Search Results (83)

The quality of machined marine propellers plays a critical role in underwater propulsion performance. Precision casting is the predominant manufacturing technique; however, deformation of wax models and rough blanks during manufacturing frequently cause deviations in the dimensions of final products and, thus, affect propellers’ performance and service life. Current inspection methods primarily involve using coordinate measuring machines and sampling. This approach is time-consuming, has high labor costs, and cannot monitor manufacturing quality in real-time. This study developed a real-time online automated measurement system containing a high-resolution CITIZEN displacement sensor, a four-degree-of-freedom measurement platform, and programmable logic controller-based motion control technology to enable rapid, automated measurement of blade deformation across the wax model, rough blank, and final product processing stages. The measurement data are transmitted in real time to a cloud database. Tests conducted on a standardized platform and real propeller blades confirmed that the system consistently achieved measurement accuracy to the second decimal place under the continual measurement mode. The system also demonstrated excellent repeatability and stability. Furthermore, the continuous measurement mode outperformed the single-point measurement mode. Overall, the developed system effectively reduces labor requirements, shortens measurement times, and enables real-time monitoring of process variation. These capabilities underscore its strong potential for application in the smart manufacturing and quality control of marine propellers. Full article

Background: Developing versatile dressings that offer wound protection, maintain a moist environment, and facilitate healing represents an important therapeutic approach for burn patients. Objectives: This study presents the development of new smart pH-sensitive collagen-hydroxyethylcellulose films, incorporating naproxen and phenol red, designed to provide controlled drug release while enabling real-time pH monitoring for burn care. Methods: Biopolymeric films were prepared by the solvent-casting method using ethanol and glycerol as plasticizers. Results: Orange-colored films were thin, flexible, and easily peelable, with uniform, smooth, and nonporous morphology. Tensile strength varied from 0.61 N/mm² to 3.33 N/mm², indicating improved mechanical properties with increasing collagen content, while wetting analysis indicated a hydrophilic surface with contact angle values between 17.61° and 75.51°. Maximum swelling occurred at pH 7.4, ranging from 5.65 g/g to 9.20 g/g and pH 8.5, with values from 4.74 g/g to 7.92 g/g, suggesting effective exudate absorption. In vitro degradation proved structural stability maintenance for at least one day, with more than 40% weight loss. Films presented a biphasic naproxen release profile with more than 75% of the drug released after 24 h, properly managing inflammation and pain on the first-day post-burn. The pH variation mimicking the stages of the healing process demonstrated the color transition from yellow (pH 5.5) to orange (pH 7.4) and finally to bright fuchsia (pH 8.5), enabling easy visual evaluation of the wound environment. Conclusions: New multifunctional films combine diagnostic and therapeutic functions, providing a promising platform for monitoring wound healing, making them suitable for real-time wound assessment. Full article

Graphene-based textile pressure sensors are emerging as promising candidates for wearable sensing applications due to their high sensitivity, mechanical flexibility, and low energy consumption. This study investigates the design, fabrication, and electromechanical behaviour of graphene-coated nonwoven textile-based piezoresistive pressure sensors, focusing on the impact of different electrode materials and fabrication techniques. Three distinct sensor fabrication methods—drop casting, electrospinning, and electro-spraying—were employed to impregnate graphene onto nonwoven textile substrates, with silver-coated textile electrodes integrated to enhance conductivity. The fabricated sensors were characterised for their morphology (SEM), chemical composition (FTIR), and electromechanical response under cyclic compressive loading. The results indicate that the drop-cast sensors exhibited the lowest initial resistance (~0.15 kΩ) and highest sensitivity (10.5 kPa⁻¹) due to their higher graphene content and superior electrical connectivity. Electro-spun and electro-sprayed sensors demonstrated increased porosity and greater resistance fluctuations, highlighting the role of fabrication methods in sensor performance. Additionally, the silver-coated knitted electrodes provided the most stable electrical response, while spun-bonded and powder-bonded nonwoven electrodes exhibited higher hysteresis and resistance drift. These findings offer valuable insights into the optimisation of graphene-based textile pressure sensors for wearable health monitoring and smart textile applications, paving the way for scalable, low-power sensing solutions. Full article

