Search Results (806)

Surface functionalisation of polymers is essential for enhancing properties such as wettability and mechanical resistance. This study presents a scalable, coating-free approach to fabricate hydrophobic and superhydrophobic Polydimethylsiloxane (PDMS) surfaces. Aluminium (AA2024) moulds were microstructured using a TruMicro femtosecond laser system to generate grid patterns with controlled hatch distances and depths, as well as laser-induced periodic surface structures (LIPSSs). These features were accurately replicated onto PDMS, as confirmed by scanning electron miscoscopy (SEM) and profilometry. Contact angle measurements showed a marked increase in hydrophobicity, reaching superhydrophobicity for optimised parameters, with surface stability maintained over four months without degradation. Full article

Polydimethylsiloxane (PDMS) is commonly used in gas-separation studies because of its high CO₂ permeability and stable mechanical properties. In this work, mixed matrix membranes (MMMs) were prepared by incorporating the bimetallic MOFs Ni-Cu-MOF-74, Ni-Co-MOF-74, and Ni-Zn-MOF-74 into a PDMS matrix. The membranes were fabricated by solution casting and characterized by SEM, XRD, FT-IR, and BET analyses, which confirmed uniform filler dispersion and the successful incorporation of the MOF-74 structures. Single-gas permeation tests showed clear performance improvements with MOF loading. The best results were obtained for the membrane containing 1 wt.% Ni-Cu-MOF-74, which reached a CO₂ permeability of 3188.25 Barrer and a CO₂/N₂ selectivity of 35.10. The improvement is attributed to the accessible metal sites and high surface area provided by the MOF-74 framework, which enhanced adsorption–diffusion pathways for CO₂ transport. These results show that PDMS/MOF-74 mixed-matrix membranes are effective for CO₂/N₂ separation, with Ni-Cu-MOF-74 achieving the highest performance. Full article

Frequent crude oil spills during offshore oil and gas production and transportation have inflicted irreversible detrimental effects on both human activities and marine ecosystems; with particular risks of secondary disasters such as combustion and explosions. To address these challenges; advanced oil sorption technologies have been developed to overcome the inherent limitations of conventional remediation methods. In this study, a flame-retardant protective coating was fabricated on melamine sponge (MS) through precipitation polymerization of octa-aminopropyl polyhedral oligomeric silsesquioxane (POSS) and hexachlorocyclotriphosphazene (HCCP), endowing the MS@PPOS-PDMS-Si composite with exceptional char-forming capability. Secondary functional layer: By coupling the complementary physicochemical properties of polydimethylsiloxane (PDMS) and SiO₂ nanofibers, we enabled them to function jointly, achieving superior performance in the material systems; this conferred enhanced hydrophobicity and structural stability to the MS matrix. Characterization results demonstrated a progressive reduction in peak heat release rate (PHRR) from 137.66 kW/m² to118.35 kW/m², 91.92 kW/m², and ultimately 46.23 kW/m², accompanied by a decrease in total smoke production (TSP) from 1.62 m² to 0.76 m², indicating significant smoke suppression. Furthermore, the water contact angle (WCA) exhibited substantial improvement from 0° (superhydrophilic) to 140.7° (highly hydrophobic). Cyclic sorption–desorption testing revealed maintained oil–water separation efficiency exceeding 95% after 10 operational cycles. These findings position the MS@PPOS-PDMS-Si composite as a promising candidate for emergency oil spill response and marine pollution remediation applications, demonstrating superior performance in fire safety, environmental durability, and operational reusability. Full article

The development of non-invasive sensors for individualised plant monitoring has become essential in smart farming to increase crop production. However current approaches are focused on the measurement of soil parameters instead, which cannot provide direct information about plant health. Moreover, equipment used for the direct monitoring of plant health are costly with complex operation, hindering their use by the wider community of farmers. This work reports for the first time the development of a flexible and highly transparent sensor, based on thin conductive PEDOT:PSS/PDMS hybrid films directly deposited onto leaves. The films were fabricated by aerosol deposition and could operate under two different modes. The first mode is used for the determination of plant dryness and concentration of ions. The second mode is used as a triboelectric generator to generate up to 7.2 µW cm⁻² electrical power through the friction of the sensors with a leaf. The device was assembled using a low-cost (GBP < 70) microcontroller incorporating environmental sensors, and an intuitive interface was designed for operation. The final sensor could determine the ionic strength at the millimolar level by means of the impedance of electrodes. This performance allowed the study of differences in ionic content and water availability in tomato leaves during day–night cycles. The high stability of the sensors also allowed the long-term monitoring of plant health. Using this technology, a decrease in the leaf ionic strength due to the lack of electrolytes was observed after watering with deionised water for 2 days. Upon supplementation with fertiliser, the recorded ionic strength and leaf water content were similar to the original values prior to the use of DI water, demonstrating the applicability of the device in the early detection of stress factors that could decrease crop production. Full article

