Fabrication Scheme Research Articles

Autonomous Chemistry Enabling Environment-Adaptive Electrochemical Energy Storage Devices

Autonomous Chemistry Enabling Environment-Adaptive Electrochemical Energy Storage Devices

Characterization of Fe-Ni-Pt(Zr) magnetron deposited thin films subjected to low-temperature annealing

Creation of FeNi-based hard magnetic materials for a high-density recording media depends on many factors including chemistry, synthesis conditions and subsequent heat-treatments. In particular Fe-Ni thin films can be fabricated by sputtering, molecular beam epitaxy and electrodeposition. The highest values of anisotropy constant are obtained for ordered tP4/L10-FeNi compound. From the viewpoint of practical use, a challenging task is to propose the relevant technological schemes for fabrication of this compound. This work is devoted to a study of three types of materials produced by radio frequency magnetron sputtering: layered Fe/(Ni,Pt) crystalline samples deposited at room temperature and subsequently annealed, homogeneous crystalline Fe(Ni,Pt) samples deposited at elevated substrate temperature and amorphous Fe-Ni-Pt-Zr samples deposited at room temperature which were further crystallized on heating. The phase composition of the sample was studied by X-ray diffractometry while the obtained nanostructure was observed by transmission electron microscopy. Thermally crystallized Fe-Ni-Pt-Zr samples exhibited the best combination of magnetic properties among the deposited films though partial oxidation of the samples took place on sputtering and annealing. Chemical composition and microstructure features, namely grain structure and defects in the Fe(Ni,Pt) samples are proposed to be main reasons responsible for the observed magnetic properties.

Stretchable printed device for the simultaneous sensing of temperature and strain validated in a mouse wound healing model

Temperature and strain are two vital parameters that play a significant role in wound diagnosis and healing. As periodic temperature measurements with a custom thermometer or strain measurements with conventional metallic gauges became less feasible for the modern competent health monitoring, individual temperature and strain measurement modalities incorporated into wearables and patches were developed. The proposed research in the article shows the development of a single sensor solution which can simultaneously measure both the above mentioned parameters. This work integrates a thermoelectric principle based temperature measurement approach into wearables, ensuring flexibility and bendability properties without affecting its thermo-generated voltage. The modified thermoelectric material helped to achieve stretchability of the sensor, thanks to its superior mechano-transduction properties. Moreover, the stretch-induced resistance changes become an additional marker for strain measurements so that both the parameters can be measured with the same sensor. Due to the independent measurement parameters (open circuit voltage and sensor resistance), the sensing model is greatly attractive for measurements without cross-sensitivity. The highly resilient temperature and strain sensor show excellent linearity, repeatability and good sensitivity. Besides, due to the compatibility of the fabrication scheme to low-temperature processing of the flexible materials and to mass volume production, printed fabrication methodologies were adopted to realize the sensor. This promises low-cost production and a disposable nature (single use) of the sensor patch. For the first time, this innovative temperature-strain dual parameter sensor concept has been tested on mice wounds in vivo. The preliminary experiments on mice wounds offer prospects for developing smart, i.e. sensorized, wound dressings for clinical applications.

Low cross talk crescent-shaped pore-assisted few-mode multi-core optical fiber for optical communication

In this paper, we propose a crescent-shaped pore-assisted structure to realize a few-mode multi-core (four-mode six-core) optical fiber with low inter-core cross talk for large-capacity long-distance communication. Using the finite element method, a theoretical analysis is conducted at a working wavelength of 1550 nm, where the proposed optical fiber achieves a total loss of less than 0.2 dB/km and an effective mode field area of greater than 108 µ m 2 . The inter-core cross talk of the fiber is less than − 56 d B / 100 k m , and the relative multiplexing factor reaches up to 28.3, which significantly increases the core density. The maximum dispersion of the four supported linear polarization modes is less than 5.85 p s / ( n m × k m ) , which is greatly advantageous in communication systems. In addition, the fabrication scheme of the proposed optical fiber is practical, and its standard-compatible 42 µm core pitch promises the feasibility of integration with commercial optical networks.