This review provides a comprehensive overview of recent advancements in biodegradable active and smart packaging utilizing pectin from various origins for food applications. It critically examines the challenges and limitations associated with these developments, initially focusing on the structural influences of pectin on the properties of packaging films. Methods such as spray drying, casting, and extrusion are detailed for manufacturing pectin films, highlighting their impact on film characteristics. In discussing active pectin films, the review emphasizes the effectiveness of incorporating essential oils, plant extracts, and nanoparticles to enhance mechanical strength, moisture barrier properties, and resistance to oxidation and microbial growth. Smart biodegradable packaging is a significant research area, particularly in monitoring food freshness. The integration of natural colorants such as anthocyanins, betacyanins, and curcumin into these systems is discussed for their ability to detect spoilage in meat and seafood products. The review details the specific mechanisms through which these colorants interact with food components and environmental factors to provide visible freshness indicators for consumers. It underscores the potential of these technologies to fulfill sustainability goals by providing eco-friendly substitutes for traditional plastic packaging. Full article

Developing pH-sensitive materials for real-time freshness monitoring is critical for ensuring seafood safety. In this study, pH-responsive indicator films were prepared by incorporating purple cabbage anthocyanin (PCA) into a κ-carrageenan/carboxymethyl cellulose (CA/CMC) matrix via solution casting, with PCA concentrations of 2.5%, 5.0%, 7.5%, and 10% (w/w). The films exhibited remarkable pH sensitivity, with distinct color changes across pH 2.0–11.0. Incorporating PCA enhanced film crystallinity, antioxidant properties, and opacity while reducing water vapor transmission (WVP). High PCA content resulted in rougher morphology, lowering tensile strength (TS) but improving elongation at break (EB). The indicator film had good environmental stability, and the color difference was not visible after 10 days in the dark and 4 °C conditions. The CA/CMC/PCA-10% film showed the most pronounced pH-responsive color changes, transitioning from purple to green as hairtail freshness deteriorated. This innovative approach highlights the potential of CA/CMC/PCA films as reliable, eco-friendly indicators for real-time seafood freshness monitoring, offering significant advancements in smart packaging technology. Full article

Supramolecular chemistry, a relatively newly grown field, has emerged as a useful tool to fabricate novel smart materials with multiple uses. Adhesives find numerous uses, from heavy engineering to biomedical science. Adhesives are available in nature; inspired by them and their mechanism of adhesion, several supramolecular adhesives have been developed. In this review, supramolecular chemistry for the design and fabrication of novel adhesives is discussed. The discussion is divided into two segments. The first one deals with key supramolecular forces, and their implication is designing novel adhesives. In the second part, key applications of supramolecular adhesives have been discussed with suitable examples. This type of review casts light on the current advancements in the field along with the prospects of development. Full article

This study presents the fabrication of a sustainable flexible humidity sensor utilizing chitosan derived from mealworm biomass as the primary sensing material. The chitosan-based humidity sensor was fabricated by casting chitosan and polyvinyl alcohol (PVA) films with interdigitated copper electrodes, forming a laminate composite suitable for real-time, resistive-type humidity detection. Comprehensive characterization of the chitosan film was performed using Fourier-transform infrared (FTIR) spectroscopy, contact angle measurements, and tensile testing, which confirmed its chemical structure, wettability, and mechanical stability. The developed sensor exhibited a broad range of measurements from 6% to 97% relative humidity (RH), a high sensitivity of 2.43 kΩ/%RH, and a rapid response time of 18.22 s with a corresponding recovery time of 22.39 s. Moreover, the chitosan-based humidity sensor also demonstrated high selectivity for water vapor when tested against various volatile organic compounds (VOCs). The superior performance of the sensor is attributed to the structural properties of chitosan, particularly its ability to form reversible hydrogen bonds with water molecules. This mechanism was further elucidated through molecular dynamics simulations, revealing that the conductivity in the sensor is modulated by proton mobility, which operates via the Grotthuss mechanism under high-humidity and the packed-acid mechanism under low-humidity conditions. Additionally, the chitosan-based humidity sensor was further seamlessly integrated into an Internet of Things (IoT) framework, enabling wireless humidity monitoring and real-time data visualization on a mobile device. Comparative analysis with existing polymer-based resistive-type sensors further highlighted the superior sensing range, rapid dynamic response, and environmental sustainability of the developed sensor. This eco-friendly, biomass-derived, eco-friendly sensor shows potential for applications in environmental monitoring, smart agriculture, and industrial process control. Full article

