Miniaturization Of Devices Research Articles

Heat Transfer Management of Thermal and Electronics Systems using Convective-Radiative Porous Fins with Thermal Contact Resistance and Diabatic Tip

The miniaturization of electronics, electrical, thermal, mechanical and optical devices and systems calls for increasing demand for efficient cooling systems with higher thermal efficiency. The use of passive mode of cooling using fins has provided unprecedented results. However, the previous transient analyses of the extended surfaces have been done without proper considerations of the imperfect contact between the fin base and the prime surface. Also, the tip of the passive device has been assumed to be adiabatic. However, the present article explores the significances of thermal contact resistance and diabatic tip on the transient thermal response of straight fin with temperature-dependent thermal conductivity and magnetic field under radiative-convective conditions. The nonlinear model is analyzed numerically using generalized Integral Transform Techniques and the numerical results are verified by the exact solution for the linear thermal model. The parametric explorations reveal that the adimensional local temperature in the conductive-radiative fin increases when the conductive-convective, conductive-radiative and magnetic field parameters increase. However, under the assumption of perfect thermal contact between the prime surface and the base of the fin, the adimensional temperature in the fin will decrease as the conductive-convective, conductive-radiative and magnetic field parameters increase. The fin temperature is significantly affected by the Biot numbers under the comparably low values of the conductive-convective, conductive-radiative, magnetic field and thermal conductivity parameters. The effects of the fin thermal conductivity parameter along the fin length depend on the respective values of thermal contact Biot number at the base of the fin and the end cooling Biot number at the tip of the fin. When the thermal conductivity parameter is amplified, the fin adimensional temperature increases when thermal contact Biot number at the base of the fin is zero and the end cooling Biot number at the tip of the fin is very large. This study will help in accurate analysis and design of heat sinks and passive devices for heat transfer enhancement for thermal and electronic systems.

Ultra-large strain response in BNT-BT-KNN thin films boosted by electric field-induced inversion of long-range ordered polarization

Bismuth sodium titanate (BNT)-based piezoelectric materials are the most promising candidates for lead-free actuator applications. With the request for integration and size miniaturization of devices, it is urgent to develop thin films for microdevices to be compatible with semiconductor processes. Through composition engineering, BNT-based thin films were fabricated on silicon substrates, with ultra-high strain response and negligible hysteresis in strain curves. The DC-dependent and temperature-dependent dielectric properties were collected to investigate the relaxor state of thin films. The structure and polarization transition and evolution as a function of electric field and time were analyzed based on the electric characterization, in-situ Raman measurements, and dynamics PFM. The reversible phase transition and polarization order-disorder transformation are the most significant features for reaching a large strain of >1.6% in BNT-based thin films.

Wavelength calibration using MEMS-enabled double filter configuration for air gap sensing in the tunable Fabry–Pérot filter

We fabricate a microelectromechanical systems (MEMS)-based device configuring the tunable air gap Fabry–Pérot filter (FPF) with a static gradient thickness filter on the same platform. The proposed double filter configuration offers a wavelength calibration approach that accurately estimates the air gap dimension in the tunable air gap FPF. The wavelength calibration is performed by utilizing the spectrally-selective and spatially-resolved transmission characteristics of the tunable air gap FPF and the static gradient thickness filter, respectively. The MEMS-compatible chip-level integration of the static gradient thickness filter facilitates device miniaturization to enable its use in handheld devices.

THE FUTURE WORKFORCE: PREPARING STUDENTS FOR CAREERS IN ELECTRONIC PACKAGING MATERIALS

The miniaturization and complexity of electronic devices are driving the demand for innovative electronic packaging materials. However, the current workforce may not be fully prepared for the specific skillset required in this evolving field. This paper explores the crucial role of electronic packaging materials and the knowledge, and skills needed for success in this industry. We propose educational strategies that integrate scientific principles, hands-on activities, and project-based learning to prepare students for careers in electronic packaging materials. The paper acknowledges potential challenges but emphasizes the exciting opportunities for educators and stakeholders to equip the future workforce with the necessary tools for technological advancements in electronics.

