Search Results (22)

A novel two-in-one sensor for both carbon dioxide and hydrogen detection has been obtained based on a hybrid heterostructure. It consists of a 30 nm thick TiO₂ nanocrystalline film grown by atomic layer deposition (ALD), thermally annealed at 610 °C, and subsequently coated with bimetallic AgAu nanoparticles and covered with a PV4D4 nanolayer, which was thermally treated at 430 °C. Two types of gas response behaviors have been registered, as n-type for hydrogen gas and p-type semiconductor behavior for carbon dioxide gas detection. The highest response for carbon dioxide has been registered at an operating temperature of 150 °C with a value of 130%, while the highest response for hydrogen gas was registered at 350 °C with a value of 230%, although it also attained a relatively good gas selectivity at 150 °C. It is considered that a thermal annealing temperature of 610 °C is better for the properties of TiO₂ nanofilms, since it enhances gas sensor sensitivity too. Polymer coating on top is also believed to contribute to a higher influence on selectivity of the sensor structure. Accordingly, to our previous research where PV4D4 has been annealed at 450 °C, in this research paper, a lower temperature of 430 °C for annealing has been used, and thus another ratio of cyclocages and cyclorings has been obtained. Knowing that the polymer acts like a sieve atop the sensor structure, in this study it offers increased selectivity and sensitivity towards carbon dioxide gas detection, as well as maintaining a relatively increased selectivity for hydrogen gas detection, which works as expected with Ag and Au bimetallic nanoparticles on the surface of the sensing structure. The results obtained are highly important for biomedical and environmental applications, as well as for further development of the sensor industry, considering the high potential of two-in-one sensors. A carbon dioxide detector could be used for assessing respiratory markers in patients and monitoring the quality of the environment, while hydrogen could be used for both monitoring lactose intolerance and concentrations in cases of therapeutic gas, as well as monitoring the safe handling of various concentrations. Full article

Silver thin films are widely utilized in plasmonic, electronic, and catalytic devices due to their excellent conductivity, optical properties, and surface activity. However, the nanostructure and performance of Ag films are highly dependent on deposition parameters, particularly during radio-frequency magnetron sputtering (RF-MS). In this study, we systematically investigate the effects of RF power, sputtering time, and substrate type on the growth behavior, crystallinity, and electrical conductivity of Ag films. Optical emission spectroscopy (OES) and Langmuir probe diagnostics were employed to analyze the plasma environment, revealing the evolution of electron temperature and plasma density with varying RF powers. Structural characterizations using XRD, SEM, and AFM demonstrate that higher RF power results in reduced grain size, increased film density, and improved crystallinity, while deposition time influences film thickness and grain coalescence. Substrate material also plays a key role, with Cu substrates promoting better crystallinity due to improved lattice matching. Electrical measurements show that denser films with larger grains exhibit lower sheet resistance. These findings provide a comprehensive understanding of the plasma–film interplay and offer strategic insights for optimizing silver nanofilms in high-performance optoelectronic and catalytic systems. Full article

This study presents a comprehensive evaluation and an equivalent circuit modeling of the skin–electrode impedance characteristics of three types of ultra-thin tattoo electrodes, all based on Parylene C nanofilms but with different active materials: Gold, Silver, and PEDOT:PSS. Their performance was compared to standard disposable Ag/AgCl electrodes. Impedance measurements were carried out on six human subjects under controlled conditions, assessing the frequency response in the range of 20 Hz to 1 kHz. For each subject, the impedance was recorded six times over one hour to investigate the stability and the temporal performance. The collected data were subsequently analyzed to model the electrical properties and interface behavior of each electrode type. The findings demonstrate that the tattoo electrodes offer impedance levels comparable to those of Ag/AgCl electrodes (in the order of tens of kΩ at 20 Hz), while providing additional benefits such as enhanced conformability, improved skin adhesion, and reduced skin irritation during use. Furthermore, the modeling of the skin–electrode interface through a more detailed equivalent circuit than the single time constant model enables a more detailed interface analysis and description, with fitting algorithm R² scores of about 0.999 and 0.979 for the impedance magnitude and impedance phase, respectively. The proposed equivalent circuit offers valuable insights for optimizing electrode design, supporting the potential of Parylene C-based tattoo electrodes as promising alternatives for next-generation wearable bioelectronic applications. Full article

