Silver Nanoparticle Thin Films Research Articles

Aerosol jet printed resistive temperature sensors with high sensitivity

Aerosol jet printing provides a facile, cost-efficient, and environmentally friendly approach to pattern thin films with nanomaterial inks. Printed flexible resistive thin-film temperature sensors play an important role in human body temperature monitoring, soft robotics, prosthetics, and real-time temperature monitoring of large area curved surfaces due to their linear response to temperature, low-cost, scalability, and flexibility. However, the temperature coefficient of the resistance of the printed resistive temperature sensors reported in the literature is much less than that of their bulk metals. In this work, we demonstrate aerosol jet printed resistive temperature sensors with silver nanoparticle ink that have a temperature coefficient of resistance close to that of bulk silver. We report a temperature coefficient of resistance of 3.7 × 10−3 ◦C−1 for the aerosol jet printed resistive temperature sensors, the highest value yet reported in literature for resistive temperature detectors composed of thermally sintered silver nanoparticle thin films. The mechanisms for the increased performance are investigated using metrological and thermal techniques with regard to the source ink and traces. Additionally, we show that the overall sensitivity of the printed sensors can be modulated by controlling the thickness of the printed thin films. Finally, we evaluate the response of the printed resistive sensors to bending strain and humidity, including an investigation into the effects of organic passivation. Overall, this work presents printed sensors with performance on par with vacuum deposited resistive temperature detectors, enabling the fabrication technique to make an industrial impact.

Optical response of plasmonic silver nanoparticles after treatment by a warm microwave plasma jet

This work investigates the effect of plasma treatment on the morphology and composition of 15 × 15 mm2 silver nanoparticle (70–80 nm) thin films. The silver nanoparticles are deposited onto thermal silica (SiO2/Si) substrates by spin-coating, then they are treated by an open-to-air microwave argon plasma jet characterized by a neutral gas temperature of 2200 ± 200 K. Scanning electron microscopy analysis reveals that the number of isolated nanoparticles in the film sample decreases after exposure to multiple jet passes, and that polygonal structures with sharp corners and edges are produced. Similar structures with much rounder edges are obtained after conventional thermal annealing at temperatures up to 1300 K. Based on localized surface plasmon resonance analysis in the range of 350–800 nm, the main extinction band of silver nanoparticles experiences a redshift after treatment with the plasma jet or with thermal annealing. Moreover, both treatments induce surface oxidation of the nanoparticles, as evidenced by x-ray photoelectron spectroscopy. However, only the plasma-exposed samples exhibit a significant rise in the surface-enhanced Raman scattering (SERS) signal of oxidized silver at 960 cm−1. 29 29 μm2 mappings of hyperspectral Raman IMAging (RIMA) and multivariate curve resolution analysis by log-likelihood maximization demonstrate that the SERS signal is controlled by large-scale micrometer domains that exhibit sharp corners and edges.

Zinc–Cobalt Oxide Thin Films: High Curie Temperature Studied by Electron Magnetic Resonance

The material with a high Curie temperature of cobalt-doped zinc oxide embedded with silver-nanoparticle thin films was studied by electron magnetic resonance. The nanoparticles were synthesized by the homogeneous nucleation technique. Thin films were produced with the pulsed laser deposition method. The main aim of this work was to investigate the effect of Ag nanoparticles on the magnetic properties of the films. Simultaneously, the coexisting Ag0 and Ag2+ centers in zinc oxide structures are shown. A discussion of the signal seen in the low field was conducted. To analyze the temperature dependence of the line parameters, the theory described by Becker was used. The implementation of silver nanoparticles causes a significant shift of the line, and the ferromagnetic properties occur in a wide temperature range with an estimated Curie temperature above 500 K.