Multilayer focal plane metalens based on all-dielectric materials in the ultraviolet band

Metalens can expand optical imaging capabilities due to the ability of metasurfaces to manipulate light propagation. Multi-focal metalens have been widely used in multi-imaging systems, detectors, and laser printing. This study presents the design of a UV metalens composed of alumina nanopillars. We investigate the focusing properties of representative UVA (343 nm) at multiple focal points on the in-plane axis, off-axis, and within a single plane. In addition, we extend the focusing ability of the metalens with multiple focal planes. We design the metalens with multiple imaging capabilities and produce focuses with different shapes in four focal planes. Simulation results show that the focal points of the planes have different shapes, the location of the maximum light intensity in the xz plane is in good agreement with our designed focal length, and the average focusing efficiency is greater than 60% in each plane. To evaluate the feasibility of planar spacing detection, we calculate the error-tolerant rate (Etr) of the device to be more than 90%. This work has important implications for the integrated miniaturization of UV photonic devices and the study of optical tomography.

Electronic Devices Based on Heterostructures of 2D Materials and Self-Assembled Monolayers.

2D materials (2DMs), known for their atomically ultrathin structure, exhibit remarkable electrical and optical properties. Similarly, molecular self-assembled monolayers (SAMs) with comparable atomic thickness show an abundance of designable structures and properties. The strategy of constructing electronic devices through unique heterostructures formed by van der Waals assembly between 2DMs and molecular SAMs not only enables device miniaturization, but also allows for convenient adjustment of their structures and functions. In this review, the fundamental structures and fabrication methods of three different types of electronic devices dominated by 2DM-SAM heterojunctions with varying architectures are timely elaborated. Based on these heterojunctions, their fundamental functionalities and characteristics, as well as the regulation of their performance by external stimuli, are further discussed.

Revolutionizing food science with mass spectrometry imaging: A comprehensive review of applications and challenges.

Food science encounters increasing complexity and challenges, necessitating more efficient, accurate, and sensitive analytical techniques. Mass spectrometry imaging (MSI) emerges as a revolutionary tool, offering more molecular-level insights. This review delves into MSI's applications and challenges in food science. It introduces MSI principles and instruments such as matrix-assisted laser desorption/ionization, desorption electrospray ionization, secondary ion mass spectrometry, and laser ablation inductively coupled plasma mass spectrometry, highlighting their application in chemical composition analysis, variety identification, authenticity assessment, endogenous substance, exogenous contaminant and residue analysis, quality control, and process monitoring in food processing and food storage. Despite its potential, MSI faces hurdles such as the complexity and cost of instrumentation, complexity in sample preparation, limited analytical capabilities, and lack of standardization of MSI for food samples. While MSI has a wide range of applications in food analysis and can provide more comprehensive and accurate analytical results, challenges persist, demanding further research and solutions. The future development directions include miniaturization of imaging devices, high-resolution and high-speed MSI, multiomics and multimodal data fusion, as well as the application of data analysis and artificial intelligence. These findings and conclusions provide valuable references and insights for the field of food science and offer theoretical and methodological support for further research and practice in food science.

Ultra-High Vacuum Cells Realized by Miniature Ion Pump Using High-Efficiency Plasma Source.

In recent years, there has been significant interest in quantum technology, characterized by the emergence of quantum computers boasting immense processing power, ultra-sensitive quantum sensors, and ultra-precise atomic clocks. Miniaturization of quantum devices using cold atoms necessitates the employment of an ultra-high vacuum miniature cell with a pressure of approximately 10-6 Pa or even lower. In this study, we developed an ultra-high vacuum cell realized by a miniature ion pump using a high-efficiency plasma source. Initially, an unsealed miniature ion pump was introduced into a vacuum chamber, after which the ion pump's discharge current, depending on vacuum pressures, was evaluated. Subsequently, a miniature vacuum cell was fabricated by hermetically sealing the miniature vacuum pump. The cell was successfully evacuated by a miniature ion pump down to an ultra-high vacuum region, which was derived by the measured discharge current. Our findings demonstrate the feasibility of achieving an ultra-high vacuum cell necessary for the operation of miniature quantum devices.

