Coated Glass Surface Research Articles

Slide electrification of drops at low velocities.

Slide electrification of drops is mostly investigated on tilted plate setups. Hence, the drop charging at low sliding velocity remains unclear. We overcome the limitations by developing an electro drop friction force instrument (eDoFFI). Using eDoFFI, we investigate slide electrification at the onset of drop sliding and at low sliding velocities ≤ 1 cm s-1. The novelty of eDoFFI is the simultaneous measurements of the drop discharging current and the friction force acting on the drop. The eDoFFI tool facilitates control on drop length and width using differently shaped rings. Hereby, slide electrification experiments with the defined drop length-to-width ratios >1 and <1 are realized. We find that width of the drop is the main geometrical parameter which determines drop discharging current and charge separation. We combine Kawasaki-Furmidge friction force equation with our finding on drop discharging current. This combination facilitates the direct measurement of surface charge density (σ) deposited behind the drop. We calculate σ ≈ 45 μC m-2 on Trichloro(1H,1H,2H,2H-perfluorooctyl)silane (PFOTS) and ≈20 μC m-2 on Trichloro(octyl)silane (OTS) coated glass surfaces. We find that the charge separation by moving drops is independent of sliding velocity ≤ 1 cm s-1. The reverse sliding of drop along the same scanline facilitates calculation of the surface neutralization time constant. The eDoFFI links two scientific communities: one which focuses on the friction forces and one which focuses on the slide electrification of drops.

Picosecond Laser-Induced Bump Formation on Coated Glass for Smart Window Manufacturing

We report a study on the process of the formation of bubble-like structures on a coated glass surface using 50 ps laser pulses. The high-intensity interaction of laser radiation on the film–glass interface allowed us to develop a process for efficient glass bump formation. The high peak energy of the picosecond pulses has allowed us to merge the processes of coating evaporation and bubble growth into one. A parameter window was established within which efficient bump formation can be achieved. Well-defined spherical structures with a height up to 60 μm and a diameter up to 250 μm were obtained at pulse energy Epulse = 2.5 ÷ 4 μJ and laser fluence F = 2.5–0.41 J/cm2). The key aspects of the bump formation process were studied and are explained.

Thiol-ene click reaction as an effective tool for the synthesis of PEG-functionalized alkoxysilanes-precursors of anti-fog coatings

The article presents a very simple method of glass modification to obtain the anti-fog effect. Silanes containing two types of functional groups, namely a hydrophilic and polar polyether group and an alkoxysilyl group (to bond with the surface of the modified material) were synthesized in thiol-ene reactions. The hydrothiolation reactions of polyethers containing a C=C terminal bond with mercaptoalkoxysilane proceeded efficiently, yielding quantitatively appropriate products under mild reaction conditions. This method enabled the synthesis of a series of alkoxysilanes functionalized with polyethers, differing in structure. The group of obtained derivatives was characterized by 1H, 13C, 29Si NMR, and FT-IR analyses, and then used to prepare coatings on glass using the sol–gel method. The coated glass surfaces exhibited transparency, superhydrophilic or hydrophilic properties, anti-fog and anti-frost performance.

Tunable ultrafast thermionic emission from femtosecond-laser hot spot on a metal surface by control of laser polarization and angle of incidence: A numerical investigation

Ultrafast laser induced thermionic emission from metal surfaces has several applications. Here, we investigate the role of laser polarization and angle of incidence on the ultrafast thermionic emission process from laser driven gold coated glass surface. The spatio-temporal evolution of electron and lattice temperatures are obtained using an improved three-dimensional (3D) two-temperature model (TTM) which takes into account the 3D laser pulse profile focused obliquely onto the surface. The associated thermionic emission features are described through the modified Richardson-Dushman equation, including dynamic space-charge effects and are included self-consistently in our numerical approach. We show that temperature-dependent reflectivity influences laser energy absorption. The resulting peak electron temperature on the metal surface monotonically increases with the angle of incidence for the P polarization, while for the S polarization it shows the opposite trend. We observe that thermionic emission duration shows a strong dependence on the angle of incidence and contrasting polarization dependent behavior. The duration of the thermionic current shows strong correlation to the intrinsic electron-lattice thermalization time, in a fluence regime well below the damage threshold of gold. The observations and insights have important consequences in designing ultrafast thermionic emitters using a metal based architecture.

