Search Results (1,800)

This work demonstrates the potential of polydimethylsiloxane sponges for removing organic UV filter compounds such as octinoxate from aqueous solutions. The sponges were fabricated using simple templates made of hydrophilic fused or pressed particles (sugar or NaCl salt) with an approximate particle size of 0.4 mm. Among the prepared sponges, those templated with sugar cubes or coarse salt exhibited the highest adsorption capacity, effectively adsorbing up to 0.6% of their own mass in octinoxate. The PDMS sponges were fully regenerable, allowing for the complete removal of octinoxate without any detectable changes in their adsorption properties or dry weight. Due to their simple fabrication, ease of handling, ability to float, and reusability, PDMS sponges present an environmentally friendly and low-maintenance alternative to conventional filtration systems for the removal of octinoxate and potentially other UV filter compounds from environmental surface waters and recreational water bodies. Full article

A modular strategy for the molecular design of silicone-based antifoaming agents was developed by precisely controlling the architecture of poly (methylhydrosiloxane) (PMHS). Sixteen PMHS variants were synthesized by systematically varying the siloxane chain length (L1–L4), backbone composition (D₃T₁ vs. D₃₀T₁), and terminal group chemistry (H- vs. M-type). These structural modifications resulted in a broad range of Si-H functionalities, which were quantitatively analyzed and correlated with defoaming performance. The PMHS matrices were integrated with high-viscosity PDMS, a nonionic surfactant, and covalently grafted fumed silica—which was chemically matched to each PMHS backbone—to construct formulation-specific defoaming systems with enhanced interfacial compatibility and colloidal stability. Comprehensive physicochemical characterization via FT-IR, ¹H NMR, GPC, TGA, and surface tension analysis revealed a nonmonotonic relationship between Si-H content and defoaming efficiency. Formulations containing 0.1–0.3 wt% Si-H achieved peak performance, with suppression efficiencies up to 96.6% and surface tensions as low as 18.9 mN/m. Deviations from this optimal range impaired performance due to interfacial over-reactivity or reduced mobility. Furthermore, thermal stability and molecular weight distribution were found to be governed by repeat unit architecture and terminal group selection. Compared with conventional EO/PO-modified commercial defoamers, the PMHS-based systems exhibited markedly improved suppression durability and formulation stability in high-viscosity environments. These results establish a predictive structure–property framework for tailoring antifoaming agents and highlight PMHS-based formulations as advanced foam suppressors with improved functionality. This study provides actionable design criteria for high-performance silicone materials with strong potential for application in thermally and mechanically demanding environments such as coating, bioprocessing, and polymer manufacturing. Full article

This study investigates the metabolic responses of the model diatom Phaeodactylum tricornutum under different growth conditions, comparing benthic (adherent) and planktonic states. Using a multiblock metabolomics approach combining LC-HRMS², NMR, and GC-MS techniques, we compared the metabolome of P. tricornutum cultivated on three laboratory substrates (glass, polystyrene, and polydimethylsiloxane) and under planktonic conditions. Our results revealed metabolic differences between adherent and planktonic cultures, particularly concerning the lipid and carbohydrate contents. Adherent cultures showed a metabolic profile with an increase in betaine lipids (DGTA/S), fatty acids (tetradecanoic and octadecenoic acids), and sugars (myo-inositol and ribose), suggesting modifications in membrane composition and lipid remodeling, which play a potential role in adhesion. In contrast, planktonic cultures displayed a higher content of cellobiose, specialized metabolites such as dihydroactinidiolide, quinic acid, catechol, and terpenes like phytol, confirming different membrane composition, energy storage capacity, osmoregulation, and stress adaptation. The adaptative strategies do not only concern adherent and planktonic states, but also different adherent culture conditions, with variations in lipid, amino acid, terpene, and carbohydrate contents depending on the physical properties of the support. Our results highlight the importance of metabolic adaptation in adhesion, which could explain the fouling process. Full article

Polyethylene oxide (PEO) is the most well-studied polymer used in solid polymer electrolytes (SPEs) for lithium ion batteries (Li-ion batteries). However, ionic conductivity is greatly reduced in the low temperature range due to the crystallization of PEO. Therefore, methods to suppress the crystallization of PEO at room temperature by cross-linking or introducing a branched structure are currently being investigated. In this study, we synthesized new comb-type ion-conducting polyethers with two different side chains such as polydimethylsiloxane (PDMS) and polyethylene glycol monomethyl ether (mPEG) segments as flexible and ion-conducting segments, respectively. The introduction of the PDMS segment was found to prevent a decrease in ionic conductivity in the low-temperature region, but led to an ionic conductivity decrease in the high temperature region. On the other hand, the introduction of mPEG segments improved ionic conductivity in the high-temperature region. The introduction of mPEG segments with longer chains resulted in a significant decrease in ionic conductivity in the low-temperature region. Full article

