Etching Technique Research Articles

In situ characterization of optical micro/nano fibers using scattering loss analysis

We experimentally demonstrate the in situ characterization of optical micro/nano fibers (MNFs). The MNF (test fiber, TF) is positioned on a microfiber (probe fiber, PF) and simulated for the scattering loss at various PF and TF diameters. The TF is fabricated using chemical etching technique. The PF is a conventional single-mode fiber with an outer diameter of 125 μm. We measure the scattering loss along the TF axis at various positions i.e., diameters by mounting it on the PF. The diameter profile of the TF is inferred from the measured scattering loss and correlated with its surface morphology measurement. This work demonstrates an effective, low-cost, and non-destructive method for in situ characterization of fabricated MNFs. It can detect and determine the irregularities on the surface of OMNFs. It can also be used to quantify the local evanescent field. Detecting such local points can improve studies that are carried out using these fields in various sensing and related study domains. It is simple to implement and can be accessed by all domains of researchers.

Fabrication of 3D porous polyurethane-graphene oxide scaffolds by a sequential two-step processing for non-load bearing bone defects

Bone defects as a common orthopedic disease lead to severe pains over a long period. Scaffolds are novel approaches in tissue engineering to treat bone problems and deal with their challenges. Here, 3D porous polyurethane (PU) scaffolds containing graphene oxide (GO) with different percentages (0, 0.1, 0.3, and 0.5 wt%) were developed through a combination of freeze-drying and salt etching techniques for bone tissue engineering applications. The morphologies of scaffolds, physicochemical properties, the degree of crystallinity, and hydrophilicity were evaluated by SEM, FTIR, XRD, and water contact angle assay, respectively. The porosity, degradation behavior, compressive strength, and elastic modulus of 3D porous scaffolds were also determined. To assess the scaffold bioactivity, the morphology of the deposited calcium phosphate layer on the scaffold with macro-structure was evaluated by SEM images. The viability and adhesion of MG63 osteoblast-like cells cultured on the fabricated scaffolds were examined by MTT assay and SEM images, respectively. The results show that adding GO particles not only had no effect on the interconnectivity and porosity of 3D porous macroscopic structures of neat PU but also smaller and more uniformed microscopically pores were obtained. The crystallinity, water contact angle, and weight loss of scaffolds increased as the higher GO concentrations were employed. Followed by increasing GO contents from 0 to 0.5 wt%, the compressive strength and Young’s modulus were increased by 232% and 245%, respectively. The bioactivity of scaffolds was fostered as GO concentration increased. Although, the MTT assay proved the biocompatibility of PU scaffolds containing 0.1 and 0.3 wt% GO, the samples loaded with 0.5 GO had a negative impact on the viability of MG63 cell lines. In conclusion, the present study demonstrates a high potential of PU scaffolds loaded with 0.1 and 0.3 wt% GO particles in bone tissue engineering applications.

Stoichiometrically Optimized Electrochromic Complex [V2O2+ξ(OH)3-ξ] Based Electrode: Prototype Supercapacitor with Multicolor Indicator.

The systematic structure modification of metal oxides is becoming more attractive, and effective strategies for structural tunning are highly desirable for improving their practical color-modulating energy storage performances. Here, the ability of a stoichiometrically tuned oxide-hydroxide complex of porous vanadium oxide, namely [V2O2+ξ(OH)3-ξ]ξ = 0:3 for multifunctional electrochromic supercapacitor application is demonstrated. Theoretically, the pre-optimized oxide complex is synthesized using a simple wet chemical etching technique in its optimized stoichiometry [V2O2+ξ(OH)3-ξ] with ξ=0, providing more electroactive surface sites. The multifunctional electrode shows a high charge storage property of 610Fg-1 at 1Ag-1, as well as good electrochromic properties with high color contrast of 70% and 50% at 428 and 640nm wavelengths, faster switching, and high coloration efficiency. When assembled in a solid-state symmetric electrochromic supercapacitor device, it exhibits an ultrahigh power density of 1066mWcm-2, high energy density of 246mWhcm-2, and high specific capacitance of 290mFcm-2 at 0.2mAcm-2. A prepared prototype device displays red when fully charged, green when half charged, and blue when fully discharged. A clear evidence of optimizing the multifunctional performance of electrochromic supercapacitor by stoichiometrical tuning is presented along with demonstrating a device prototype of a 25cm2 large device for real-life applications.

