Search Results (1,621)

This paper presents the design of an inverted-F antenna intended for integration into a smartwatch operating in the 2.4 GHz band. The antenna design addresses spatial constraints imposed by the device’s miniaturized form factor and the proximity of electronic components, including the printed circuit board, display, and battery. The influence of the user’s body on the antenna’s performance characteristics was considered during the design phase through numerical simulations employing the Finite-Difference Time-Domain (FDTD) method with a heterogeneous human body model. Simulation results and measurements of a fabricated prototype antenna are presented, demonstrating satisfactory performance in terms of impedance matching with VSWR below 1.5 in the whole band and gain of −1 dBi. Full article

With the ongoing trend of miniaturization and intelligent power transmission equipment, the compact design of environmentally friendly gas-insulated switchgear (GIS) has emerged as a critical technical challenge. This study presents a detailed case study of a 40.5 kV dry air-insulated switchgear under specific dimensional constraints. Specifically, the cabinet width was reduced from 1000 mm to 800 mm, significantly narrowing the phase-to-phase and phase-to-ground clearances. A high-fidelity three-dimensional electric field model was established using the finite element method to evaluate the dielectric stress distribution within the enclosure. Numerical results indicate pronounced electric field concentrations at critical regions—including copper busbar joints, disconnector contacts, and the inlet bushing shielding rings—where local intensities exceeded the insulation safety threshold. To mitigate these issues, integrated design refinement strategies were evaluated, encompassing the structural modification of shielding rings, the application of silicone rubber coatings, and insulation reinforcement via heat-shrinkable tubing. Comparative analysis and experimental results demonstrate that the refined configuration effectively suppressed the peak electric field intensity. Finally, the design was validated through comprehensive dielectric tests, including a 215 kV lightning impulse withstand voltage test. This work may offer useful engineering references and quantitative data for the ultra-compact design of eco-friendly switchgear under similar constraints. Full article

Background: Follicular unit extraction (FUE) has become the dominant donor site harvesting technique in modern hair transplantation due to its ability to avoid linear scar formation and its procedural flexibility. However, the donor site is a limited non-regenerative source. Excessive or poorly planned extraction can lead to visible thinning, hypopigmented scarring, and reduced reserve for future procedures. Objective: This study aimed to synthesize current evidence on donor biology, preoperative assessment, extraction strategy, and complication prevention in FUE, and to propose a reproducible clinical framework for donor preservation. Methods: A structured narrative review was conducted using PubMed/MEDLINE, Scopus, and Google Scholar to identify English-language publications related to donor site biology, donor evaluation, extraction density thresholds, complication prevention, repeat session planning, and emerging FUE technologies. Priority was given to recent reviews, clinical trials, consensus statements, and practice-oriented surgical literature. Articles were selected not for formal meta-analytic pooling, but because of their relevance to donor conservation and long-term donor management. Results: The literature reviewed consistently identifies excessive local extraction density, harvesting beyond conservative limits, donor miniaturization, and inadequate reassessment before repeated procedures as the primary drivers of donor morbidity. Evidence from reviews, clinical trials, and expert guidelines supports conservative extraction thresholds, widespread spatial distribution, individualized donor mapping, and phased long-term planning as key strategies for preserving donor aesthetics and reserve. Conclusions: Donor preservation is central to ethical and sustainable FUE surgery. Integration of biologically informed assessment, disciplined extraction control, and mandatory reassessment protocols can reduce morbidity while preserving long-term graft flexibility in patients with progressive androgenetic alopecia. Full article