A Two-Dimensional Superconducting Electron Gas in Freestanding LaAlO3/SrTiO3 Micromembranes

Freestanding oxide membranes constitute an intriguing material platform for new functionalities and allow integration of oxide electronics with technologically important platforms such as silicon. Sambri et al. recently reported a method to fabricate freestanding LaAlO3/SrTiO3 (LAO/STO) membranes by spalling of strained heterostructures. Here, we first develop a scheme for the high-yield fabrication of membrane devices on silicon. Second, we show that the membranes exhibit metallic conductivity and a superconducting phase below ∼200 mK. Using anisotropic magnetotransport we extract the superconducting phase coherence length ξ ≈ 36-80 nm and establish an upper bound on the thickness of the superconducting electron gas d ≈ 17-33 nm, thus confirming its two-dimensional character. Finally, we show that the critical current can be modulated using a silicon-based backgate. The ability to form superconducting nanostructures of LAO/STO membranes, with electronic properties similar to those of the bulk counterpart, opens opportunities for integrating oxide nanoelectronics with silicon-based architectures.

Reduced On-Resistance and Improved 4H-SiC Junction Barrier Schottky Diodes Performance by Laser Annealing on C-Face Ohmic Regions in Thin Structures

In this study, we investigated the characteristics of the n-type Ni/SiC ohmic contact using the laser annealing process on thin wafers. The electrical behavior of the ohmic contacts was tested in 4H-SiC JBS diode devices. As a result, a wafer thickness of 100 μm in the 4H-SiC JBS diode achieved a forward voltage of 1.33 V at 20 A with a laser annealing process using Ni silicide. Using a laser annealing process on a wafer thickness of 100 μm, an on-resistance decrease of almost 22% was demonstrated. Based on our experimental results, we suggest an alternative laser annealing fabrication scheme to obtain low on-resistance SiC power devices with thin structures after SiC grinding.

In Vivo Performance of a Cell and Factor Free Multifunctional Fiber Mesh Modulating Postinfarct Myocardial Remodeling

AbstractGuidance of postinfarct myocardial remodeling processes by an epicardial patch system may alleviate the consequences of ischemic heart disease. As macrophages are highly relevant in balancing immune response and regenerative processes their suitable instruction would ensure therapeutic success. A polymeric mesh capable of attracting and instructing monocytes by purely physical cues and accelerating implant degradation at the cell/implant interface is designed. In a murine model for myocardial infarction the meshes are compared to those either coated with extracellular matrix or loaded with induced cardiomyocyte progenitor cells. All implants promote macrophage infiltration and polarization in the epicardium, which is verified by in vitro experiments. 6 weeks post‐MI, especially the implantation of the mesh attenuates left ventricular adverse remodeling processes as shown by reduced infarct size (14.7% vs 28–32%) and increased wall thickness (854 µm vs 400–600 µm), enhanced angiogenesis/arteriogenesis (more than 50% increase compared to controls and other groups), and improved heart function (ejection fraction = 36.8% compared to 12.7–31.3%). Upscaling as well as process controls is comprehensively considered in the presented mesh fabrication scheme to warrant further progression from bench to bedside.

Continuously Adjustable Micro Valve Based on a Piezoelectric Actuator for High-Precision Flow Rate Control

A MEMS-based micro valve fitted with a piezoelectric actuator is presented in order to achieve a continuously adjustable flow rate control. The micro valve is realized using a cost-effective fabrication scheme with simple polyimide (PI) bonding, which has an average shear strength of up to 39.8 MPa, indicating a relatively high reliability. The simulation results based on the finite element method (FEM) show that the valve membrane is able to seal the inlet and cut off the flow successfully with a piezoelectric force of 3N when the differential pressure is 200 kPa. The measurement of the flow rate through the outlets shows that the micro valve can control the flow rate effectively in a large range under different actuation voltages and differential pressures. When the actuation voltage is 140 V, the measured leak flow of the closed micro valve is smaller than 0.5 sccm with a differential pressure of 200 kPa.

