Fabrication Steps Research Articles

The effect of fabrication procedures and thermomechanical loading on the structural properties of screw-retained metal-ceramic implant restorations: An in vitro study.

Metal-ceramic screw-retained implant restorations persist as a fundamental choice in specific clinical scenarios. Little is known about the effects of fabrication steps and aging on their structural properties. This study aimed to investigate how laboratory fabrication procedures and thermomechanical loading affect the structural properties of screw-retained metal-ceramic implant restorations. Ten screw-retained metal-ceramic restorations were conventionally cast using UCLA chromium-cobalt overcast abutments. After 500 cycles of thermocycling and 500,000 cycles of mechanical loading, changes in connection dimensions and rotational freedom (RF) were measured and compared at various fabrication steps and post-thermomechanical loading. A generalized estimating equations (GEE) model was employed to analyze trends across the studied time points within the fabrication stage and after thermomechanical loading, with LSD post-hoc tests applied for pairwise comparisons. The level of significance was set at α = 0.05. Significant changes were observed across the analyzed time points: the average hexagonal side length (L) decreased (p < 0.001), and the average hexagonal angle deformation (P) increased, with notable differences observed in most comparisons between different fabrication steps (p < 0.001). Short (T1) and long (T2) diagonals of the hexagon showed downward trends (p < 0.001), while concentricity (O) and RF increased (p < 0.001), except between porcelain firing and loading steps for RF (p = 0.637). Casting had the greatest impact on variations in O (93.33%), T1 (88.88%), and T2 (45%), while porcelain firing significantly affected L (71.42%), P (71.42%), with the greatest effect on RF (75.32%). The fabrication processes and simulated clinical use adversely impacted the structural integrity and RF of abutments in screw-retained chromium-cobalt overcast implant restorations.

Micro-Transfer printing of InGaAs/InP Avalanche Photodiode on Si Substrate

Abstract We report on the fabrication and micro-transfer printing of InGaAs/InP avalanche photodiodes (APDs) onto silicon substrates. A process flow was developed to suspend the devices using semiconductor tethers. The developed process reduces the number of fabrication steps required compared to methods based on the use of photoresist tethers. Furthermore, our process is compatible with devices that may be susceptible to damage induced by the photoresist removal process. APDs were characterised in linear mode operation both before suspension and after printing. Despite the additional fabrication steps required to suspend the APD membranes and the physical nature of the micro-transfer printing process, the electrical characteristics of the devices were preserved. No degradation in the optical performance of the devices was measured. Our work represents the first demonstration of micro-transfer printing of InGaAs/InP avalanche photodiodes onto silicon substrates. The results highlight the viability of micro-transfer printing for effective heterogeneous integration of InGaAs/InP avalanche photodiodes with silicon photonic integrated circuits for optical and quantum communication and other light detection applications.&amp;#xD;

One-pot construction of all-in-one flexible asymmetrical supercapacitors for extreme-condition applications

All-in-one flexible energy storage devices hold great application potential in the flexible and wearable electronics by virtue of unique configuration, however, still face severe challenges including complex fabrication steps, single variety of symmetrical supercapacitors and limited scenario application. For the first time, we propose a facile one-pot approach to fabricate all-in-one flexible asymmetrical supercapacitors (AFASCs) through magnetic driving localization of magnetic FeOOH anode away from MnO2 cathode in the electrolyte containing ethylene vinyl alcohol copolymers toward multi-scenario application. Distinctly different from the reported all-in-one approaches, this one-pot approach dramatically simplifies fabrication steps and especially extends more variety of electroactive materials for asymmetrical supercapacitors and even aqueous battery systems. A well-integrated configuration without any interfaces forms in the FeOOH/MnO2 AFASCs with low interfacial resistance, high areal capacitance, good cyclic stability and remarkable energy density. Significantly, the FeOOH/MnO2 AFASCs achieve superhigh capacitance retention not only in long-term bending and twisting deformations, but also under various extreme conditions including cutting, rolling, hammering, puncturing, sewing, soaking and washing in the water, as well as low temperature. Furthermore, the FeOOH/MnO2 AFASCs are demonstrated to power wearable smart bracelet, health monitoring, intelligent positioning system and running pod. Those findings can open up a new approach for one-pot construction of all-in-one flexible energy storage devices to meet future needs of flexible and wearable electronic devices under harsh working conditions.

