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Transition metal oxide shows great potential in catalytic formaldehyde (HCHO) pollution degradation at room temperature, while it is still difficult to overcome the efficiency attenuation caused by limited reactive oxygen species (ROS) generation during catalysis. An elastic spongy catalyst with Cu‐modified polydimethylsiloxane (PDMS) organic skeleton (PDMS@Cu) supported hydroxy‐modified MnOx (MnOx‐OH) is prepared hereon, named PDMS@Cu/MnOx‐OH. Deformation of the elastic carrier causes the contact‐separation friction between Cu and PDMS to generate electrostatically induced nonuniform charges, which provide enriched electrons and transient electric field (EF) to enhance ROS generation and HCHO catalytic oxidation. In HCHO dynamic tests (∼12 ppm at the weight hourly space velocity (WHSV) of 120 000 mL gcat.−1 h), the catalyst PDMS@Cu/MnOx‐OH achieved ∼100% HCHO removal efficiency, with an HCHO‐to‐CO2 conversion efficiency of 82.47%, which is 32.47% higher than that without non‐uniform electrostatic charges, and sustained complete real‐time HCHO degradation within 24 h at room temperature. Coupled with Density Functional Theory (DFT) calculations and COMSOL physics simulations, the potential pathway of nonuniform surface charges and transient EF enhancing HCHO catalytic oxidation is unveiled, offering a theoretical foundation and novel strategy for efficient and long‐term indoor pollutant degradation under the action of sustainably electrostatically induced charges. [ABSTRACT FROM AUTHOR]

Microfractal-type structures are abundantly found in nature. To highlight a few, micro fractals are being observed in leaf venation, cardio muscular structures, ice flakes, and so on. These intricate structures can be replicated using the concept of viscous fingering within a Hele-Shaw cell, a setup consisting of two flat plates containing a high-viscosity fluid. Microfractals form when a low-viscosity fluid infiltrates the high-viscosity fluid confined between the plates. The characteristics of these microfractals, such as their shape and size, depend significantly on the properties of the fluids involved and the geometric design of the plates. Therefore, resin characteristics are vital in designing a desired micro fractal. Hence, resin is the governing design of the fractal. Further, a very narrow gap is required maintained in the plate of the Hele-Shaw cell inducing surface tension forces. Here, surface tension and inertial forces governed the formation of fractals. These forces also depend on the viscosity of the resin. Therefore, there is a great need to characterize the resin system. This paper proposed a new resin system that is exhaustively characterized by varying viscosity. The study conducted presents comprehensive computational analysis involving multiple iterations of changing velocity to obtain the desired resin. Various experiments are conducted to produce resins with different viscosities and are assessed for their suitability using the Hele-Shaw cell. This computation work yields the proper design of the microfractals. Photopolymer resin systems are well-known for their suitability in creating microfractals due to their advantageous post-processing capabilities, transitioning from a green state to solid microstructures. This paper explores the comparative analysis of the photopolymer resin system to the proposed low-cost Sodium; 5-chloro-2-(2,4-dichlorophenoxy) phenol; fluoride. The proposed solution is synthesised to review its compatibility with the Hele-Shaw configuration and subsequently employed in the manufacturing process to create various micro fractal shapes and sizes. These micro fractal structures are in their green state. They are then cured by exposure to direct sunlight, eliminating the need for a laser-based photo-curing system typically used with photopolymer resin systems. [ABSTRACT FROM AUTHOR]

Methods such as gas stripping and vacuum-assisted gas stripping (VAGS) result in significant removal of water from the bioreactor, thus requiring continuous water replenishment in the bioreactor. In this study, we developed a hydrophobic stainless steel meshes capable of selectively recovering concentrated ABE stream from the bioreactor during VAGS. Three stainless steel meshes with pore sizes of 180 µm, 300 µm, and 425 µm were made hydrophobic and oleophilic with zinc oxide (ZnO) and polydimethylsiloxane (PDMS). Butanol concentrations in the model solutions range from 3 to 10 g/L which mimic concentrations typically produced during batch ABE fermentation. The meshes were integrated in a 5-L bioreactor containing 2.5 L of operational ABE model solution followed by the evaluation of selective extraction of ABE from both cell-free and Clostridium beijerinckii-rich ABE model solutions. The results show that the 180-µm ZnO/PDMS-coated mesh retained 54–64% more water in the bioreactor without C. beijerinckii cells and 61–65% more water with cells compared to the uncoated mesh. Furthermore, the butanol concentration of condensates recovered with 180-µm ZnO-PDMS-coated mesh was up to 10.8-fold greater than that of uncoated counterpart. Our data demonstrate that the developed ZnO-PDMS mesh can recover high concentrations of ABE while selectively retaining water in the bioreactor. Additionally, this technology demonstrates the potential for real-time ABE recovery during the fermentation of lignocellulosic and colloidal materials, without the concern of clogging the separation system. Key points: • Hydrophobic mesh enhanced water retention in the bioreactor by up to 1.65-fold. • Butanol concentration in the collected condensate was increased by up to 10.8-fold. • Hydrophobic mesh is compatible with fermentation of lignocellulose. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and characterization of hexadecyl-modified SiO2 (HD-SiO2) nanoparticles and their application in the fabrication of a multilayered elastomer hybrid sheet to enhance water resistance in implantable biomedical devices. The surface modification of SiO2 nanoparticles was confirmed via FT-IR and TGA analyses, showing the successful grafting of hydrophobic hexadecyl groups. FE-SEM and DLS analyses revealed spherical HD-SiO2 nanoparticles with an average size of 360 nm. A multilayered elastomer hybrid sheet, consisting of a PDMS-based circuit-protecting body, a water resistance layer of HD-SiO2, a planarization layer, and a biocompatible layer of polydopamine, was fabricated and characterized. The water resistance layer exhibited superhydrophobic properties, with a water contact angle of 154.7° and a 27% reduction in water vapor transmission rate (WVTR) compared to the circuit-protecting body alone. The device packaged with both the circuit-protecting body and water resistance layer demonstrated a tenfold increase in operational lifespan in water medium compared to the device without the water resistance layer. Cytotoxicity and cell proliferation tests on human dermal fibroblast cells (HDFn) confirmed the biocompatibility of the multilayered sheet, with no significant cytotoxicity observed over 48 h. [ABSTRACT FROM AUTHOR]