Electrochromic devices (ECDs) are devices that change their optical properties in response to a low applied voltage. These devices typically consist of an electrochromic layer, a transparent conducting substrate, and an electrolyte. The advancement in solid-state ECDs has been driven by the need for improved durability, optical performance, and energy efficiency. In this study, we investigate varying the temperature to the casting solution for polymethylmethacrylate (PMMA)-based electrolytes for solid-state ECDs with a structure of glass/ITO/WO₃/PMMA electrolyte/ITO/glass. The electrochromic layer, composed of WO₃, was deposited using the sol-gel method, while the electrolyte, comprising lithium perchlorate (LiClO₄) in propylene carbonate (PC) with PMMA, was prepared via solution casting. Various electrolyte samples were heated at different temperatures of 25, 40, 60, 80, and 100 °C to analyze the impact on the devices’ performance. Our findings indicate that the devices with electrolytes at 25 °C exhibited superior anodic and cathodic diffusion. An increase in heating temperature corresponded with an increase in switching time. Notably, the sample heated at higher temperatures (60, 80, and 100 °C) demonstrated exceptional cycle stability. Nevertheless, samples with higher temperatures displayed a decrease in optical modulation. Additionally, the 100 °C sample exhibited the highest coloration efficiency compared to other samples at lower temperatures. This research highlights the potential of varying the temperature of solution casting on PMMA-based electrolytes in optimizing the performance of solid-state ECDs, particularly regarding coloration efficiency and durability. Full article

Distal radius fractures (DRF) are one of the most prevalent injuries a person may sustain. The current treatment of DRF involves the use of casts made from Plaster of Paris or fiberglass. The application of these materials is a serious endeavor that influences their intended use, and should be conducted by specially trained personnel. In this research, with the use of the full-body 3D scanner Vitus Smart, 3D modelling software Rhinoceros 3D, and 3D printer Creality CR-10 max, an easy, yet effective workflow of orthosis fabrication was developed. Furthermore, samples that represent segments of the orthosis were subjected to static loading. Lastly, fragments that occurred due to excessive force were characterized with the use of a digital microscope. It was observed that with the implementation of the designed workflow, a faster 3D printing process was present. Samples subjected to mechanical loading had values that exceeded those of conventional Plaster of Paris; the minimum recorded value was 681 N, while the highest was 914 N. Microscopic characterization enabled a clear insight into the occurrence of fragments, as well as their potential risk. Therefore, in this research, an insight into different stages of fabrication, characterization of undesirable events, as well as the risks they may pose were presented. Full article

This paper investigates the synthesis and characterization of eco-friendly piezoelectric composite thin films composed of chitosan and Ln₂O₃-doped Na_0.5Bi_0.5TiO₃-BaTiO₃ (NBT-BT) nanoparticles. The films were fabricated using a solution-casting technique, successfully embedding the particles into the chitosan matrix, which resulted in enhanced piezoelectric properties compared to pure chitosan. Characterization methods, such as photoluminescence spectroscopy and piezo-response force microscopy (PFM) which revealed strong electromechanical responses, with notable improvements in piezoelectric performance due to the inclusion of NBT-BT nanoparticles. X-ray diffraction (XRD) analysis revealed a pure perovskite phase with the space group R3c for NBT-BT and NBT-BT-Ln particles. Scanning electron microscopy (SEM) images showed a non-uniform distribution of NBT-BT particles within the chitosan matrix. The results also suggest that the incorporation of rare earth elements further enhances the electrical and piezoelectric properties of the composites, highlighting their potential in flexible and smart device applications. Overall, these findings underscore the potential of chitosan-based composites in addressing environmental concerns while offering effective solutions for energy harvesting and biomedical applications. Full article

This study focused on preparing composite nanomats by incorporating silver nanoparticles (AgNPs) in polyvinylidene fluoride (PVDF) nanofibers through the electrospinning process. A short review of piezoelectric PVDF-related research is presented. PVDF is known for its biocompatibility and piezoelectric properties. Since electrical signals in biological tissues have been shown to be relevant for therapeutic applications, the influence of the addition of AgNPs to PVDF on its piezoelectricity is studied, due to the ability of AgNPs to increase the piezoelectric signal, along with providing antibacterial properties. The prepared samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. In addition, the biological activity of composites was examined using a cytotoxicity assay and an assessment of the antibacterial activity. The obtained results show that the incorporation of AgNPs into PVDF nanofibers further enhances the piezoelectricity (crystalline β-phase fraction), already improved by the electrospinning process, compared to solution-casted samples, but only with a AgNPs/PVDF concentration of up to 0.3%; a further increase in the nanoparticles led to a β-phase reduction. The cytotoxicity assay showed a promising effect of PVDF/AgNPs nanofibers on the MDA-MB-231 breast cancer cell line, following the non-toxicity displayed in regard to the healthy MRC-5 cell line. The antibacterial effect of PVDF/AgNPs nanofibers showed promising antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus, as a result of the Ag content. The anticancer activity, combined with the electrical properties of nanofibers, presents new possibilities for smart, multifunctional materials for cancer treatment development. Full article

