Search Results (563)

In this study, six serpentine resistive strain sensors are manufactured on two cantilevers made of FR-4 (Flame Retardant 4) with dimensions of 25 mm × 140 mm. Three strain sensors are printed on each substrate using particle-free EI 615 silver ink. The method of fabrication is hybrid in nature and consists of aerosol jet (AJ) printing a layer of conductive material and selectively sintering certain regions before removing the non-sintered material with 1-dodecene solvent. The gauges on one cantilever are coated with a 10 µm dielectric layer using Norland Electronic Adhesives (NEA) 121, which serves as the passivation layer, while the three gauges on the other cantilever are left exposed. The samples are subjected to two standard thermal–mechanical loading conditions: namely, a vibration test according to the MIL-STD-883 method 2007 Cond A and a high-temperature soak test according to the Mil-Std-883 method 1008 Cond B. The reliability of the devices is quantified by assessing the percent change in their resistances and gauge factors (GF) between tests. The percent change is then used to ascribe a reliability metric to the gauges. Full article

Extrusion-based bioprinting faces significant challenges in achieving the shape fidelity and internal porosity necessary for cell viability, often hindered by subjective assessment methods. This study investigated the relationship between rheological properties and print quality using a natural polymer biomaterial ink composed of 12% gelatin, 5% alginate, and 1% carboxymethylcellulose. We conducted a comparative analysis between traditional pneumatic systems and screw-driven volumetric extrusion, utilizing a suite of quantitative metrics: Spreading Ratio (SR), Printability Index (P_r), Uniformity Ratio (UF), Collapse Angle (θ), and evaluated porosity. Our results demonstrate that the screw-driven system’s positive displacement mechanism provides superior control over filament morphology by enabling precise volumetric modulation. While the pneumatic system exhibited a high SR of 1.82 and the lowest porosity at 59.92%, the screw-driven system allowed for “under-extrusion” to compensate for viscoelastic die swell. Reducing the flow rate to 50% in the screw system lowered the SR to 1.09, nearly matching the nozzle diameter, and increased porosity to 76.46%. Furthermore, the screw-driven system achieved an ideal P_r of 1.0, whereas the pneumatic system produced distorted, rounded pores with a P_r of 1.57. The findings indicate that screw-driven extruders can decouple line complex rheology from the printing process, allowing for finer spatial resolution and better pore interconnectivity. Full article

Printed biosensors have attracted increasing attention as platforms for rapid, low-cost, and portable diagnostics because they can be fabricated on flexible or rigid substrates using scalable printing techniques. Their performance is strongly influenced by both the printing process and the materials employed, since factors such as ink rheology, particle dispersion, interfacial behavior, and post-processing conditions directly affect device architecture, sensing performance, and manufacturing reliability. This review summarizes recent advances in printed biosensors from the combined perspectives of printing technologies and functional materials. Commonly employed printing techniques, including inkjet, screen, aerosol jet, and roll-to-roll gravure printing, are discussed with emphasis on their processing characteristics and material requirements. The review also examines key material platforms used in printed biosensors, including carbon-based nanomaterials, metal oxides, metal nanoparticles, conductive polymers, dielectric materials, and hybrid composites, highlighting their roles in electrical conductivity, catalytic activity, biomolecule immobilization, mechanical flexibility, and overall analytical performance. Finally, current challenges and emerging research directions are outlined with respect to ink stability, post-processing strategies, sensor reliability, manufacturability, and practical translation. Overall, this review emphasizes that the development of high-performance printed biosensors depends on the synergistic integration of rational material design with optimized printing strategies. Full article

Flexible resistive sensors are promising for wearable and ergonomic applications because they can be easily fabricated on textiles or flexible substrates and enable real-time monitoring of human movement and posture, especially in health monitoring systems. This review presents an overview of recent developments in an interdisciplinary way and summarises advances in materials, fabrication methods, and ergonomic applications. A structured literature search was conducted across major databases, including only studies focused on resistive sensing. The selected works were analysed in terms of conductive materials, fabrication techniques (e.g., direct ink writing (DIW) and textile-based methods), and their integration into wearable systems. Flexible resistive sensors are widely used for monitoring joint motion, posture, and physiological signals in healthcare and industrial environments. However, several challenges remain, including limitations in sensitivity, signal stability, material durability, and the need for reliable calibration in real-world conditions. This review highlights current progress and existing limitations and outlines future research directions toward more robust and user-friendly wearable sensing solutions for ergonomic applications. Full article

