Search Results (471)

The advancement of polymeric materials for orthopedic applications has enabled the development of lightweight, adaptable structures that support patient-specific solutions. This study focuses on the design, fabrication, and mechanical characterization of additively manufactured (AM) polymeric polylactic acid (PLA) components produced via Material Extrusion (MEX), commonly known as Fused Filament Fabrication (FFF). By optimizing geometric configurations and process parameters, these structures demonstrate enhanced flexibility, energy absorption, and load distribution, making them well-suited for orthopedic products and assistive devices. A comprehensive mechanical testing campaign was conducted to evaluate the elasticity, ductility, and strength of FFF-fabricated samples under tensile and three-point bending loads. Key process parameters, including nozzle diameter, layer thickness, and printing orientation, were systematically varied, and their influence on mechanical performance was recorded. The results reveal that these parameters affect mechanical properties in a complex, interdependent manner. To better understand these relationships, an automated routine was developed to calculate the experimental mechanical response, specifically, stiffness and strength. This methodology enables an automated evaluation of the output, considering parameter ranges for future applications. The outcome of the analysis of variance (ANOVA) of the experimental investigation reveals that the printing orientation has a strong impact on the mechanical anisotropy in FFF, while layer thickness and nozzle diameter demonstrate moderate-to-weak importance. Thereafter, the experimental findings were applied on an innovative orthopedic wrist splint design to be fabricated by means of FFF. The most suitable mechanical properties were selected to test the mechanical response of the designed components under operational bending loading by means of linear elastic finite element (FE) analysis. The computational results indicated the importance of employing the actual mechanical properties derived from the applied printing process parameters compared to data sheet values. Hereby, an additional parameter to adjust the mechanical response is the product’s design topology. Finally, this framework lays the foundation for future training of neural networks to optimize specific mechanical responses, reducing reliance on conventional trial-and-error processes and improving the balance between orthopedic product quality and manufacturing efficiency. Full article

Two-dimensional materials and their van der Waals heterostructures have shown great potential in quantum physics, flexible electronics, and optoelectronic devices. However, interfacial bubbles originated from trapped air, solvent residues, adsorbed molecules and reaction byproducts remain a key limitation to performance. This review provides a comprehensive overview of the formation mechanisms, characteristics, impacts, and optimization strategies related to bubbles in 2D heterostructures. We first summarize common fabrication approaches for constructing 2D heterostructures and discuss the mechanisms of bubble formation together with their physicochemical features. Then, we introduce characterization techniques ranging from macroscopic morphological observation to atomic-scale interfacial analysis, including optical microscopy, atomic force microscopy, transmission electron microscopy, and spectroscopic methods systematically. The effects of bubbles on the mechanical, electrical, thermal, and optical properties of 2D materials are subsequently examined. Finally, we compare key interface optimization strategies—such as thermal annealing, chemical treatments, AFM-based cleaning, electric field-driven approaches, clean assembly and AI-assisted methods. We demonstrate that, although substantial advances have been made in understanding interfacial bubbles, key fundamental challenges persist. Future breakthroughs will require the combined advancement of mechanistic insight, in situ characterization, and process engineering. Moreover, with the rapid adoption of AI and autonomous experimental platforms in materials fabrication and data analysis, AI-enabled process optimization and real-time characterization are emerging as key enablers for achieving high-cleanliness and scalable van der Waals heterostructures. Full article

A piezoelectric ultrasonic transducer has been developed to detect flow rate, occlusion, and bubble formation in a portable peritoneal dialysis system. This transducer works by utilizing the piezoelectric effect to convert electrical energy into ultrasonic waves and detect the reflected waves through the tube wall. In addition, organic thin film transistors (OTFTs) were tested at annealing temperatures of 75 °C, 100 °C, and 125 °C to evaluate the effect of temperature on mobility and on/off ratio. The best results were obtained at 100 °C with a mobility of 0.816 cm²/Vs and an on/off ratio of 1.4 × 10³ correlated with grain size. This study aims to report the fabrication process and initial characterization of the OTFT device as a first step towards the development of a portable biosensor that can be integrated into a point-of-care system. The transducer is designed for use in PeritoCare^® (Bangi, Malaysia), a portable peritoneal dialysis system developed by Universiti Kebangsaan Malaysia (UKM). The integration of piezoelectric transducers and OTFTs into the PeritoCare^® system enables the development of a more flexible, efficient, and mobile peritoneal dialysis system for young, active end-stage renal disease (ESRD) patients. Full article