Liquid manipulation using tubular actuators finds diverse applications ranging from microfluidics, printing, liquid transfer to micro‐reactors. Achieving flexible and simple regulation of manipulated liquid droplets during transport is crucial for the tubular liquid actuators to perform complex and multiple functions, yet it remains challenging. Here, a facile tubular actuator for directional transport of various liquid droplets under the control of an externally applied magnetic field is presented. The surfaces of the actuator can be engineered with submillimeter‐sized through‐hole pores, which enables the liquid droplet to be easily modulated in the transport process. Furthermore, the liquid actuator with featured through‐hole pores is expanded to function as a switch in an integrated external electric circuit by magnetically controlling the motion of a conductive liquid droplet. This work develops a strategy for regulating liquid droplets in the tubular actuation systems, which may inspire ideas for designing functional liquid actuators with potential applications in microfluidics, microchemical reaction, liquid switch, and liquid robotics. [ABSTRACT FROM AUTHOR]

In recent years, flexible pressure sensors have garnered significant attention. However, the development of large-area, low-cost, and easily fabricated flexible pressure sensors remains challenging. We designed a flexible fiber optic pressure sensor for contact force detection based on the principle of backward Rayleigh scattering using a single-mode optical fiber as the sensing element and polymer PDMS as the encapsulation material. To enhance the sensor's sensitivity and stability, we optimized its structural design, parameters, and fabrication process and measured the fiber strain using an optical frequency domain reflectometer (OFDR). The results showed that the sensor achieved a high sensitivity of 6.93247 με/kPa with a PDMS concentration ratio of 10:1, a curing time of 2 h, and a substrate thickness of 5 mm. The sensor demonstrated excellent linearity and repeatability in static performance tests and was successfully used to monitor the plantar pressure distribution in real time. This flexible fiber optic pressure sensor can be developed via a simple fabrication process, has a low cost, and has high sensitivity, highlighting its potential applications in smart wearables and medical diagnostics. [ABSTRACT FROM AUTHOR]

Dust deposition poses a significant challenge in the implementation of photovoltaic panels (PV) especially in hot and dusty environments, such as the Middle East and North Africa (MENA) region. This issue leads to progressive degradation of PV efficiency and output power. In this context, this research work aims to improve PV performance by developing self-cleaning sprays as a preventative solution. Different concentrations of SnO2 and TiO2 nanoceramics were dispersed in isopropyl alcohol solvent to reduce the mixture's viscosity and facilitate smooth spraying on solar panels, whose efficiency was continually assessed in outdoor conditions. Although less commonly used for this application, the nano-SnO2 was selected for the purpose of enhancing the surface hydrophobicity, whereas nano-TiO2 was included for its favorable photocatalytic properties. Polydimethylsiloxane (PDMS) oil, known for its self-cleaning characteristic, was served as the base material in the developed sprays. The described blend of materials represents a novel combination. The results indicated that 2.5% nano-SnO2 and 2.5% nano-TiO2 in PDMS oil enhanced efficiency by 5.4% compared to a non-sprayed panel after five weeks of outdoor exposure. This efficiency gain was experimentally justified and attributed to the spray's ability to achieve a water contact angle (WCA) of 100.6°, forming a hydrophobic surface conducive to self-cleaning. Further characterization results, including photocatalysis and zeta potential have been gathered and analyzed. [ABSTRACT FROM AUTHOR]

Surface coatings such as hydrophobic and transparent coatings were applied to cement concrete surfaces using Polydimethylsiloxane (PDMS) coatings, which have nanometer-sized particles. The degree of contact between the liquid and the coated surface reveals the surface’s ability to repel water, commonly referred to as hydrophobicity. By depositing silicon coating on the surface, we successfully achieved superhydrophobicity on cement concrete, providing excellent resistance against water damage. We are striving to replicate the natural superhydrophobic properties found in nature to create artificial surfaces with similar characteristics. In this study, we experimented to develop and evaluate superhydrophobic coatings on cement concrete. The application of PDMS on the cement concrete yielded fascinating results, with the typical contact angle of the coated layer measuring 178 degrees. We utilized ImageJ software to analyze the results. This innovative approach holds great promise for enhancing water repellency in the field of construction. [ABSTRACT FROM AUTHOR]

AbstractA high-sensitivity temperature sensor based upon an optical fiber Fabry-Perot interferometer (FPI) filled with polydimethylsiloxane (PDMS) is reported that employed a single mode fiber (SMF) and a hollow core fiber (HCF) to enhance the sensitivity. The sensing characteristics were investigated from 20 °C to 40 °C. The experimental results demonstrate that the sensor is sensitive to temperature due to the high thermal optical coefficient (TOC) and high thermal expansion coefficient (TEC) of PDMS, achieving a high sensitivity of 2.155 nm/°C. The designed sensor shows great potential for high-precision temperature sensing applications due to its high sensitivity, compact structure, and simple preparation. [ABSTRACT FROM AUTHOR]

Laser micromachining has been used as an alternative to producing microfluidics structures and simplifying the conventional soft lithography process. In this paper we characterize the excimer laser micromachining parameters and demonstrate its application by producing several microfluidic structures in polydimethylsiloxane (PDMS). The parameters include the number of laser pulses, laser energy and rectangular variable aperture (RVA) in both x- and y-directions. We found that the laser energy and pulse rate affect the depth of micromachining d channels, while RVA in both x- and y-directions affects the width of the channels. Repetition of laser scan does not change the channel width but significantly changes the channel depth. Proper adjustment for laser energy and pulse rate is required to fabricate a desired channels depth. In order to demonstrate the microfabrication capability of an excimer laser with the optimal operating parameters, several microfluidic structures were micromachining d into PDMS with a KrF excimer laser. [ABSTRACT FROM AUTHOR]

Infrared (IR) filters and screens find application in energy‐efficient buildings, windows, and solar panels. Such filters benefit solar cells by preventing efficiency losses caused by heating. Polymer‐nanocomposite films are good candidates for developing IR screens. Compared to prior research on IR filters, we show how the addition of silver nanoparticles (AgNPs) can improve the material's IR reflective nature while retaining high transmittance in the visible region. Polydimethylsiloxane (PDMS) film with AgNPs (~100 μm thick) is made using the doctor blade technique. We observe no transparency loss over the 0.005–0.02 vol% loading of AgNPs in PDMS, indicating the promising application of this transparent film. Furthermore, the distribution of AgNPs is found to be uniform, ensuring consistency, and preventing agglomeration. A contact angle of ~1120 is observed for these films, which is comparable to pristine PDMS film. Using a UV–Vis–NIR spectrophotometer, greater than 7.66% weighted average reflectance is observed in the near‐infrared (NIR) region and above 91.5% transmittance in the visible region. The precise role and influence of the functional group's presence were revealed by Fourier transform infrared (FTIR) spectroscopy. The thermal analysis (TGA) of the films revealed thermal stability of up to 400°C, which is comparable to pristine PDMS. Overall, the synergistic combination of AgNPs and PDMS produces a hydrophobic IR filter with enhanced optical characteristics and thermal stability. [ABSTRACT FROM AUTHOR]

