Functional Devices Research Articles

Ab Initio Investigation of the Mechanics and Thermodynamics of the Cubic EuAlO3 and GdAlO3 Perovskites for Optoelectronic Applications

Perovskites are currently becoming common in the field of optoelectronics, owing to their promising properties such as electrical, optical, thermoelectric, and electronic. Although mechanical and thermal properties also play a crucial part in the functioning of the optoelectronic devices, they have scarcely been explored. The present work performed an ab initio study of the mechanical and thermal properties of the cubic EuAlO3 and GdAlO3 perovskites for the first time using density functional theory. Quantum Espresso and Themo_pw codes were utilized by employing the generalized gradient approximation. Although the results showed that both materials have good mechanical and thermal properties that are ideal for the above–mentioned applications, EuAlO3 possessed better structural and thermal stability, bulk modulus, Poisson ratio, thermal expansion coefficient, and thermal stress; while GdAlO3 possessed better Young’s modulus and shear modulus. Moreover, the mechanical properties of the two materials turned out to be much better than those of the common materials for optoelectronic applications, while their thermal properties were comparable to that of sapphire glass. Since this study was computational, an experimental verification of the computed properties of the two materials needs to be carried out before they can be commercialized.

Ferroelectric Domains Engineering in 2D Van Der Waals Ferroelectric α‑In2Se3 Via Flexoelectric Effect.

2D) Van der Waals ferroelectrics offer the opportunity for developing novel nanoelectronics devices. For device applications, it is necessary to generate controllable ferroelectric polarization domains and achieve non-destructive polarization switching. However, it is very challenging to use the electric field to manipulate the domain state of ultra-thin ferroelectric film due to the large leakage current and even electric breakdown. Here, the flexoelectric effect on the manipulation of polarization states at bending α-In2Se3 flakes is explored via piezoresponse force microscopy (PFM). By introducing patterned Si trench substrates, the stripe micron-scale ferroelectric domains with alternating arrangements of the out of-plane polarization in the curved α-In2Se3 are observed. It is found that the polarization at the bending region of α-In2Se3 can be directly reversed by the large flexoelectric field. The controllable mechanical modulation of α-In2Se3 ferroelectric domains opens up potential applications of ferroelectrics in strain engineering functional devices.

Electrically induced insulator-to-metal transition in InP-based ion-gated transistor

With the growing awareness of energy savings and consumption for a sustainable ecosystem, the concept of iontronics, that is, controlling electronic devices with ions, has become critically important. Composite devices made of ions and solid materials have been investigated for diverse applications, ranging from energy storage to power generation, memory, biomimetics, and neuromorphic devices. In these studies, three terminal transistor configurations with liquid electrolytes have often been utilized because of their simple device structures and relatively easy fabrication processes. To date, oxide semiconductors and layered materials have mainly been used as active materials. However, inorganic compound semiconductors, which have a long history of basic and applied research, hardly function as channel materials in ion-gated transistors, partly because of the Schottky barrier at the electrode interface. Herein, we show that a typical group III–V compound semiconductor, InP, is available as a high-performance channel for ion-gated transistors with an on/off current ratio of ≈ 105 and a subthreshold swing as small as 93 mV/dec at room temperature. We fabricated AuGe/Ni contact electrodes via annealing to obtain the Ohmic contacts over a wide temperature range. The electrical resistance of InP was drastically decreased by the ionic liquid gating, which led to an electrically induced insulator-to-metal transition. Bulk compound semiconductors are well characterized and have relatively high carrier mobilities; thus, devices combined with electrolytes should prompt the development of iontronics research for novel device functionalities.

Glass Silicone Oil Free Pre-filled Syringe as Primary Container in Autoinjector.