Surface decoration with leucine tetrapeptide: An antibacterial strategy against Gram-negative bacteria

Surface-associated microbe contamination by Gram-negative bacteria poses a serious problem in medical care. Cationic peptides or polymers are the main materials used for antibacterial surface coating, but the positive charge may lead to blood coagulation. Therefore, exploiting surface coating which is free of positive charge and is effective for Gram-negative bacteria inactivation is in urgent need. In this study, inspired by the affinity between lipopolysaccharides of Gram-negative bacteria and Toll-like receptors of immune cells, we develop a leucine-based tetrapeptide coating strategy for combating Gram-negative bacteria. The obtained surface has excellent bactericidal activity against Gram-negative bacteria like Pseudomonas aeruginosa and Escherichia coli. A 1 mm2 coated glass surface could kill > 9.9 × 104 CFU bacteria in 1 h and has nearly no damage to mammal cells. Moreover, this surface coating strategy could be applied on various surfaces like glass slices, glass capillary cavity and thermoplastic polyurethane slices. And the coated surface could largely mitigate the microbe contamination in an in vivo subcutaneous implantation. This work paves a new way for antibacterial surface-coating which is behaving no positive charge and is of great importance for biomedical devices.

Nanoparticle Coatings on Glass Surfaces to Prevent Pseudomonas fluorescens AR 11 Biofilm Formation.

Microbial colonization of surfaces is a sanitary and industrial issue for many applications, leading to product contamination and human infections. When microorganisms closely interact with a surface, they start to produce an exo-polysaccaridic matrix to adhere to and protect themselves from adverse environmental conditions. This type of structure is called a biofilm. The aim of our work is to investigate novel technologies able to prevent biofilm formation by surface coatings. We coated glass surfaces with melanin-ZnO2, melanin-TiO2, and TiO2 hybrid nanoparticles. The functionalization was performed using cold plasma to activate glass-substrate-coated surfaces, that were characterized by performing water and soybean oil wetting tests. A quantitative characterization of the antibiofilm properties was done using Pseudomonas fluorescens AR 11 as a model organism. Biofilm morphologies were observed using confocal laser scanning microscopy and image analysis techniques were used to obtain quantitative morphological parameters. The results highlight the efficacy of the proposed surface coating to prevent biofilm formation. Melanin-TiO2 proved to be the most efficient among the particles investigated. Our results can be a valuable support for future implementation of the technique proposed here in an extended range of applications that may include further testing on other strains and other support materials.

Spreading and retraction of the concentric impact of a drop with a sessile drop of the same liquid: Effect of surface wettability

The concentric impact on a sessile drop is relevant in many applications, including spray coating and icing phenomena. Herein, the spreading and retraction phases yielded during the impact of a coaxial drop with a sessile drop on a solid substrate were empirically and analytically examined. We analyzed the effects of surface wettability on the impact outcomes utilizing five distinctive surfaces (i.e., smooth glass, aluminum, copper, Teflon, and coated glass). The results showed that the merged drop takes longer to attain its maximum spreading diameter at a relatively higher contact angle of the sessile drop with the solid surface. Furthermore, based on energy balance, a model for predicting the maximum spreading diameter of the drop with varying surface wettability was presented. This model considers the assumption of viscous energy loss during the merging of falling and sessile drops and at the maximum spreading diameter. Additionally, the maximum retraction height during the impact on the coated glass surface was investigated. Our model results matched well with the experimental data.