Photosensitive polyimide enabled simple, reversible and environmentally friendly selective metallization on diverse substrates

For breaking through the limitation of metal patterning in constructing conductive pathways of electronic devices, which is proposed to be an upgrade of traditional etching technique, a photo-reversible, transparent and soluble polyimide carrying spiropyran side chains is synthesized. The merocyanine isomers produced from the spiropyran moieties under digitalized ultraviolet irradiation bind the silver−histidine complexes in water, while the absorbed silver ions are in-situ reduced into metal silver seeds by the photo-generated radicals from histidine molecules, catalyzing copper deposition and yielding the desired copper patterns. Accordingly, the conventional time-consuming steps (like surface modification, immobilization of catalytic ions and (photo)chemical reduction) are simplified to a single one, and the environmentally unfriendly solvent and costly/toxic palladium reagent are excluded. The Cu patterns deposited on the polyimide show high resolution, electrical conductivity (1.785 × 10−6 Ω‧cm), adhesion strength (18.14 MPa) and fatigue resistance (> 2.6 million cycles of bending). Due to the absence of invasive surface treatments (e.g., surface hydrolysis and laser direct structuring), extremely low surface roughness of 7.83 nm is achieved. Besides, the developed strategy can be easily expanded to stretchable elastomer and other organic/inorganic substrates with irregular surfaces, showing promising application prospects. The solubility of the polyimide and ultraviolet/visible light triggered reversibility of the included spiropyran groups further enable repeated recycling, erasing and re-patterning.

Study of various adhesive systems’ bond strength for bracket placement

Relevance . Today, the dental market offers a large selection of adhesive systems developed based on various concepts. Improving adhesive technology in orthodontic practice is aimed at simplifying methods of use, improving the composition and ability of adhesion of orthodontic elements to the tooth structure. The aim of this study is to compare the shear bonding strength of different generations of adhesive systems for metal brackets placement. Materials and Methods . The study sample consisted of 40 recently extracted human upper premolars. The premolars were divided into four groups 10 each. The first group used the bond Transbond XT 3M Unitek (USA), the second - Beauty Ortho Bond (Japan), the third - Tetric N bond Universal (Vivapen) (USA) with acid etching with phosphoric acid (LI), the fourth - Tetric N bond Universal (Vivapen) (USA) without acid etching with phosphoric acid. The study used metal brackets for upper premolars (Gemini Bracket MBT, 3M Unitek, USA) with a micro-patterned base, the area of which was defined as 10.61 mm2. Mechanical shear strength tests were carried out using the Instron Universal Test machine (USA). One-way analysis of variance and the TUKEY test were used to examine significant differences in adhesive strength and shear strength between study groups. Results and Discussion. The highest adhesive shear strength was established when using the Transbond XT adhesive system (12.28 MPa) and the Tetric N Bond Universal system using the total etching (12.66 MPa) and self-etching (11.44 MPa) techniques; statistically significant differences between these adhesives were not detected. The second group of Beauty Ortho Bond (5.34 MPa) demonstrated the lowest adhesion force among the studied adhesives, with a statistically significant difference from the other groups. Conclusion : This study concluded that there are no notable differences in the comparison of the universal system with or without etching with the Transbond system. Regarding the use of the beauty Ortho bond, it obtained the lowest strength with significant difference from the remaining groups.