For meeting the growing demand for lightweight impact-resistant materials, this study designed and fabricated a carbon hollow microsphere (CHM)-reinforced polydimethylsiloxane (PDMS) composite and systematically investigated the influence of CHM packing structure on its energy absorption performance. Through optimizing the controllable preparation processes of the CHMs, CHMs with low breaking rates and novel structural stability were successfully prepared. A vacuum-assisted mixing–casting method was employed to synthesize the CHM/PDMS composites with varying CHM contents (0~10 wt.%). The results demonstrated that the incorporation of CHMs significantly enhanced the compressive strength, compressive modulus, and energy absorption efficiency of the PDMS matrix. Under quasi-static loading, the composite with 4 wt.% CHM exhibited optimal comprehensive performance, achieving a 124.68% increase in compressive strength compared to pure PDMS. In dynamic impact tests, the compressive strength and energy absorption at a strain rate of 4500 s⁻¹ increased by 1245.09% and 1218.32%, respectively. The improvement of mechanical properties can be mainly attributed to the introduction of CHMs with an appropriate percentage, which can form a dense stacking structure so that the interaction force between the CHMs and PDMS matrix can be improved through the dense stacking effect, and the external force can be effectively dissipated through interface interaction, in addition to the energy dissipated by the deformation of the matrix deformation and crush of the CHMs. Additionally, the introduction of CHMs elevated the onset thermal decomposition temperature of the materials, leading to an enhanced thermal stability of the CHM/PDMS composite compared to that of the pure PDMS. Overall, this study provides theoretical and experimental foundations for designing lightweight impact-resistant materials and demonstrates the potential of CHM/PDMS composites for multifunctional safety protection. Full article

We propose a simulation-based design for a flexible color filter (FCF) using a lithium niobate metamaterial (LNM) to investigate its color filtering potential. The FCF is composed of three periodically arranged half-ellipse LN arrays on a polydimethylsiloxane (PDMS) substrate, denoted as LNM-1, LNM-2, and LNM-3. The electromagnetic responses of the FCF can be controlled by adjusting the periods of the LNMs. Our simulations predict high-quality (Q) factors in transmission spectra, ranging from 100 to 200 for LNM-1, 290 to 360 for LNM-2, and 140 to 300 for LNM-3. When the FCF is exposed to the surrounding environments with different refractive indexes, it exhibits a theoretical figure of merit (FOM) up to 900 RIU⁻¹ and a sensitivity reaching 130 nm/RIU. The electromagnetic field distributions reveal strong confinement within the LNM nanostructures, confirming an efficient light–matter interaction. These results indicate that the proposed LNM-based FCF presents a promising design concept for high-performance color sensing and filtering applications. Full article

Cell migration assays provide valuable insights into pathological conditions, such as tumor metastasis and immune cell infiltration, and the regenerative capacity of tissues. In vitro tools commonly used for cell migration studies exploit commercial transwell systems, whose functionalities can be improved through engineering of the pore pattern. In this context, we propose the fabrication of a transwell-like device pursued by combining the proton beam writing (PBW) technique with wet etching onto thin layers of polydimethylsiloxane (PDMS). The resulting transwell-like device incorporates a PDMS membrane with finely controllable pore patterning that was used to study the arrangement and migration behavior of HCMEC/D3 cells, a well-established human brain microvascular endothelial cell model widely used to study vascular maturation in the brain. A comparison between commercial polycarbonate membranes and the PBW-holed membranes highlights the impact of the ordering of the pattern and porosity on cellular growth, self-organization, and transmigration by combining fluorescent microscopy and advanced digital processing. Endothelial cells were found to exhibit distinctive clustering, alignment, and migratory behavior close to the pores of the designed PBW-holed membrane. This is indicative of activation patterns associated with cytoskeletal remodeling, a critical element in the angiogenic process. This study stands up as a novel approach toward the development of more biomimetic barrier models (such as organ-on-chips). Full article

It is difficult to simultaneously achieve surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) for noble metals. Herein, a composite substrate is demonstrated based on the rational construction of Ag nanoparticles (Ag NPs) and inverse opal polydimethylsiloxane (PDMS) for surface Raman fluorescence dual enhancement. The well-designed Ag nanoparticle (Ag NP)-decorated inverse opal PDMS (AIOP) composite substrate is fabricated using the polystyrene (PS) photonic crystal method and the sensitization reduction technique. The inverse opal PDMS enhances the electromagnetic (EM) field by increasing the loading of Ag NPs and plasmonic coupling of Ag NPs, leading to SERS activity. The thin shell layer of polyvinyl pyrrolidone (PVP) in core–shell Ag NPs isolates the detected molecule from the Ag core to prevent the fluorescence resonance energy transfer and charge transfer to eliminate fluorescence quenching and enable SEF performance. Based on the blockage of the core–shell structure and the enhanced EM field originating from the inverse opal structure, the as-fabricated AIOP composite substrate shows dual enhancement in surface Raman fluorescence. The AIOP composite substrate in this work, which combines improved SERS activity and SEF performance, not only promotes the development of surface-enhanced spectroscopy but also shows promise for applications in flexible sensors. Full article