Preliminary steps for fabrication of microfluidic systems for swine sperm sorting: Materials, perfusing systems and flow

The success rate of assisted reproductive techniques in the livestock production can be optimized by improving the quality of the semen sample by selecting only the good quality sperm from the ejaculate. Microfluidic technology has been studied for sperm sorting mainly in human ejaculates but has not been studied for boar sperm. Spermatozoa have been proven to be highly sensitive to different microplastics, but the potential toxic effects of the materials used to set up microfluidic systems have not been studied. The main goal of this study was to assess the possible toxic effect on boar sperm of materials commonly used for a microfluidic system and to evaluate the effect of different flow control systems (peristaltic pump, syringe pump and a microfluidic flow controller) at different flow rates (10 μl*min-1, 100 μl*min-1 and 1 ml*min-1) on sperm quality, as preliminary information for the development of a swine sperm sorting microfluidic system. Results showed no negative effect of the different materials at different concentrations. The control reached the highest curvilinear velocity compared to the peristaltic pump and the pressure-based flow control system. In the flow rates, 10 μm*min-1 showed the poorest results and no significant differences were observed between control and 1 mlmin-1 flow in any of the parameters. In conclusion, all materials that were studied for microfluidic fabrications were suitable for sperm sorting, any of the pumps would be suitable for sperm selection and 1 ml*min-1 flow rate would be the flow rate of choice for sperm pumping.

High Performance Conductive Composites and E-skins with Large-scale Manufacturing for Wearable Electronic Sensor Systems

Objective: High performance wearable sensors for biological and bio-technological recognition of human epidermal movements and muscle tissue deformations are attracting widespread attention and demonstrate fascinating potential for future wearable electronics. Methods: This work demonstrates conductive networks and film cracks-based stretchable strain sensors using carbonic sensing layers / mold star silicone elastomer nanocomposites. Results: The as-fabricated stretchable strain sensors demonstrate captivating superiority, including simplicity in the fabrication steps and ultra-high strain sensitivity far exceeding recently reported state-of-the-art strain sensors. Prominently, the stretchable strain sensors exhibit dazzling piezoresistivity with a high gauge factor of 2,185 and a wide sensing range of 30% strain. The working mechanism depends on the electrical resistance variations, which is strikingly altered by a percolating network crack surface microstructure due to strain concentration during tensile deformations. The ultra-sensitive sensing performance in conjunction with a wide sensing range, prominent linearity (R2&gt;0.99 in the strain range of 15-30%), excellent reversibility characteristics and remarkable durability (more than 1,300 stretch-release cycles under a large-scale strain of 30%) for large-scale tensile deformations. Conclusion: The stretchable strain sensors to be employed as wearable strain monitoring devices for the diverse-range of practical applications, including but not confined to multi-scale monitoring, electronic skins, smart robotics, human-machine / computer interfaces, as well as sports performance monitoring.

Prospective LCA of brown seaweed-based bioplastic: Upscaling from pilot to industrial scale

Seaweed-based bioplastics are considered a possible alternative to conventional fossil-based plastics due to their potential environmental advantages. The cultivation of seaweed is a fast-growing practice that requires no arable land, freshwater, or fertilizers, perceiving it as an advantageous option for bioresource production. However, research on the environmental impacts of seaweed-based bioplastics is still limited, highlighting the need for a life cycle assessment (LCA) to evaluate their potential. In this article, a prospective LCA is conducted to assess the environmental impacts of brown seaweed-based bioplastic production, from pilot to industrial scale. Upscaling techniques are combined for each life-cycle stage, using interviews to upscale seaweed production and process simulation for the biorefinery and film fabrication steps, and the end-of-life scenario is modelled as composting. All the processes were upscaled to 4000 tonnes (t) per year in 2030 and 2 million tonnes (Mt) per year in 2035, including marginal suppliers of brown seaweed. The results show that the production of 1 kg of brown seaweed-based bioplastic resulted in approximately 1.37 kg CO2-eq. in the best-performing scenario, producing 2 Mt per year in 2035 accounting for the carbon uptake, which is lower than low-density polyethylene (LDPE) with an impact of 3.6 kg CO2-eq. The impact in marine eutrophication in the 2 Mt scenario is −0.009 kg N-eq., and −0.002 kg P-eq. in freshwater eutrophication. This study provides for the first time estimates of prospective industrial-scale impacts of the emerging seaweed-based bioplastic and shows how different upscaling techniques can be successfully combined, i.e., interviews and process simulation, to conduct a prospective LCA of seaweed-based bioplastics. The results demonstrate the potential of seaweed-based bioplastics as a sustainable alternative to conventional plastics.