Plant-inspired multi-stimuli and multi-temporal morphing composites

Plants are inspiring models for adaptive, morphing systems. In addition to their shape complexity, they can respond to multiple stimuli and exhibit both fast and slow motion. We attempt to recreate these capabilities in synthetic structures, proposing a fabrication and design scheme for multi-stimuli and multi-temporal responsive plant-inspired composites. We leverage a hierarchical, spatially tailored microstructural and compositional scheme to enable both fast morphing through bistability and slow morphing through diffusion processes. The composites consisted of a hydrogel layer made of gelatine and an architected particle-reinforced epoxy bilayer. Using magnetic fields to achieve spatially distributed orientations of magnetically responsive platelets in each epoxy layer, complex bilayer architectural patterns in various geometries were realised. This feature enabled the study of plant-inspired complex designs, via finite element analysis and experiments. We present the design and fabrication strategy utilizing the material properties of the composites. The deformations and temporal responses of the resulting composites are analysed using digital image correlation. Finally, we model and experimentally demonstrate plant-inspired composite shells whose stable shapes closely mimic those of the Venus flytrap, while maintaining the multi-stimuli and multi-temporal responses of the materials. The key to achieving this is to tune the local in-plane orientations of the reinforcing particles in the bilayer shapes, to induce distributed in-plane mechanical properties and shrinkage. How these particles should be distributed is determined using finite element modelling. The work presented in this study can be applied to autonomous applications such as robotic systems.

Gate‐Controlled Quantum Dots Based on 2D Materials

Abstract2D materials are a family of layered materials exhibiting rich exotic phenomena, such as valley‐contrasting physics. Down to single‐particle level, unraveling fundamental physics and potential applications including quantum information processing in these materials attracts significant research interests. To unlock these great potentials, gate‐controlled quantum dot architectures have been applied in 2D materials and their heterostructures. Such systems provide the possibility of electrical confinement, control, and manipulation of single carriers in these materials. In this review, efforts in gate‐controlled quantum dots in 2D materials are presented. Following basic introductions to valley degree of freedom and gate‐controlled quantum dot systems, the up‐to‐date progress in etched and gate‐defined quantum dots in 2D materials, especially in graphene and transition metal dichalcogenides, is provided. The challenges and opportunities for future developments in this field, from views of device design, fabrication scheme, and control technology, are discussed. The rapid progress in this field not only sheds light on the understanding of spin–valley physics but also provides an ideal platform for investigating diverse condensed matter physics phenomena and realizing quantum computation in the 2D limit.

261 Engineering Synthetic Scaffolds to Achieve Periodontal Ligament Cell-Mediated Tissue Regeneration

OBJECTIVES/GOALS: Autologous periodontal ligament cells (PDLCs) are a promising tool for rebuilding tooth-supporting (periodontal) tissues but require scaffolds that enable delivery while maintaining PDLC bioactivity. The goal of this study was to design a synthetic hydrogel that fulfilled these criteria to support clinical translation of PDLC delivery. METHODS/STUDY POPULATION: Hydrogels were formed using poly(ethylene glycol) (PEG) polymers and synthetic peptides. PDLCs were isolated from human 3rd molars following informed consent and were cultured using established techniques. Integrin-binding peptides were utilized to promote specific PDLC behaviors, testing PDLCs from 3 human donors in a design of experiments (DOE) approach. Two promising hydrogel designs, identified in the DOE, were selected for validation testing using PDLCs from 3 additional donors. Finally, a small animal model for hydrogel-mediated PDLC delivery was used to determine if benchtop outcomes could predict in vivo tissue regeneration. RESULTS/ANTICIPATED RESULTS: Hydrogel scaffolds maintained high PDLC viability and controlled differentiation of each donor’s PDLCs based on differential presentation of integrin-binding peptides RGD and GFOGER. Two hydrogel designs were selected that optimized either PDLC alkaline phosphatase (ALP) activity or matrix mineralization, outcomes typically associated with cementum and bone formation. ALP activity-optimized hydrogels displayed enhanced PDLC pyrophosphate regulation while mineralization-optimized hydrogels promoted PDLC osteogenic differentiation. When used to deliver PDLCs to periodontal defects, both ALP activity-optimized and mineralization-optimized hydrogels stimulated new cementum formation with inserting PDL fibers, while mineralization-optimized hydrogels promoted enhanced bone formation. DISCUSSION/SIGNIFICANCE: Numerous challenges remain for translating PDLC regenerative potential to clinical practice. This study demonstrates that a synthetic hydrogel scaffold could overcome certain barriers, including controlling PDLC bioactivity with a simplified fabrication and delivery scheme, and may be a promising scaffold for periodontal tissue regeneration.