Pre-filled syringes (PFSs) have become popular as a convenient and cost-effective container closure system for delivering biotherapeutics. However, standard siliconized PFSs may compromise the stability of therapeutic proteins due to their exposure to the silicone oil-water interface. To address this concern, silicone oil-free (SOF) glass syringes coupled with silicone-oil free plunger stoppers have been developed. This study aims to compare the impact of silicone oil-free (SOF) and siliconized syringes as primary container on protein stability and device functionality of the combination products. The stability of proteins with different modalities was assessed in SOF and siliconized 1mL glass syringes for up to 6months at 5℃, 25℃, and 40℃ with levels of subvisible particles and soluble aggregate determined by micro-flow imaging (MFI) and ultra performance size-exclusion chromatography (UP-SEC). The functionality of SOF glass syringes, including break loose force, extrusion force and delivery time in autoinjectors, was evaluated at different time points during the stability study. Additionally, SOF glass syringes were filled with viscosity surrogate ranging from 1 to 90 cP to understand the impact of solution viscosity on break loose force, extrusion force, and autoinjector delivery time. SOF demonstrates compatibility with proteins and exhibited significantly low particle counts compared to siliconized PFS. SOF syringes show significantly higher break-loose and extrusion forces. However, unlike siliconized syringes where silicone oil migration increases extrusion force, no significant change in functionality was observed in SOF glass syringe during stability testing. Overall, SOF glass syringes showed great potential as an alternative package for biologics with comparable performance on functionality as siliconized PFS. The combination of SOF glass and its PTFE coated stopper presents a new primary container closure system with both adequate protein stability and desired functionality features.

Digitally Programmable Microphase Separation in Polymer Network Generates Microstructure Pattern.

Polymers with microstructure patterns are crucial to many applications, such as separation, optics, electronics, metamaterials, etc. However, introducing microstructure patterns with diverse morphologies and feature sizes ranging from nanometers to micrometers into large-area polymers remains a significant challenge. Here, we design a material system that enables digital programming microphase separation in a polymer network to generate microstructure patterns. The polymer network is engineered to allow digital programming of local modulus, which arrests the length scale of microphase separation to generate various microstructures. These local modulus-regulated microstructures exhibit either bicontinuous or sea-island morphology and have various feature sizes ranging from ∼100 nm to several micrometers. Using household devices of an ink printer and an ultraviolet light lamp, the microstructure patterns can be programmed with fine resolutions (∼100 μm) over large areas (≫100 mm). The locally varied microstructures have different capabilities to scatter light and result in a visible pattern. We further demonstrate this design with a soft anticounterfeiting device. This approach of digital programming microphase separation in polymer networks is applicable to various polymers and provides a platform for designing many other functional devices.

A stochastic encoder using point defects in two-dimensional materials

While defects are undesirable for the reliability of electronic devices, particularly in scaled microelectronics, they have proven beneficial in numerous quantum and energy-harvesting applications. However, their potential for new computational paradigms, such as neuromorphic and brain-inspired computing, remains largely untapped. In this study, we harness defects in aggressively scaled field-effect transistors based on two-dimensional semiconductors to accelerate a stochastic inference engine that offers remarkable noise resilience. We use atomistic imaging, density functional theory calculations, device modeling, and low-temperature transport experiments to offer comprehensive insight into point defects in WSe2 FETs and their impact on random telegraph noise. We then use random telegraph noise to construct a stochastic encoder and demonstrate enhanced inference accuracy for noise-inflicted medical-MNIST images compared to a deterministic encoder, utilizing a pre-trained spiking neural network. Our investigation underscores the importance of leveraging intrinsic point defects in 2D materials as opportunities for neuromorphic computing.

A Molecular Engineering Approach to Conformationally Regulated Conductance Dualism in a Molecular Junction

AbstractOne key aspect for the development of functional molecular electronic devices is the ability to precisely tune and reversibly switch the conductance of individual molecules in electrode‐molecule‐electrode junctions in response to external stimuli. In this work, we present a new approach to access molecular switches by deliberately controlling the flexibility in the molecular backbone. We here describe two new conductance switches based on bis(triarylamines) that rely on the reversible toggling between two conformers, each associated with vastly different conductances. By molecular design, we were able to realize an on/off ratio Ghigh/Glow of ~103, which is one of the largest values reported to date. Flicker noise analysis and molecular transport calculations indicate that on/off switching relies on a change of the conduction pathway and vast differences in molecule‐electrode coupling. We thereby provide a new scaffold for further development of molecular conductance switches that are both efficient and easily refined.

3D Printing of Functional Hydrogel Devices for Screenings of Membrane Permeability and Selectivity

3D Printing of Functional Hydrogel Devices for Screenings of Membrane Permeability and Selectivity

Photothermal Laser Printing of Sub-Micrometer Crystalline ZnO Structures.