A new black to highly transmissive switching bilayer polymer composite films with electroactive pEA as a color buffer layer for improving electrochromic stability

AbstractTwo reported D‐A‐D monomers based on 3,4‐ethylenedioxythiophene (EDOT) were selected for electrochemical copolymerization to obtain copolymer film, named pRG. Then, a soluble polymer poly[3,4‐ethylenedioxythiophene‐alt‐3,4‐bis([2‐ethylhexyl]oxy)thiophene] (pEA) based on the EDOT derivative was screened out, which is complementary to the absorption trough of the pRG film in visible region and matched with its working potential. The bilayer composite film pRG/pEA was obtained by spinning pEA basement membrane on fluorine doped tin oxide (FTO) coated glass surface, and then in situ electrochemical polymerization of pRG film. Compared to the pRG monolayer film, the bilayer composite film shows a more saturated black color in the neutral state and significant improvement on cyclic stability (only decreased by 1.7% after 250 cycles, while pRG film decreased by 17.1%). The introduction of pEA buffer layer not only achieves the full spectral absorption of the composite film in the visible region, but also significantly improves the cyclic stability of the bilayer composite film. The assembled EC prototype device based on the pRG/pEA composite film exhibits a “black to high transmission” reversible switch. Finally, this method combining electrochemical copolymerization, spin‐coating, lamination and other methods provides a new research idea for designing and preparing black to transmissive electrochromic materials.

UV- and Visible-Light Photopatterning of Molecular Gradients Using the Thiol–yne Click Reaction

The rational design of chemical coatings is used to control surface interactions with small molecules, biomolecules, nanoparticles, and liquids as well as optical and other properties. Specifically, micropatterned surface coatings have been used in a wide variety of applications, including biosensing, cell growth assays, multiplexed biomolecule interaction arrays, and responsive surfaces. Here, a maskless photopatterning process is studied, using the photocatalyzed thiol-yne "click" reaction to create both binary and gradient patterns on thiolated surfaces. Nearly defect-free patterns are produced by first coating glass surfaces with mercaptopropylsilatrane, a silanizing agent that forms smoother self-assembled monolayers than the commonly used 3-mercaptopropyltrimethoxysilane. Photopatterning is then performed using UV (365 nm) or visible (405 nm) light to graft molecules onto the surface in tunable concentrations based on the local exposure. The technique is demonstrated for multiple types of molecular grafts, including fluorescent dyes, poly(ethylene glycol), and biotin, the latter allowing subsequent deposition of biomolecules via biotin-avidin binding. Patterning is demonstrated in water and dimethylformamide, and the process is repeated to combine molecules soluble in different phases. The combination of arbitrary gradient formation, broad applicability, a low defect rate, and fast prototyping thanks to the maskless nature of the process creates a particularly powerful technique for molecular surface patterning that could be used for a wide variety of micropatterned applications.

Fabrication of TiO2 ̶ KH550 ̶ PEG Super-Hydrophilic Coating on Glass Surface without UV/Plasma Treatment for Self-Cleaning and Anti-Fogging Applications

In this study, we have developed a self-cleaning transparent coating on a glass substrate by dip coating a TiO2 – KH550 – PEG mixed solution with super-hydrophilicity and good antifogging properties. The fabrication of the thin-film-coated glass is a one-step solution blending method that is performed by depositing only one layer of modified TiO2 nanoparticles at room temperature. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine the structure and morphology of the nanoparticles and the thin-film-coated glass. The surface functional groups were investigated using Fourier-transform infrared spectroscopy (FT-IR), and the optical properties of the glass coating were measured using a UV/Vis spectrometer. The results revealed that the KH-500-modified TiO2 film coating was in an anatase crystalline form. The hydrophilicity of the coated and uncoated glass substrates was observed by measuring their water contact angle (WCA) using a contact angle instrument. The maximum transparency of the coated glass measured in the visible region (380–780 nm) was approximately 70%, and it possessed excellent super-hydrophilic properties (WCA ~0°) at an annealing temperature of 350 °C without further need of UV or plasma treatment. These results demonstrate the super-hydrophilic coated glass surface has potential for use in self-cleaning and anti-fogging applications.