Addressing the challenges of electromagnetic compatibility testing and non-destructive inspection of internal structures in miniaturized electronic devices. This paper reports a non-destructive testing method based on wide-field imaging using diamond nitrogen-vacancy (NV) centers, and systematically demonstrates its application on a black-epoxy-encapsulated Universal Serial Bus (USB) flash drive. In the experiment, a swept microwave signal from 2.82 GHz to 2.97 GHz was sequentially injected into the four external interface pins of the USB drive. A bulk diamond served as the quantum sensing layer, and optically detected magnetic resonance (ODMR) was employed to perform wide-field imaging of the microwave field distribution on the surface of the signal lines within a 1 × 1 mm² region of interest. The experimental results show that the microwave field distributions corresponding to different interface channels are significantly different. Based on these differences, the connection relationship between each signal line and its corresponding interface pin can be clearly identified, and the differences in field distribution as well as crosstalk characteristics among channels can be revealed. The method established in this work provides an effective technical pathway for non-destructive electromagnetic testing and functional verification of electronic products. Full article

Existing ground-slotted coplanar waveguide (CPW) spoof surface plasmon polariton (SSPP) low-pass filters (LPFs) remain constrained by the difficulty of achieving a wide stopband while maintaining a compact size, as well as by undesired radiation leakage arising from their open-aperture slot configuration. To address these issues, a grounded coplanar waveguide spoof surface plasmon polariton (GCPW-SSPP) low-pass filter based on a multi-arm star-shaped slot (MASS) loading topology is proposed. An equivalent-circuit interpretation and full-wave dispersion analysis show that the multi-arm slots introduce enhanced distributed reactive loading, thereby lowering the asymptotic frequency and enabling compact SSPP implementations. The near-field characteristics further demonstrate tighter electromagnetic confinement, as reflected by an approximately 48% reduction in the electric-field confinement width along the z-direction. To alleviate the trade-off between miniaturization and wide-stopband performance in cascaded SSPP LPFs, the single-cell S-parameters of the proposed topology are investigated. A single MASS unit exhibits a sharp cutoff and a deep transmission notch, allowing a wide stopband to be obtained with fewer cascaded cells. Radiation characteristics are subsequently quantified by a loss-decomposition method, and the MASS topology is found to suppress the radiation leakage of open-aperture ground-slotted structures, yielding a maximum radiation-loss reduction of approximately 75%. To validate the design methodology, a MASS-loaded GCPW-SSPP LPF is designed, fabricated, and measured. The measured results are in good agreement with the simulated ones, confirming the effectiveness of the proposed scheme. By simultaneously achieving a wide stopband, compact size, and suppressed radiation leakage, the proposed filter offers a promising low-interference filtering solution for highly integrated microwave and RF front-end systems. Full article

“Spinal cord stimulation (SCS)” is an established therapy for chronic pain and an emerging modality for functional recovery after spinal cord injury (SCI) and other clinical applications. Despite its clinical potential, current implantable SCS systems remain constrained by high power consumption, limited adaptability, device size, and long-term stability. Recent advances in closed-loop neuromodulation and integrated circuit (IC) design are enabling more adaptive, efficient, and miniaturized SCS systems. This narrative review focuses on integrated circuit and system-on-chip (SoC) architectures that enable more advanced closed-loop SCS modalities, including stimulation, sensing, and wireless power/data subsystems. Specifically, the present work examines stimulation drivers and charge-balancing circuits that ensure safe and precise current delivery, wireless power transfer, telemetry methods which maintain reliable energy and data flow in implanted systems, and analog front-end circuits that enable closed-loop biopotential monitoring for adaptive feedback control. It aims to highlight innovations in IC design, energy harvesting, and wireless communication strategies while discussing trade-offs in power efficiency, die area, thermal limits, and biocompatibility. Emerging trends emphasize miniaturized and adaptive neural implants that integrate circuit-level efficiency with therapeutic flexibility, thereby advancing the next generation of closed-loop neuromodulation technologies. Ultimately, innovations in microelectronics are paving the way for enhanced long-term efficacy, safety, and clinical applicability of implantable SCS systems to optimize functional impacts. Full article