Solution-processed MoS2 nanostructures and thermal oxidization on carbon fabric with enhanced thermopower factor for wearable thermoelectric application

Miniaturization of electronic devices has become the new phase of modern technology. Wearable Thermoelectric Generators (WTEG), being flexible, lightweight, self-sustained, and safe are the only replacement for conventional batteries for mobile applications. Molybdenum Disulfide (MoS2), a graphene akin compound having diverse transport behaviour and low thermal conductivity is one of the most preferable candidates for thermoelectric application. However, limited reports are available on MoS2 for Wearable thermoelectric applications. In this study, we have accomplished successful growth of MoS2 nanostructures on conductive carbon fabric via one step hydrothermal method and the effect of thermal oxidation of MoS2 has been studied at various annealing temperature. The structural and elemental analysis confirms the transformation of MoS2 into MoO3. Annealing creates an MoS2/MoO3 interface thus enhancing the carrier mobility resulting in enhancement of power factor (481 nW.m−1K−2) of the sample annealed at 200 °C (M1) by 1.29 times than that of pristine MoS2. The sample possessing high performance has been employed to fabricate a WTEG and its real time output has been measured. The design and operating conditions of the device is studied and optimized to obtain the output open circuit voltage as high as 6.4 mV. This paves a promising route to fabricate self- powered wearable biomedical devices.

Perfect Spin Filtering, Giant Magnetoresistance, and Rectification Behavior Induced by V‐Doped Zigzag Graphene Nanoribbons

AbstractEmploying the constructs of density functional theory (DFT) and the Nonequilibrium Green's Function (NEGF), the investigation extensively explores the electronic and transport properties of zigzag graphene nanoribbons (ZGNRs) doped with vanadium (V). Notably, this inquiry unveils that strategic doping can transform V‐doped ZGNRs into spintronic nanodevices with distinctive transport attributes. Initially, the simulations showcase remarkably high spin‐filtering efficiencies (SFEs) at certain bias voltages. Furthermore, a giant magnetoresistance (GMR) peaking at 6.87 10 is detected. In conclusion, the examination discerns a spin rectifier that exhibits a significant rectification ratio (RR) of 9.62 10. This research delineates a viable trajectory for the refinement of high‐performance spintronics in ZGNRs via vanadium doping. The implications of this study indicate that the model harbors considerable promise for application in miniature spintronic devices.

Size-Effect-Based Dimension Compensations in Wet Etching for Micromachined Quartz Crystal Microstructures.

Microfabrication technology with quartz crystals is gaining importance as the miniaturization of quartz MEMS devices is essential to ensure the development of portable and wearable electronics. However, until now, there have been no reports of dimension compensation for quartz device fabrication. Therefore, this paper studied the wet etching process of Z-cut quartz crystal substrates for making deep trench patterns using Au/Cr metal hard masks and proposed the first quartz fabrication dimension compensation strategy. The size effect of various sizes of hard mask patterns on the undercut developed in wet etching was experimentally investigated. Quartz wafers masked with initial vias ranging from 3 μm to 80 μm in width were etched in a buffered oxide etch solution (BOE, HF:NH4F = 3:2) at 80 °C for prolonged etching (>95 min). It was found that a larger hard mask width resulted in a smaller undercut, and a 30 μm difference in hard mask width would result in a 17.2% increase in undercut. In particular, the undercuts were mainly formed in the first 5 min of etching with a relatively high etching rate of 0.7 μm/min (max). Then, the etching rate decreased rapidly to 27%. Furthermore, based on the etching width compensation and etching position compensation, new solutions were proposed for quartz crystal device fabrication. And these two kinds of compensation solutions were used in the fabrication of an ultra-small quartz crystal tuning fork with a resonant frequency of 32.768 kHz. With these approaches, the actual etched size of critical parts of the device only deviated from the designed size by 0.7%. And the pattern position symmetry of the secondary lithography etching process was improved by 96.3% compared to the uncompensated one. It demonstrated significant potential for improving the fabrication accuracy of quartz crystal devices.