This study explores the optimisation of nozzle design for external twin fluid, single-stage atomisation in handling high-viscosity, shear-thinning polydimethylsiloxane (PDMS). A single PDMS grade was employed and atomised using unheated sonic air and the viscosity was varied by the fluid temperature. A systematic experimental approach was used, varying nozzle geometry—specifically apex angle, gas nozzle diameter, and number of gas nozzles—to identify the optimal nozzle configuration (ONC). The spray qualities of the nozzle configurations were evaluated via high-speed imaging at 75,000 FPS. Shadowgraphy was employed for the optical characterisation of the spray, determining the optimal volumetric air-to-liquid ratio (ALR), a key parameter influencing energy efficiency and operational cost, and for assessing droplet size distributions under varying ALR and viscosity of PDMS. The ONC yielded a Sauter mean diameter $d_{32}$ of 570 × 10⁻⁶$\mathrm{m}$, at an ALR of 8532 and a zero-shear viscosity of 15.9 $\mathrm{Pa}$ $\mathrm{s}$. The results are relevant for researchers and engineers developing twin fluid atomisation systems for challenging industrial fluids with similar physical properties, such as those in wastewater treatment and coal–water slurry atomisation (CWS). This study provides design guidelines for external twin fluid atomisers to enhance atomisation efficiency under such conditions. Full article

Polylactic acid (PLA) fabrics exhibit significant sunlight reflectivity and high emissivity within the atmospheric window, making them suitable as the foundational material for this study. This research involves the modification of one side of the fabric with hydrophilic agents and titanium dioxide (TiO₂), while the opposite side is treated with MXene and subsequently coated with polydimethylsiloxane (PDMS) to inhibit oxidation of the MXene. Through these surface modifications, a thermal management fabric based on PLA was successfully developed, capable of passively regulating temperature in response to environmental conditions and user requirements. The study discusses the optimal concentrations of TiO₂ and MXene for the fabric, and characterizes and evaluates the functional surface of the PLA. Surface morphology analyses and tests indicate that the resulting functional PLA fabrics possess excellent ultraviolet (UV) resistance, favorable air permeability, high sunlight reflectivity on the TiO₂-treated side, and superior photothermal conversion capabilities on the MXene-treated side. Furthermore, photothermal effect tests conducted under a light intensity of 1000 W/m² reveal that the MXene-treated fabric exhibits a heating effect of approximately 25 °C, while the TiO₂-treated side demonstrates a cooling effect exceeding 5 °C. This study developed PLA functional fabrics with heating and cooling capabilities. Full article

Diabetic foot ulcers (DFUs) represent a critical global health issue, necessitating the development of advanced smart, flexible, and wearable sensors for continuous monitoring that are reimbursable within foot orthotics. This study presents the design and characterization of a pressure sensor implemented into a shoe insole to monitor diabetic wound pressures, emphasizing the need for a high sensitivity, durability under cyclic mechanical loading, and a rapid response time. This investigation focuses on the electrical and mechanical properties of carbon nanotube (CNT) composites utilizing Ecoflex and polydimethylsiloxane (PDMS). Morphological characterization was conducted using Transmission Electron Microscopy (TEM), Laser Confocal Microscopy, and Scanning Electron Microscopy (SEM). The electrical and mechanical properties of the CNT/Ecoflex- and the CNT/PDMS-based sensor composites were then investigated. CNT/Ecoflex was then further evaluated due to its lower variability performance between cycles at the same pressure, as well as its consistently higher capacitance values across all trials in comparison to CNT/PDMS. The CNT/Ecoflex composite sensor showed a high sensitivity (2.38 to 3.40 kPa⁻¹) over a pressure sensing range of 0 to 68.95 kPa. The sensor’s stability was further assessed under applied pressures simulating human weight. A custom insole prototype, incorporating 12 CNT/Ecoflex elastomeric matrix-based sensors (as an example) distributed across the metatarsal heads, midfoot, and heel regions, was developed and characterized. Capacitance measurements, ranging from 0.25 pF to 60 pF, were obtained across N = 3 feasibility trials, demonstrating the sensor’s response to varying pressure conditions linked to different body weights. These results highlight the potential of this flexible insole prototype for precise and real-time plantar surface monitoring, offering an approachable avenue for a challenging diabetic orthotics application. Full article