Turbine engine discs operate at high speeds with heavy loads. Any failure may result in the engine stopping or being destroyed. Therefore, it is necessary to check the normal modes and determine the rotational speeds at which they may occur. The aim of this article is to present a method of non-contact measurement of normal modes using the single and three-dimensional modes. The test element is the isolated first compressor stage of the DGEN-380 miniature jet engine (minijet). The disc has the shape of a hollow truncated cone with large blades. Vibration measurements were carried out in a non-contact manner using a scanning Doppler vibrometer. The measurement was made in 1D and 3D mode. The 1D mode is simpler and easier to prepare. In 3D mode, the calibration of three scanning heads significantly complicates the measurement preparation, but allows researchers to obtain the deformation in three-dimensional space The summary shows the measured frequencies using both modes. The shapes of deformation are also summarized. It is described how close the 1D measurement is to the 3D mode and in what frequency range. Finally, it is shown to what extent it is possible to describe the nature of structural oscillations in the 1D measurement mode. Full article

Catechol, a prevalent phenolic pollutant in food products, poses a significant threat to food safety, necessitating the development of rapid and sensitive detection methods. To overcome the limitations of conventional analytical techniques, such as expensive equipment and operational complexity, electrochemical sensors have gained considerable attention owing to their rapid response and facile miniaturization. However, the rational design of sensing materials that exhibit both high sensitivity and selectivity remains a significant challenge. Herein, a series of PdCu bimetallic nanoparticles supported on reduced graphene oxide (PdCu@rGO) composites with varying Pd/Cu molar ratios was synthesized via a one-step liquid-phase reduction method. Owing to the synergistic electronic effects between Pd and Cu and the high electrical conductivity of the rGO support, the resulting nanocomposites exhibited excellent electrocatalytic activity toward catechol oxidation. At the optimal Pd/Cu molar ratio of 1:2, the fabricated Pd₁Cu₂@rGO/SPE sensor demonstrated a broad linear range of 0.5–500 μM, a low limit of detection of 200 nM (S/N = 3), good repeatability (RSD = 4.9%), and robust anti-interference capability. Furthermore, the proposed sensor was successfully applied to the detection of catechol in spiked green tea and fruit juice samples without complex pretreatment, achieving satisfactory recoveries of 91.0–101.4% and 98.6–104.8%, respectively. This work provides a reliable platform for the rapid, on-site screening of catechol in food matrices and offers valuable experimental insights into the rational design of bimetallic alloy–graphene heterostructures. Full article

This paper presents a fully integrated E-band (83/95 GHz) diplexer realized in STMicroelectronics’ BiCMOS 55 nm technology. The design directly addresses the critical trade-off between miniaturization and the performance required for high-frequency on-chip systems. The key innovation is a novel patch resonator optimally exploiting the multi-layer structure of the technology’s Back-End-Of-Line. It achieves significant compactness by jointly combining two distinct miniaturization techniques: slotted structures and mushroom-type capacitive loading. This method results in an impressive 77% size reduction compared to conventional designs. Furthermore, we introduce precisely controlled transmission zeros (TZs) to maximize inter-band isolation. The fabricated diplexer achieves a remarkably narrow fractional bandwidth (FBW) of 8.2%—the lowest reported to date for integrated BiCMOS/CMOS E-band implementations—and a robust inter-band isolation exceeding 25 dB, while demonstrating excellent return loss (better than 25 dB). Hence, this work validates a highly compact and scalable approach for integrated E-band transceivers, paving the way for future 6G front-end applications. Full article