For several decades, aging in Saccharomyces cerevisiae has been studied in hopes of understanding its causes and identifying conserved pathways that also drive aging in multicellular eukaryotes. While the short lifespan and unicellular nature of budding yeast has allowed its aging process to be observed by dissecting mother cells away from daughter cells under a microscope, this technique does not allow continuous, high-resolution, and high-throughput studies to be performed. Here, we present a protocol for constructing microfluidic devices for studying yeast aging that are free from these limitations. Our approach uses multilayer photolithography and soft lithography with polydimethylsiloxane (PDMS) to construct microfluidic devices with distinct single-cell trapping regions as well as channels for supplying media and removing recently born daughter cells. By doing so, aging yeast cells can be imaged at scale for the entirety of their lifespans, and the dynamics of molecular processes within single cells can be simultaneously tracked using fluorescence microscopy. Key features This protocol requires access to a photolithography lab in a cleanroom facility. Photolithography process for patterning photoresist on silicon wafers with multiple different feature heights. Soft lithography process for making PDMS microfluidic devices from silicon wafer templates.

Abstract Liquid manipulation using tubular actuators finds diverse applications ranging from microfluidics, printing, liquid transfer to micro‐reactors. Achieving flexible and simple regulation of manipulated liquid droplets during transport is crucial for the tubular liquid actuators to perform complex and multiple functions, yet it remains challenging. Here, a facile tubular actuator for directional transport of various liquid droplets under the control of an externally applied magnetic field is presented. The surfaces of the actuator can be engineered with submillimeter‐sized through‐hole pores, which enables the liquid droplet to be easily modulated in the transport process. Furthermore, the liquid actuator with featured through‐hole pores is expanded to function as a switch in an integrated external electric circuit by magnetically controlling the motion of a conductive liquid droplet. This work develops a strategy for regulating liquid droplets in the tubular actuation systems, which may inspire ideas for designing functional liquid actuators with potential applications in microfluidics, microchemical reaction, liquid switch, and liquid robotics.

Three-dimensional (3D) porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity. Given their amphiphilic surface, they have a propensity to simultaneously absorb water and oil, which restricts their range of applications. In this study, a reduced graphene oxide and titanium dioxide nanocomposite (rGO/TiO2) was used to fabricate an ultrahydrophobic melamine sponge (MS) through interfacial modification using a solution immersion technique. To further modify it, polydimethylsiloxane (PDMS) was grafted onto its surface to establish stronger covalent bonds with the composite. The water contact angle of the sponge (rGO/TiO2/PDMS/MS) was 164.2°, which satisfies the condition for ultrahydrophobicity. The evidence of its water repellency was demonstrated by the Cassie–Baxter theory and the lotus leaf effect. As a result of the increased density of rGO/TiO2/PDMS/MS, it recorded an initial capacity that was 2 g/g lower than the raw MS for crude oil absorption. The raw MS retained 53% of its initial absorption capacity after 20 cycles of absorption, while rGO/TiO2/PDMS/MS retained 97%, suggesting good recyclability. Excellent oil and organic solvent recovery (90%–96%) was demonstrated by rGO/TiO2/PDMS/MS in oil–water combinations. In a continuous separation system, it achieved a remarkable separation efficiency of 2.4 × 106 L/(m3·h), and in turbulent emulsion separation, it achieved a demulsification efficiency of 90%–91%. This study provides a practical substitute for massive oil spill cleaning.

Triboelectric nanogenerators (TENGs) have emerged as viable micro power sources for an array of applications. Since their inception in 2012, TENGs have been the subject of significant advancements in terms of structural design and the development of friction materials. Despite these advancements, the complexity of their structural designs and the use of costly friction materials hinder their practical application. This study introduces a simplified TENG model utilizing an economical composite film of fullerene carbon soot (FS)-doped polydimethylsiloxane (PDMS) (FS-TENG). It confirms the FS-TENG's ability to convert mechanical energy into electrical energy, as demonstrated through experimental validation. The generated electricity by the FS-TENG can power devices such as light-emitting diodes (LEDs), digital watches, kitchen timers, and sports stopwatches, highlighting its efficiency. This research enhances the development of TENGs featuring low-cost, streamlined structures for sustainable and autonomous energy sensing applications. [ABSTRACT FROM AUTHOR]

To address the issues of corrosion weakening of solid-waste-based backfill material caused by mine water, a novel hydrophobic solid waste backfill (HSBF) material was developed using polydimethylsiloxane (PDMS) and a silane coupling agent (SCA) as hydrophobic modification additives, and NaOH (SH) and sodium silicate (SS) as alkali activators. Fly ash and slag were chosen as the primary raw solid waste materials. The rheological properties of the hydrophobic-treated backfill slurries were measured, and the resulting physicochemical properties were compared with the unmodified reference group. This study reveals that the fresh HSBF slurry follows a Modified Bingham (M-B) model with shear-thinning characteristics. The addition of PDMS causes an increase in the water contact angle of the hardened HSBF material with F8S2 to up to 134.9°, indicating high hydrophobicity. Morphological observations indicated that PDMS mainly attaches to the inorganic particles' surface through the bridging action of SCA for the hydrophobic modification of the backfill material. The overall strength of the HSBF materials was further ensured via fly ash–slag ratio optimization, and was found to be enhanced up to 98% by increasing slag content from 20% to 50%. This is mainly attributed to the hydration of slag, forming C-S(A)-H gel, which contributes to the increased strength. The novel HSBF material enables the elimination of cement in mine backfilling applications, demonstrating good economic benefits. Its excellent mechanical and hydrophobic properties can not only prevent overburden displacement in goaf areas, but can also mitigate water resource loss from overlying strata and simultaneously reduce the safety risks associated with long-term mine water deterioration. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) has attracted great attention in various fields due to its excellent properties, but its inherent hydrophobicity presents challenges in many applications that require controlled wettability. The purpose of this review is to provide a comprehensive overview of some key strategies for modifying the wettability of PDMS surfaces by providing the main traditional methods for this modification and the results of altering the contact angle and other characteristics associated with this property. Four main technologies are discussed, namely, oxygen plasma treatment, surfactant addition, UV-ozone treatment, and the incorporation of nanomaterials, as these traditional methods are commonly selected due to the greater availability of information, their lower complexity compared to the new techniques, and the lower cost associated with them. Oxygen plasma treatment is a widely used method for improving the hydrophilicity of PDMS surfaces by introducing polar functional groups through oxidation reactions. The addition of surfactants provides a versatile method for altering the wettability of PDMS, where the selection and concentration of the surfactant play an important role in achieving the desired surface properties. UV-ozone treatment is an effective method for increasing the surface energy of PDMS, inducing oxidation, and generating hydrophilic functional groups. Furthermore, the incorporation of nanomaterials into PDMS matrices represents a promising route for modifying wettability, providing adjustable surface properties through controlled dispersion and interfacial interactions. The synergistic effect of nanomaterials, such as nanoparticles and nanotubes, helps to improve wetting behaviour and surface energy. The present review discusses recent advances of each technique and highlights their underlying mechanisms, advantages, and limitations. Additionally, promising trends and future prospects for surface modification of PDMS are discussed, and the importance of tailoring wettability for applications ranging from microfluidics to biomedical devices is highlighted. Traditional methods are often chosen to modify the wettability of the PDMS surface because they have more information available in the literature, are less complex than new techniques, and are also less expensive. [ABSTRACT FROM AUTHOR]