Advances in High-Performance Autonomous Energy and Self-Powered Sensing Textiles with Novel 3D Fabric Structures.

The seamless integration of emerging triboelectric nanogenerator (TENG) technology with traditional wearable textile materials has given birth to the next-generation smart textiles, i.e., textile TENGs, which will play a vital role in the era of Internet of Things and artificial intelligences. However, low output power and inferior sensing ability have largely limited the development of textile TENGs. Among various approaches to improve the output and sensing performance, such as material modification, structural design, and environmental management, a 3D fabric structural scheme is a facile, efficient, controllable, and scalable strategy to increase the effective contact area for contact electrification of textile TENGs without cumbersome material processing and service area restrictions. Herein, the recent advances of the current reported textile TENGs with 3D fabric structures are comprehensively summarized and systematically analyzed in order to clarify their superiorities over 1D fiber and 2D fabric structures in terms of power output and pressure sensing. The forward-looking integration abilities of the 3D fabrics are also discussed at the end. It is believed that the overview and analysis of textile TENGs with distinctive 3D fabric structures will contribute to the development and realization of high-power output micro/nanowearable power sources and high-quality self-powered wearable sensors.

1D NiO–3D Fe2O3 mixed dimensional heterostructure for fast response flexible broadband photodetector

Conventional heterojunction photodetectors rely on planar junction architecture which suffer from low interfacial contact area, inferior light absorption characteristics and complex fabrication schemes. Heterojunctions based on mixed dimensional nanostructures such as 0D-1D, 1D-2D, 1D-3D etc have recently garnered exceptional research interest owing to their atomically sharp interfaces, tunable junction properties such as enhanced light absorption cross-section. In this work, a flexible broadband UV–vis photodetector employing mixed dimensional heterostructure of 1D NiO nanofibers and 3D Fe2O3 nanoparticles is fabricated. NiO nanofibers were synthesized via economical and scalable electro-spinning technique and made composite with Fe2O3 nanoclusters for hetero-structure fabrication. The optical absorption spectra of NiO nanofibers and Fe2O3 nanoparticles exhibit peak absorption in UV and visible spectra, respectively. The as-fabricated photodetector displays quick response times of 0.09 s and 0.18 s and responsivities of 5.7 mA W−1 (0.03 mW cm−2) and 5.2 mA W−1 (0.01 mW cm−2) for UV and visible spectra, respectively. The fabricated NiO–Fe2O3 device also exhibits excellent detectivity in the order of 1012 jones. The superior performance of the device is ascribed to the type-II heterojunction between NiO–Fe2O3 nanostructures, which results in the localized built-in potential at their interface, that aids in the effective carrier separation and transportation. Further, the flexible photodetector displays excellent robustness when bent over ∼1000 cycles thereby proving its potential towards developing reliable, diverse functional opto-electronic devices.