Thin-film organic solar cells (TFOSCs) are gaining momentum as next-generation photovoltaic technologies due to their lightweight nature, mechanical flexibility, and low cost-effective fabrication. In this pioneering study, we report for the first time the incorporation of cobalt-doped zinc sulfide $(\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o})$ nanoparticles (NPs) into a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) bulk-heterojunction photoactive layer. $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs were successfully synthesized via a wet chemical method and integrated at varying concentrations (1%wt, 3%wt, and 5%wt) to systematically investigate their influence on device performance. The optimal doping concentration of 3%wt yielded a remarkable power conversion efficiency (PCE) of 4.76%, representing a 102% enhancement over the pristine reference device (2.35%) under ambient laboratory conditions. The observed positive trend is attributed to the localized surface plasmon resonance (LSPR) effect and near-field optical enhancement induced by the presence of ZnS/Co NPs in the active layer, thereby increasing light-harvesting capability and exciton dissociation. Comprehensive morphological and optical characterizations using high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy (HRTEM), and spectroscopic techniques confirmed uniform nanoparticle dispersion, nanoscale crystallinity, and effective light absorption. These findings highlight the functional role of $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs as dopants in enhancing TFOSC performance, providing valuable insights into optimizing nanoparticle concentration. This work offers a scalable and impactful strategy for advancing high-efficiency, flexible, and wearable organic photovoltaic devices. Full article

The escalating demand for high-performance energy storage devices has driven extensive research into flexible electrode materials for supercapacitors. Integrating structured carbon nanomaterials with flexible substrates to construct binder-free electrode architectures represents a promising strategy for improving supercapacitor capacitance and rate capability. However, achieving stable, binder-free integration of structure-controlled nanostructured carbon materials with flexible substrates remains a critical challenge. In this study, we report a direct synthesis approach for one-dimensional (1D) carbon nanofibers (CNFs) on commercial flexible carbon fabric (CF) via chemical vapor deposition (CVD). The resulting CNFs exhibit two typical average diameters—approximately 25 nm and 50 nm—depending on the growth temperature, with both displaying highly graphitized structures. Electrochemical characterization of the CNFs/CF composites in 1 M H₂SO₄ electrolyte revealed typical electric double-layer capacitor (EDLC) behavior. Notably, the 25 nm-CNFs/CF electrode achieves a high specific capacitance of 87.5 F/g, significantly outperforming the 50 nm-CNFs/CF electrode, which reaches 50.2 F/g. Compared with previously reported carbon nanotube CNTs/CF electrodes, the 25 nm-CNFs/CF electrode exhibits superior capacitance and lower resistance. Full article

Background: Soft actuation relies on materials that are lightweight, flexible, and responsive to external stimuli. In biomedical applications, miniaturization and biocompatibility are key requirements for developing smart devices. Thermoplastic polyurethane (TPU) is particularly attractive due to its elasticity, processability, and biocompatibility; however, an improvement in its shape-recovery performance would significantly enhance its suitability for actuation systems. This study aims to develop TPU-based shape memory polymer (SMP) composites with improved functional behavior for biomedical applications. Methods: TPU was modified with aluminum nanoparticles (AlNPs) and multi-walled carbon nanotubes (MWCNTs), incorporated individually (1 wt.% and 3 wt.%) and in hybrid combinations (MWCNT:AlNP ratios of 2:1, 5:1, and 10:1). Samples were produced by compression molding and characterized through thermal, mechanical, electrical, and shape-recovery tests, supported by morphological analysis. Results: AlNPs moderately improved thermal conductivity, while MWCNTs significantly enhanced electrical conductivity and doubled the recovery force compared with neat TPU. Hybrid composites showed intermediate properties, with the 5:1 MWCNT:AlNP ratio offering the best balance between recovery force and activation speed. Conclusions: The synergistic combination of MWCNTs and AlNPs effectively enhances TPU’s multifunctional behavior, demonstrating strong potential for soft actuation in biomedical devices. Full article