Zero-depth nanopores present a promising solution to the challenges associated with ultrathin membranes used in solid-state resistive pulse sensors for DNA sequencing. Most existing fabrication methods are either complex or lack the nanoscale precision required. In this study, we introduce a cost-effective approach that combines PDMS molding at the intersection of silicon micro-blades with an innovative high-resolution nano-positioning technique. These blades are created through photolithography and a two-step KOH wet etching process, allowing for the formation of sub-50 nm 3D rhombic zero-depth nanopores featuring large vertex angles. To address the limitations of SEM imaging—such as dielectric charging and deformation of PDMS membranes under electron beam exposure—we devised a finite element model (FEM) that correlates electrical conductance with pore size and electrolyte concentration. This model aligns closely with experimental data, yielding a mean absolute percentage error of 3.69%, thereby enabling real-time indirect sizing of the nanopores based on the measured conductance. Additionally, we identified a critical channel length beyond which pore resistance becomes negligible, facilitating a linear relationship between conductance and pore diameter. The nanopores produced using this method exhibited a 2.4-fold increase in conductance compared to earlier designs, highlighting their potential for high-precision DNA sequencing applications. Full article

Quantum dots (QDs) have tremendous potential for next-generation displays due to their high color purity, photoluminescence efficiency, and power efficiency. In this work, we present a simple and cost-effective method for fabricating flexible single- and multiple-layer films, and they can be detached and attached to the outside of OLEDs as a light-scattering and color-conversion layer. Light extraction efficiency is enhanced by forming low-density structures by using the reactive ion etching (RIE) process. As a result, the QD/PDMS composite film allowed for color conversion and achieved an excellent light extraction efficiency of up to 9.2%. Furthermore, the QD/PDMS composite film and greenish-blue OLED produced white light (CIEx,y = 0.28, 0.41), demonstrating the potential for application in broad areas, from flexible displays to lighting. The method provides a simple and cost-effective alternative to conventional processes. Full article

Bone defect repair presents a significant clinical challenge, especially for critical-sized defects, due to the limitation of conventional 3D-printed scaffolds to provide simultaneous mechanical support and bioactivity. Herein, this study developed a bioactive composite scaffold through a low-temperature rapid prototyping (LT-RP) 3D printing technology. The scaffold comprises a polyurethane (PU) matrix enhanced with bioactive manganese dioxide (MnO₂) nanoparticles, combining structural integrity with versatile bioactivity for bone repair. By incorporating 2, 6-pyridinedimethanol (PDM) into the PU molecular network, a coordination system is formed, enabling homogeneous distribution and structural integration of MnO₂ nanoparticles. As designed, the bioactive scaffolds are fabricated through LT-RP 3D printing technology with a regular porous architecture for improving cell growth. With 10 wt% MnO₂, the scaffolds (PPM10) have optimal comprehensive properties, with a modulus of ~14.1 MPa, improved thermal stability, good cytocompatibility, and enhanced osteogenic differentiation. Furthermore, in vitro degradation tests revealed the responsive release of Mn²⁺ from the PPM10 scaffolds in a glutathione-rich microenvironment. This functionality indicates the potential of the scaffolds to modify the tumor microenvironment for ultimate bone regeneration after bone tumor surgery. Full article

In recent years, the development of stretchable electronic devices with mechanical properties similar to those of human tissues has attracted increasing research interest in biomedical engineering, wearables, and other fields. These devices have demonstrated, and some other researchers have already shown, promising advancements towards applications that span from measurements of the disruption of model barrier tissues to wearable or implantable devices, soft robotics, and the development of flexible and stretchable batteries. For example, models of barrier tissues, consisting of two compartments separated by a porous membrane, have been used to measure their integrity as well as to investigate the passage of drugs, toxins, and cancer cells through these tissues. Some of these models include an elastomeric membrane which can be stretched to model processes such as breathing and gut peristalsis, while others include electrodes for real-time measurement of barrier tissue integrity. However, to date, microelectrodes have not been fabricated directly on a porous elastomeric membrane. Here, we present lithographically patterned gold electrodes on porous PDMS membranes that enable electronic sensing capabilities in addition to mechanical manipulation. These membranes are incorporated into vacuum-actuated devices which impart cyclic mechanical strain, and their suitability for electrical impedance measurements, even after 1000 stretching cycles under fluids similar to cell culture media, is demonstrated. In the future, we expect to use these electrodes to measure the disruption in model cell barriers as well as to dielectrophoretically trap cells in a region of interest for more rapid assembly of a model tissue. Other areas like wearables, robotics, and power sources will greatly benefit from the further development of this technology. Full article