During light-driven 3D additive manufacturing, an object represented in digital form is initially translated into a spatial distribution of light intensity (sequentially or in parallel), which then results in a spatial material distribution. To date, this process typically proceeds by photoexcitation of small functional molecules, leading to photochemically induced crosslinking of soft materials. Alternatively, thermal triggers can be employed, yet thermal processes are often slow and provide only low spatial localization. Nevertheless, sub-micrometer ZnO structures for functional microelectronic devices have recently been laser-printed. Herein, the photothermal laser-printing of ZnO is advanced by i) introducing single-crystalline rather than amorphous sub-micrometer ZnO shapes that crystallize in the hexagonal ZnO wurtzite structure, ii) employing dimethyl sulfoxide (DMSO) instead of water, enabling higher local process temperatures without micro-bubble formation, and iii) using substrates tailored for light absorption and heat management, resolving the challenge of light to heat conversion. Finally, the herein-demonstrated ZnO printing requires no post-processing and is a cleanroom-free technique for the fabrication of crystalline semiconductors.

Emergent local negative electrostriction induced by oxygen vacancy in BaHfO3: Defect engineering

Realization of ultrasmall scale electromechanical materials has been promising for advanced functional devices. Recently, single-atom devices have been proposed as the ultimate miniaturization of functional devices beyond the nanoscale; however, achieving an atomic-scale local electromechanical response is still challenging due to physical size limitation of electromechanical properties as well as technical difficulties in fabricating the functional materials in a single atom precision. Here, we demonstrate a non-trivial negative electromechanical response at an oxygen vacancy in paraelectric BaHfO3 using first-principles finite electric field calculations. We find an electrostrictive response at the vacancy site in the same order of magnitude in well-known oxide materials. Surprisingly, we also discover an unusual “negative” sign of electrostriction in the oxygen vacancy. The detailed electronic structure analysis demonstrates that a unique electric field response of a localized defect electronic structure is the origin of this negative electrostriction of vacancy. The present results provide an important implication for the design of ultra-small electromechanical functions at an atomic scale.

Strain-Engineered 2D Materials: Challenges, Opportunities, and Future Perspectives.

Strain engineering is a powerful strategy that can strongly influence and tune the intrinsic characteristics of materials by incorporating lattice deformations. Due to atomically thin thickness, 2D materials are excellent candidates for strain engineering as they possess inherent mechanical flexibility and stretchability, which allow them to withstand large strains. The application of strain affects the atomic arrangement in the lattice of 2D material, which modify the electronic band structure. It subsequently tunes the electrical and optical characteristics, thereby enhances the performance and functionalities of the fabricated devices. Recent advances in strain engineering strategies for large-area flexible devices fabricated with 2D materials enable dynamic modulation of device performance. This perspective provides an overview of the strain engineering approaches employed so far for straining 2D materials, reviewing their advantages and disadvantages. The effect of various strains (uniaxial, biaxial, hydrostatic) on the characteristics of 2D material is also discussed, with a particular emphasis on electronic and optical properties. The strain-inducing methods employed for large-area device applications based on 2D materials are summarized. In addition, the future perspectives of strain engineering in functional devices, along with the associated challenges and potential solutions, are also outlined.

A performance evaluation of commercially available and 3D-printable prosthetic hands: a comparison using the anthropomorphic hand assessment protocol

Despite significant technological progress in prosthetic hands, a device with functionality akin to a biological extremity is far from realization. To better support the development of next-generation technologies, we investigated the grasping capabilities of clinically prescribable and commercially available (CPCA) prosthetic hands against those that are 3D-printed, which offer cost-effective and customizable solutions. Our investigation utilized the Anthropomorphic Hand Assessment Protocol (AHAP) as a benchtop evaluation of the multi-grasp performance of 3D-printed devices against CPCA prosthetic hands. Our comparison sample included three open-source 3D-printed prosthetic hands (HACKberry Hand, HANDi Hand, and BEAR PAW) and three CPCA prosthetic hands (Össur i-Limb Quantum, RSL Steeper BeBionic Hand V3, and Psyonic Ability Hand), along with including previously published AHAP data for four additional 3D-printed hands (Dextrus v2.0, IMMA, InMoov, and Limbitless). Our findings revealed a notable grasping performance disparity, with 3D-printed prostheses generally underperforming compared to their CPCA counterparts, specifically in cylindrical, diagonal volar, extension, and spherical grips. We propose that the observed performance shortfalls are likely attributed to the design or build quality of the 3D-printed prostheses, owing to the fact that 3D-printed hands often have a lower technology readiness level for widespread use. Addressing the limitations highlighted in this work and subsequent research will play a crucial role in refining the design and functionality of both 3D-printed and CPCA prosthetic devices.