Development and characterization of saturated fatty acids and biopolymer based novel multilayer encapsulated phase change materials system for buildings

Application of encapsulated phase change materials (PCM) is becoming an attractive passive measure to develop energy efficient buildings. In the present work, the eutectic mixture of two saturated fatty acids (lauric acid and palmitic acid in 80:20 ratio, HTPCM) was selected and encapsulated in a novel multilayer architecture to develop PCM beads. The bead architecture includes a PCM core enveloped by thermally conductive calcium alginate (Ca-Alg) biopolymer + multiwall carbon nanotubes intermediate shell to promote heat transfer from the core and the outer rugged coating of flyash + water-based polyurethane (PU) to improve mechanical integrity and interlocking with wet cement mortar matrix during mix preparation. The thermal characteristics of four pure PCM (capric acid, lauric acid, myristic acid, and stearic acid) and one eutectic mixture (HTPCM) were measured using differential scanning calorimetry (DSC) to select the suitable PCM as per prevailing local ambient temperature. As per scanning electron microscopy (SEM) results, the average core size is in the range of 1.5 – 2.0 mm and PCM is stored in the bead core as tiny globules separated by Ca-Alg membrane. Single bead compression test performed on multilayer PCM (m-PCM) bead show that the shell of the bead possesses sufficient mechanical strength. The Fourier transformed infrared spectroscopy (FTIR) analysis and thermogravimetric analysis (TGA) studies confirm that the HTPCM and coating materials are chemically / thermally stable through different steps of fabrication and heating / cooling thermal cycles. Finally, the filter paper leakage test showed that the multilayer bead shell can prevent the PCM leakage from the core during bead heating. The various test results reported herein corroborate that the proposed architecture provides good physical properties and mechanical strength to the encapsulated PCM beads.

Microstructural and mechanical characterization of steel-copper composite structures fabricated by laser powder bed fusion and induction melting

Composite structures, coupling properties from different materials, are systematically evaluated, examined with different fabrication processes. In this work, a hybrid fabrication process is proposed for steel-Cu metal-metal composites: Laser Powder Bed Fusion is utilized for printing 316L stainless steel lattices, which are later infiltrated with CuCrZr alloy powder, melted through induction heating. Microstructure characterization is accompanied by neutron imaging analysis, providing insight into critical aspects of the structures regarding the texture and strain distribution after each fabrication step, and the austenite-to-ferrite transformation on the steel-Cu interface. Thermodynamic modeling of the induction melting process examines the elemental interdiffusion phenomena, showing the impact of inter-difussion in the formation of a ferritic band on the steel-Cu interface. The mechanical performance of the composites is characterized by nano hardness indentation and compression testing, revealing the impact of the 316L lattice in reinforcing the overall hardness and strength of the composites. The current work proposes an alternative fabrication route for crack free steel-Cu composites, where the AM structure and the induction heating condition can be used as a tool to control the microstructure and the mechanical performance of the composites.