This work showcases the production of flexible polydimethylsiloxane/multiwalled carbon nanotube (PDMS/MWCNT) composites with multilayer structures via the glucose template method followed by vacuum‐assisted filtration and hot pressing. The properties of the single‐layer and multilayer composites have been systematically investigated. In the X‐band, thanks to the ohmic loss, the interfacial polarization loss at the interfaces and the multiple reflections between PDMS/MWCNT layers, the 5‐layer PDMS/MWCNT composites achieves 65.9 dB. Furthermore, all multilayer PDMS/MWCNT composites present a high retention rate of about of 90% after repeated bending with curvature radius of 1.8 mm at a frequency of 1 cycle per 2 s for 1000 times. Highlights: The PDMS/MWCNT composites are fabricated by the glucose template method.The 5‐layer PDMS/MWCNT composites can reach 65.9 dB in X‐band.The PDMS/MWCNT composites present high stability even after repeated bending. [ABSTRACT FROM AUTHOR]

With the increasing awareness of marine ecological environment, biocide-free marine antifouling coatings have been gaining increased attention in the field of marine antifouling. Among all the antifouling approaches, constructing fouling-release coatings (FRCs) may be the most effective and economical way caused by the biocide-free. However, the low mechanical strength, weak adhesion to substrates, and poor static fouling resistance of traditional silicone-based FRCs, which limiting their applications. In this work, we synthesized a polyurethane with hydroxyl terminated polydimethylsiloxane (PDMS), polytetrahydrofuran (PTMG) and isophorone diisocyanate (IPDI) as main chains, 2,2'-Bis (hydroxymethyl)butyric acid (DMBA) as chain extender, and γ-aminopropyl triethoxysilane (KH-550) as crosslinker by condensation polymerization. Meanwhile, Triclosan (TCS) was used as an antibacterial agent and mixed into the polymer system with uniformly dispersed. We introduced urethane groups into silicone, which improved the mechanical strength (ultimate tensile strength: 1.379 MPa, elongation at break: 282%). As a result, the laboratory bioassays using bacteria (E. coli, and S. aureus) showed that the anti-bacterial efficiency could respectively reach ∼95% and ∼93%, which demonstrated an outstanding antifouling property of the D:K = 0.7:1.3/1.0. This work overcomes the low strength issue of traditional fouling-release coatings and provides a simple strategy for silicone-based polyurethane antifouling coatings. [ABSTRACT FROM AUTHOR]

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Adhesives with excellent adhesion and high elongation at cryogenic temperatures are necessary for fields such as aerospace, transportation, superconductors, and medicine, but have difficult requirements. This study aimed to develop a solvent-free, two-component polyurethane (PU) adhesive with excellent adhesion and high elongation, especially in ultra-low temperature conditions. we incorporated bulky polydimethylsiloxane (PDMS) diol into the hard segment of the PU adhesive to enhance flexibility and improve physical cross-linking within the adhesive matrix. The resulting PDMS-based PU adhesive showed a tensile strength of 120 MPa at −170 °C and a high elongation of approximately 4 %. It showed a lap-shear strength of up to 13 MPa at −196 °C. Additionally, the adhesive was curable at 23 °C. In this study, the cryogenic applicability of the PU adhesive was evaluated at −170 °C (103 K, liquid natural gas) and −196 °C (77 K, liquid nitrogen). Future research on the polymer adhesive materials applicable to ultra-low temperatures, such as 20 K, may be necessary if storage and transportation of liquid hydrogen become feasible.

The majority of crack sensors do not offer simultaneously both a significant stretchability and an ultrahigh sensitivity. In this study, we present a straightforward and cost-effective approach to fabricate metal crack sensors that exhibit exceptional performance in terms of ultrahigh sensitivity and ultrahigh stretchability. This is achieved by incorporating a helical structure into the substrate through a modeling process and, subsequently, depositing a thin film of gold onto the polydimethylsiloxane substrate via sputter deposition. The metal thin film is then pre-stretched to generate microcracks. The sensor demonstrates a remarkable stretchability of 300%, an exceptional sensitivity with a maximum gauge factor reaching 107, a rapid response time of 158 ms, minimal hysteresis, and outstanding durability. These impressive attributes are attributed to the deliberate design of geometric structures and careful selection of connection types for the sensing materials, thereby presenting a novel approach to fabricating stretchable and highly sensitive crack-strain sensors. This work offers a universal platform for constructing strain sensors with both high sensitivity and stretchability, showing a far-reaching significance and influence for developing next-generation practically applicable soft electronics.

This study presents the synthesis and characterization of hexadecyl-modified SiO2 (HD-SiO2) nanoparticles and their application in the fabrication of a multilayered elastomer hybrid sheet to enhance water resistance in implantable biomedical devices. The surface modification of SiO2 nanoparticles was confirmed via FT-IR and TGA analyses, showing the successful grafting of hydrophobic hexadecyl groups. FE-SEM and DLS analyses revealed spherical HD-SiO2 nanoparticles with an average size of 360 nm. A multilayered elastomer hybrid sheet, consisting of a PDMS-based circuit-protecting body, a water resistance layer of HD-SiO2, a planarization layer, and a biocompatible layer of polydopamine, was fabricated and characterized. The water resistance layer exhibited superhydrophobic properties, with a water contact angle of 154.7° and a 27% reduction in water vapor transmission rate (WVTR) compared to the circuit-protecting body alone. The device packaged with both the circuit-protecting body and water resistance layer demonstrated a tenfold increase in operational lifespan in water medium compared to the device without the water resistance layer. Cytotoxicity and cell proliferation tests on human dermal fibroblast cells (HDFn) confirmed the biocompatibility of the multilayered sheet, with no significant cytotoxicity observed over 48 h.