Numerical investigation of flow and heat transfer characteristics of special-shaped fuel

Helical cruciform fuel, a relatively new type of fuel element, has garnered significant interest due to its distinctive attributes, such as transverse mixing characteristics and self-supporting properties. However, helical cruciform fuel still faces numerous challenges. To address the issue of high central temperatures, an annular helical cruciform fuel is introduced, and its internal flow and heat transfer characteristics are evaluated through numerical simulation in comparison to helical cruciform fuel. The results indicate that fuel elements with a helical structure exhibit lower maximum temperatures and higher convective heat transfer coefficients. Specifically, the maximum temperature of helical cruciform fuel at a power density of 200 WM/m3 is 712.26 K, whereas for annular helical cruciform fuel under the same heat generation rate, the maximum temperature is only 686.34 K. Regarding convective heat transfer, the annular helical cruciform fuel element demonstrates an improvement of approximately 20% compared to the helical cruciform fuel element. Consequently, annular helical cruciform fuel contributes more to the safety of the reactor core and the miniaturization of nuclear power devices. This study could serve as a reference for the subsequent design and enhancement of reactor cores.

Unraveling intrinsic mobility limits in two-dimensional (AlxGa1−x)2O3 alloys

β-(AlxGa1−x)2O3 presents a diverse material characterization exhibiting exceptional electrical and optical properties. Considering the miniaturization of gallium oxide devices, two-dimensional (AlxGa1−x)2O3 alloys, as a critical component in the formation of two-dimensional electron gases, demand an in-depth examination of their carrier transport properties. Herein, we investigate the temperature-dependent carrier mobility and scattering mechanisms of quasi-two-dimensional (2D) (AlxGa1−x)2O3 (x ≤ 5) by solving the Boltzmann transport equation from first-principles. Anisotropic electron mobility of 2D (AlxGa1−x)2O3 is limited to 30−80 cm2/Vs at room temperature, and it finds that the relatively large ion-clamped dielectric tensors (Δɛ) suggest a major scattering role for polar optical phonons. The mobility of 2D (AlxGa1−x)2 is less than that of bulk β-(AlxGa1−x)2O3 and shows no quantum effects attributed to the dangling bonds on the surface. We further demonstrate that the bandgap of 2D (AlxGa1−x)2O3 decreases with the number of layers, and the electron localization function also shows an anisotropy. This work comprehensively interprets the scattering mechanism and unintentional doping intrinsic electron mobility of (AlxGa1−x)2O3 alloys, providing physical elaboration and alternative horizons for experimental synthesis, crystallographic investigations, and power device fabrication of 2D (AlxGa1−x)2O3 atomically thin layered systems.

3D Printed Hydrogel Sensor for Rapid Colorimetric Detection of Salivary pH.

Salivary pH is one of the crucial biomarkers used for non-invasive diagnosis of intraoral diseases, as well as general health conditions. However, standard pH sensors are usually too bulky, expensive, and impractical for routine use outside laboratory settings. Herein, a miniature hydrogel sensor, which enables quick and simple colorimetric detection of pH level, is shown. The sensor structure was manufactured from non-toxic hydrogel ink and patterned in the form of a matrix with 5 mm × 5 mm × 1 mm individual sensing pads using a 3D printing technique (bioplotting). The authors' ink composition, which contains sodium alginate, polyvinylpyrrolidone, and bromothymol blue indicator, enables repeatable and stable color response to different pH levels. The developed analysis software with an easy-to-use graphical user interface extracts the R(ed), G(reen), and B(lue) components of the color image of the hydrogel pads, and evaluates the pH value in a second. A calibration curve used for the analysis was obtained in a pH range of 3.5 to 9.0 using a laboratory pH meter as a reference. Validation of the sensor was performed on samples of artificial saliva for medical use and its mixtures with beverages of different pH values (lemon juice, coffee, black and green tea, bottled and tap water), and correct responses to acidic and alkaline solutions were observed. The matrix of square sensing pads used in this study provided multiple parallel responses for parametric tests, but the applied 3D printing method and ink composition enable easy adjustment of the shape of the sensing layer to other desired patterns and sizes. Additional mechanical tests of the hydrogel layers confirmed the relatively high quality and durability of the sensor structure. The solution presented here, comprising 3D printed hydrogel sensor pads, simple colorimetric detection, and graphical software for signal processing, opens the way to development of miniature and biocompatible diagnostic devices in the form of flexible, wearable, or intraoral sensors for prospective application in personalized medicine and point-of-care diagnosis.