We report a new concept of a pressure sensor fully made from polydimethylsiloxane with a solid core and porous cladding that operates through (frustrated) total internal reflection. A flexible and sensitive rectangular cross-section waveguide was fabricated via the casting and molding method. The waveguide’s optical losses can be temperature-controlled during the fabrication process by controlling the quantity of microbubbles incorporated (2% approximately for samples made at 70 °C). By controlling the precuring temperature, the microbubbles are incorporated into the waveguides during the simple and cost-effective fabrication process through the casting and molding method. For these samples, we measured good optical loss tradeoff of the order of 1.85 dB/cm, which means that it is possible to fabricate a solid-core/clad waveguide with porous cladding able to guide light properly. We demonstrated the microbubble concentration control in the waveguide, and we measured an average diameter of 239 ± 16 µm. A sensitivity to pressure of 0.1035 dB/kPa optical power loss was measured. The results show that in a biomedical dynamic pressure range (0 to 13.3 kPa), this new device indicates the critical pressure threshold level, which constitutes a crucial asset for potential applications such as pressure injury prevention. Full article

Ketones, which are key biomarkers of fat oxidation, are relevant for metabolic health maintenance and disease development, making continuous monitoring essential. In this study, we introduce a novel colorimetric sensor designed for potential continuous acetone detection in biological fluids. The sensor features a polydimethylsiloxane (PDMS) shell that encapsulates a sensitive and specific liquid-core acetone-sensing probe. The microsphere sensors were characterized by evaluating their size, PDMS shell thickness, colorimetric response, and sensitivity under realistic conditions, including 100% relative humidity (RH) and CO₂ interference. The microsphere size and sensor sensitivity can be controlled by modifying the fabrication parameters. Critically, the sensor showed high selectivity for acetone detection, with negligible interference from CO₂ concentrations up to 4%. In addition, the sensor displayed good reproducibility (CV < 5%) and stability under realistic storage conditions (over two weeks at 4 °C). Finally, the accuracy of the microsphere sensor was validated against a gold standard gas chromatography-mass spectrometry (GC-MS) method using simulated and real breath samples from healthy individuals and type 1 diabetes patients. The correlation between the microsphere sensor and GC-MS produced a linear fit with a slope of 0.948 and an adjusted R-squared value of 0.954. Therefore, the liquid-core microsphere-based sensor is a promising platform for acetone body fluid analysis. Full article

This study examined the effect of build orientation on the surface finish of micro-optofludic (MoF) devices fabricated via a polydimethylsiloxane (PDMS)-based 3D-printing primary–secondary fabrication protocol, where an inkjet 3D-printing technique was implemented. The molds (i.e., primaries) for fabricating the MoF devices were 3D-printed in two orientations: along $XY$ (Dev-1) and across $YX$ (Dev-2) the printhead direction. Next, the surface finish was characterized using a profilometer to acquire the primary profile of the surface along the microchannel’s edge. The results indicated that the build orientation had a strong influence on the latter, since Dev-1 displayed a tall and narrow Gaussian distribution for a channel width of 398.43 ± 0.29 µm; Dev-2 presented a slightly lower value of 393.74 ± 1.67 µm, characterized by a flat and broader distribution, highlighting greater variability due to more disruptive, orthogonally oriented, and striated patterns. These results were also confirmed by hydrodynamically testing the two MoF devices with an air–water slug flow process. A large experimental study was conducted by analyzing the mean period trend in the slug flow with respect to the imposed flow rate and build orientation. Dev-1 showed greater sensitivity to flow rate changes, attributed to its smoother, more consistent microchannel geometry. The slightly narrower average channel width in Dev-2 contributed to increased flow velocity at the expense of having worse discrimination capability at different flow rates. This study is relevant for optimizing 3D-printing strategies for the fabrication of high-performance microfluidic devices, where precise flow control is essential for applications in biomedical engineering, chemical processing, and lab-on-a-chip systems. These findings highlight the effect of microchannel morphology in tuning a system’s sensitivity to flow rate modulation. Full article

The possibility of tightly controlling the cellular microenvironment within microfluidic devices represents an important step toward precision analysis of cellular phenotypes in vitro. Microfluidic platforms that allow both long-term mammalian cell culture and dynamic modulation of the culture environment can support quantitative studies of cells’ responses to drugs. Here, we report the design and testing of a novel microfluidic device of simple production (single Polydimethylsiloxane layer), which integrates a micromixer with vacuum-assisted cell loading for long-term mammalian cell culture and dynamic mixing of four different culture media. Finite element modeling was used to predict flow rates and device dimensions to achieve diffusion-based fluid mixing. The device showed efficient mixing and dynamic exchange of media in the cell-trapping chambers, and viability of mammalian cells cultured for long-term in the device. This work represents the first attempt to integrate single-layer microfluidic mixing devices with vacuum-assisted cell-loading systems for mammalian cell culture and dynamic stimulation. Full article