Direct ink writing (DIW) is a rapidly expanding additive manufacturing (AM) technique valued for its cost-efficiency and material adaptability. While DIW offers substantial process flexibility, achieving precise manufacturing demands a thorough understanding of its printability parameters. Key process variables such as printing speed, nozzle-bed gap, pulses for extrusion, and extrusion multiplier wield significant influence over the shape and dimensions of printed components. In this study, a machine learning model based on k-nearest neighbors is employed to predict dimensional accuracy. The model is trained using measured width and thickness data from printed rings, with flow and printing-speed tests defining parameter boundaries for printing. The final model demonstrates an accuracy of 81% and 74% for two PDMS-CNT composite ink compositions. The principal components analysis underscores the pivotal roles of the extrusion factor and printing speed in achieving superior geometric fidelity. Additionally, retraction-residual tests were conducted, revealing that the initial 10 seconds of extrusion hold critical importance as they can lead to distortions when traversing printed regions or perimeters, necessitating consideration in part design. To evaluate layer adhesion strength, a crucial aspect of AM, T-peel tests were performed. Furthermore, rheological tests provided insights into extrudability, printable reinforcing percentages, shape retention, and yield stress. Highlights • Rheological tests yield insights into minimum reinforcing% and shape retention. • Developed k-NN model predicts accuracy using measured printed rings' data. • PC analysis shows key roles of extrusion factor and print speed. • Retraction-residual tests reveal initial 10 seconds are critical. • Model validation results show 83.45% and 77.95% accuracy, close to prediction. [ABSTRACT FROM AUTHOR]

Recently, the manufacturing of porous polydimethylsiloxane (PDMS) with engineered porosity has gained considerable interest due to its tunable material properties and diverse applications. An innovative approach to control the porosity of PDMS is to use transient liquid phase water to improve its mechanical properties, which has been explored in this work. Adjusting the ratios of deionized water to the PDMS precursor during blending and subsequent curing processes allows for controlled porosity, yielding water emulsion foam with tailored properties. The PDMS-to-water weight ratios were engineered ranging from 100:0 to 10:90, with the 65:35 specimen exhibiting the best mechanical properties with a Young's Modulus of 1.17 MPa, energy absorption of 0.33 MPa, and compressive strength of 3.50 MPa. This led to a porous sample exhibiting a 31.46% increase in the modulus of elasticity over a bulk PDMS sample. Dowsil SE 1700 was then added, improving the storage capabilities of the precursor. The optimal storage temperature was probed, with −60 °C resulting in great pore stability throughout a three-week duration. The possibility of using these water emulsion foams for paste extrusion additive manufacturing (AM) was also analyzed by implementing a rheological modifier, fumed silica. Fumed silica's impact on viscosity was examined, revealing that 9 wt% of silica demonstrates optimal rheological behaviors for AM, bearing a viscosity of 10,290 Pa·s while demonstrating shear-thinning and thixotropic behavior. This study suggests that water can be used as pore-formers for PDMS in conjunction with AM to produce engineered materials and structures for aerospace, medical, and defense industries as sensors, microfluidic devices, and lightweight structures. [ABSTRACT FROM AUTHOR]

Microphysiological systems (MPSs) are promising in vitro technologies for physiologically relevant predictions of the human absorption, distribution, metabolism, and excretion (ADME) properties of drug candidates. However, polydimethylsiloxane (PDMS), a common material used in MPSs, can both adsorb and absorb small molecules, thereby compromising experimental results. This study aimed to evaluate the feasibility of using the PDMS-based Emulate gut-on-chip to determine the first-pass intestinal drug clearance. In cell-free PDMS organ-chips, we assessed the loss of 17 drugs, among which testosterone was selected as a model compound for further study based on its substantial ad- and absorptions to organ chips and its extensive first-pass intestinal metabolism with well-characterized metabolites. A gut-on-chip model consisting of epithelial Caco-2 cells and primary human umbilical vein endothelial cells (HUVECs) was established. The barrier integrity of the model was tested with reference compounds and inhibition of drug efflux. Concentration–time profiles of testosterone were measured in cell-free organ chips and in gut-on-chip models. A method to deduce the metabolic clearance was provided. Our results demonstrate that metabolic clearance can be determined with PDMS-based MPSs despite substantial compound loss to the chip. Overall, this study offers a practical protocol to experimentally assess ADME properties in PDMS-based MPSs. [ABSTRACT FROM AUTHOR]

Incorporation of bovine serum-derived albumin formulation (AlbuMAX) into a basic culture medium, MEMa, enables the completion of in vitro spermatogenesis through testicular tissue culture in mice. However, this medium was not effective in other animals. Therefore, we sought an alternative approach for in vitro spermatogenesis using a synthetic medium without AlbuMAX and aimed to identify its essential components. In addition to factors known to be important for spermatogenesis, such as retinoic acid and reproductive hormones, we found that antioxidants (vitamin E, vitamin C, and glutathione) and lysophospholipids are vital for in vitro spermatogenesis. Moreover, based on our experience with microfluidic devices (MFD), we developed an alternative approach, the PDMS-ceiling method (PC method), which involves simply covering the tissue with a flat chip made of PDMS, a silicone resin material used in MFD. The PC method, while straightforward, integrates the advantages of MFD, enabling improved and uniform oxygen and nutrient supply via tissue flattening. Furthermore, our studies underscored the significance of lowering the oxygen concentration to 10-15%. Using an integrated cultivation method based on these findings, we successfully achieved in vitro spermatogenesis in rats, which has been a long-standing challenge. Further improvements in culture conditions would pave the way for spermatogenesis completion in diverse animal species. [ABSTRACT FROM AUTHOR]

Measuring elasticity without physical contact is challenging, as current methods often require deconstruction of the test sample. This study addresses this challenge by proposing and testing a photoacoustic effect-based method for measuring the elasticity of polydimethylsiloxane (PDMS) at various mixing ratios, which may be applied on the wide range of applications such as biomedical and optical fields. A dual-light laser source of the photoacoustic (PA) system is designed, employing cross-correlation signal processing techniques. The platform systems and a mathematical model for performing PDMS elasticity measurements are constructed. During elasticity detection, photoacoustic signal features, influenced by hardness and shapes, are analyzed using cross-correlation calculations and phase difference detection. Results from phantom tests demonstrate the potential of predicting Young's modulus using the cross-correlation method, aligning with the American Society for Testing and Materials (ASTM) standard samples. However, accuracy may be affected by mixed materials and short tubes. Normalization or calibration of signals is suggested for aligning with Young's coefficient.