Newton–Cotes quadrature formula, 3/8 rule, and Boole’s rule integration of the Current minus the Short-Circuit Current, to obtain the Co-Content function and photovoltaic device parameters with more precision, in the case of constant percentage noise

In this article, the Newton–Cotes quadrature formula, the 3/8 rule, and the Boole’s rule integration techniques are used to integrate the Current minus the Short-Circuit Current, to obtain a more accurate Co-Content function, and from this one, deduce with more accuracy the photovoltaic device parameters, namely, the Shunt Resistance, the Series Resistance, the Ideality Factor, the Saturation Current, and the Light Current, compared with the usually used trapezoidal integration technique. Less than 5% error (in some cases 1% or smaller) can be obtained on the extracted photovoltaic device parameters, for 31 measured points per volt, or less, in case the percentage noise is <0.05%.

Ordered Solid Solution γ′-Fe4N-Based Absorber Synthesized by Nitridation Engineering and Applied for Electromagnetic Functional Devices

Ordered Solid Solution γ′-Fe4N-Based Absorber Synthesized by Nitridation Engineering and Applied for Electromagnetic Functional Devices

Fabrication and characterization of lead lanthanum zirconate titanate ceramic-based fully transparent piezoelectric loudspeakers for next-generation electronic devices

Transparency is a critical attribute of next-generation electronic devices; this ensures unobstructed visibility while maintaining device functionality. Traditional electromagnetic coils are opaque, and piezoelectric materials with high optical transparency, low power consumption, and rapid responses are required when preparing innovative transparent electronics. In this study, we developed lead lanthanum zirconate titanate (PLZT) ceramics with excellent transparency (PLZT S1 = 65 %, PLZT S2 = 42 % at 550 nm) and piezoelectric properties (PLZT S1 = 180 pC/N, PLZT S2 = 470 pC/N). An indium tin oxide (ITO)-coated PLZT ceramic (PLZT S2) was used to create a fully transparent transducer with a glass diaphragm. This delivered outstanding sound output, attaining 105 dB at the resonance frequency (5.6 kHz) at an input of only 5 Vpp. To demonstrate the versatility of PLZT in terms of transparent electronic applications, PLZT transducers were placed on a desiccator wall; this showcased their capacity to emit a warning sound without compromising visibility when gas leaked inside the desiccator. An ITO-coated PLZT disc was employed to fabricate a loudspeaker with a polyethylene terephthalate (PET) diaphragm; this produced sounds from 30 dB to 68 dB across the entire voice frequency spectrum (500 Hz–8 kHz) with an input of 10 Vpp. This loudspeaker meets the demands of next-generation transparent electronics; optical visibility and high-quality sound reproduction are assured without any compromise in terms of sound quality or visual transparency.

In Vitro Analysis of Left Ventricular Assist Device Outflow Graft Orientations and Their Effect on Aortic Hemodynamics.

Continuous-flow left ventricular assist devices have become an important treatment option for patients with advanced heart failure. However, adverse hemodynamic effects as consequence of an altered blood flow within the aorta and the aortic root remain a topic of concern. In this work, we investigated the influence of the outflow graft orientation on the hemodynamic profile and flow parameters within the thoracic aorta. Aortic models with different outflow graft orientations were designed and three-dimensional (3D) printed to mimic common implantation configurations and were integrated into a pulsatile mock circulatory flow loop. Assist device function was achieved using a rotary pump, replicating nonpulsatile, continuous support flows of 1-5 L/min. Flow velocity, wall shear stress, and pressure gradients were investigated for each configuration using sonography and four-dimensional (4D) flow magnetic resonance imaging. Mean wall shear stresses measured in 4D flow software were lowest for a graft inclination angle of 45°. Streamline visualization revealed areas of nonuniform, retrograde, and vortex flow in all models but most prominent for the aortic model with an outflow graft inclination of 60°. The insights gained from this research may aid in understanding clinical outcomes following assist device implantation and long-term mechanical circulatory support.

Application of classification algorithms for smishing detection on mobile devices: literature review

Smishing is a form of phishing carried out via mobile devices to steal confidential information from victims. The number of smishing attacks has increased in recent years due to the large number of users acquiring these easy-to-use and functional devices. This literature review objective is to examine the techniques and methods used in smishing attacks using classification algorithms. To do so, we conducted a manual search process and selected 155 articles from Scopus and 29 articles from access to research for development and innovation (ARDI). Of these, 36 articles met the inclusion criteria. In addition, the algorithms most commonly used by the studies were random forest classification techniques, decision trees, and neural networks. These studies analyzed various machine learning models for detecting phishing and smishing messages. The attack simulation scenarios included generating web pages, sending fake links (URLs), and installing malicious applications. The analysis evaluated web pages and SMS messages using a database containing legitimate as well as smishing messages. Based on the results, it is suggested to combine these methods to improve detection performance, making it more robust and promising.