Silver‐Copper Oxide Core‐Shell Nanoparticles/β‐Cyclodextrin Functionalized Single‐Walled Carbon Nanotubes Based Electrochemical Sensor for 4‐Chloro‐3‐Methylphenol Detection

AbstractChlorophenols are high‐priority organic pollutants that harm the environment and human health. Therefore, it is crucial and urgent to detect and quantify chlorophenols in the environment selectively and sensitively. For this, the introduction of smart nanomaterials to create electrochemical sensors is a noteworthy development. In the present article, a glassy carbon electrode was fabricated by Agcore‐CuOshell nanoparticles (Ag@CuO) and β‐cyclodextrin functionalized single‐walled carbon nanotubes (β‐CD‐fSWCNT) through drop‐casting method (Ag@CuO‐β‐CD‐fSWCNT‐nafion‐GC) and applied for the selective and sensitive detection of chlorophenols, particularly 4‐chloro‐3‐methylphenol (CMP). The Ag@CuO nanoparticles with core‐shell configuration were synthesized and characterized by using various analytical techniques like UV–vis spectroscopy, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), high‐resolution transmission electron microscopy (HR‐TEM), selected area electron diffraction pattern (SAED), and energy dispersive X‐ray spectroscopy (EDS). The electrode fabrication steps were monitored and confirmed by using field‐emission scanning electron microscopy (FE‐SEM), attenuated total reflectance – Fourier transform infrared spectroscopy (ATR‐FTIR), and cyclic voltammetry (CV) studies. The electrochemical sensing of CMP was done by using differential pulse voltammetry (DPV) and the results showed that the peak current is linear with increasing concentration in the range of 10–50 µM at the modified electrode. The detection limit of 1.4 nM (S/N = 3) was obtained with a correlation coefficient of 0.998. The electrode showed good reproducibility with a relative standard deviation (RSD) of 1.56% and sensitivity of 15.67 µAcm−2µM−1 toward CMP. The sensor showed anti‐interference properties and long‐term stability. The real sample analysis results indicated that the sensor electrode could be used to detect low concentrations of CMP in wastewater with a recovery of 103.3% and has good potential for use in practical applications.

A three-components-based disposable electrochemical sensor for the detection of heavy metal ions in water

The development of an efficient sensor based on a novel three-components nanocomposite is presented for the detection of heavy metal ions (Cd2+ and Pb2+) in water. For the preparation of three-components nanocomposite surface, the polydopamine reduced graphene oxide (PyDA/RGO) composite was initially prepared by a one-step polymerization of dopamine (DA) on RGO followed by surface modification of the prepared composite with cysteine (Cys). The formation of three-components nanocomposite surface (i.e., Cys/PyDA/RGO) was initially confirmed through physical characterization techniques, including X-ray diffraction and infrared spectroscopy, whereas scanning electron microscopy revealed the surface morphology after each step of sensor fabrication. The electrochemical properties of the sensing platform were evaluated through electrochemical techniques, including cyclic voltammetry and electrochemical impedance spectroscopy with an external ferri‐−/ferrocyanide redox probe. The prepared three-components nanocomposite on disposable pencil graphite electrode (Cys/PyDA/RGO/PGE) showed an improved charge transfer rate as compared to PyDA/RGO/PGE and bare PGE electrode. Targeted heavy metal ions were detected on the sensor surface using differential pulse voltammetry with greater sensitivity, showing detection limits of 0.77 and 1.13 ppb for Cd+2 and Pb+2 ions in citrate buffer solution, respectively. The sensor demonstrated comparable performance in the tap water samples.

Improving the ON/OFF Current Ratio and Ambipolarity of Doping-Less Tunneling Carbon-Nanotube FET Using Drain Engineering Technique

This paper presents a novel structure utilizing a doping-less (DL) tunneling carbon nanotube field-effect transistor (T-CNTFET) with dual drain work functionality aimed at enhancing the ON/OFF current ratio. The proposed design features a zigzag carbon nanotube (CNT) of type (13, 0) with a diameter of 1 nm. It employs HfO2 as the gate oxide, which is 2 nm thick and has a dielectric constant of 16. The CNT serves as an intrinsic semiconductor for the source and drain regions, which are composed of metals with appropriate work functions. By selecting appropriate metals for the source and drain regions, the necessity for doping as a fabrication step is avoided, simplifying construction and reducing costs for the nanoscale device. This design includes two drain electrodes, each measuring 15 nm in length and having different work functions (DWFs). The work function of the drain positioned closest to the channel (DWFAC) is set at 3.9 eV, which is 0.5 eV lower than that of the CNT, while the other drain section has a work function of 3.4 eV, 1 eV lower than the CNT. The electrical properties of the device were examined through quantum numerical simulations using the non-equilibrium Green's function (NEGF) method. The results indicate that the proposed structure significantly decreases the OFF-state current and improves the ON/OFF current ratio. Additionally, the leakage current is substantially lowered, resulting in favorable changes to the device's ambipolarity, along with a reduction in hot carrier effects and subthreshold swing (SS).