Characterization and antimicrobial evaluation of green synthesized silver nanoparticle thin films with reusable applications

Green synthesis of silver nanoparticles (AgNPs) using medicinal plants are compartivley easier and have gained much interest due to their high surface to volume ratio and enhanced antimicrobial activity. In this study, we have synthesized AgNPs using methanolic leaf extract of Senna alata plant and characterized them using UV–Visible Spectroscopy, (Transmission Electron Microscope) TEM, Dynamic Light Scattering (DLS), and Raman Spectroscopy (RS). Further, AgNPs and plant leaf extracts were impregnated in an agar matrix and dehydrated to prepare a thin-filmnanocomposite. The Minimum Inhibitory Concentration (MIC) of obtained thin-film was in the range of 29–58 µg/mL for Staphylococcus aureus, Escherichia coli, Candida albicans and Enterococcus faecalis. The release of leaf extract-AgNPs from the nanocomposite was time-dependent against test organisms and allowed reuse.

Experimental and theoretical study of the characteristics of LSPR peaks for metal NPs produced by controlling Ar ambient gas pressure to enhance the efficiency of solar cells

In this study, silver (Ag) nanoparticle thin films were deposited on microscope slide glass and Si wafer substrates using the pulsed-laser deposition (PLD) technique in Ar ambient gas pressures of 1 × 10−3 and 7.5 × 10−1 mbar. AFM analysis has shown that the number of Ag nanoparticles reaching the substrate decreased with increasing Ar gas pressure. As a result of Ar ambient gas being allowed into the vacuum chamber, it was observed that the size and height of Ag nanoparticles decreased and the interparticle distances decreased. According to the absorption spectra taken by a UV–vis spectrometer, the wavelength where the localised surface plasmon resonance (LSPR) peak appeared was shifted towards the longer wavelength region in the solar spectrum as Ar background gas pressure was decreased. This experiment shows that LSPR wavelength can be tuned by adjusting the size of metal nanoparticles, which can be controlled by changing Ar gas pressure. The obtained extinction cross section spectra for Ag nanoparticle thin film was theoretically analysed and determined by using the metal nanoparticle–boundary element method (MNPBEM) toolbox simulation program. In this study, experimental spectrum and simulation data for metal nanoparticles were acquired, compared, and determined to be in agreement.

Effect of laser power on conductivity and morphology of silver nanoparticle thin films prepared by a laser assisted electrospray deposition method

Silver nanoparticle-based electrodes were studied extensively in recent years as an electrode material for wearable and flexible electronics due to their stability and conductivity. A wet chemical deposition technique is considered as a low-cost scalable technique. The current wet chemical-based nanoparticle deposition techniques include electrospray deposition, drop casting, spin coating, and the inkjet printing process. These techniques generally require a separate postdeposition annealing step. This can be a problem for substrates with a low melting point. In addition, some of the above-mentioned methods require physical contact, which increases the probability of cross-contamination. In this research, we present a technique that combines electrospray and laser radiation to deposit and sinter nanoparticles simultaneously on a rigid or flexible substrate. In this process, the microdroplets of aqueous silver nanoparticle suspension ejected in what is known as the microdripping mode from a metallic capillary nozzle, which can be controlled by an electric potential. A conical hollow laser beam is used to vaporize the liquid and sinter the nanoparticles at desired locations on a substrate. This is a promising technique compared to the traditional methods to fabricate conductive micropatterns due to its simplified one step deposition, suppressed cross-contamination, and applicability to various surfaces. Thin-film micropatterns of silver nanoparticles were fabricated using a Nd:YAG laser with powers from 5 to 13 W. The correlation between the grain size distribution, composition, and electrical resistivity was studied using a scanning electron microscope, energy-dispersive x ray, and four-point probe analysis. The results are comparable to the conventional thermal sintering method.