High-friction surface treatments (HFSTs) are widely applied to improve pavement safety by enhancing long-term skid resistance. Although epoxy resins are commonly used due to their strength and durability, their high cost, susceptibility to delamination, incompatibility with substrates of flexible pavements, and adverse environmental concerns limit their long-term performance. This study presents crumb rubber modified (CRM) asphalt as a sustainable alternative binder for HFST applications. CRM binders offer high performance and compatibility with existing pavement surfaces, cost effectiveness and reduced environmental impacts as compared to epoxy binders. In addition, the binder development utilizes enhanced recycling technologies for interacting with used tire rubber with asphalt. The evaluated CRM binders were prepared under varying interaction temperatures, crumb rubber contents, and types. The developed binders were evaluated for friction performance with two aggregate sources, calcined bauxite (CB) and rhyolite (Rhy). Binder characterization included rheological testing conducted through both frequency sweep and temperature sweep procedures. HFST mixes were evaluated using the British Pendulum Test (BPT), the Dynamic Friction Tester (DFT), and the Circular Track Meter (CTM) in collaboration with the Three-Wheel Polishing Device (TWPD) to simulate the traffic-induced polishing effect. The results showed that CRM content influenced binder performance under polishing. CRM asphalt-based HFST with a relatively high CRM content (15%) maintained a greater coefficient of friction (COF) and exhibited polishing resistance, showing low reduction in the COF after the total number of polishing cycles. In contrast, mean profile depth (MPD) analysis revealed that the most macrotexture efficiency was found in binders with a lower CRM content (10%) after completing the total number of polishing cycles. Analysis of Variance (ANOVA) showed a significant effect of the interaction conditions and rheological properties of CRM binders on the British pendulum number (BPN) loss due to the polishing process. As expected, aggregate source further influenced the resistance to polishing; CB outperformed Rhy with significantly lower aggregate loss under polishing. Overall, the results confirmed that CRM asphalt binders can effectively serve as a sustainable, flexible, and cost-effective alternative binder in HFST. Full article

Chronic wounds constitute a major global public health challenge, characterized by a high risk of infection, prolonged healing times, and frequent recurrence. Conventional wound assessment methods, which primarily rely on visual clinical inspection and laboratory-based analyses, are limited by inherent subjectivity, delayed feedback, and a lack of capacity for real-time monitoring of the dynamic biochemical changes at the wound site. Significantly, recent advancements in flexible electronics, nanomaterials, and energy harvesting technologies have boosted the rapid development of wearable electrochemical biosensors. These devices have emerged as a transformative platform for the continuous, non-invasive analysis of critical biomarkers within the wound microenvironment, including pH, temperature, inflammatory cytokines, metabolites, and pathogen-derived molecules. This review critically examines the latest progress in wearable electrochemical biosensors for wound monitoring and management. Key discussions include (1) the special requirements for sensor design, targeting the chronic wound’s pathological characteristics; (2) cutting-edge development in self-powered systems, multimodal sensor integration, closed-loop theranostics, and artificial intelligence (AI)-assisted decision-making; and (3) a critical appraisal of challenges in accuracy, stability, biocompatibility, energy management, and clinical translation. Finally, the review explores future trends, such as biodegradable sensors, multi-parameter fusion algorithms, and remote intelligent management systems, with the aim of establishing a foundational framework and providing technical guidance for developing next-generation intelligent wound care solutions. Full article

Transparent conductive electrodes that combine flexibility with effective electromagnetic interference (EMI) shielding are important for next-gen flexible electronics and 5G/6G communication devices. Achieving high optical transparency, low sheet resistance, and broadband shielding performance remains a sophisticated task. This work demonstrates a solution: the synthesis and comprehensive characterization of flexible In₂O₃/Ag/In₂O₃ (IAI) structures on polyethylene terephthalate substrates. The optimized structure with a 13.2 ± 1.1 nm silver interlayer achieves an incredible combination of properties: high optical transmittance (82.59% at 500 nm), low sheet resistance (6.4 ± 0.8 Ω/sq), and insignificant optical haze (1.04%). Broadband EMI shielding measurements from 10 MHz to 1 THz reveal a uniform shielding effectiveness of 25–30 dB across band from radiowave to terahertz. The IAI structures also show outstanding mechanical resilience, maintaining their electrical and shielding performance under repeated bending. This unique set of attributes positions IAI thin films as a prospective material for transparent EMI shielding in advanced telecommunications and flexible optoelectronics. Full article