3D benchmark experiments of tritium in tungsten for tritium measurements by detecting β-ray induced X-rays

Tungsten is one of the most promising materials for plasma facing components (PFCs), and β-ray induced X-ray spectrometry (BIXS) is an important non-destructive method to obtain tritium depth profile and retention information for the development of PFCs, recovery of fuel and control of tritium safety in a fusion reactor. In this article, benchmark experiments to obtain tritium 3D profile in tungsten have been firstly performed using layer-by-layer chemical etching (LLCE) and imaging plate (IP) techniques. BIXS spectra have been detected at each layer. The average layer thickness of each erosion was controlled to be around 150 nm and 8 layers (the total thickness was 1.21 μm) were eroded, and the maximum uncertainty of tritium activity was 7.91 % in the LLCE experiments. Monte-Carlo simulations of BIXS spectra with Geant 4 code and four kinds of physical packages (Penelope, Livermore, EmStd. Opt1 and EmStd. Opt4) have been benchmarked against to the experimental results. Results show that all the four physical packages are not suitable to calculate the intensity of the BIXS spectra, and the current mode or cross sections should be improved to simulate the interaction between low electron/photon and tungsten accurately. However, the relative intensity of W-Mα peak and W-Lα can be simulated well using current physical packages such as EmStd. Opt4 and Livermore, which is a good indicator for tritium depth profile in tungsten.

THERMOREGULATION SYSTEM FOR BIOSENSORS BASED ON FIELD-EFFECT TRANSISTORS WITH A NANOWIRE CHANNEL

In this work we present an automatic thermoregulation system for biosensors based on field-effect transistors with a nanowire channel, which provides full control on the required temperature regime in bioanalytical analises. The system elements, including field-effect transistors with a nanowire channel, temperature sensors and heaters, were fabricated on a single silicon cristal using electron beam lithography, reactive ion etching and high-vacuum deposition techniques. Unicue electronics have been developed to control and maintain temperature. The dependence of thermometer readout on heating power was measured, which is in good agreement with the results of numerical simulation. A demonstration of a thermoregulation system with PID-feedback was carried out, ensuring the establishment of a desiered temperature in the range of 30-70◦ C in 18 s in liquid. A demonstration of a thermoregulation system for detecting nucleic acids was carried out using synthetic single-stranded DNA, which is a gene fragment from the bacterium Escherichia coli. The minimal detectable response was observed for a sample with a concentration of 3 fM.

Morphological features of unmodified eutectic Si and morphological transformation after solution treatment

The morphological features of unmodified eutectic Si microstructure before and after solution treatment were revealed by the deep etching technique with a hypoeutectic Al-Si casting alloy as the study material. Before the solution treatment, the unmodified eutectic Si particles showed multi-faceted morphological features such as sheet-like, parallel hexahedral, truncated pyramidal, triangular platelet-like, octahedral, etc. After the six-hour solution treatment, the eutectic Si particles exhibit non-faceted morphological features such as spheroidal, cylindrical, and edge rounding. In addition, the edge rounding transformation of the octahedral Si particle during the holding process of solution treatment is visualised in combination with the molecular dynamics simulation.

Courtly Experiments: Early Portrait Etchings by Lucas van Leyden and Jan Gossart

For a brief moment in the early sixteenth-century Low Countries, etching became a significant technique for elite commissions. I examine the two earliest etchings made in the Low Countries as a case study: the portrait of Maximilian I by Lucas van Leyden and the portrait of Charles V by Jan Gossart, both made for the Hapsburg-Burgundian court in 1520. The etching technique was integral to the success of the two portrait prints, for both artists as well as their patron. This is a localized instance of artistic emulation and competition within the emergence of a new technique and subject: the Netherlandish portrait print.

Active Surface Area-Dependent Water Harvesting of Desert Beetle-Inspired Hybrid Wetting Surfaces.

The increasing frequency of water scarcity is an acute worldwide problem. Nature-inspired water harvesting from fog is an important method to obtain freshwater in arid areas. Existing literature reports varied and diversified results in water harvesting capacity by employing a biphilic surface with control over hydrophilic and hydrophobic patterns. In this study, we first demonstrate a facile and scalable method to fabricate a biphilic surface using a simple electroless etching and desilanization technique. Considering the nucleation, growth, and transport of condensate, biphilic surfaces with controlled active surface area of hydrophilic spots were given special attention. We studied the water collection performance of pattern shape with its associated active surface area and further evaluated the critical surface area beyond which the water collection efficiency decreases. A high water collection capacity of 2050 mg cm-2 h-1 was achieved, and the hydrophilic active area-engineered surface retained its efficiency even after 50 test cycles. We further demonstrate high collection efficiency with a square pattern compared to a triangular path-like-patterned surface. The observations and surface engineering strategies reported in this study can provide insights into efficient and sustainable water harvesting devices.