Persistent near-infrared photoconductivity of ZnO nanoparticles based on plasmonic hot charge carriers

We report on the coupling of ZnO nanoparticles with plasmonic gold nanoislands in a solution-processed photodetector, which results in a clear enhancement in the optical absorption and the electrical responsivity of ZnO nanoparticles, to cover the visible and the near-IR (NIR) spectral range, well beyond its intrinsic optical absorption. This enhancement, which arises from the coupling between ZnO nanoparticles and the plasmonically mediated hot electron generation in the Au plasmonic nanoislands, results in a significant plasmonically driven photoresponse in the NIR of 2.5 × 10−5 A/W. The recorded photocurrent exhibits a persistent behavior, which is attributed to surface defect states in the ZnO nanoparticles. This study provides a route to the solution-processed, low-cost device fabrication schemes with important implications on low processing temperature optoelectronics technology to enhance the performance of photovoltaic devices over a wide solar spectrum. Additionally, this unusual behavior paves the way toward harnessing plasmonic resonances to probe and examine the surface defects of metal oxide semiconductors.

Designing thermotolerant and flame-resistant PAN-based separator via surface engineering with heteroatoms doped carbon framework encapsulated with CoS2 nanocatalysts towards safe lithium-sulfur batteries

Owing to the superior merits of high energy density , low cost and environmental benignity, lithium-sulfur batteries (LSBs) are greatly favored by researchers. However, the intrinsic shortages including serious shuttling behavior and lithium dendrites growth, are deemed as stumbling blocks on the way of commercializing LSBs. Also, the inferior thermostability and flame retardancy of common separator may cause safety hazard to LSBs. Here, the designing of thermotolerant and flame-resistant PAN-based separator (MPAN) via surface engineering with heteroatoms doped carbon framework encapsulated with CoS 2 nanocatalysts, is proposed. By utilizing MPAN separators, the efficient hinderances on shuttling behavior and marked promotions in polysulfides conversion are achieved, leading to the superior electrochemical properties . Notably, the cycling performances of LSBs under high temperature are obviously enhanced. As expected, the inhibited dendrites growth is obtained, corroborating the improved safety of LSBs. In short, this work may shed a light on constructing thermotolerant and flame-resistant separator with efficacy in suppressing shuttling behavior and lithium dendrites growth. (a) Fabrication scheme of MPAN separator; (b) Suppressing mechanism of polysulfides shuttling action and lithium dendrites growth. • A thermotolerant and flame-resistant separator (MPAN) is rationally designed. • By using MPAN separator, the shuttling behavior is efficiently suppressed. • Cycling performances of cells under high temperature are obviously enhanced. • The suppressed growth of lithium dendrites demonstrates the superior battery safety.

Ultrafast and Highly Deformable Electromagnetic Hydrogel Actuators Assembled from Liquid Metal Gel Fiber

Hydrogel actuators are ultrasoft and pliable but achieving high driving speeds with large deformation and fine local controllability is difficult because the driving force originates from the external air pressure or heat, and the base material is fragile. Herein, hydrogel actuators that allow high‐speed driving and large deformation with high‐frequency local controllability while maintaining softness are fabricated based on liquid metal gel fibers as electrodes by using microfluidic technology. The Lorentz force produced by an electric current and a magnet is used for actuation control. An ultrafast response of 260.5 mm s−1 with high‐frequency controllability (6 Hz) and a large deformation of 172% with hydrogel actuation are observed. As proof of concept, moving stages, micromixers, and grippers exhibiting high speeds with high mechanical deformability while maintaining the inherent characteristics of hydrogel phases are demonstrated. Different hydrogels can be used with the proposed actuator architecture and fabrication scheme, enabling different functionalities.

Deionized Water Electrochemical Machining Hybridized with Alumina Powder Polishing for Microcavity of M-333 Mold Steel

An electrochemical machining (ECM) process for microcavity fabrication with deionized water (DI-water) and an ECM polishing hybrid with alumina powder of 1.0 μm grains on a single micro-EDM machine are proposed. The process adopts tungsten carbide as tool electrode and M-333 tool steel as the mold material. It reveals that employing the 30 μm/min feed rate with 50 mA and 0.2 ms of pulse-width is suitable for DI-water electrochemical machining. The DI-water ECM process can achieve an excellent surface roughness at Ra 0.169 µm on a semispherical round cavity. Combining the ECM with hybrid polishing with the alumina powder can achieve a better profile for a much deeper cavity than pure electrolytic discharge machining. The hybrid ECM polishing can efficiently finish a micro square insert of 0.6 mm length at 64 μm depth. Such ECM milling can achieve an S-shaped microchannel of radius 1.0 mm and a slot of 1.0 × 0.5 mm2 with 110 μm depth, demonstrating its feasibility and the surface integrity with accurate profile and roughness of Ra 0.227 μm. This study provides a cost-effective scheme for micro mold fabrication with a conventional micro-EDM machine tool and an intuitive and convenient optional process. However, some micro-electrical discharges occurred due to the breakdown of insulation, which creates micro craters on the surface of the parts.