Thermoplasmonic heat generation by silver (Ag) nanoparticles can harness visible light to efficiently produce localized heating. Flame spray pyrolysis (FSP) is a powerful one-step synthesis technology for fabricating plasmonic Ag-based nanostructures. In the present study, we employed FSP to engineer core@shell Ag@SiO₂ nanoparticles coated with an ultrathin (1–2 nm) silica (SiO₂) nanolayer in a single step in tandem with their deposition as films onto solid substrates. Accordingly, we engineered a library of Ag@SiO₂ nanofilms with precisely controlled thicknesses in the range of 1–23 μm. A systematic study of the thermoplasmonic heat-generation efficiency (ΔT) of the films under visible-light irradiation (LED, λ = 405 nm) revealed that the films’ compactness and thickness are key parameters governing the heat-generation efficiency and thermal response rate. Moreover, we show that the substrate type can also play a key role; Ag@SiO₂ films on glass-fiber filters (PGFFs) enabled faster temperature increase (dT/dt) and a higher maximum temperature gain (ΔT_max) compared with Ag@SiO₂ films on glass substrates (PGSs). The photothermal conversion efficiencies were approximately 60%, with the highest efficiency (η = 65%) observed in the thinner impinged film. This study demonstrates that FSP-derived Ag@SiO₂ nanofilms provide a versatile and scalable platform for thermoplasmonic heat generation applications with significant industrial potential. Full article

The emergence of 2D materials has significantly expanded the wide range of nanomaterials with diverse applications. Notably, their high conductivity, catalytic efficiency, and hydrophobicity have fueled heightened research interests for water treatment applications. This research aimed to investigate the synthesis and characterization of MXene and reduced graphene oxide (rGO) nanocomposites with silver nanoparticles (Ag) for enhanced catalytic activity in the decomposition of Direct Blue-24 dye. In this study, we employed well-established methods, previously documented in the literature, to prepare two distinct nanocomposites. Novel nanocomposites, namely reduced graphene oxide–silver nanoparticles (rGO–Ag) and MXene–silver nanoparticles (MXene–Ag), were synthesized using the hydrothermal and direct reduction method with an ammoniacal solution (aqueous solution). Comprehensive characterization using advanced tools revealed that the introduced Ag particles integrated seamlessly onto the parent nanofilms of the Carbon derivatives, forming a secondary phase with enhanced catalytic functionality. These nanocomposites demonstrated significant improvements in the catalytic decomposition reactions in simulated wastewater. Verification involved the reduction reaction of Direct Blue-24 dye at known nanocomposite concentrations. The results indicated that MXene–Ag exhibited a superior catalytic activity of 98% in 10 min compared to the rGO–Ag nanocomposite films, which achieved 96% in 35 min. The results indicated that MXene–Ag nanocomposites exhibited a 20–25% increase in catalytic efficiency compared to the rGO–Ag nanocomposites. The outcomes of this research hold promise for practical applications in textile wastewater management and various industrial sectors dealing with mutagenic and carcinogenic chemicals containing azo and/or phthalocyanine products. Full article

This study focuses on synthesizing a composite material of Ag/ZnO/BiOCl using Ag, ZnO, and BiOCl as raw materials. The material was prepared by loading Ag and BiOCl onto ZnO nanofilms, aiming to enhance the photocatalytic degradation of ciprofloxacin (CIP). Optimization of the photocatalytic degradation process through single-factor experiments revealed that under conditions of an initial CIP pH of 9, an Ag/ZnO/BiOCl dosage of 1 g/L, and an initial CIP concentration of 5 mg/L the conversion efficiency of CIP reached 98.79% after 150 min of exposure to a 250 W xenon lamp simulating sunlight. Furthermore, the composite material maintained a conversion efficiency of 86.17% for CIP even after five cycles of reuse, demonstrating its excellent stability. The optical properties, elemental composition, valence state, crystallinity, and morphology of the samples were analyzed using techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), UV–visible diffuse reflectance spectroscopy (UV-vis DRS), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that the introduction of Ag expanded the light response range of ZnO, while the addition of BiOCl improved the separation efficiency of electron–hole pairs in the composite nanomaterial. The photocatalytic mechanism was further elucidated through radical scavenging experiments, confirming that ·OH and h⁺ are the main active species in the degradation process. Full article

In this study, an innovative Ag/ZnO/BC nanofilms composite material was synthesized by loading zinc oxide and silver on biochar nanofilms using a combination of hydrothermal and calcination methods using zinc oxide, silver and biochar as raw materials. Subsequent characterization analysis confirmed the successful synthesis of Ag/ZnO/BC nanofilms photocatalysts, and the Ag/ZnO nanocomposite particles were effectively loaded on the biochar nanofilms (BC). The composite exhibited robust photocatalytic removal under visible light irradiation under simulated wastewater conditions with an ammonia nitrogen concentration of 50 mg/L. The photocatalytic removal of ammonia and nitrogen pollutants in the composite was achieved by the use of Ag/ZnO nanoparticles. Specifically, the degradation of ammonia nitrogen pollutant reached a peak efficiency of 83.28%. Notably, the photocatalyst maintained over 80% degradation efficiency after four cycles, highlighting its sustained photocatalytic activity and stability. In conclusion, this study elucidated a feasible method to fabricate metal oxide–biochar thin-film composites with excellent adsorption and photocatalytic properties, thus providing a promising pathway for the remediation of organic wastewater, especially wastewater containing ammonia and nitrogen pollutants. Full article