Soft magnetic composite materials have a low total loss and high magnetic conductivity and are highly desirable for high-frequency motors, semiconductors, and 5G communication technologies. However, these composites often contain a high-volume fraction of soft magnetic metallic powders and are difficult to process into complex shapes. Herein, iron-based amorphous powders were surface-modified with silane coupling agents (DTMS and KH570) and applied in 3D direct ink writing (DIW). The modified powders exhibit improved compatibility and dispersion in epoxy resin. The optimized 92.3 wt% FeSiB@3.35 wt% KH570/EP slurry shows favorable rheological properties and a dense interfacial microstructure. The printed composite achieves the best magnetic performance (M_s: 137.02 ± 1.2 emu/g, H_c: 6.63 ± 0.2 Oe) and stable permeability up to 1 GHz. The surface modification enhanced slurry fluidity, preventing nozzle blockage and increasing powder loading. Various shaped magnetic cores were successfully fabricated with excellent magnetic properties and printing quality. Our work paves a new way for realizing the high processibility of soft magnetic composites, which lays a foundation for a technique for the wide applications of these materials in various electronic devices. Full article

Recent evidence links lens epithelial cell (LEC) dysfunction and cellular senescence—an irreversible cell cycle arrest with a pro-inflammatory secretory phenotype—to age-related cataract (ARC) progression. This systematic review synthesizes current knowledge on LEC senescence, its molecular features, and laboratory methods for senescence assessment in the ARC. Following PRISMA guidelines, a comprehensive search of PubMed, Scopus and Cochrane databases retrieved 3417 records from inception to 9 February 2025, with 14 studies ultimately included (821 patients and multiple in vitro LEC models). The following multiple senescence expression pathways were identified: SA-β-gal activity, p53/p21 and p16INK4A pathway activation, mitochondrial dysfunction, oxidative stress, and secretion of senescence-associated secretory phenotype (SASP) factors. Notably, cortical cataract demonstrated direct association with local senescent cell accumulation, while nuclear cataract reflected cumulative oxidative damage from impaired LEC-mediated antioxidant defense. Senescence markers correlated positively with cataract severity across multiple studies. Several potential therapeutic targets emerged, including metformin (AMPK activation/autophagic restoration), circMRE11A silencing, NLRP3 inflammasome inhibition, and modulation of FYCO1/PAK1 and MMP2 pathways. This review establishes LEC senescence as a central process in ARC pathogenesis and highlights promising senotherapeutic approaches. Future research should prioritize human surgical samples, develop standardized senescence detection panels (SA-β-gal + p21/p16 + SASP factors), and conduct longitudinal studies to establish causal relationships between senescence accumulation and cataract progression. Full article

Printed electronics have emerged as a versatile manufacturing platform for next-generation biosensors, enabling on-demand and low-cost fabrication of functional devices on flexible, stretchable, and unconventional substrates. One major challenge in this field lies in the sintering of printed features, as conventional high-temperature processing is incompatible with polymeric substrates and thermally sensitive biological components. Low-temperature sintering inks, typically processed below 200 °C or even at room temperature, have become a critical enabling technology for bio-integrated electronics. This review provides an overview of the current state-of-the-art and key challenges associated with low-temperature sintering inks for printed bioelectronics. We discuss inks based on metal nanoparticles, metal–organic decomposition precursors, metal oxides, chalcogenides, and hybrid material systems. The emphasis is on how ink chemistry, ligand selection, and precursor structure govern rheology, stability, and sintering behavior. In addition, key low-temperature sintering and curing strategies, including thermal, photonic, laser, plasma, microwave, and chemical sintering, are compared in terms of energy delivery, densification mechanisms, and substrate compatibility. Finally, we outline emerging directions towards low temperature and room-temperature sintering inks, and sustainable biobased ink formulations, and discuss their applications for wearable, implantable, and soft biosensing platforms. Full article

Reliable property prediction in extrusion-based additive manufacturing remains challenging under extreme data scarcity (e.g., sample size of <50), particularly when experiments are constrained by designed studies such as Taguchi orthogonal arrays. In direct ink writing of lignocellulosic composites, limited experimental runs restrict the development of predictive models capable of guiding formulation and process optimization. This study introduces a physics-consistent data augmentation framework to enhance predictive reliability while preserving material-consistent behavior. Synthetic data are evaluated using four criteria: sensitivity to augmentation size, distributional consistency with experimental observations, stability with respect to boosting depth in regression modeling, and preservation of physics-consistent factor hierarchies through interpretability analysis. The framework is validated using compressive strength data from direct ink writing experiments conducted under an extremely small data regime. Results show that augmentation performance depends on the augmentation scale and model capacity. Variational autoencoder-based augmentation produced more stable and physically consistent predictions than conditional tabular generative adversarial networks in this application. Increasing predictive accuracy alone, or applying excessive augmentation, can distort material hierarchies and reduce physics consistency. The proposed evaluation framework supports reliable and interpretable property prediction in additive manufacturing when experimental data are severely limited. Full article