A Two-Step Dry Etching Model for Non-Uniform Etching Profile in Gate-All-Around Field-Effect Transistor Manufacturing.

The Gate-All-Around Field-Effect Transistor (GAAFET) is proposed as a successor to Fin Field-Effect Transistor (FinFET) technology to increase channel length and improve the device performance. The GAAFET features a complex multilayer structure, which complicates the manufacturing process. One of the most critical steps in GAAFET fabrication is the selective lateral etching of the SiGe layers, essential for forming the inner-spacer. Industry commonly encounters a non-uniform etching profile during this step. In this paper, a continuous two-step dry etching model is proposed to investigate the mechanism behind the formation of the non-uniform profiles. The model consists of four modules: anisotropic etching simulation, Ge atom diffusion simulation, Si/SiGe etch selectivity calculation and SiGe selective etching simulation. By calibrating and verifying this model with experimental data, the edge rounding and gradient etching rates along the sidewall surface are successfully simulated. Based on further examination of the influence of chamber pressure on the profile using this model, the inner-spacer shape is improved experimentally by appropriately reducing the chamber pressure. This work aims to provide valuable insights for etching process recipes in advanced GAAFETs manufacturing.

On the Effect of Cooling Parameters on Solidification Structure in NdFeB Alloys

The elaboration of suitable NdFeB‐based permanent magnets is essential for high‐performance electrical machines in a number of applications. In this respect, the understanding of the relationship between heat transfer phenomena and the final solidified microstructure is the key to the control of the grain size and the improvement of the magnetic properties. The problem is even more acute with the emergence of new manufacturing processes, such as the laser powder bed fusion, where the cooling rates are much higher than those encountered in the standard strip casting process and where the microstructure can be considered as fixed from the fabrication step. The objective of the present work is to identify correlations between interstructural spacings in the solidified alloys and cooling conditions. This study is based on a methodology coupling experimental and numerical simulation approaches featuring three solidification processes: strip casting, arc melting, and laser fusion. The obtained results cover more than four orders of magnitude in terms of cooling rates R and allow to propose a reliable empirical relationship between the interstructural spacing λ and R of the form λ [μm] = 83 R [K s−1]−0.36. This relation can thus be used to estimate cooling rates from metallographic observations.

Advancements in Flexible Electronics Fabrication: Film Formation, Patterning, and Interface Optimization for Cutting-Edge Healthcare Monitoring Devices.

Flexible electronics can seamlessly adhere to human skin or internal tissues, enabling the collection of physiological data and real-time vital sign monitoring in home settings, which give it the potential to revolutionize chronic disease management and mitigate mortality rates associated with sudden illnesses, thereby transforming current medical practices. However, the development of flexible electronic devices still faces several challenges, including issues pertaining to material selection, limited functionality, and performance instability. Among these challenges, the choice of appropriate materials, as well as their methods for film formation and patterning, lays the groundwork for versatile device development. Establishing stable interfaces, both internally within the device and in human-machine interactions, is essential for ensuring efficient, accurate, and long-term monitoring in health electronics. This review aims to provide an overview of critical fabrication steps and interface optimization strategies in the realm of flexible health electronics. Specifically, we discuss common thin film processing methods, patterning techniques for functional layers, interface challenges, and potential adjustment strategies. The objective is to synthesize recent advancements and serve as a reference for the development of innovative flexible health monitoring devices.

Comparative Evaluation of Condylar Guidance Obtained by Digital Panoramic Radiographic Images Using Two Different Interocclusal Recording Material During Jaw Relation in Completely Edentulous Patients: An In Vivo Study.