Stretchable Electronics: Highly Reliable Liquid Metal–Solid Metal Contacts with a Corrugated Single‐Walled Carbon Nanotube Diffusion Barrier for Stretchable Electronics (Adv. Funct. Mater. 51/2018)

In article number 1806014, Yongtaek Hong and co-workers report highly reliable and stretchable liquidmetal-solid-metal contacts with a single-walled carbon nanotube diffusion barrier formed on corrugated silver nanoparticle thin film. The chemical inertness and mechanical robustness of the entangled structure of carbon nanotubes suppress liquid metal penetration through contacted other metals even under mechanical deformation.

On the sintering of solution-based silver nanoparticle thin-films for sprayed and flexible antennas

In this work, we report on the fabrication and characterization of sub-300 nm electrode films based on solution-processed silver nanoparticles (AgNPs). Following the deposition of the electrode material using a scalable and homogenous spray process, the films are treated with thermal or photonic sintering to promote the coalescence of the nanoparticles and in turn decrease the resistivity of the films. After sintering, a resistivity of 63 ± 13 nΩ m is achieved for the AgNP films, which is only by a factor of four larger than the literature value for bulk silver. Both post-deposition treatments show a similar performance with regard to the achieved resistivity. However, photonic sintering avoids the need for thermal annealing at substrate temperatures of 150 °C and above. In addition, the photonic sintering process can easily be embedded in a roll-to-roll process and is extremely fast with light exposure times below 3 ms. Thus, this manufacturing technique paves the way for the use of flexible substrates in electronics. As a simple and practical application, we present the use of AgNP films for antennas operating in the 5 GHz band on flexible polyethylene terephthalate substrate. An original coplanar design is employed for the fabrication of antennas with a single conductive layer that exhibit a maximum return loss and radiation of −27 dB and 95%, respectively.

Silver Nanoparticle Effect on Spectral-Kinetic Properties of Thin Nickel Phthalocyanine Films

We have investigated spectral and spectral-kinetic properties of hybrid plasmonic nanocomposites on silver nanoparticle monolayers and thin nickel phthalocyanine films. The spectroscopic results obtained by the femtosecond pump-probe technique demonstrate that a fast optical response in the range of long-wavelength nickel phthalocyanine electronic absorption bands becomes observable and registered when the nickel phthalocyanine thin films contact with silver nanoparticles. This could be assigned to the plasmon-related modification and the enhancement of organic subsistent absorption at steady-state absorption spectra of hybrid nanostructures.

Controlling the crack formation in inkjet-printed silver nanoparticle thin-films for high resolution patterning using intense pulsed light treatment

During the last years, intense pulsed light (IPL) processing has been employed and studied intensively for the drying and sintering of metal nanoparticle layers deposited by means of printing methods on flexible polymer substrates. IPL was found to be a very fast and substrate-gentle approach qualified for the field of flexible and large-area printed electronics, i.e. manufactured via roll-to-roll processing. In this contribution, IPL is used for the fine-patterning of printed silver nanoparticle layers. The patterning is obtained by induced and controlled crack formation in the thin silver layer due to the intense exposure of IPL. The crack formation is controlled by selection of the substrate material, the fine-tuning of the morphology of the silver layer and an application of a dielectric layer on top of the silver layer that acts as a stress concentrator. Careful optimization of the IPL parameters allowed to adjust the lateral width of the crack. This novel approach turned out to be a fast and reproducible high-resolution patterning process for multiple applications, e.g. to pattern the source-drain electrodes for all-inkjet-printed thin-film transistors.

Engineering Crack Formation in Carbon Nanotube-Silver Nanoparticle Composite Films for Sensitive and Durable Piezoresistive Sensors.

We report highly sensitive and reliable strain sensors based on silver nanoparticle (AgNP) and carbon nanotube (CNT) composite thin films. The CNT/AgNP was prepared by a screen printing process using a mixture of a CNT paste and an AgNP ink. It is discovered that the sensitivity of such sensors are highly dependent on the crack formation in the composites. By altering the substrate use and the relative ratios of AgNPs and CNTs, the formation and propagation of cracks can be properly engineered, leading to piezoresistive strain sensors with enhanced sensitivity and robustness.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1626-z) contains supplementary material, which is available to authorized users.