Human papillomavirus (HPV)-driven oropharyngeal squamous cell carcinoma (OPSCC) has emerged as a biologically distinct entity, typically affecting younger, non-smoking patients and showing improved survival compared to HPV-negative tumors. Accurate HPV status determination is essential for correct staging, prognostic assessment, and treatment de-escalation. Despite advances, substantial variability persists among diagnostic methods and clinical workflows. A narrative review of PubMed, Scopus, and Web of Science databases was conducted up to July 2025. Studies addressing HPV detection techniques in OPSCC—including p16^INK4a^ immunohistochemistry (IHC), HPV DNA and RNA assays, liquid biopsy approaches, and computational surrogates—were critically analyzed regarding diagnostic accuracy, clinical applicability, and emerging innovations. Tissue-based assays remain the diagnostic reference standard. p16 IHC provides high sensitivity but limited specificity and should be confirmed with nucleic acid-based methods such as DNA PCR, in situ hybridization (ISH), or E6/E7 mRNA detection. Combined or “orthogonal” testing minimizes discordance and refines risk stratification. Liquid biopsy detection of circulating HPV DNA using droplet digital PCR or next-generation sequencing has shown high sensitivity and specificity in cohorts of patients with HPV-associated OPSCC, supporting its potential role as a complementary biomarker for treatment monitoring and surveillance. However, circulating HPV DNA alone does not unequivocally identify the anatomic source of HPV DNA and should be interpreted together with clinical, radiologic, and tissue-based findings. Oral rinse and saliva assays show moderate diagnostic performance, while artificial intelligence-based radiomic and histopathologic models are emerging as complementary tools. Reliable HPV attribution in OPSCC requires a multimodal diagnostic strategy integrating p16 IHC, molecular confirmation, and ctHPV-DNA monitoring. Methodological standardization and prospective validation are essential to implement precision-guided, cost-effective workflows in routine clinical practice. Full article

This paper presents a qualitative sustainability assessment of an innovative, water-based, partially bio-based, and potentially removable screen-printing ink designed to replace conventional PVC-based inks in the textile industry. The assessment is conducted in alignment with the European Commission’s tiered Safe and Sustainable by Design (SSbD) framework, applying a simplified screening approach suitable for innovations with limited sustainability data availability. The evaluation is conducted using the LCBROM (Life Cycle Based Risk and Opportunity Mapping) methodology, which is a structured approach designed to identify potential environmental, economic, and social drawbacks and benefits throughout the product’s life cycle, from production and use to end of life. The screening incorporates the MET+Ec+S matrix (Material, Energy, Toxicity, and Economic and Social dimensions), providing a comprehensive overview of the sustainability performance of the removable PVC-free ink at each stage of its life cycle. The novel removable PVC-free ink formulation incorporates bio-based pigments, thickeners, and plasticisers, and is designed to facilitate recyclability and reuse in textile applications. Compared to traditional plastisol inks, the screening indicates potential reductions in toxicity and environmental persistence compared to PVC-based plastisol inks, subject to validation in future quantitative studies. However, key trade-offs include reliance on fossil-based ingredients (as bio-based alternatives are still being developed), increased material costs, and durability concerns. Despite these issues, the removable PVC-free ink’s compatibility with existing printing infrastructure and alignment with emerging EU sustainability regulations indicate its potential relevance for circular textile production, subject to validation through quantitative life-cycle assessment and pilot-scale implementation. The results do not constitute a quantitative life cycle assessment but instead provide a structured qualitative basis for guiding further development, data collection, and future LCA modeling. By explicitly positioning the work within a simplified SSbD tier, this study demonstrates how early-stage screening can support innovation design while transparently addressing uncertainty and trade-offs. Full article

Escalating requirements for smart energy management are driving advances in functional electrochromic devices (ECDs), which are pivotal for the regulation of light, heat, and reduction in energy consumption in buildings, transportation, and smart devices. However, the commercialization of ECDs is hindered by com plex designs, high fabrication costs, and slow switching speeds. Additive manufacturing (AM, 3D-printing) emerges as a promising approach to overcome these limitations, as it enables the creation of complex structures, enhances design flexibility, and can reduce production costs. For such printed devices, materials combining poly(ionic liquids) (PILs) with ionogels—an emerging and promising class of materials known for their high ionic conductivity, stability, and tunable properties—are particularly suitable for integration with 3D printing. Comparing previous reviews that address PILs, ionogels, or AM modalities in isolation, this work uniquely combines the structure–property–processing relationships specific to the synergistic integration of these fields. Current work highlights recent progress in PIL/ionogel-based ECDs and distills specific design guidelines for optimizing ink rheology, balancing ionic conductivity with mechanical integrity, and selecting appropriate printing modalities. These insights provide a roadmap for overcoming current fabrication challenges and scaling up next-generation smart devices. Full article