Preparation, characterization and photocatalytic activity of novel 1,2,4-triazole based Cu(II) and Zn(II) phthalocyanines modified TiO2 nanoparticles

Hybrid organic-inorganic, photocatalytic nanocomposite coatings that containing novel 1,2,4-triazole based Cu(II) and Zn(II) phthalocyanines modified TiO2 nanoparticles were developed with the sol-gel process. Tetraethyl orthosilicate, 3-(glycidyloxypropyl)triethoxysilane and triethoxymethylsilane were used for hybrid polymer network. The phthalocyanines modified TiO2 nanoparticles prepared by the sol-gel method were added to the obtained hybrid polymer network at of 10%, 25%, and 50%, and the glass substrates were coated the obtained coating solutions by spray method. The photocatalytic activity, optical characterization, morphological and mechanical properties of the coated glass surfaces were examined. The adhesions of the obtained films were classified as 5B, and the pencil and newton hardness were > 9H and 2.6 N, respectively. This study acquired photocatalytic hybrid nanocomposite films that are highly transparent and do not have color changes and that also exhibit hight photocatalytic activitiy.

Digitally Driven Aerosol Jet Printing to Enable Customisable Neuronal Guidance.

Digitally driven manufacturing technologies such as aerosol jet printing (AJP) can make a significant contribution to enabling new capabilities in the field of tissue engineering disease modeling and drug screening. AJP is an emerging non-contact and mask-less printing process which has distinct advantages over other patterning technologies as it offers versatile, high-resolution, direct-write deposition of a variety of materials on planar and non-planar surfaces. This research demonstrates the ability of AJP to print digitally controlled patterns that influence neuronal guidance. These consist of patterned poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) tracks on both glass and poly(potassium 3-sulfopropyl methacrylate) (PKSPMA) coated glass surfaces, promoting selective adhesion of SH-SY5Y neuroblastoma cells. The cell attractive patterns had a maximum height ≥0.2 μm, width and half height ≥15 μm, Ra = 3.5 nm, and RMS = 4.1. The developed biocompatible PEDOT:PSS ink was shown to promote adhesion, growth and differentiation of SH-SY5Y neuronal cells. SH-SY5Y cells cultured directly onto these features exhibited increased nuclei and neuronal alignment on both substrates. In addition, the cell adhesion to the substrate was selective when cultured onto the PKSPMA surfaces resulting in a highly organized neural pattern. This demonstrated the ability to rapidly and flexibly realize intricate and accurate cell patterns by a computer controlled process.

Electrochemically activated laser-induced graphene coatings against marine biofouling

Biofouling can severely impact the function of devices in contact with sea- or brackish water. Laser-induced graphene (LIG) was previously discovered to resist bacterial attachment and when electrochemically activated to reduce their viability. Here we investigated the suitability of LIG and electrochemically activated LIG to counteract the attachment of marine organisms in high salinity media. We fabricated LIG on poly(ether)sulfone with optimized electrical conductivity and varied the wettability of the surfaces using atmospheric plasma and chemical modification. The superhydrophilic and superhydrophobic LIG surfaces were challenged with the marine bacterium Cobetia marina in a dynamic attachment assay, which showed that superhydrophobic LIG coatings are capable to resist bacteria accumulation. An extended biofilm growth experiment revealed that even unfunctionalized LIG coatings outperformed control gold coated glass surfaces modified with 1-dodecanthiol after 36 h by showing a reduced biofilm coverage. Electrochemical measurements performed under static conditions showed reduction of bacteria accumulation for potentials above +1.4 V. This effect was attributed to the formation of H2O2, which was detected at µM levels. The results underline the promising potential of LIG surface modification as method to counteract marine fouling.

Integrating microsphere resonator and ZnO nanorods coated glass for humidity sensing application

A humidity sensor is proposed by integrating a microsphere resonator onto ZnO nanorods coated glass surface. The glass substrate was coated with ZnO nanorods for 12 h using the hydrothermal method and the microsphere was set at a diameter of 234 µm. The proposed sensor produced sensitivity of 0.0748 dBm/%RH and 0.0142 nm/%RH when exposed to humidity level ranging from 35 %RH to 85 %RH. Standard deviation and resolution of the proposed sensor improve by a factor of 1.7 and 2.4 respectively as compared to the straight microfiber laid on the ZnO nanorods coated glass. It utilized the ultra-high Q factor of microsphere and the changeable refractive index of the ZnO nanorods coated glass. Combination of these elements enhanced the interaction between the whispering gallery mode evanescent components with surrounds analyte. It also solves the issues pertaining to the complicated handling of microfibers during the coating process. The proposed sensor has shown exceptional experiment results for humidity sensing applications.