Incorporation of bovine serum-derived albumin formulation (AlbuMAX) into a basic culture medium, MEMα, enables the completion of in vitro spermatogenesis through testicular tissue culture in mice. However, this medium was not effective in other animals. Therefore, we sought an alternative approach for in vitro spermatogenesis using a synthetic medium without AlbuMAX and aimed to identify its essential components. In addition to factors known to be important for spermatogenesis, such as retinoic acid and reproductive hormones, we found that antioxidants (vitamin E, vitamin C, and glutathione) and lysophospholipids are vital for in vitro spermatogenesis. Moreover, based on our experience with microfluidic devices (MFD), we developed an alternative approach, the PDMS-ceiling method (PC method), which involves simply covering the tissue with a flat chip made of PDMS, a silicone resin material used in MFD. The PC method, while straightforward, integrates the advantages of MFD, enabling improved and uniform oxygen and nutrient supply via tissue flattening. Furthermore, our studies underscored the significance of lowering the oxygen concentration to 10–15%. Using an integrated cultivation method based on these findings, we successfully achieved in vitro spermatogenesis in rats, which has been a long-standing challenge. Further improvements in culture conditions would pave the way for spermatogenesis completion in diverse animal species.

In recent years, flexible pressure sensors have garnered significant attention. However, the development of large-area, low-cost, and easily fabricated flexible pressure sensors remains challenging. We designed a flexible fiber optic pressure sensor for contact force detection based on the principle of backward Rayleigh scattering using a single-mode optical fiber as the sensing element and polymer PDMS as the encapsulation material. To enhance the sensor’s sensitivity and stability, we optimized its structural design, parameters, and fabrication process and measured the fiber strain using an optical frequency domain reflectometer (OFDR). The results showed that the sensor achieved a high sensitivity of 6.93247 με/kPa with a PDMS concentration ratio of 10:1, a curing time of 2 h, and a substrate thickness of 5 mm. The sensor demonstrated excellent linearity and repeatability in static performance tests and was successfully used to monitor the plantar pressure distribution in real time. This flexible fiber optic pressure sensor can be developed via a simple fabrication process, has a low cost, and has high sensitivity, highlighting its potential applications in smart wearables and medical diagnostics.

Amniotic membrane (AM) is an effective and widely used dressing in ocular injuries to reconstruct the cornea. Due to its low mechanical strength, high biodegradation rate, and difficult handling, its usage in medical interventions remains challenging. In this study, decellularized AM was covered with an ultrathin layer of Polydimethylsiloxane (PDMS) through a spinning method, which in turn resulted in an ultrathin (less than 80 µm in thickness) bilayer corneal wound dressing membrane with improved mechanical behavior and transparency. The biomechanical, biological, and antibacterial properties of the bilayer membranes were measured both in vitro and in vivo. The optimized microsized membrane was applied on a corneal defect wound created in a rabbit model to evaluate the corneal healing. The results demonstrated a significant decrease in degradation rate, improved mechanical properties, and AM/PDMS transparency compared with AM. The corneal transparency improved until 21 days post-surgery in AM/PDMS group. Histological evaluations revealed that AM/PDMS had better epithelial delaminated cell morphology. The results of the RT-PCR showed a significant increase in MMP9, a significant decrease in Col1A1, TGF-β1, TNF-α and IL-6 in both AM and AM/PDMS compared with control wounds. This study suggessts AM/PDMS membrane as an excellent corneal wound dressing.

The microfluidic droplet polymerase chain reaction (PCR), which enables simultaneous DNA amplification in numerous droplets, has led to the discovery of various applications that were previously deemed unattainable. Decades ago, it was demonstrated that the temperature holding periods at the denaturation and annealing stages in thermal cycles for PCR amplification could be essentially eliminated if a rapid change of temperature for an entire PCR mixture was achieved. Microfluidic devices facilitating the application of such fast thermocycling protocols have significantly reduced the time required for PCR. However, in microfluidic droplet PCR, ensuring successful amplification from single molecules within droplets has limited studies on accelerating assays through fast thermocycling. Our developed microfluidic cartridge, distinguished for its convenience in executing single-molecule droplet PCR with common laboratory equipment, features droplets positioned on a thin glass slide. We hypothesized that applying fast thermocycling to this cartridge would achieve single-molecule droplet PCR amplification. Indeed, the application of this fast protocol demonstrated successful amplification in just 22 min for 30 cycles (40 s/cycle). This breakthrough is noteworthy for its potential to expedite microfluidic droplet PCR assays, ensuring efficient single-molecule amplification within a remarkably short timeframe. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS)—the simplest and most common silicone compound—exemplifies the central characteristics of its class and has attracted tremendous research attention. The development of PDMS‐based materials is a vivid reflection of the modern industry. In recent years, PDMS has stood out as the material of choice for various emerging technologies. The rapid improvement in bulk modification strategies and multifunctional surfaces has enabled a whole new generation of PDMS‐based materials and devices, facilitating, and even transforming enormous applications, including flexible electronics, superwetting surfaces, soft actuators, wearable and implantable sensors, biomedicals, and autonomous robotics. This paper reviews the latest advances in the field of PDMS‐based functional materials, with a focus on the added functionality and their use as programmable materials for smart devices. Recent breakthroughs regarding instant crosslinking and additive manufacturing are featured, and exciting opportunities for future research are highlighted. This review provides a quick entrance to this rapidly evolving field and will help guide the rational design of next‐generation soft materials and devices. [ABSTRACT FROM AUTHOR]

Wearable photodetectors have emerged in recent years offering a wide range of applications such as environmental monitoring, health care, and security systems. Here, we present a method for producing a polymer-based ultraviolet photodetector (UV-PD) using enhanced networked 1D nanostructure semiconductors that are rubbery and intrinsically stretchable. We fabricated a metal–semiconductor–metal (MSM) UV-PD from ZnO nanostructures embedded in polydimethylsiloxane (PDMS). The fabricated devices exhibited excellent mechanical durability, tolerating stretching of up to 100% without any structural deformation within the nanostructure network or even the electrodes. Current–voltage measurements, carried out after multiple bending cycles followed by stretching, showed no significant change, indicating electrical stability under harsh mechanical conditions. The electrical characteristics of the ZnO PD showed a remarkable enhancement after adding silver. We demonstrate that UV-PD with the employment of the ZnO/Ag (SZO) nanostructure increased the measured detectivity. The responsivities of ZnO and SZO nanorod-based PDs are approximately 15.73 (mA/W) and 17.30 (mA/W) at 5 V bias under 57 μW illumination, respectively. The reproducibility of the SZO PD is verified through transient response measurements under different illumination powers. This research not only indicates that Ag-doping can improve the ZnO nanostructures-based PDs but also proposes a promising method for fabricating cost-effective, highly stretchable/flexible MSM PDs with interdigitated electrodes on rubbery polymers, shedding light on future practical wearable photodetector devices. [ABSTRACT FROM AUTHOR]