Sensor technologies have been increasingly recognized as a cornerstone for advancing tumor diagnostics amid the global health challenge posed by cancer. Traditional diagnostic methods are often constrained by inherent tumor heterogeneity, while liquid biopsy has emerged as a transformative minimally invasive alternative, with biosensors playing a pivotal role in its clinical translation. This review summarizes the progress of tumor diagnostic biosensors, focusing on electrochemical and fluorescent sensors. Electrochemical sensors excel in quantitative precision, miniaturization, and point-of-care (POCT) applicability, enabling ultra-sensitive detection of biomarkers such as circulating tumor cells, circulating tumor DNA, and exosomes through nanomaterial modification and signal amplification strategies. Fluorescent sensors, meanwhile, offer superior multiplexing capability and in situ imaging performance, which are further enhanced by novel nanomaterials. Additionally, it covers other promising sensor types including Surface-Enhanced Raman Scattering, microfluidic, photoelectrochemical, field-effect transistor, and clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins-based sensors. Current research efforts are concentrated on multiplexed detection, point-of-care integration, and translation toward higher-order clinical functions such as cancer subtype discrimination, risk stratification, and prognosis. Future directions will focus on multimodal integration, intelligent data analysis, and prospective clinical validation against hard endpoints to facilitate the implementation of precision oncology. Full article

There is a growing demand for extreme miniaturization and enhanced sensitivity in next-generation sensing systems, including wearable devices and bioelectronics. Such advanced platforms require highly conductive, biocompatible, and mechanically robust architectures capable of conforming to dynamic surfaces. Conventional metallic thin-film fabrication techniques have reached their fundamental physicochemical limits, often suffering from suboptimal mechanical strength, complex multi-step processing, and high costs. In contrast, additive manufacturing methodologies offer streamlined microfabrication, yet traditional printing methods frequently struggle with low-viscosity constraints, insufficient metal loading, and significant material losses. This paper covers the morphological fidelity, mechanical resilience, and electrical performance of rheologically tailored, high-concentration (above 90%) gold nanoparticle paste deposited via Ultra-Precise Dispensing (UPD) technology. The capability of the UPD system to print complex, high-density fractal geometries with linewidths down to 5 μm is evaluated on both rigid and flexible substrates, glass and polyimide, respectively. The mechanical structural integrity of these conductive traces is characterized under initial 360-degree bending tests. Finally, the electrical stability and thermal response of a printed proof-of-concept temperature sensor are evaluated. The printed fractal microstructures exhibit good resolution and the fabricated sensor demonstrates good stability, displaying a linear thermal response with a temperature coefficient of resistance of 1.98·10⁻³ °C⁻¹, validating this combined material-deposition approach for microelectronics. Full article

Protein biomarkers can be used for monitoring the occurrence and development of diseases. Accurate, sensitive, and low-cost methods for protein detection can facilitate therapeutic intervention, improve clinical outcome, and reduce economic pressure for patients. Molecularly imprinted polymers (MIPs) have been considered as a type of biomimetic materials for developing biosensing technologies due to their advantages of high stability, low preparation cost, and good reusability over classical biometric recognition elements such as antibodies and aptamers. Electrochemical biosensors have become the most promising technology in sensing applications in view of their high sensitivity, fast response speed, cost-effectiveness, good stability, and ease of miniaturization. Efforts have been made to develop various electrochemical biosensors for protein detection with MIPs as recognition elements. This article provides an overview of the progress in molecular imprinting methods for the design and application of electrochemical protein biosensors. The strategies for imprinting and removing templates and preparing MIPs-modified sensing electrodes are comprehensively discussed. Finally, the challenges and future perspectives of protein-imprinted electrodes are addressed. This work will contribute to the development of innovative analytical devices based on MIPs for monitoring and managing various diseases by determining protein biomarkers. Full article