Increasing photon absorption by capturing light is an important way to increase the efficiency of photovoltaic devices. In this regard, the small optical band gap (E_g) and high absorption coefficient of Se-containing thin nanofilms make them ideal for next generation photovoltaic devices based on selenides. Amorphous selenium was introduced into polyamide-6 (PA 6) via a chemical synthesis in a bath and the influence of the products of its reaction with Cd²⁺ and Ag⁺ ions on the film phase composition, topographic and optical properties were evaluated. AFM data have revealed that the surface roughness of the a-Se/PA 6 composite noticeably increases compared to that of unreacted PA 6. However, at later stages of film deposition, the roughness decreases, and the thin film becomes smoother and uniform. The incorporation of solid inorganic nanoparticles into flexible polyamide network causes chain stretching, which has been confirmed by ATR-FTIR spectroscopy data. The data of X-ray diffraction analysis, depending on the stage of synthesis, showed the crystalline composition of the film with peaks of Se₈, CdSe, Ag₂Se and Ag, which may explain the observed optical properties. The optical properties of the composites indicate a shift in the band gap from 4.46 eV for PA 6 to 2.23–1.64 eV upon the stepwise deposition of amorphous Se, CdSe and Ag₂Se. E_g is conveniently located in the visible region of solar energy, making the obtained nanofilms ideal for solar energy harvesting. Full article

Label-free surface-enhanced Raman scattering (SERS) analysis shows tremendous potential for the early diagnosis and screening of colon cancer, owing to the advantage of being noninvasive and sensitive. As a clinical diagnostic tool, however, the reproducibility of analytical methods is a priority. Herein, we successfully fabricated Ag NPs/cellulose nanocrystals/graphene oxide (Ag NPs/CNC/GO) nanocomposite film as a uniform SERS active substrate for label-free SERS analysis of clinical serum. The Ag NPs/CNC/GO suspensions by self-assembling GO into CNC solution through in-situ reduction method. Furthermore, we spin-coated the prepared suspensions on the bacterial cellulose membrane (BCM) to form Ag NPs/CNC/GO nanocomposite film. The nanofilm showed excellent sensitivity (LOD = 30 nM) and uniformity (RSD = 14.2%) for Nile Blue A detection. With a proof-of-concept demonstration for the label-free analysis of serum, the nanofilm combined with the principal component analysis-linear discriminant analysis (PCA-LDA) model can be effectively employed for colon cancer screening. The results showed that our model had an overall prediction accuracy of 84.1% for colon cancer (n = 28) and the normal (n = 28), and the specificity and sensitivity were 89.3% and 71.4%, respectively. This study indicated that label-free serum SERS analysis based on Ag NPs/CNC/GO nanocomposite film combined with machine learning holds promise for the early diagnosis of colon cancer. Full article

Transparent conductive films are widely used in electronic products and industrial fields. Ultra-thin Ag conductive nanofilm (ACF) was prepared on a soda lime silica glass (ordinary architectural glass) substrate with industrial magnetron sputtering equipment with AZO (Al₂O₃ doped ZnO) as the crystal bed and wetting layer. In order to improve the corrosion resistance and conductivity of the ACF, graphene nanosheets were modified on the surface of the ACF by electrospraying for the first time. The results show that this graphene modification could be carried out continuously on a meter scale. With the modification of the graphene layer, the corrosion rate of graphene-decorated ACF (G/ACF) can be reduced by 74.56%, and after 72 h of salt spray test, the conductivity of ACF samples without modification of graphene can be reduced by 34.1%, while the conductivity of G/ACF samples with modification of graphene can be reduced by only 6.5%. This work proves the potential of graphene modified ACF to prepare robust large-area transparent conductive film. Full article