We present an advanced, low-cost 3D printing system capable of fabricating intricate silicone structures using commercially available off-the-shelf materials. Our system used a custom-designed, motorised syringe pump with a driving lead screw and excellent control of material extrusion to accommodate the high viscosity of silicone printing ink, which is composed of polydimethylsiloxane (PDMS), diluent, and a photo-initiator (LAP). We modified an open-source desktop 3D printer to mount the syringe pump and programmed it to deposit controlled intricate patterns in a layer-by-layer fashion. To ensure the structural integrity of the printed objects, we introduced an intra-layer curing approach that fused the deposited layers using a custom-built UV curing system. Our experiments demonstrated the successful fabrication of silicone structures at different infill percentages, with excellent resolution and mechanical properties. Our low-cost solution (costing less than USD 1000 and requiring no specialised facilities or equipment) shows great promise for practical applications in areas such as micro-fluidics, prosthesis, and biomedical engineering based on our initial findings of 300 μ m width channels (with excellent scope for smaller channels where desirable) and tunable structural properties. Our work represents a significant advance in low-cost desktop 3D printing capabilities, and we anticipate that it could have a broad impact on the field by providing these capabilities to scholars without the means to purchase expensive fabrication systems. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) is a popular material to rapidly manufacture microfluidic deterministic lateral displacement (DLD) devices for particle separation. However, manufacturing and operation challenges are encountered with decreasing device dimensions required to separate submicron particles. The smaller dimensions, notably, cause high hydraulic resistance, resulting in significant pressure even at relatively low throughputs. This high pressure can lead to PDMS deformation, which, in turn, influences the device performance. These effects may often be overlooked in the design and operation of devices but provide a systematic source of error and inaccuracies. This study focuses in detail on these effects and investigates pillar deformation in detail. Subsequently, we discuss a potential solution to this deformation using thermal annealing to stiffen the PDMS. We evaluate the influence of stiffness on the separation performance at elevated sample flow rates with submicron particles (0.45 and 0.97 µm diameter). An excellent separation performance at high throughput is successfully maintained in stiffer PDMS-based DLD devices, while the conventional devices showed decreased separation performance. However, the increased propensity for delamination constrains the maximal applicable throughput in stiffer devices. PDMS deformation measurements and numerical simulations are combined to derive an iterative model for calculating pressure distribution and PDMS deformation. Finally, the observed separation characteristics and encountered throughput constraints are explained with the iterative model. The results in this study underline the importance of considering pressure-induced effects for PDMS-based DLD devices, provide a potential mitigation of this effect, and introduce an approach for estimating pressure-induced deformation. [ABSTRACT FROM AUTHOR]

Microfluidics evolved with the appearance of polydimethylsiloxane (PDMS), an elastomer with a short processing time and the possibility for replication on a micrometric scale. Despite the many advantages of PDMS, there are well-known drawbacks, such as the hydrophobic surface, the absorption of small molecules, the low stiffness, relatively high cost, and the difficulty of scaling up the fabrication process for industrial production, creating a need for alternative materials. One option is the use of stiffer thermoplastics, such as the cyclic olefin copolymer (COC), which can be mass produced, have lower cost and possess excellent properties. In this work, a method to fabricate COC microfluidic structures was developed. The work was divided into process optimization and evaluation of material properties for application in microfluidics. In the processing step, moulding, sealing, and liquid handling aspects were developed and optimized. The resulting COC devices were evaluated from the point of view of molecular diffusion, burst pressure, temperature resistance, and susceptibility to surface treatments and these results were compared to PDMS devices. Lastly, a target DNA hybridization assay was performed showing the potential of the COC-based microfluidic device to be used in biosensing and Lab-on-a-Chip applications. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) has attracted great attention in various fields due to its excellent properties, but its inherent hydrophobicity presents challenges in many applications that require controlled wettability. The purpose of this review is to provide a comprehensive overview of some key strategies for modifying the wettability of PDMS surfaces by providing the main traditional methods for this modification and the results of altering the contact angle and other characteristics associated with this property. Four main technologies are discussed, namely, oxygen plasma treatment, surfactant addition, UV-ozone treatment, and the incorporation of nanomaterials, as these traditional methods are commonly selected due to the greater availability of information, their lower complexity compared to the new techniques, and the lower cost associated with them. Oxygen plasma treatment is a widely used method for improving the hydrophilicity of PDMS surfaces by introducing polar functional groups through oxidation reactions. The addition of surfactants provides a versatile method for altering the wettability of PDMS, where the selection and concentration of the surfactant play an important role in achieving the desired surface properties. UV-ozone treatment is an effective method for increasing the surface energy of PDMS, inducing oxidation, and generating hydrophilic functional groups. Furthermore, the incorporation of nanomaterials into PDMS matrices represents a promising route for modifying wettability, providing adjustable surface properties through controlled dispersion and interfacial interactions. The synergistic effect of nanomaterials, such as nanoparticles and nanotubes, helps to improve wetting behaviour and surface energy. The present review discusses recent advances of each technique and highlights their underlying mechanisms, advantages, and limitations. Additionally, promising trends and future prospects for surface modification of PDMS are discussed, and the importance of tailoring wettability for applications ranging from microfluidics to biomedical devices is highlighted. Traditional methods are often chosen to modify the wettability of the PDMS surface because they have more information available in the literature, are less complex than new techniques, and are also less expensive.

Abstract Polydimethylsiloxane (PDMS)—the simplest and most common silicone compound—exemplifies the central characteristics of its class and has attracted tremendous research attention. The development of PDMS‐based materials is a vivid reflection of the modern industry. In recent years, PDMS has stood out as the material of choice for various emerging technologies. The rapid improvement in bulk modification strategies and multifunctional surfaces has enabled a whole new generation of PDMS‐based materials and devices, facilitating, and even transforming enormous applications, including flexible electronics, superwetting surfaces, soft actuators, wearable and implantable sensors, biomedicals, and autonomous robotics. This paper reviews the latest advances in the field of PDMS‐based functional materials, with a focus on the added functionality and their use as programmable materials for smart devices. Recent breakthroughs regarding instant crosslinking and additive manufacturing are featured, and exciting opportunities for future research are highlighted. This review provides a quick entrance to this rapidly evolving field and will help guide the rational design of next‐generation soft materials and devices.

