 1-to-8 power divider function and an integrated 11th-order filtering response. To enhance heat dispersion performance for high power applications, cooling fins, and cooling slots are strategically incorporated into the filtering power divider. The selective laser melting (SLM) 3D printing fabrication technology is employed for the cost-effective monolithic fabrication of the prototype. The measured results demonstrate that the return loss of the input port is over 12 dB within the frequency range of 27.0–31.4 GHz. The phase and amplitude difference between outputs are less than ±8° and ±0.6 dB. The transmission coefficient is approximately 9.7 dB, indicating an excellent low-loss performance of the 1-to-8 power divider. Beyond the operating bands, the transmission coefficient experiences a decline of over 55 dB/GHz, demonstrating an 11th-order filtering response. The proposed filtering power divider excels in low loss, superior frequency selectivity, and enhanced heat dispersion, promising advancements in high-power millimeter-wave systems.

3D-printed metal-organic framework encapsulated Keggin heteropolyacid for catalytic purpose

To address the limitations of metal-organic frameworks for large-scale applications and the challenges associated with the heterogenization of heteropolyacids, we developed a catalytic monolith leveraging the encapsulation concept and 3D-printing technology. In this approach, a Keggin-type heteropolyacid was encapsulated within a Fe-based metal-organic framework through an in-situ method and subsequently incorporated into a 3D printing ink for the fabrication of a catalytic monolith. The monolith underwent comprehensive characterization, elucidating its morphological, structural, and mechanical features. Moreover, the catalytic performance of the 3D-printed monolith was thoroughly evaluated in Knoevenagel condensation reaction, highlighting its remarkable catalytic activity and exceptional recyclability. Characterization of the recycled catalyst, along with a hot filtration test, further confirmed the stability of the catalyst, the suppression of heteropolyacid leaching, and the manifestation of true heterogeneous catalysis.

Facile fabrication of hydrophobic porous monoliths from charge-driven assembled polymers-stabilized high internal phase emulsion for oil spills reclamation

Oil leakage/spillage and discharge of organic liquids pose severely threat to ecological environment and human health. Herein, hydrophobic porous monolith was fabricated via the polymerization of high internal phase emulsions (HIPEs) stabilized from charge-driven assembled polymers and the introduction of butyl methacrylate (BMA), and the water contact angle is up to 129 ± 2°. The monolith was hierarchical porous, leading to absorb various oils and organic solvents. The absorption capacity of monolith for different solvents ranges from 17.3 to 53.0 g/g, demonstrating excellent absorption. Meanwhile, the monolith shows excellent oil/water separation effect and high cycle efficiency. Therefore, the novel sponge might be an ideal candidate in dealing with oil contamination.

Direct ink written ZnS:Cu photocatalytic luminous monoliths

Traditional monolithic contactors have the advantages of good mass transfer and lower pressure drops; however, similar to packed bed and annular (wall-coated) reactors, monoliths are also plagued with low light utilization efficiencies. Multifunctional luminous monoliths for potential photocatalytic applications were printed using a Direct Ink Writing (DIW) approach in order to achieve intrinsic illumination of monoliths even after an external light source was terminated. A ZnS:Cu - based monolith incorporated with SrAlO4:Eu:Dy blue phosphor (Bp), that emitted light in the absorption range of ZnS:Cu was developed. Results demonstrated that the printed monoliths maintained the absorption profile of the base ZnS:Cu catalyst, exhibited whole structure luminescence, and showed a multipeak photoluminescence profile post excitation, that was representative of the peaks of the phosphor and ZnS:Cu. Additionally, the ZnS:Cu:Bp print exhibited steady illumination for up to 30 min. DIW guidelines were developed for the fabrication of afterglow monoliths, and a route to ameliorate the light distribution challenge of monolithic systems was achieved due to the whole luminescence that was displayed by the prints. Although this work was focused on a specific starting semiconductor (ZnS:Cu), the methods are broadly applicable to different materials that form printable inks.

Cold Temperature Direct Air CO2 Capture with Amine-Loaded Metal-Organic Framework Monoliths.

Zeolites, silica-supported amines, and metal-organic frameworks (MOFs) have been demonstrated as promising adsorbents for direct air CO2 capture (DAC), but the shaping and structuring of these materials into sorbent modules for practical processes have been inadequately investigated compared to the extensive research on powder materials. Furthermore, there have been relatively few studies reporting the DAC performance of sorbent contactors under cold, subambient conditions (temperatures below 20 °C). In this work, we demonstrate the successful fabrication of adsorbent monoliths composed of cellulose acetate (CA) and adsorbent particles such as zeolite 13X and MOF MIL-101(Cr) by a 3D printing technique: solution-based additive manufacturing (SBAM). These monoliths feature interpenetrated macroporous polymeric frameworks in which microcrystals of zeolite 13X or MIL-101(Cr) are evenly distributed, highlighting the versatility of SBAM in fabricating monoliths containing sorbents with different particle sizes and density. Branched poly(ethylenimine) (PEI) is successfully loaded into the CA/MIL-101(Cr) monoliths to impart CO2 uptakes of 1.05 mmol gmonolith-1 at -20 °C and 400 ppm of CO2. Kinetic analysis shows that the CO2 sorption kinetics of PEI-loaded MIL-101(Cr) sorbents are not compromised in the monoliths compared to the powder sorbents. Importantly, these monoliths exhibit promising working capacities (0.95 mmol gmonolith-1) over 14 temperature swing cycles with a moderate regeneration temperature of 60 °C. Dynamic breakthrough experiments at 25 °C under dry conditions reveal a CO2 uptake capacity of 0.60 mmol gmonolith-1, which further increases to 1.05 and 1.43 mmol gmonolith-1 at -20 °C under dry and humid (70% relative humidity) conditions, respectively. Our work showcases the successful implementation of SBAM in making DAC sorbent monoliths with notable CO2 capture performance over a wide range of sorption temperatures, suggesting that SBAM can enable the preparation of efficient sorbent contactors in various form factors for other important chemical separations.

Simplified top-down fabrication of sub-micron silicon nanowires

Abstract Silicon nanowires are among the most promising nanotechnology building blocks in innovative devices with numerous applications as nanoelectromechanical systems. Downscaling the physical size of these devices and optimization of material functionalities by engineering their structure are two promising strategies for further enhancement of their performance for integrated circuits and future-generation sensors and actuators. Integration of silicon nanowires as transduction elements for inertial sensor applications is one prominent example for an intelligent combination of such building blocks for multiple functionalities within a single sensor. Currently, the efforts in this field are marred by the lack of batch fabrication techniques compatible with semiconductor manufacturing. Development of new fabrication techniques for such one-dimensional structures will eliminate the drawbacks associated with assembly issues. The current study aims to explore the limits of batch fabrication for a single nanowire within a thick Si layer. The objective of the current work goes beyond the state of the art with significant improvements to the recent viable approach on the monolithic fabrication of nanowires, which was based on a conformal side-wall coating for the protection of the nanoscale silicon line followed by deep etch of the substrate transforming the protected layer into a silicon nanowire. The newly developed fabrication approach eliminates side wall protection and thereby reduces both process complexity and process temperature. The technique yields promising results with possible improvements for future micro and nanofabrication processes.