The Effects of Etchant on via Hole Taper Angle and Selectivity in Selective Laser Etching.

This research focuses on the manufacturing of a glass interposer that has gone through glass via (TGV) connection holes. Glass has unique properties that make it suitable for 3D integrated circuit (IC) interposers, which include low permittivity, high transparency, and adjustable thermal expansion coefficient. To date, various studies have suggested numerous techniques to generate holes in glass. In this study, we adopt the selective laser etching (SLE) technique. SLE consists of two processes: local modification via an ultrashort pulsed laser and chemical etching. In our previous study, we found that the process speed can be enhanced by changing the local modification method. For further enhancement in the process speed, in this study, we focus on the chemical etching process. In particular, we try to find a proper etchant for TGV formation. Here, four different etchants (HF, KOH, NaOH, and NH4F) are compared in order to improve the etching speed. For a quantitative comparison, we adopt the concept of selectivity. The results show that NH4F has the highest selectivity; therefore, we can tentatively claim that it is a promising candidate etchant for generating TGV. In addition, we also observe a taper angle variation according to the etchant used. The results show that the taper angle of the hole is dependent on the concentration of the etchant as well as the etchant itself. These results may be applicable to various industrial fields that aim to adjust the taper angle of holes.

Demonstration of MOCVD based in situ etching of β-Ga2O3 using TEGa

In this work, we demonstrate an in situ etch technique for β-Ga2O3 inside a metalorganic chemical vapor deposition (MOCVD) reactor using triethylgallium (TEGa) as the etching agent. At sufficiently high substrate temperatures (Tsub), TEGa is introduced into the MOCVD reactor which undergoes pyrolysis, resulting in the deposition of Ga on the β-Ga2O3 surface. These Ga adatoms react with Ga2O3 to form gallium suboxide (Ga2O), which desorbs from the β-Ga2O3 surface resulting in the etching of the epilayer. MOCVD chamber parameters such as TEGa molar flow rate, substrate temperature, and chamber pressure were shown to be key in controlling the etch rate and surface morphology. A wide range of etch rates from ∼0.3 to 8.5 μm/h is demonstrated by varying the etch parameters. In addition, smooth surface morphology on (010) and (001) β-Ga2O3 substrates is also demonstrated. This new etch technique could enable damage free fabrication of 3D structures like fins and trenches, which are key components in many β-Ga2O3 device structures.

Inorganic perovskite-based active multifunctional integrated photonic devices

The development of highly efficient active integrated photonic circuits is crucial for advancing information and computing science. Lead halide perovskite semiconductors, with their exceptional optoelectronic properties, offer a promising platform for such devices. In this study, active micro multifunctional photonic devices were fabricated on monocrystalline CsPbBr3 perovskite thin films using a top-down etching technique with focused ion beams. The etched microwire exhibited a high-quality micro laser that could serve as a light source for integrated devices, facilitating angle-dependent effective propagation between coupled perovskite-microwire waveguides. Employing this strategy, multiple perovskite-based active integrated photonic devices were realized for the first time. These devices included a micro beam splitter that coherently separated lasing signals, an X-coupler performing transfer matrix functions with two distinguishable light sources, and a Mach-Zehnder interferometer manipulating the splitting and coalescence of coherent light beams. These results provide a proof-of-concept for active integrated functionalized photonic devices based on perovskite semiconductors, representing a promising avenue for practical applications in integrated optical chips.

Cobalt etched graphite felt electrode for enhanced removal of organic pollutant in aqueous solution with a solid polymer electrolyte.

In this study, cobalt etched graphite felt electrodes were produced using a simple etching technique. It was used in combination with a solid polymer electrolyte (SPE) for the degradation of the target contaminant Orange II by Electro-Fenton (EF) technique in low conductivity water. In this method, 94% of Orange II in low conductivity water was removed in 90min. The characterization analysis substantiates the hypothesis that the electrodes produced exhibit a three-dimensional porous structure, augmented defect concentration, and enhanced electron transfer capability. In addition, the potential reaction mechanism was inferred from the radical quenching experiments, and hydroxyl radicals (·OH) were deemed the main reactive substances. The combination of cobalt etched graphite felt electrodes with SPE demonstrates remarkable efficacy in the treatment of organic wastewater characterized by low electrical conductivity.