High Accuracy Localization for Miniature Ingestible Devices Using Mutual Inductance.

This article demonstrates an inductively coupled high-accuracy localization system for miniature ingestible devices. It utilizes an inductance double capacitances-series capacitance (LCC-S) compensation architecture that enables mutual inductance measurement at primary side that is positioned outside the human body and less constrained by power budget and size than the miniature ingestible. Depending on the secondary circuit architecture, only limited and simple cooperative measurements are needed from the ingestible secondary side, which saves power and area in the miniature device. The errors in the system are modeled thoroughly, providing insights about system require-ments for a particular localization accuracy target for efficient design and to identify key building blocks with large influence on overall performance. The model shows that sub-centimeter localization root-mean-square error (RMSE) can be achieved with a modest external ADC (18bit) using three primary coils and three secondary coils. The localization is verified along a complete small intestine tract with realistic dimensions. The proposed model is verified by simulation and experiment showing that at the selected frequency range up to 5 MHz the body has no influence on the accuracy. The use of 0.9% saline as phantom is proposed which guarantees the analysis validity for all body types.

Applying User-Centered Design Principles to the Development of Wearable Technology in Fashion Design

This paper explores the integration of user-centered design (UCD) principles into the development of wearable technology within the fashion industry. As wearable devices become more prevalent, the necessity for these products to not only serve functional purposes but also align with fashion aesthetics and user preferences becomes increasingly critical. This study provides an extensive overview of the historical development of wearable technology, highlighting key shifts from basic functional devices to advanced systems that merge seamlessly with user lifestyles and fashion choices. Through detailed case studies of products such as the Apple Watch and Fitbit, the paper illustrates the successful application of UCD principles, emphasizing customization, health monitoring, and interactive user engagement. It also discusses various design methodologies, including Human-Centered Design, Agile Development, and Sustainable Design, and their roles in addressing both user needs and rapid technological changes. Furthermore, the paper examines the challenges faced by designers, such as device miniaturization, aesthetic integration, and privacy concerns, alongside opportunities for innovation in health monitoring, sustainable practices, and augmented reality. The study underscores the critical importance of UCD in enhancing user acceptance and market success, advocating for continued research and cross-disciplinary collaboration to foster innovation in wearable technology.

Recent progresses in transmission electron microscopy studies of two-dimensional ferroelectrics

The rich potential of two-dimensional materials endows them with superior properties suitable for a wide range of applications, thereby attracting substantial interest across various fields. The ongoing trend towards device miniaturization aligns with the development of materials at progressively smaller scales, aiming to achieve higher integration density in electronics. In the realm of nano-scaling ferroelectric phenomena, numerous new two-dimensional ferroelectric materials have been predicted theoretically and subsequently validated through experimental confirmation. However, the capabilities of conventional tools, such as electrical measurements, are limited in providing a comprehensive investigation into the intrinsic origins of ferroelectricity and its interactions with structural factors. These factors include stacking, doping, functionalization, and defects. Consequently, the progress of potential applications, such as high-density memory devices, energy conversion systems, sensing technologies, catalysis, and more, is impeded. In this paper, we present a review of recent research that employs advanced transmission electron microscopy (TEM) techniques for the direct visualization and analysis of ferroelectric domains, domain walls, and other crucial features at the atomic level within two-dimensional materials. We discuss the essential interplay between structural characteristics and ferroelectric properties on the nanoscale, which facilitates understanding of the complex relationships governing their behavior. By doing so, we aim to pave the way for future innovative applications in this field.