Polybutylene adipate terephthalate (PBAT), a flexible biodegradable polyester, has gained widespread use in packaging applications due to its ability to degrade under controlled conditions, producing non-toxic substances. While this property makes PBAT particularly attractive for the development of transient electronic devices, this potential application remains unexplored. To address this research gap, we developed PBAT-based composites and modified their electrical properties through CO₂ laser functionalization. Although laser treatment of neat PBAT primarily resulted in material ablation, the incorporation of lignin and silica-based fillers enabled the formation of electrically conductive pathways. Among the various fillers tested, dealkaline lignin (DEALK) and glass fibers (GFs) provided the optimal combination of electrical conductivity, mechanical properties, and processability. Characterization techniques (electrical measurements, optical microscopy, SEM, EDX, and TGA) highlighted that by optimizing laser treatment and the filler concentration, it is possible to produce conductive tracks with remarkably low sheet resistance. Hybrid composites containing 10–15 wt% of GF and 20–25 wt% of lignin demonstrated the best electrical performance with values as low as 3.5 Ω/sq, which were further reduced to 1.72 Ω/sq after laser process optimization. These findings establish PBAT composites as promising candidates for sustainable transient electronics. Full article

In this study, a systematic investigation was undertaken to elucidate the influence of polymeric surfactants such as polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and their hybrid combination (PVP/PEG) on the structural, morphological, and electrochemical evolution of Fe₂O₃ electrodes designed for high-performance supercapacitor applications. Fe₂O₃ nanostructures were synthesized via a controlled hydrothermal route, wherein the surfactant composition was precisely tuned to modulate crystal growth, particle dispersion, and surface active-site density. Detailed physicochemical characterization revealed that hybrid PVP/PEG incorporation induced a hierarchically nanograined morphology with optimized porosity. The optimized PVP/PEG-Fe electrode exhibited the largest CV area, lowest equivalent series resistance (0.33 Ω), and superior areal capacitance of 9.17 F cm⁻² at 8 mA cm⁻², attributed to accelerated redox kinetics and efficient ion diffusion. Long-term cycling demonstrated remarkable structural resilience, with ~85.1% capacitance retention after 12,000 cycles. Furthermore, an asymmetric pouch-type supercapacitor (PVP/PEG-Fe//AC) was assembled to validate practical performance, achieving a wide potential window of 1.5 V, an areal capacitance of 0.260 F cm⁻², energy density of 0.081 mWh cm⁻², and coulombic efficiency of 95.73% after 7000 cycles. This work highlights the critical role of cooperative polymer–metal oxide interactions in achieving structural uniformity, optimized electrochemical kinetics, and long-term durability, offering a versatile strategy for engineering cost-effective, high-performance transition metal oxide electrodes for next-generation flexible energy storage devices. Full article

The progressive aging of the population requires reliable, non-invasive, and real-time tools to monitor hydration, prevent dehydration-related complications, and promote active aging in elderly patients. Wearable sensors based on interdigitated electrodes (IDEs) and on Electrochemical Impedance Spectroscopy (EIS) represent a promising tool thanks to their miniaturization, sensitivity to dielectric variations with humidity, and compatibility with flexible substrates. This study reports the design, fabrication, and metrological characterization of inkjet-printed IDEs for skin hydration monitoring, as a building block of a multisensor wearable device. IDEs were fabricated on polyimide substrates using silver nanoparticle-based ink. Their characterization involved the following: (i) morphological evaluation by scanning electron microscopy; (ii) EIS measurements in KCl solutions, leading to developing a regression model to correlate impedance with salt concentration; (iii) in vitro EIS validation on agar gel samples, which demonstrated a robust linear relationship between the impedance phase shift at 199.5 $\mathrm{Hz}$ and water loss, with consistent sensitivity values across sensors. The results confirm the feasibility of IDEs for hydration monitoring, identifying optimal frequency ranges and validating regression models. These findings represent a critical step toward the development of multisensor wearable devices for elderly monitoring, enabling decentralized and continuous health monitoring to improve healthcare sustainability and telemedicine. Full article