A novel synthesis from instability difference between SiC 3-C and 6-H crystal to form nanoparticles stems by alkali solution and its degrading various environmental pollutants

In this paper, the nano silicon carbide with different sizes was prepared without hydrofluoric acid by using simple milling and related low temperature etching process in normal pressure. Also, it was the first time verified that 3-C dominated crystalline form of polycrystalline silicon carbide is etched, leaving the 6-H silicon carbide crystalline form by the Raman spectra and HAADF-STEM (high-angle-annular dark-field scanning transmission electron microscopy) imaging that. The application of the alkali etching technique could precise control the partial structural transformation of silicon carbide crystals to a certain extent, which further expands the traditional crystal structure transformation process. In addition, this paper demonstrates the silicon carbide composites in photocatalytic removal of various organic pollutants from aqueous solutions. In the photo degradation of MB (Methylene Blue), the removal rate of the modified silicon carbide shown ten times as much as the commercial silicon carbide. The 1-h degradation efficiency was significantly higher in the 50 μL H2O2 system (100.0%, 86.8% and 89.9% removal of MB, Rhodamine B, Methyl Orange and Tetracycline hydrochloride, respectively). Furthermore, the unit spin concentrations of vacancy defects, superoxide radicals and hydroxyl radicals were quantitatively analyzed. The vacancy defects of the etched material were 1000 times higher than before, and the modified silicon carbide had higher transmittance to infrared and visible light. It strongly absorbs ultraviolet light. Conversely, the research on micron-sized silicon carbide loaded with Ag and Pt atoms found that it had a nitrogen fixation effect during the warming up process, in a nitrogen atmosphere.

Comparative analysis of X‐band FSS fabricated by inkjet printing and conventional etching technique

AbstractAn investigation of a single‐layer band‐stop frequency selective surface (FSS) is designed and analyzed for X‐band application. The proposed FSS design primarily involves a cross‐shaped conductive patch with four square slots on each corner, and it is fabricated on the 3D‐printed polylactic acid (PLA) substrate. The design is resonating at 12 GHz with an insertion loss greater than 60 dB. The 10 dB bandwidth of the designed structure is 8.3% with respect to the resonant frequency. The results show that the design has polarization‐independent and angle‐insensitive transmission characteristics for incidence angles up to 60°. The simulation is carried out using CST Microwave Studio Suite, and the results are obtained. The physical mechanism of the designed structure is evaluated using the surface current distribution. The designed FSS is fabricated using two techniques, namely inkjet printing and conventional etching. Finally, the measurements of the fabricated structure are done using a vector network analyzer setup.

Novel high-voltage cathode for aqueous zinc ion batteries: Porous K0.5VOPO4·1.5H2O with reversible solid-solution intercalation and conversion storage mechanism

Cathode materials that possess high output voltage, as well as those that can be mass-produced using facile techniques, are crucial for the advancement of aqueous zinc-ion battery (ZIBs) applications. Herein, we present for the first time a new porous K0.5VOPO4·1.5H2O polyanionic cathode (P-KVP) with high output voltage (above 1.2 V) that can be manufactured at room temperature using straightforward coprecipitation and etching techniques. The P-KVP cathode experiences anisotropic crystal plane expansion via a sequential solid-solution intercalation and phase conversion pathway throughout the Zn2+ storage process, as confirmed by in-situ synchrotron X-ray diffraction and ex-situ X-ray photoelectron spectroscopy. Similar to other layered vanadium-based polyanionic materials, the P-KVP cathode experiences a progressive decline in voltage during the cycle, which is demonstrated to be caused by the irreversible conversion into amorphous VOx. By introducing a new electrolyte containing Zn(OTF)2 to a mixed triethyl phosphate and water solution, it is possible to impede this irreversible conversion and obtain a high output voltage and longer cycle life by forming a P-rich cathode electrolyte interface layer. As a proof-of-concept, the flexible fiber-shaped ZIBs based on modified electrolyte woven into a fabric watch band can power an electronic watch, highlighting the application potential of P-KVP cathode.