Microneedle arrays (MNAs) consist of a few dozens of submillimeter needles, which tend to penetrate through the stratum corneum layer of the skin and deliver hardly penetrating drugs to the systemic circulation. The application of this smart dosage form shows several advantages, such as simple use and negligible pain caused by needle punctures compared to conventional subcutaneous injections. Dissolving MNAs (DMNAs) represent a promising form of cutaneous drug delivery due to their high drug content, biocompatibility, and ease of use. Although different technologies are suitable to produce microneedle arrays (e.g., micromilling, chemical etching, laser ablation etc.), many of these are expensive or hardly accessible. Following the exponential growth of the 3D-printing industry in the last decade, high-resolution desktop printers became accessible for researchers to easily and cost-effectively design and produce microstructures, including MNAs. In this work, a low force stereolithography (LFS) 3D-printer was used to develop the dimensionally correct MNA masters for the spin-casting method. The present study aimed to develop and characterize drug-loaded DMNAs using a two-level, full factorial design for three factors focusing on the optimization of DMNA production and adequate drug content. For the preparation of DMNAs, carboxymethylcellulose and trehalose were used in certain amounts as matrices for dexamethasone sodium phosphate (DEX). Investigation of the produced DexDMNAs included mechanical analysis via texture analyzer and optical microscopy, determination of drug content and distribution with HPLC and Raman microscopy, dissolution studies via HPLC, and ex vivo qualitative permeation studies by Raman mapping. It can be concluded that a DEX-containing, mechanically stable, biodegradable DexDMNA system was successfully developed in two dosage strengths, of which both efficiently delivered the drug to the lower layers (dermis) of human skin. Moreover, the ex vivo skin penetration results support that the application of DMNAs for cutaneous drug delivery can be more effective than that of a conventional dermal gel. Full article

Converting low-grade thermal energy into electrical energy is crucial for the development of modern smart wearable energy technologies. The free-standing films of PEDOT@Bi₂Te₃ prepared by tape-casting hold promise for flexible thermoelectric technology in self-powered sensing applications. Bi₂Te₃ nanosheets fabricated by the solvothermal method are tightly connected with flat-arranged PEODT molecules, forming an S-Bi bonded interface in the composite materials, and the bandgap is reduced to 1.63 eV. Compared with the PEDOT film, the mobility and carrier concentration of the composite are significantly increased at room temperature, and the conductivity reaches 684 S/cm. Meanwhile, the carrier concentration decreased sharply at 360 K indicating the creation of defect energy levels during the interfacial reaction of the composites, which increased the Seebeck coefficient. The power factor was improved by 68.9% compared to PEDOT. In addition, the introduction of Bi₂Te₃ nanosheets generated defects and multidimensional interfaces in the composite film, which resulted in weak phonon scattering in the conducting polymer with interfacial scattering. The thermal conductivity of the film is decreased and the ZT value reaches 0.1. The composite film undergoes 1500 bending cycles with a 14% decrease in conductivity and has good flexibility. This self-supporting flexible thermoelectric composite film has provided a research basis for low-grade thermal energy applications. Full article

Supramolecular chemistry is a relatively new field of study that utilizes conventional chemical knowledge to produce new edges of smart materials. One such material use of supramolecular chemistry is the development of sensing platforms. Biologically relevant molecules need frequent assessment both qualitatively and quantitatively to explore several biological processes. In this review, we have discussed supramolecular sensing techniques with key examples of sensing several kinds of bio-analytes and tried to cast light on how molecular design can help in making smart materials. Moreover, how these smart materials have been finally used as sensing platforms has been discussed as well. Several useful spectroscopic, microscopic, visible, and electronic outcomes of sensor materials have been discussed, with a special emphasis on device-based applications. This kind of comprehensive discussion is necessary to widen the scope of sensing technology. Full article

Issues in construction safety in Tanzania cast a long shadow, claiming lives and hindering project success. Understanding the complex dynamics at play is crucial for improving safety performance. This research aims to develop a system dynamics model to understand the factors influencing safety performance in building construction projects. Smart PLS was used to identify key variables using factor reduction, and 19 factors were determined as key factors to be used in this study from 143 variables from a questionnaire; then, STELLA was used to develop system dynamic modelling. A study was conducted on 255 building construction projects in five regions of Tanzania, Dar es Salaam, Dodoma, Arusha, Mwanza, and Mbeya, and later, the model was tested in one contractor’s company. By simulating the interactions between these diverse elements and their impact on accident rates, it was found that both safety performance and safety management processes for construction projects are not stagnant but are expected to rise at the beginning of the project and to grow steadily as the project execution approaches its end. The sensitivity analysis conducted on the system dynamics model found that the extent, frequency, and cost of incidences are positively correlated. This study contributes facts on the status of safety climate, a new definition of safety climate, and the integration of different analysis methods in evaluating safety performance in Tanzania. Full article