Rapid blood type detection in point-of-care testing (POCT) scenarios is crucial for various clinical treatments. In this study, we present a sensitive, cost-effective, and straightforward biosensing approach for visual blood typing that notably simplifies the procedure by eliminating any need for blood sample pretreatment. Our technique achieves this by directly trapping and accumulating red blood cell (RBC) clusters within a photolithography-based microfluidic chip, thereby bypassing complex preprocessing. By employing an antigen–antibody assay involving isoagglutinins A, B, and/or D on the RBC surface and their corresponding antibodies, we effectively determine blood types. When antibodies are present, the corresponding RBCs bind to the antibody-conjugated RBC clusters, which are subsequently trapped within the microfluidic accumulation chip, resulting in the formation of a visible bar. The blood group can then be readily identified by observing this visual bar with the naked eye or under microscopy. Notably, we integrate two continuous mixing units (Z and S) at the entrance of the biochip to improve mixing efficiency and accelerate the antigen–antibody interaction. This method demonstrates high selectivity, accuracy, and stability across various clinical blood samples. Moreover, the sensor operates with minimal sample volume (as low as 10 μL) and delivers results within 5 min. The fabrication cost of the PDMS-based biochip is approximately $0.2 per chip, and the limit of detection (LOD) is determined to be 3 × 10⁶ cells/mL, indicating excellent sensitivity and affordability for practical use. Overall, this biochip provides a fast, low-cost, and reliable solution for emergency blood typing, particularly in resource-limited settings. Full article

Conventional thermoplastic polyurethane (TPU) films are commonly used in the field of waterproof and moisture-permeable textiles because of their excellent mechanical properties and flexibility. However, the high water absorption of TPU films limits their application in sophisticated waterproof and moisture-permeable products, particularly in extremely humid environments, where it may compromise the waterproof performance of textiles and negatively affect the wearing comfort. Therefore, to enhance the durability of these films, TPU was hydrophobically modified with end-hydroxy polydimethylsiloxane (PDMS). Because of its unique low-surface-energy properties and excellent hydrophobicity, PDMS substantially reduces the surface energy of the films and provides them with excellent water repellency, effectively addressing the excessive water absorption issue of TPU films. On this basis, a microporous film featuring waterproof and moisture-permeable properties is produced using phase conversion technology. Compared with that of the unmodified sample, the surface energy of silicone-modified TPU (Si-TPU) decreased by 10.56 mJ/m². Furthermore, the water contact angle increased from 83° to 105°, whereas the water absorption rate considerably reduced after the modification. Moreover, Si-TPU was employed for the fabrication of a microporous membrane, which displayed exceptional moisture permeability (8651.34 g/(m²⸱24 h)). Full article

Flexible pressure sensors are essential for wearable electronics, human–machine interfaces, and soft robotics. However, conventional Polydimethylsiloxane (PDMS)-based sensors often suffer from limited conductivity, poor filler dispersion, and low structural integration with textile substrates. In this work, we present a robotic drop-coating approach for fabricating graphite–copper nanoparticle (G-CuNP)/PDMS composite pressure sensors with textile-integrated electrodes. By precisely controlling droplet deposition, a three-layer sandwiched structure was realized that ensures uniformity and scalability while avoiding the drawbacks of conventional full-line coating. The effects of filler loading and graphite nanoparticle (GNP) and copper nanoparticle (CuNP) ratios were systematically investigated, and the optimized sensor was obtained at 40 wt% total fillers with a graphite content of 55 wt%. The fabricated device exhibited high sensitivity in the low-pressure region, stable performance in the medium- and high-pressure ranges, and an exponential saturation fitting with R² = 0.998. The average hysteresis was 7.42%, with excellent cyclic stability over 1000 loading cycles. Furthermore, a hand-shaped sensor matrix composed of five distributed sensing units successfully distinguished grasping behaviors of lightweight and heavyweight objects, demonstrating multipoint force mapping capability. This study highlights the advantages of robotic drop-coating for scalable fabrication and provides a promising pathway toward low-cost, reliable, and wearable soft pressure sensors. Full article

Flexible and wearable thermoelectric devices can convert body waste heat into electricity, showing a new direction to solve the long-lasting issue of energy supply on portable devices. However, thermoelectric fibers are prone to short circuits and failure due to sweat stains and washing practices. Therefore, it is quite necessary to solve this problem to realize the practical thermoelectric device. PDMS, with its excellent insulation and flexibility, can effectively address short-circuit issues by encapsulating the surface of thermoelectric fibers. In this work, hydrophilic nano-silica (H-SiO₂)-modified PDMS that insulates materials was prepared and coated on the surfaces of polyethyleneimine (PEI)- and hydrochloric acid (HCl)-treated dual-surface-modified thermoelectric fibers. The encapsulated fibers were then woven into spacer fabric to prepare thermoelectric textiles (TETs). After 50 water washing cycles, the fibers retained 97% of their conductivity, and the textiles continued to function normally underwater, indicating that the thermoelectric fibers are effectively protected under PDMS encapsulation. Full article