Objective To compare the condylar guidance value obtained during jaw relation by two different interocclusal recording materials to that obtained from OPG (Orthopantomogram). Materials and methods Two different interocclusal recording materials were used, namely bite registration wax (reinforced wax, by MAARC Dental Company) and bite registration paste (jet bite, coltene) for interocclusal records during jaw relations. An OPG is shot prior to the treatment, and horizontal condylar guidance (HCG) is traced joining the bony landmarks in a completely edentulous patient seeking complete denture treatment. All the conventional steps for complete denture fabrication up to jaw relation are performed. A facebow transfer is done on a Hanau H2 articulator, and height tracers (extra oral tracing devices) are attached. After satisfactory training, the tracing is performed by the patient, and the interocclusal records are obtained. The articulator is programmed to obtain the value of HCG using protrusive records, which are then compared to the value obtained from OPG. Statistics were carried out to determine angles. Followed by statistical analysis with Pearson correlation to analyze the results (α = 0.01). Results A substantial relationship was discovered between the horizontal condylar inclination between two interocclusal recording materials and the corresponding OPG for both the right (p = 0.0015) and left (p = 0.0007) sides. Conclusion The condylar guidance obtained with jet bite was closer than the condylar guidance value obtained with reinforced wax when compared with the horizontal condylar inclination obtained in OPG by tracing with a mean difference of 10° for polyvinyl siloxane and 20° for reinforced wax in seven subjects evaluated.

Metal Nanocomposites Reinforced by Ceramic Nanoarchitecture: Exploiting Extrinsic Size Effects for High Mechanical Strength.

The pursuit of harnessing superior mechanical properties achieved through the size effect on a macroscopic scale has been a prominent focus in engineering, as size-induced strengthening is enabled only in the nanoscale regime. This study presents a metal/ceramic/metal (MCM) nanocomposite reinforced by ceramic nanoarchitectures. Through proximity-field nanopatterning, the inch-scale production of nanoarchitecture films is enabled in a single fabrication step. The developed three-dimensional (3D) Ni/Al2O3/Ni nanocomposite film exhibits significantly high compressive strength, corresponding to an increase of approximately 30% compared with that calculated using the upper limits of the conventional rule of mixtures. The exceptional strength of the 3D MCM nanocomposite can be attributed to the extrinsic size effect of the ceramic nanoarchitectures. By combining size-induced strengthening of ceramics with the strengthening law for composites, a new type of strengthening model is derived and experimentally validated using the 3D MCM nanocomposite.

Physical Properties of an Efficient MAPbBr3/GaAs Hybrid Heterostructure for Visible/Near-Infrared Detectors.

Semiconductor photodetectors can work only in specific material-dependent light wavelength ranges, connected with the bandgaps and absorption capabilities of the utilized semiconductors. This limitation has driven the development of hybrid devices that exceed the capabilities of individual materials. In this study, for the first time, a hybrid heterojunction photodetector based on methylammonium lead bromide (MAPbBr3) polycrystalline film deposited on gallium arsenide (GaAs) was presented, along with comprehensive morphological, structural, optical, and photoelectrical investigations. The MAPbBr3/GaAs heterojunction photodetector exhibited wide spectral responsivity, from 540 to 900 nm. The fabrication steps of the prototype device, including a new preparation recipe for the MAPbBr3 solution and spinning, will be disclosed and discussed. It will be shown that extending the soaking time and refining the precursor solution's stoichiometry may enhance surface coverage, adhesion to the GaAs, and film uniformity, as well as provide a new way to integrate MAPbBr3 on GaAs. Compared to the pristine MAPbBr3, the enhanced structural purity of the perovskite on GaAs was confirmed by X-ray Diffraction (XRD) upon optimization compared to the conventional glass substrate. Scanning Electron Microscopy (SEM) revealed the formation of microcube-like structures on the top of an otherwise continuous MAPbBr3 polycrystalline film, with increased grain size and reduced grain boundary effects pointed by Energy-Dispersive Spectroscopy (EDS) and cathodoluminescence (CL). Enhanced absorption was demonstrated in the visible range and broadened photoluminescence (PL) emission at room temperature, with traces of reduction in the orthorhombic tilting revealed by temperature-dependent PL. A reduced average carrier lifetime was reduced to 13.8 ns, revealed by time-resolved PL (TRPL). The dark current was typically around 8.8 × 10-8 A. Broad photoresponsivity between 540 and 875 nm reached a maximum of 3 mA/W and 16 mA/W, corresponding to a detectivity of 6 × 1010 and 1 × 1011 Jones at -1 V and 50 V, respectively. In case of on/off measurements, the rise and fall times were 0.40 s and 0.61 s or 0.62 s and 0.89 s for illumination, with 500 nm or 875 nm photons, respectively. A long-term stability test at room temperature in air confirmed the optical and structural stability of the proposed hybrid structure. This work provides insights into the physical mechanisms of new hybrid junctions for high-performance photodetectors.