Multifunctional polyimide/boron nitride nanosheet/Ti3C2Tx MXene composite film with three-dimensional conductive network for integrated thermal conductive, electromagnetic interference shielding, and Joule heating performances

With the demand for further miniaturization and higher frequency operation of electronic devices, polymer films with high thermal conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) are urgently required. Herein, polyimide (PI)/boron nitride nanosheets (BNNS) aerogels with oriented porous structure are fabricated by unidirectional-freezing and freeze-drying methods. Subsequently, hierarchical PI/BNNS/Ti3C2Tx composite films with consecutively electrically and thermally conductive networks are successfully prepared via a unidirectional PI/BNNS aerogels-assisted immersion and hot-pressing strategy. Owing to the three-dimensional conductive dual networks of BNNS and Ti3C2Tx, the composite film exhibits excellent thermal conductivity with the maximum in-plane value of 4.73 W/(m·K), increased by 456 % compared to pure PI film. Moreover, the conductive network of Ti3C2Tx is conducive to the excellent EMI shielding performance, endowing the PI/BNNS/Ti3C2Tx composite film with an outstanding EMI SE value of 49.2 dB at 8.2 GHz with a low MXene content of 6 wt% and thickness of 300 μm. Furthermore, the composite film shows the superior Joule heating performance with fast thermal response and sufficient reliability. Therefore, the resulting composite film exhibits excellent thermal conductive, EMI shielding and Joule heating performance, which enables the potential application of multifunctional composites for thermal management and EMI shielding.

Multi-spectral compatible metasurface with low infrared emissivity, independent microwave complex-amplitude control, and high visible transparency.

With the rapid development of communication technology and detection technology, it is difficult for devices operating in a single spectrum to meet the application requirements of device integration and miniaturization, resulting in the exploration of multi-spectrum compatible devices. However, the functional design of different spectra is often contradictory and difficult to be compatible. In this work, a transparent slit circular metasurface with a high filling ratio is proposed to achieve the compatibility of microwave, infrared and visible light. In the microwave, based on the Pancharatnam-Berry phase theory, the continuous amplitude and binary phase can be customized only by rotating the slit angle to achieve an Airy beam function at 8-12 GHz. In the infrared, the mean infrared emissivity is reduced to 0.3 at 3-14 µm by maintaining high conductive filling ratio, and in visible light, based on the transparency of materials, the mean transmittance can achieve 50% at 400-800 nm. All the results can verify the multi-spectral compatibility performance, which can also verify the validity of our design method. Importantly, the multi-spectral compatible metasurface contributes an option for multifunctional integration, which can be further applied in communication, camouflage, and other fields.

Integrating high-efficiency thermal channel construction and structural wave absorption design within vertically oriented SiC-coated carbon fibers/silicone resin composites

To match the increasing miniaturization and integration of electronic devices, higher requirements are put forward for the electromagnetic wave absorption (EWA) and thermal conductivity (Tc) of heat conduction-microwave absorption integrated materials (HCMWAIMs) to overcome the problems of electromagnetic wave (EMW) pollution and heat accumulation. Herein, a simple and efficient shear force induction technique is used to construct a carbon/magnetic isolation network within the silicone resin matrix, where ferrite particles are well dispersed in vertically oriented SiC-coated carbon fibers array. Benefiting from the orderly interconnection of CFs@SiC in the array, the prepared composites have a high Tc of 7.86 W m−1 K−1. The introduction of magnetic ferrite particles within the CFs@SiC array can induce electrical-magnetic coupling, optimize impedance matching, and enhance EMW attenuation. This synergy of V-CFs@SiC/ferrite isolation network structure gives the composites an excellent effective absorption bandwidth (EAB) of 5.88 GHz and a minimal reflection loss (RLmin) of −47.5 dB at a thickness of 1.5 mm. Moreover, the as-prepared composites exhibit outstanding elastic compressibility of 43.2 % and rebound rate of 45.1 % under a pressure of 35psi. This strategy offers a distinguishing understanding of preparing high-performance HCMWAIMs in modern electronic devices.