This study proposes and demonstrates a highly sensitive displacement sensor based on a flexible random laser. The sensor utilizes a polydimethylsiloxane (PDMS) film where a self-assembled surface grating structure is formed via oxygen plasma surface treatment combined with bending prestress. This structure acts as a photon-trapping microcavity and multiple scattering feedback center, integrated with embedded laser dye PM597 as the gain medium to form a flexible grating random laser. Experiments show that the device generates random lasing emission under 532 nm pumping (threshold ~21 mJ/cm²) with a linewidth of ~0.25 nm and a degree of polarization of ~0.82. Applying micro-displacement alters the PDMS film curvature, subsequently changing the grating morphology (height, angle). This modifies photon trapping efficiency and geometric deflection loss within the equivalent resonator cavity, leading to significant modulation of the random laser output intensity. A linear correspondence between displacement and lasing intensity was established (R² ≈ 0.91), successfully demonstrating displacement sensing functionality. This scheme not only provides a low-cost method for fabricating flexible grating random lasers but also leverages the extreme sensitivity of random lasing modes to local disordered structural changes, paving the way for novel high-sensitivity mechanical sensors and on-chip integrated photonic devices. Full article

In this work, we used a label-free biosensor that provides optical readouts to perform continuous detection of human interleukin 8 (IL-8), which is especially overexpressed in certain cancers and, thus, could be an effective biomarker for cancer prognosis estimation and therapy evaluation. For this purpose, we engineered a compact, portable, and easy-to-assemble biosensing module device. It combines a fluidic chip for reagent flow, a biosensing chip for signal transduction, and an optical readout head based on fiber optics in a single module. The biosensing chip is based on independent arrays of resonant nanopillar transducer (RNP) networks. We integrated the biosensing chip with the RNPs facing down in a simple and rapidly fabricated polydimethyl siloxane (PDMS) microfluidic chip, with inlet and outlet channels for the sample flowing through the RNPs. The RNPs were vertically oriented from the backside through an optical fiber mounted on a holder head fabricated ad hoc on polytetrafluoroethylene (PTFE). The optical fiber was connected to a visible spectrometer for optical response analysis and consecutive biomolecule detection. We obtained a sensogram showing anti-IL-8 immobilization and the specific recognition of IL-8. This unique portable and easy-to-handle module can be used for biomolecule detection within minutes and is particularly suitable for in-line sensing of physiological and biomimetic organ-on-a-chip systems. Cancer biomarkers’ continuous monitoring arises as an efficient and non-invasive alternative to classical tools (imaging, immunohistology) for determining clinical prognostic factors and therapeutic responses to anticancer drugs. In addition, the multiplexed layout of the optical transducers and the simplicity of the monolithic sensing module yield potential high-throughput screening of a combination of different biomarkers, which, together with other medical exams (such as imaging and/or patient history), could become a cutting-edge technology for further and more accurate diagnosis and prediction of cancer and similar diseases. Full article

The escalating crisis of bacterial antimicrobial resistance poses a severe threat to global health, necessitating novel strategies beyond conventional antibiotics. Photothermal therapy (PTT) has emerged as a promising alternative that leverages heat generated by laser irradiation to induce localized cellular damage and eradicate bacteria. Among various photothermal agents, carbon-based nanomaterials like graphene nanoplatelets (GNPs) offer exceptional properties for PTT applications. This study introduces a novel urinary catheter (UC) embedded with GNPs (GNPUC), specifically designed for photothermal sterilization to combat catheter-associated bacterial infections. GNPs were systematically incorporated into polydimethylsiloxane (PDMS) catheters at varying weight percentages (1% to 10%). The fabricated GNPUCs exhibited low wettability, hydrophobic characteristics, and low adhesiveness, properties that are crucial for minimizing bacterial interactions and initial adhesion. Upon exposure to near-infrared (NIR) laser irradiation (808 nm, 1.5 W/cm²), the UC containing 10 weight percent of GNPs (10GNPUC) achieved a significant temperature of 68.8 °C, demonstrating its potent photothermal conversion capability. Quantitative agar plate tests confirmed the enhanced, concentration-dependent photothermal antibacterial activity of GNPUCs against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Notably, 5% and higher GNP concentrations achieved 100% mortality of S. aureus, while 1% and higher concentrations achieved 100% mortality of E. coli. These findings underscore the significant potential of GNP-embedded catheters as a highly effective photothermal antibacterial platform for future clinical applications in combating catheter-associated infections. Full article