Biofouling presents numerous challenges across various sectors, including aquaculture, agriculture, infrastructure, and medicine. The development of anti-biofouling techniques remains a significant challenge. In the water industry, biofouling on monitoring sensors substantially compromises the accuracy of measurements by interfering with the sensors’ measuring ability. Biofouling also significantly increases the running costs by increasing the frequency of maintenance needed to keep sensors clean and accurate. Consequently, anti-biofouling techniques are widely employed to clean in situ optical sensors, ensuring accurate measurements while minimizing overall system costs. The conventional approach for preventing biofouling from in situ sensors typically involves the application of coatings, mechanical brushes, ultraviolet radiation, and ultrasonic waves, which possess distinct advantages and disadvantages contingent upon their application. The challenges associated with protecting the small windows of water quality sensors from biofouling over extended periods using current methods are either expensive or adversely affect the integrity of monitoring data. This study introduces a low-cost centimeter-scale high-frequency surface acoustic wave (SAW) device to protect the small windows of in situ water quality sensors continuously from biofouling, functioning as an auxiliary anti-biofouling mechanism. This study found that this 16 MHz SAW device can mitigate the formation of biofilms by adhesive diatom strains CS-1664, CS-1665, and by planktonic algae CS-327 by approximately 98% in comparison to control conditions, functioning effectively as an anti-biofouling tool for itself and surrounding surfaces without adversely affecting aquatic organisms. The dimension and resonance frequency (RF) of the SAW device are also capable of being fabricated according to the area requiring cleaning. A miniaturized 16 MHz SAW device can sustain operation for prolonged periods up to a couple of months without maintenance, at a low cost and power consumption, providing a new anti-biofouling technology. This methodology aims to assist the Australian inland and coastal water quality monitoring system by reducing maintenance costs while simultaneously enhancing the longevity of sensors submerged in water for extended periods. Full article

The pervasive contamination of aquatic environments by microplastic particles necessitates the development of rapid, cost-effective and field-deployable detection methodologies to complement established but laboratory-bound spectroscopic techniques such as Fourier-transform infrared and Raman microscopy. The demand for field-suitable methods with a broad accessibility comes from researchers themselves. In this review we systematically examine recent advances in optical methods for microplastics identification with a particular emphasis on birefringence as a key diagnostic feature of partially crystalline synthetic polymers. In particular, we analyze three complementary technological directions: liquid crystal-based sensors that exploit orientational order disruptions at interfaces for label-free microplastics detection; polarization holographic imaging combined with machine learning for high-throughput particle classification; and on-chip polarization light microscopy enabling compact and portable analyzing systems. Liquid crystal platforms demonstrate exceptional sensitivity to submicron particles and enable real-time visualization of microplastics aggregation at aqueous interfaces, though they currently lack polymer-specific chemical identification. Conversely, smart polarization holography integrated with Stokes polarimetry and deep learning algorithms achieves over 90% accuracy in distinguishing microplastics from natural particles while processing up to 10,000 particles per minute. Emerging on-chip polarized light microscopy offers a pathway toward miniaturized, low-cost devices suitable for field applications. By synthesizing insights from foundational studies, this review identifies convergent interdisciplinary trends—particularly the integration of artificial intelligence with multimodal optical imaging—and outlines persistent challenges including standardization, interference from natural organic matter, and the transition from laboratory prototypes to robust field-deployable instruments. The systematization of birefringence-based approaches aims to guide future research towards integrated monitoring systems capable of addressing water quality concerns. Full article

This study explores the miniaturization of the Controlled Reception Pattern Antenna (CRPA) for Global Positioning System (GPS) receivers, addressing the challenge of mutual coupling, which adversely affects antenna performance. In this work, a miniaturized CRPA is designed and manufactured by using Rogers RO3006 substrate. To provide a performance benchmark, a four-element reference CRPA array was also designed with a 0.5 λ inter-element spacing, yielding an overall aperture size of 149.58 mm × 150.24 mm and a worst-case inter-element isolation larger than 14.4 dB. For the miniaturized CRPA, the target inter-element spacing was set to be 0.3 λ. To overcome isolation limitations, several coupling-mitigation techniques were developed and integrated into the miniaturized design. The final configuration consisted of a four-element CRPA, with each element rotated by 90° relative to its neighbor, inter-element slots incorporated into the shared ground-plane, and an individual ground plane segmentation to reduce surface–wave coupling. The proposed miniaturized CRPA achieved an overall footprint of 104.21 mm × 104.55 mm with the worst-case isolation exceeding 18.36 dB, surpassing the isolation performance of the reference array. This work demonstrates that it is possible to realize a compact CRPA with enhanced inter-element isolation by integrating tailored coupling suppression methods. Full article