Heavy metal ions (HMIs) threaten ecosystems and human health due to their carcinogenicity, bioaccumulativity, and persistence, demanding highly sensitive, low-cost real-time detection. Electrochemical sensing technology has gained significant attention owing to its rapid response, high sensitivity, and low cost. Molybdenum disulfide (MoS₂), with its layered structure, tunable bandgap, and abundant edge active sites, demonstrates significant potential in the electrochemical detection of heavy metals. This review systematically summarizes the crystal structure characteristics of MoS₂, various preparation strategies, and their mechanisms for regulating electrochemical sensing performance. It particularly explores the cooperative effects of MoS₂ composites with other materials, which effectively enhance the sensitivity, selectivity, and detection limits of electrochemical sensors. Although MoS₂-based materials have made significant progress in theoretical and applied research, practical challenges remain, including fabrication process optimization, interference from complex-matrix ions, slow trace-metal enrichment kinetics, and stability issues in flexible devices. Future work should focus on developing efficient, low-cost synthesis methods, enhancing interference resistance through microfluidic and biomimetic recognition technologies, optimizing composite designs, resolving interfacial reaction dynamics via in situ characterization, and establishing structure–property relationship models using machine learning, ultimately promoting practical applications in environmental monitoring, food safety, and biomedical fields. Full article

Deep-sea mining has gradually emerged as a core domain in global resource exploitation. Underwater autonomous robots, characterized by low cost, high flexibility, and lightweight properties, demonstrate significant advantages in deep-sea mineral development. To address the limitations of traditional deep-sea mining equipment, such as large volume, high energy consumption, and insufficient flexibility, this paper proposes an innovative Underwater Vehicle Collector System (UVCS). Integrating bionic design with autonomous robotic technology, this system features a collection device mimicking the large opening–closing kinematics of the mouth of deep-sea dragonfish (Stomiidae). A dual-rocker mechanism is employed to realize the mouth opening-closing function, and the collection process is driven by the pitching motion of the vehicle without the need for additional motors, thus achieving the advantages of high flexibility, low energy consumption, and light weight. The system is capable of collecting seabed polymetallic nodules with diameters ranging from 1 to 12 cm, thus providing a new solution for sustainable deep-sea mining. Based on the dynamics of UVCS, this paper verifies its attitude stability and collection efficiency in planar motions through single-cycle and multi-cycle simulation analyses. The simulation results indicate that the system operates stably with reliable collection actions. Furthermore, water tank testings demonstrate the opening and closing functions of the UVCS collection device, fully confirming its design feasibility and application potential. In conclusion, the UVCS system, through the integration of bionic design, opens up a new path for practical applications in deep-sea resource exploitation. Full article

Triboelectric nanogenerators (TENG) are mechanical energy harvesters characterized by high sensitivity and simple structure and are currently being widely developed for use in human body motion sensing. Among them, fiber-based TENGs (FTENG) are particularly suitable for wearable human motion sensors due to their unique structure, which offers flexibility, high durability, and comfort. However, studies involving doping to further modify the electrical output characteristics of FTENGs are very limited. Here, we propose an innovative approach that combines graphite (GP) doping with fiber-based TENG fabrication, successfully developing a graphite-doped polyester fiber-based TENG (GP@PET-TENG). Proper graphite doping can increase the amount of transferred charge and thus improve the output electrical performance of TENG, but this method has rarely been explored in FTENG. With the incorporation of 3%wt graphite, the open-circuit voltage of the GP@PET-TENG increased from 103.3 V to 202.1 V, and the short-circuit current increased from 60.7 μA to 105.1 μA, compared to the pure polyester fiber based TENG (PET-TENG). The device achieved a maximum output power of 4.15 mW (2.59 W/m²), demonstrates the capability to charge various capacitors, and successfully lit up 200 LEDs. By attaching the GP@PET tribo-layer to human skin, a single-electrode mode TENG can be formed, which captures the subject’s motion signals through skin contact and separation, converting them into voltage outputs. In fist-clenching and wrist-bending tests, motion-induced voltage signals up to 0.6 V were recorded, demonstrating the potential applications in rehabilitation assistance and mechanical control. Full article