Antibiofilm activity of Fmoc-phenylalanine against Gram-positive and Gram-negative bacterial biofilms.

Biofilm associated infections are the major contributor of mortality, morbidity and financial burden in patients with a bacterial infection. About 65% of all bacterial infections are associated with the information of bacterial biofilms. Bacterial biofilms not only reduce the efficacy of antibacterial treatment but also increases the threat of developing antibacterial resistance. Recently, our group has discovered the antibacterial activity of Fmoc-phenylalanine (Fmoc-F) and other Fmoc-amino acids (Fmoc-AA). Fmoc-F and other Fmoc-AA showed antibacterial activity due to their surfactant properties. Surfactants are known to eradicate biofilm and enhance antimicrobial activity in biofilm. Thus, in the present study, we evaluated the anti-biofilm activity of Fmoc-F against clinically relevant bacteria. We found that Fmoc-F not only inhibits the biofilm formation in Staphylococcus aureus and Pseudomonas aeruginosa, but also eradicates the already formed biofilms over the surface. Further, Fmoc-F coated glass surface resists S. aureus and P. aeruginosa biofilm formation and attachment, when biofilm is grown over the surface. The mechanistic investigation suggests that Fmoc-F reduces the extracellular matrix (ECM) components such as proteins, carbohydrates and eDNA in the biofilm and affect its stability via direct interactions with ECM components and/ or indirectly through reducing bacterial cell population. Finally, we showed that Fmoc-F treatment in combination with vancomycin and ampicillin synergistically inhibit biofilm formation. Overall, the study demonstrates the potential application of Fmoc-F and other Fmoc-AA molecules individually as well as in combination as anti-biofilm coating material for treating biofilm associated infections.

Formaldehyde sensor with enhanced performance using microsphere resonator-coupled ZnO nanorods coated glass

An enhanced formaldehyde (CH2O) sensor incorporating microsphere resonator and zinc oxide (ZnO) nanorods coated glass is reported. The microsphere resonator with a diameter of 234 µm and the ZnO nanorods coated glass surface was fabricated using the hydrothermal synthesis method for 12 h. A significant response to formaldehyde concentration levels ranging from 0 ppm to 0.18 ppm was observed. Sensitivity improves by a factor of 1.84 and 1.33 in terms of output power and wavelength shift, respectively, compared to straight microfiber laid on the ZnO coated glass substrate. It produces exceptionally good resolution with 0.0031 ppm as compared to its counterpart with 0.0058 ppm. The proposed formaldehyde sensor utilizes a high energy density behaviour of a microsphere resonator for evanescent field coupling with the surrounding analyte. It also possesses a robust chemisorption process on the ZnO nanorods surface to enhance the sensitivity towards formaldehyde vapour. Besides improving performance, it exhibits a simple approach that reduced the complexity to handle the microfiber during the synthesis process. This proposed technique has shown excellent experiment results for formaldehyde sensing applications.

Anti-wettability of Chemically and Physically Modified Glass Surfaces

The demand for new advanced functional materials has driven scientific work over the past decades. Nature has been inspiring in the creation of different types of self-cleaning and super repellent surfaces mimicking those of plants (lotus leaves), animals (shark skin) or insects (butterfly wings, water strider). To produce and maintain super repellent materials, chemical modification of the surface by using low surface energy materials such as fluoropolymers and/or siloxanes is necessary. Also, physical modification of surface roughness enhances super-repellency against various liquids. The surface roughness can be achieved e.g., by the deposition of nano particles (NPs) using Liquid Flame Spray (LFS). Industrial applications like paper coatings, oil-water separation, and microfluidic devices have benefited from the fabrication of super-hydrophobic surfaces by LFS. In our work, glass substrates were fluorinated by chemical vapor deposition (CVD) method, and others were additionally pre-coated with silica NPs by LFS. The coated glass surfaces were characterized for their anti-wettability by measuring the contact angles of water and compare that to bare glass. The influence of the produced coatings on the wettability of surface with different liquids was examined through measuring advancing/receding contact angles as well as the roll off angle. Results showed that compared to bare glass only fluorination of glass increased the water static contact angle from 18 to almost 112 . This is indicative of hydrophobic behaviour. Coating glass with silica NPs by LFS before fluorination, enhanced the water anti-wetting property for super hydrophobicity. LFS coating provided good oleophobic characteristic.