The flexible, anti-fouling, and bionic surface-enhanced Raman scattering (SERS) biochip, which has a Nepenthes peristome-like structure, was fabricated by photolithography, replicated technology, and thermal evaporation. The pattern of the bionic Nepenthes peristome-like structure was fabricated by two layers of photolithography with SU-8 photoresist. The bionic structure was then replicated by polydimethylsiloxane (PDMS) and grafting the zwitterion polymers (2-methacryloyloxyethyl phosphorylcholine, MPC) by atmospheric plasma polymerization (PDMS-PMPC). The phospholipid monomer of MPC immobilization plays an important role; it can not only improve hydrophilicity, anti-fouling and anti-bacterial properties, and biocompatibility, but it also allows for self-driving and unidirectional water delivery. Ag nanofilms (5 nm) were deposited on a PDMS (PDMS-Ag) substrate by thermal evaporation for SERS detection. Characterizations of the bionic SERS chips were measured by a scanning electron microscope (SEM), optical microscope (OM), X-ray photoelectron spectrometer (XPS), Fourier-transform infrared spectroscopy (FTIR), and contact angle (CA) testing. The results show that the superior anti-fouling capability of proteins and bacteria (E. coli) was found on the PDMS-PMPC substrate. Furthermore, the one-way liquid transfer capability of the bionic SERS chip was successfully demonstrated, which provides for the ability to separate samples during the flow channel, and which was detected by Raman spectroscopy. The SERS intensity (adenine, 10⁻⁴ M) of PDMS-Ag with a bionic structure is ~4 times higher than PDMS-Ag without a bionic structure, due to the multi-reflection of the 3D bionic structure. The high-sensitivity bionic SERS substrate, with its self-driving water capability, has potential for biomolecule separation and detection. Full article

The combination of titania nanofilms and silver nanoparticles (NPs) is a very promising material, with antibacterial and osseointegration-induced properties for titanium implant coatings. In this work, we successfully prepared TiO₂ nanolayer/Ag NP structures on titanium disks using atomic layer deposition (ALD). The samples were studied by scanning electron microscopy (SEM), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), contact angle measurements, and SEM-EDS. Antibacterial activity was tested against Staphylococcus aureus. The in vitro cytological response of MG-63 osteosarcoma and human fetal mesenchymal stem cells (FetMSCs) was examined using SEM study of their morphology, MTT test of viability and differentiation using alkaline phosphatase and osteopontin with and without medium-induced differentiation in the osteogenic direction. The samples with TiO₂ nanolayers, Ag NPs, and a TiO₂/Ag combination showed high antibacterial activity, differentiation in the osteogenic direction, and non-cytotoxicity. The medium for differentiation significantly improved osteogenic differentiation, but the ALD coatings also stimulated differentiation in the absence of the medium. The TiO₂/Ag samples showed the best antibacterial ability and differentiation in the osteogenic direction, indicating the success of the combining of TiO₂ and Ag to produce a multifunctional biocompatible and bactericidal material. Full article

Low-temperature Cu-Cu bonding technology plays a key role in high-density and high-performance 3D interconnects. Despite the advantages of good electrical and thermal conductivity and the potential for fine pitch patterns, Cu bonding is vulnerable to oxidation and the high temperature of the bonding process. In this study, chip-level Cu bonding using an Ag nanofilm at 150 °C and 180 °C was studied in air, and the effect of the Ag nanofilm was investigated. A 15-nm Ag nanofilm prevented Cu oxidation prior to the Cu bonding process in air. In the bonding process, Cu diffused rapidly to the bonding interface and pure Cu-Cu bonding occurred. However, some Ag was observed at the bonding interface due to the short bonding time of 30 min in the absence of annealing. The shear strength of the Cu/Ag-Ag/Cu bonding interface was measured to be about 23.27 MPa, with some Ag remaining at the interface. This study demonstrated the good bonding quality of Cu bonding using an Ag nanofilm at 150 °C. Full article

A composite material comprised of graphene nanoplatelet and silver particles (GNPs–AgPs) was used for the deposition of GNPs–AgPs’ nanofilms with cold plasma on silk. α-Cyclodextrin was used as a modifier of the active surface of the disposable sensor. The disposable stochastic sensor was used in screening tests for the assay of heregulin-α in whole blood and tissue samples. The disposable stochastic sensor showed a low limit of determination (4.10 fg mL⁻¹) and can be used with high sensitivity on a wide concentration range (4.10 fg mL⁻¹–0.04 µg mL⁻¹). The screening method was validated against ELISA when good correlations (confirmed also by the t-test) were obtained. Full article

Nanolayer deposition(s) of Ag and AgC composite on a plastic substrate was used to design disposable stochastic sensors. The first sensor was based on an Ag nanofilm deposited on plastic; for the second sensor, an AgC composite was deposited on plastic, and, for the third sensor, on the plastic was deposited first a nanofilm of Ag and on top of it a nanofilm of the AgC composite. α-Cyclodextrin was used to modify the active surface of the sensor. Full article