Sandwich-Type Self-Healing Sensor with Multilevel for Motion Detection.

Real-time detection of various parts of the human body is crucial in medical monitoring and human-machine technology. However, existing self-healing flexible sensing materials are limited in real-life applications due to the weak stability of conductive networks and difficulty in balancing stretchability and self-healing properties. Therefore, the development of wearable flexible sensors with high sensitivity and fast response with self-healing properties is of great interest. In this paper, a novel multilevel self-healing polydimethylsiloxane (PDMS) material is proposed for enhanced sensing capabilities. The PDMS was designed to have multiple bonding mechanisms including hydrogen bonding, coordination bonding, disulfide bonding, and local covalent bonding. To further enhance its sensing properties, modified carbon nanotubes (CNTs) were embedded within the PDMS matrix using a solvent etching technique. This created a sandwich-type sensing material with improved stability and sensitivity. This self-healing flexible sensing material (self-healing efficiency = 70.1% at 80 °C and 6 h) has good mechanical properties (stretchability ≈413%, tensile strength ≈0.69 MPa), thermal conductivity, and electrical conductivity. It has ultrahigh sensitivity, which makes it possible to be manufactured as a multifunctional flexible sensor.

Internal Adaptation of Composite Fillings Made Using Universal Adhesives-A Micro-Computed Tomography Analysis.

This study aimed to evaluate internal tooth-filling interfaces of composite fillings made using universal adhesives using micro-computed tomography (µCT). Sixty class V cavities were randomly assigned into six groups: Peak Universal etch and rinse (PER), Peak Universal self-etch (PSE), Adhese Universal etch and rinse (AER), and Adhese Universal self-etch (ASE). Two further adhesives considered gold standards were used as control groups: OptiBond FL (OER) for the etch and rinse technique and Clearfil SE for the self-etch technique (CSE). All teeth were subjected to thermomechanical loading and four-year water storage. Next, they were analyzed using µCT to investigate the internal tooth-filling interfaces. The proportions between the gap volume (GV) at the tooth-filling interface and the volume of applied composite filling (FV), between the gap and cavity volumes (CV), and between the gap volumes at the tooth-filling interface of the external (EGV) and internal (IGV) parts were calculated. Adhese Universal achieved the significantly lowest gap-to-filling- and gap-to-cavity-volume ratios for both types of etching techniques comparing to those of the Peak Universal and control groups. Significant differences between the gaps in external and internal parts of the tooth-filling interface were only noted in the control groups. Internal gap formation and development at the tooth-filling interface depend on the material as well as the type of its application.

Micron-scale FETs of fully epitaxial perovskite oxides using chemical etching

Advent of high mobility perovskite oxide semiconductor BaSnO3 (BSO) has enabled all-perovskite oxide heterostructures such as 2DEGs and FETs. To date all-perovskite oxide device demonstrations have been focused on finding and integrating the compatible perovskite dielectric oxides such as polar LaInO3 and LaScO3 and non-polar BaHfO3 and SrHfO3. For these demonstrations the length scale of BSO-based heterostructure devices has been about 100 µm, primarily due to the use of stencil masks for patterning. In order to further reduce the length scale, we employed a top-down approach using both photolithography and chemical etching techniques to pattern FETs made entirely of perovskite oxide materials: Ba0.997La0.003SnO3 channel layer, degenerately doped Ba0.96La0.04SnO3 contact layer, and SrHfO3 gate oxide layer. FETs of 3 µm channel length were fabricated using hydrofluoric acid and aqua regia as etchants. The FET exhibits a mobility of 38.8 cm²/Vs, an on/off ratio of 5.06 × 107, and a drain current density of 6.05 × 10−2 mA/μm, consistent with our expectation. These findings demonstrate the feasibility of patterning BSO through photolithography and chemical etching while maintaining the subsequent epitaxial growth, suggesting that BSO can be employed in a broader range of applications as well as for more precise studies of its intrinsic properties.