Integrated graphene quantum dot decorated functionalized nanosheet biosensor for mycotoxin detection.

Decoration of graphene quantum dots (GQDs) on molybdenum disulfide (MoS2) nanosheets serves as an active electrode material which enhances the electrochemical performance of the analyte detection system. Herein, ionic surfactant cetyltrimethylammonium bromide (CTAB)-exfoliated MoS2 nanosheets decorated with GQD material are used to construct an electrochemical biosensor for aflatoxin B1 (AFB1) detection. An antibody of AFB1 (aAFB1) was immobilized on the electrophoretically deposited MoS2@GQDs film on the indium tin oxide (ITO)-coated glass surface using a crosslinker for the fabrication of the biosensor. The immunosensing study investigated by the electrochemical method revealed a signal response in the range of 0.1 to 3.0ng/mL AFB1 concentration with a detection limit of 0.09ng/mL. Also, electrochemical parameters such as diffusion coefficient and heterogeneous electron transfer (HET) were calculated and found to be 1.67 × 10-5cm2/s and 2 × 10-5 cm/s, respectively. The effective conjugation of MoS2@GQDs that provides abundant exposed edge sites, large surface area, improved electrical conductivity, and electrocatalytic activity has led to an excellent biosensing performance with enhanced electrochemical parameters. Validation of the fabricated immunosensor was performed in a spiked maize sample, and a good percentage of recoveries within an acceptable range were obtained (80.2 to 98.3%).Graphical abstract.

Morphology, Structure, and Dynamics of Pentacene Thin Films and Their Nanocomposites with [C2 C1 im][NTf2 ] and [C2 C1 im][OTF] Ionic Liquids.

In this study, a homogeneous thin film growth of pentacene onto indium tin oxide (ITO) coated glass surfaces is explored using a high-resolution and reproducible vapor deposition methodology. Moreover, vacuum thermal evaporation of ionic liquids (ILs) ([C2 C1 im][NTf2 ] and [C2 C1 im][OTF]) onto ITO, gold/palladium (AuPd) and pentacene surfaces were performed. A greater wettability behavior of ILs is observed for surfaces containing AuPd. Sequential and simultaneous depositions of ILs and pentacene were explored. Simultaneous depositions lead to the formation of nanocomposites films, consisting of IL micro- and nanodroplets covered by pentacene layers. Plasma surface treatment was used to induce the ILs droplets coalescence and explore the dynamics and phase separation of the nanocomposites. The [C2 C1 im][OTF] droplets were found to be completely covered with pentacene, which suggests a great affinity between cation-anion pairs and the aromatic moiety. Pentacene films and their nanocomposites with ILs exhibit a typical optical band gap of Egap =1.77 eV, indicating that the nanocomposite phase domains are large enough to behavior as the bulk.

Humidity Effects on the Growth of ZnO Nanorods using Hydrothermal Method

The effects of ZnO nanorod samples with different growth times samples to the morphological structures and output light intensity are reported. The proposed structure comprises of silica microfiber integrated with Zinc Oxide (ZnO) nanorods coated glass surface. The silica microfiber is tapered into constant waist diameter of 10 μm using flame brushing technique. While the glass surface is coated with ZnO nanorods using hydrothermal method for 6 hours, 9 hours, 12 hours, 15 hours and 18 hours growth times. The samples are exposed to the different humidity levels ranging from 35%RH to 85%RH to observe the effect of the morphological structures such as length, diameter and density and the output light intensity. The resulted measurements provide the correlation between the growth time during the synthesis process to the ZnO nanorods physical structure as well as the output light intensity in different humidity levels. It utilizes the unique features of the scattering and surface absorption of the microfiber and ZnO nanomaterials coated glass surface to alter the output light intensity. The reported results may contribute to the optimal ZnO nanorods growth time for humidity sensing applications.