Influence of substrate temperature on the properties of pulsed laser deposited silver nanoparticle thin films and their application in SERS detection of bovine serum albumin

The effect of substrate temperature (Ts) on electrical conductance, surface plasmon resonance (SPR), and surface-enhanced Raman scattering (SERS) activity of silver nanoparticle (AgNP) thin films is presented. AgNP films are grown on glass substrates by pulsed laser deposition in a controlled Ar atmosphere at a pressure of 0.1 mbar and varying Ts. Different Ts results in different morphologies, as observed by scanning electron microscopy. The effect of interparticle distance on the electrical conductance of AgNPs is highlighted. The current–voltage characteristics display negative resistance effect and is attributed to the charge trapping process in AgNPs. The film deposited at room temperature presents a SPR peak at λ = 460 nm, and its wavelength first increases until Ts reaches 300 °C and then decreases with further increasing Ts. The quantitative analysis of SERS studies reveals that SERS intensity of bovine serum albumin (BSA) adsorbed on AgNP substrate deposited at 300 °C exhibits a higher intensity as compared with that of BSA adsorbed on the SERS active substrates at any other Ts.

Laser wavelength effect on laser-induced photo-thermal sintering of silver nanoparticles

This work is concerned with the laser wavelength effect on the electrical properties and surface morphology of laser-sintered nanoparticle thin films. Silver nanoparticle thin films spin-coated on soda lime glass substrates were irradiated with lasers of three different wavelengths (near ultraviolet 405 nm, green 514.5 nm, near infrared 817 nm) at varied laser intensities and scanning speeds. Scanning electron microscopy images and ex situ resistivity measurements show that the photo-thermal sintering alters significantly the film surface morphology and electrical properties, depending on the processing parameters (laser wavelength, laser intensities and scanning speed). While the optical response of the material is determined largely by the processing laser wavelength, the laser beam intensity and scanning speed regulate the induced temperature field. Examination of the optical properties of as-deposited silver nanoparticle thin film in conjunction with scanning electron microscopy images taken from the laser-sintered lines helps elucidate how the processing laser wavelength modulates the optical response of silver nanoparticle thin film and therefore affects the thermal response.

A silver nanoparticle thin film modified glass substrate as a colourimetric sensor for hydrogen peroxide

In this work, a silver nanoparticle (AgNP) coated glass slide was developed as a device for sensing hydrogen peroxide. AgNPs were synthesised using borohydride reduction with a citrate stabiliser, resulting in a negatively charged stabilised particle surface. The particles were attached to the glass surface using the layer-by-layer (LbL) technique. Poly (diallyldimethylammonium chloride) and poly (styrene sulphonate) were used as cationic and anionic polyelectrolyte layers, respectively. The glass slide was modified with polyelectrolytes leaving a cationic layer on the top surface. The AgNPs were subsequently deposited on the slide via electrostatic interaction. As a result, a dark yellow film of AgNPs was obtained with maximum absorption at 410 nm. Film fabrication based on LbL assembly provided acceptable reproducibility (relative standard deviation = 6.5%). The fabricated film had long-term stability (>6 weeks). A very small quantity of AgNPs was used in this method. Fabrication was performed under ambient conditions. Therefore this fabrication was considered as a green method. The AgNP modified slide was developed to sense hydrogen peroxide. Detection is based upon oxidation of AgNPs by hydrogen peroxide. This results in a change in colour of the film from dark yellow to colourless. Linear calibration was obtained over the range of 1.0--100.0 mM of hydrogen peroxide. The device was successfully used for measuring hydrogen peroxide in urine.