Oral delivery of macromolecules remains highly challenging due to their rapid degradation in the gastrointestinal tract and poor absorption across the tight junctions of the epithelium. In the last decade, researchers have investigated several medical devices to overcome these challenges using various approaches, some of which involve piercing through the intestine using micro and macro needles. We have developed a new generation of medical devices called self-unfolding proximity enabling devices, which makes it possible to orally deliver macromolecules without perforating the intestine. These devices protect macromolecules from the harsh conditions in the stomach and release their active pharmaceutical ingredients in the vicinity of the intestinal epithelium. One device version is a self-unfolding foil that we have used to deliver insulin and nisin to rats and pigs respectively. In our study, this device has shown a great potential for delivering peptides, with a significant increase in the absorption of solid dosage of insulin by ∼12 times and nisin by ∼4 times in rats and pigs, respectively. With the ability to load solid dosage forms, our devices can facilitate enhanced absorption of minimally invasive oral macromolecule formulations. [Display omitted] • Advancing oral delivery: optimizing self-unfolding foil (SUF) as an effective oral delivery device for macromolecules • Enhanced visualization: incorporating contrast materials for in vivo tracking of SUFs • Boosting insulin bioavailability in rats: achieving 12-fold increase using SUFs • Scaling up success: optimizing SUFs for efficient oral delivery device in large animals • Maximizing nisin bioavailability: a 4-fold increase was achieved by oral administration of SUFs in pigs [ABSTRACT FROM AUTHOR]

This work investigates the friction between polydimethylsiloxane (PDMS) and silicon oxide (SiOx) in single asperity sliding contact by atomic force microscopy (AFM). Two friction dependences on the normal force are identified: a tensile regime and a compressive regime of normal forces. In the compressive regime, friction is governed by the shear deformation and rupture of junctions between PDMS and SiOx. In this case, the shear strength τ ≈ 10 MPa is comparable with the cohesive strength of PDMS under compressive loading. In contrast, friction in the tensile regime is also affected by the elongation of the junctions. The single SiOx-asperity follows a stick-slip motion on PDMS in both normal force regimes. Statistical analysis of stick-slip as a function of the normal force allows determining the necessary amount of energy to break a SiOx/PDMS junction. Friction between a SiOx-asperity and a PDMS surface can be rationalized based on an energy criterion for the deformation and slippage of nanometer-scale junctions. [ABSTRACT FROM AUTHOR]

Silicone is already widely used in biomedical applications thanks to its outstanding properties. Now additive manufacturing (AM) of silicone can achieve submillimeter details and is offered by SpectroPlast AG as a service. AM of silicone is particularly interesting for designs with complex internal structures such as bioreactors or oxygenators where oxygen permeability is important. Therefore, the oxygen permeability of additively manufactured silicone membranes made from TrueSil (SpectroPlast AG) is studied. Measurements are performed with two membrane thicknesses (0.5 and 0.8 mm) and four different Shore hardnesses (20A, 35A, 50A, and 60A) at 15, 20, and 25°C. The oxygen increase due to diffusion through the membrane is recorded In a cup sealed by the membrane. The oxygen permeability decreases with increasing Shore hardness. TrueSil 20A is comparable to ELASTOSIL® Film (Wacker Chemie AG) in terms of oxygen permeability. However, there is a percentage difference of approximately 27% between the measured permeability of ELASTOSIL® and the data from the supplier. Membrane thickness does not affect permeability, but the Shore hardness affects the thickness. Membranes with Shore hardness 20A or 35A are manufactured over 0.1 mm thicker than designed, while for Shore hardness 50A and 60A the deviation from the design is less than 0.04 mm. [ABSTRACT FROM AUTHOR]

In this study, we demonstrated organic light-emitting diodes (OLEDs) outcoupling with a flexible polydimethylsiloxane (PDMS) film with a micro-convex structure using the breath figure (BF) method. We can easily control the micro-convex pattern by adjusting the concentration of polystyrene and the humidity during the BF process. As process conditions to fabricate the micro-convex structure, polymer concentrations of 10, 20, 40, and 80 mg/mL and 60, 70, and 80% relative humidity were used. To evaluate the optical properties, we analyzed the transmission, diffusion, and electroluminescence with or without the micro-convex structure on the OLEDs. The shape and density of the micro-convex structure are related to its optical properties and outcoupling and we have experimentally demonstrated this. By applying a micro-convex structure, it achieved up to a 42% improvement in the external quantum efficiency compared to bare OLEDs (without any light extraction film). We expect the fabricated flexible light extraction film to be effective for outcoupling and applicable to flexible devices. [ABSTRACT FROM AUTHOR]

The development of biofuels and the question of finding renewable energy sources are important issues nowadays, due to the increasing shortage of other supplies. Hydrogen has gained very much attention as biofuel, as it is highly energetic and a clean energy source. A very interesting method to produce hydrogen is dark fermentation. It generates a clean energy from organic wastes with low value and at low energy requirements. The production of hydrogen and bio-hydrogen from waste and wastewaters can have a positive environmental impact in terms of creation of highly effective energy fuel and reduction of waste. Due to their nutrients, organic waste and wastewaters are suitable substrates to obtain bio-hydrogen. In this paper we investigate the behaviour and the stability of porous scaffolds containing iron oxide particles in a dark fermentation environment and explore the possibility of hosting mixed cultures of clostridia on them, aiming to an increase in hydrogen production. We address the effect of embedding hematite particles (in different concentrations) in the scaffolds, to see whether there is an increase in bio-hydrogen-production. This latter can be enhanced, if particles of various metal oxides are present, as they can increase bacterial growth and encourage the bioactivity of species that produce hydrogen. The scaffolds analysed consist of polydimethylsiloxane (PDMS) containing Fe 2 O 3 particles and were produced via the sugar template method. X-ray diffraction patterns, SEM images as well as dark fermentation tests in batch procedure are presented and discussed. Bacteria colonies could be detected after long treatment in municipal wastewater and production of biohydrogen was ascertained for all samples investigated. [Display omitted] • Porous foams made of polydimethylsiloxane were used as catalysts in dark fermentation. • Hydrogen production could be detected in porous foams containing bacteria. • Polymer foams hosting bacteria did not deteriorate during treatment in wastewater. [ABSTRACT FROM AUTHOR]

Abstract This work investigates the friction between polydimethylsiloxane (PDMS) and silicon oxide (SiOx) in single asperity sliding contact by atomic force microscopy (AFM). Two friction dependences on the normal force are identified: a tensile regime and a compressive regime of normal forces. In the compressive regime, friction is governed by the shear deformation and rupture of junctions between PDMS and SiO x . In this case, the shear strength τ ≈ 10 MPa is comparable with the cohesive strength of PDMS under compressive loading. In contrast, friction in the tensile regime is also affected by the elongation of the junctions. The single SiO x -asperity follows a stick-slip motion on PDMS in both normal force regimes. Statistical analysis of stick-slip as a function of the normal force allows determining the necessary amount of energy to break a SiO x /PDMS junction. Friction between a SiO x -asperity and a PDMS surface can be rationalized based on an energy criterion for the deformation and slippage of nanometer-scale junctions.