Quantum Dots: An Emerging Approach for Cancer Therapy

Nanotechnology is indisputably a scientific technique that offers the prospect of new therapies, and hope, for the treatment of malignant illnesses. It is a novel technology that offers new approaches for the diagnosis and management of diverse diseases. Although the discovery of Quantum dots (QD) nano-transporters has already led to a few positive developments, QD nano-transporters are still at their initial stage, though have yet proven valuable to society. The excertion of QD indicates conversion in natural imaging along with photograph have established incredible suitability in bio-imaging, new drug development, targeted gene deliverance, biosensing, photodynamic treatment as well as diagnosis. The present review aimed to confer the significance of QD in diagnosis as well as in management of cancer. This review aims to impart fundamental insight as well as conception of QD its merits, properties, utilization as well as mode of action. This review highlight of different designing schemes of QD like hydrothermal, drop-casting, ultrasonic, solvothermal, spin-coating, atomic layer desorption, layer by layer, polymethylmethacrylate aided-transfer, electrochemical, ion beam sputtering deposition. Moreover, we have elaborated on the diverse researches related to cytotoxic examination to reveal that QDs are harmless. Concisely, the present review summarizes the fabrication schemes, current research and utilization of QD in cancer treatment.

Low-crosstalk laser-direct-writing FI/FO device for 8×100-Gbps optical interconnection.

Fan-in/fan-out (FI/FO) device with low crosstalk is essential for weakly coupled short-reach optical interconnect based on multicore fibers (MCF), for which the laser-direct-writing (LDW) technique is one of the preferred fabrication schemes. In this paper, the influence of FI/FO crosstalk on short-reach intensity-modulation/direction-detection MCF optical interconnection is firstly evaluated, and the crosstalk related to different refractive-index profiles of waveguides and misalignment is analyzed for LDW-FI/FO devices. Then low-crosstalk compact LDW-FI/FO devices matching 8-core MCF are fabricated, adopting multiple-scan method for waveguides with a flat-top refractive-index profile and aberration correction method for precise alignment. Owing to the low crosstalk, 8×100-Gbps optical interconnection over 10-km MCF is experimentally demonstrated with only 0.5-dB penalty compared to 10-km G.652D single-mode fiber transmission. Simulation results indicate that the transmission reach can be further extended to over 40 km. The proposed prototype system with low crosstalk is promising for high-speed optical interconnection applications.

A Test IC for Wafer-Level Characterization of an IntraCMOS-MEMS Fabrication Process

Monitoring of fabrication processes and the measurement of the electrical and mechanical properties of materials and devices at the silicon-wafer level are of vital importance on integrated system technologies. In this work, a test integrated circuit (IC) for the development of an IntraCMOS-MEMS fabrication process is presented. The test devices contained in the test IC are designed in such a way that 1) they can be used in CMOS-MEMS fabrication technologies using different materials, 2) take into account the capabilities of the manufacturing infrastructure, and 3) consider the selected integrated fabrication scheme; thus, any monolithic CMOS-MEMS process can be evaluated before, during and after the fabrication. The acquired data from the test devices will be useful to identify possible electrical and/or mechanical variations, in the properties of the materials used and in the performance characteristics of the devices, due to the fabrication process. The information acquired will help to adjust the simulation routines and the analytical modeling expressions. Finally, using the infrastructure of the MEMS Innovation Laboratory (LIMEMS-INAOE Mexico) preliminary experimental results are presented.