Programming-via-spinning: Electrospun shape memory polymer fibers with simultaneous fabrication and programming

Porous shape memory polymer (SMP) scaffolds are promising ‘smart’ materials for potential use in a wide range of biomedical applications. Electrospinning provides an approach to produce fibrous SMP scaffolds to enhance their porosity, mass transfer, and flexibility. Here, we studied the effects of electrospinning parameters (rotating collector rotational speed and solvent) on shape memory and mechanical properties of a biostable thermoplastic polyurethane (PUr) SMP. Scanning electron microscopy confirmed that fiber diameter and tortuosity could be tuned using varied collector rotation speeds and/or solvents. Mechanical properties, including modulus, tensile strength, and ultimate elongation, were tuned independently of chemistry based on variations in fiber architectures. All scaffolds demonstrated shape memory properties. Additionally, due to strains that are trapped in the fibers during the electrospinning process, SMP fibers are programmed into a strained, temporary shape during the fabrication step. These fibers can be immediately triggered to recover to a non-strained primary shape after fabrication to reduce sample preparation time and complexity. As a proof-of-concept, bacterial protease-responsive SMPs were electrospun and exposed to S. aureus in programmed secondary shapes. Upon exposure to bacteria, these SMPs underwent shape recovery, which resulted in reduced bacterial attachment and biofilm formation. These materials could be employed as bacteria-responsive wound dressings in future work. Overall, electrospinning provides a valuable tool for tuning mechanical and shape memory properties independently from chemistry and for programming SMPs during fabrication to enable scale-up of electrospun SMP scaffolds.

Universal and large-scale transform engineering from commercial metals to micron/nanoporous metals via an induced oxidation-reduction reaction

Three-dimensional (3D) nanoporous metals are being increasingly utilized in various fields such as catalysis, energy storage, and sensing. However, the conventional fabrication approaches for 3D nanoporous metals, such as dealloying and template methods, require additional sacrificial materials and multiple fabrication steps and generate chemical waste. Herein, we propose a novel gaseous (O2 and H2) oxidation-reduction (GOR) method to directly transform various transition metals/alloys into 3D micron/nanoporous materials by utilizing the spontaneous reconstruction of metallic atoms. This method eliminates the need for sacrificial materials and acidic/alkaline solutions, making it facile, cost-effective, and environmentally friendly. The resulting micron/nanoporous Ni/Ni alloy exhibits excellent mechanical properties, atomic hydrogen adsorption capability, and hydrophilicity, leading to outstanding electrocatalytic activity and durability for hydrogen evolution reaction.

Scalable transfer printing approach to heterogeneous integration of InP lasers on silicon-on-insulator waveguide platform

InP-based edge-emitting O-band lasers are integrated onto silicon photonics circuit employing micro-transfer printing technology. Blocks of unpatterned InP gain material of typical size 1000 × 60 μ m2 are first transferred onto 400 nm thick silicon rib waveguides with the fabrication steps performed on the target wafer to realize the final lasers. As a result, the InP ridge waveguides are aligned with lithographic accuracy to the underlying Si waveguides resulting in an approach free from any misalignment stemming from the transfer printing process. The fabricated Distributed Bragg Reflector laser shows lasing around 100 mA current injection with minimum 1 mW of output power coupled to a single mode fiber. This integration method paves a reliable route toward scaling-up the integration of active devices such as lasers, modulators, and detectors on 300-mm diameter silicon wafers, which requires high-uniformity across the wafer.