This paper presents a comprehensive investigation into the synthesis, morphological characteristics, electrical conductivity, dielectric behavior, and electrocatalytic activity of perovskite-structured iron manganite (FeMnO₃), with a specific focus on its performance in the hydrogen evolution reaction (HER). FeMnO₃(FMO) nanoparticles (NPs) were synthesized using a sol–gel-type Pechini method and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (FESEM-EDS). XRD analysis confirmed the formation of a crystalline structure with cubic symmetry assigned to the Ia-3 space group, with an average crystallite size of 52.47 nm. FESEM images revealed a relatively uniform morphology with an average particle diameter of 55.84 nm. The redox and oxidation states of Fe and Mn can be studied by temperature-programmed oxidation (TPO-O₂) in order to understand oxygen uptake and metal oxidation processes occurring within the FMO lattice. The dielectric constant, dielectric loss, electric modulus and electrical conductivity were calculated as a function of frequency and temperature using a Novocontrol Alpha-A broadband dielectric spectrometer (Novocontrol system) coupled with the LCR-800 precision meter. The dielectric data reveal that the FMO has semiconducting behavior with dominant charge- or ionic-relaxation processes. The electrocatalytic activity toward the HER was evaluated using linear sweep voltammetry (LSV), with the working electrode modified by an FMO catalyst ink. The material exhibited significant catalytic activity within the HER potential range, and an increase in the number of cycles led to stabilized current and enhanced hydrogen evolution. These results highlight the stability of FeMnO₃ for hydrogen generation. Full article

The following paper aims to provide the results of an innovative structural crack detection technique using printed adaptive sensors. They were manufactured using conductive ink with silver microparticles and polymer insulators. The technique leveraged the unique properties of Direct Ink Write additive manufacturing combined with domain knowledge in the field of technical condition monitoring. The goal was to achieve high sensitivity and precision in detecting fatigue-crack-induced changes in structural components. The sensors’ fabrication repeatability, output stability, and crack detection capabilities were investigated. Based on preliminary measurements of the sensors’ output characteristics, the analyzed data showed that a tolerance in the range of 5% can be obtained for batch production. Damage size estimation using this new crack gauge during a fatigue crack growth test was high compared to the reference, with less than 1 mm precision over 30 mm of crack length. Throughout the fatigue test of up to 1.5 million cycles, all CCPSs remained fully functional, with no failure-related changes in their output signal patterns. The proposed sensor has proven its reliability for the detection of fatigue cracks and propagation monitoring and is a good alternative to other SHM technologies for this purpose. Full article

Motivation: Accurate spectral reconstruction of printed halftone images is essential for achieving high-fidelity color reproduction and robust color management across modern printing systems. However, traditional physics-based models, such as the Yule–Nielsen and Clapper–Yule formulations, rely on simplified empirical assumptions and often fail to capture the complex nonlinear and asymmetric interactions induced by multi-ink overlays and substrate light scattering. Meanwhile, existing data-driven approaches based on single learning models exhibit limited capability in modeling the complementary and symmetrical characteristics inherent in halftone structures, resulting in suboptimal prediction accuracy and generalization performance. Method: To address these limitations, we propose a Stacking Ensemble Spectral Prediction (SESP) framework. The proposed method adopts a two-layer stacking architecture that integrates heterogeneous base regressors, including Support Vector Regression (SVR), Random Forest (RF), and eXtreme Gradient Boosting (XGBoost 3.0.3), with Ridge Regression employed as the meta-learner for optimal prediction aggregation. This ensemble design enables effective modeling of both halftone pattern symmetry and complex substrate scattering behavior. Results: Extensive experiments conducted on printed halftone image datasets demonstrate the superior performance of the proposed SESP framework. Compared with the best-performing reference method (PCA-IPSO-DNN), SESP achieves relative reductions in RMSE and CIEDE2000 of 12.8% and 6.8% under illuminant A, 9.5% and 6.9% under D50, and 12.2% and 7.2% under D65, respectively. In addition, SESP consistently outperforms traditional physics-based models, including Yule–Nielsen and Clapper–Yule, in terms of both spectral prediction accuracy and colorimetric fidelity. These results confirm the effectiveness of the proposed framework in modeling the intricate nonlinear and asymmetric relationships between CMYK halftone patterns and spectral reflectance. Full article

Biodegradable hydrogel-based conductive inks, with application in additive circuit manufacturing, are synthesized from agarose, sodium alginate and functional carbon-based particles (carbon nanotubes and graphite). Rheological measurements are conducted to evaluate the printing performance of each ink. The synthesized functional inks are printed, and their conductivity properties are evaluated as a function of the functional material concentration. Promising conductivity values are achieved, demonstrating their potential application for low-cost and low-environmental-impact circuital and electromagnetic designs. Full article