Enhanced Electromagnetic Interference Shielding in Cement Composites Utilizing Carbon Fiber Clustered Networks with Dual Different Lengths

Electromagnetic interference (EMI) shielding is crucial for radio frequency ranges, particularly around 1 GHz, to ensure the functionality and security of electronic devices and wireless communications especially within building materials. The inherent properties of typical metallic materials, such as their heavy weight and high cost, make them less suitable for mass production, particularly in the construction applications. Herein, we present a novel approach to improve EMI shielding efficiency of cement composites by incorporating two types of carbon fibers with distinct lengths as fillers and optimizing the clustering network among these fillers. By precisely controlling the length and proportion of long (mother) and short (anchor) carbon fibers, we demonstrate that a 7:3 ratio of 6 mm mother fibers to 2 mm anchor fibers yields optimal shielding efficiencies, delivering 65.3 dB at a low radio frequency (1 GHz) and 44.5 dB in the high X-band frequency range (8.2 – 12.4 GHz). Significantly, two-dimensional matrix simulations corroborate the geometric modifications occurring between fillers as the length and ratio of carbon fibers are altered, showing excellent agreement with our experimental results. Combined with an intriguing approach to fine-tune the clustered network of carbon fibers, this study highlights the critical role of filler geometry within the matrix in developing high-performance EMI shielding materials, offering new insights for the design of advanced EMI shielding solutions.

Continuous fiber printing of a modular heater for ion mobility spectrometry

Ion mobility spectrometry (IMS) is a powerful analytical method for separating and detecting gaseous substances like volatile organic compounds (VOCs). It is highly versatile, used both as a standalone technique and in combination with chromatographic methods for pre-separation or mass spectrometry for complex matrix analysis. This study explores the use of an advanced 3D printing technology to print a heater for an IMS-device.A continuous fiber printer, commonly used to enhance the mechanical properties of printed objects, was used to create a customized heating element by embedding a copper wire within the polymer matrix during the printing process. Cyclic olefin copolymer (COC) was chosen as the matrix material due to its analytical properties, such as low off-gassing and higher thermal stability, compared to the more commonly used polylactic acid (PLA).The 3D printed heater was incorporated into a drift tube ion mobility spectrometer, and its performance was evaluated by analyzing the separation of various ketones. The results show that the 3D printed heater effectively controlled the temperature within the drift tube, improving the resolving power of overlapping peaks.This study shows the potential of 3D printing technology to improve fabrication and functionality of IMS devices. The flexibility in design and material selection afforded by 3D printing not only enhances the analytical performance of IMS but also allows for customization and rapid prototyping of other analytical instruments or laboratory devices.

Tuneability and optimum functionality of plasmonic transparent conducting oxide-Ag core-shell nanostructures

Tunning localized surface plasmon resonance (LSPR) in transparent conducting oxides (TCO) has a great impact on various LSPR-based technologies. In addition to the commonly reported mechanisms used for tunning LSPR in TCOs (e.g., size, shape, carrier density modifications via intrinsic and extrinsic doping), integrating them in core-shell structures provides an additional degree of freedom to expand its tunability, enhance its functionality, and widen its versatility through application-oriented core-shell geometrical optimization. In this work, we explore the tuneability and functionality of two TCO nanostructures; indium doped tin oxide (ITO) and gallium doped zinc oxide (GZO) encapsulated with silver shell within the extended theoretical Mie theory formalism. The effect of core and shell sizes on LSPR peak position and line width as well as absorption and scattering coefficients is numerically investigated. Simulations showed that LSPRs of ITO-Ag and GZO-Ag core-shell nanostructures have great tunning capabilities, spanning from VIS to IR spectral range including therapeutic window of human tissue and essential solar energy spectrum. Potential functionality as refractive index sensor (RIS) and solar energy absorber (SEA) are examined using appropriate figure of merits (FoM). Simulations indicate that a geometrically optimized core-shell architecture with exceptional FoMs for RIS and SEA can be realized. Contrary to carrier density manipulation, integrating TCO cores to metallic shells proves to be an effective approach to enhance tunability and optimize functionality for high performance TCO-based plasmonic devices, with minimum impact on the inherited physical and chemical properties of the used TCO-core materials.