Silver Nanoparticle Thin Films Deposited on Glass Surface Using an Ionic Silsesquioxane as Stabilizer and as Crosslinking Agent

Thin films containing silver nanoparticles homogeneously dispersed, with narrow size distribution below 10 nm, were synthesized on flat glass surface, by using an ionic silsesquioxane as stabilizer and crosslinking agent. The films can be prepared without previous functionalization of substrate surfaces and without addition of other components. The films were heat treated up to 200 oC and characterized by ultraviolet-visible, transmission electron microscopy, atomic force microscopy, thermogravimetric analysis and ellipsometry. The films were thermally stable when heated up to 200 oC, presenting the same thickness, and maintaining both optical and morphological properties of silver nanoparticles. The antibacterial activity of the films, containing the silver nanoparticles, was evaluated against Staphylococcus aureus by using the film applicator coating method, showing an excellent performance even after the third cycle of sterilization.

Thermal Assisted UV-Ozone Treatment to Improve Reliability of Ag Nanoparticle Thin Films

We employed UV-Ozone treatment method for the fabrication of dense and highly conductive nanoparticle thin films. We demonstrated the UV-Ozone treatment effect on the silver nanoparticle thin films as a function of time and temperature. The capping layers of nanoparticles were decomposed after UV-Ozone treatment and dense nanoparticle thin films were obtained. Moreover, electrical and mechanical properties of the thin films after UV-Ozone treatment were measured by using resistance measurements under tension in an in-situ tensile tester. The initial resistance of nanoparticle thin films was decreased by 82.6% with optimized UV-Ozone treatment condition of <TEX>$150^{\circ}C$</TEX> for 20 minutes.

Tuning the surface plasmon resonance and surface-enhanced Raman scattering of pulsed laser deposited silver nanoparticle films by ambience and deposition temperature

Silver nanoparticle (AgNP) thin films were deposited by pulsed laser deposition onto glass substrates, at different fixed temperatures, under inert gas ambience and vacuum. Their morphology, surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) activities were investigated. AFM analysis of the films showed the formation of densely packed nanoparticles of varying size and shape by changing the ambience and deposition temperature (Ts). A SPR peak is not evidently observed in the spectrum of films deposited at room temperature, in either high vacuum or neon ambience. The SPR frequency blue shifts from 569 to 470 nm and from 581 to 574 nm with increasing Ts for the films processed in high vacuum and in neon ambience, respectively, while the absorption band becomes narrower with increasing Ts. The SERS intensity of Rhodamine B (RhB) adsorbed on a AgNP substrate grown at 600 °C in neon ambience exhibits a higher intensity compared with that of RhB adsorbed on the SERS active substrates at other values of Ts. Good correlation has been observed between the SPR and SERS activities and the morphology of the NPs.

Deposition of hexagonal boron nitride thin films on silver nanoparticle substrates and surface enhanced infrared absorption

Silver nanoparticle thin films with different average particle diameters are grown on silicon substrates. Boron nitride thin films are then deposited on the silver nanoparticle interlayers by radio frequency (RF) magnetron sputtering. The boron nitride thin films are characterized by Fourier transform infrared spectra. The average particle diameters of silver nanoparticle thin films are 126.6, 78.4, and 178.8 nm. The results show that the sizes of the silver nanoparticles have effects on the intensities of infrared spectra of boron nitride thin films. An enhanced infrared absorption is detected for boron nitride thin film grown on silver nanoparticle thin film. This result is helpful to study the growth mechanism of boron nitride thin film.

Tensile characteristics of metal nanoparticle films on flexible polymer substrates for printed electronics applications

Metal nanoparticle solutions are widely used for the fabrication of printed electronic devices. The mechanical properties of the solution-processed metal nanoparticle thin films are very important for the robust and reliable operation of printed electronic devices. In this paper, we report the tensile characteristics of silver nanoparticle (Ag NP) thin films on flexible polymer substrates by observing the microstructures and measuring the electrical resistance under tensile strain. The effects of the annealing temperatures and periods of Ag NP thin films on their failure strains are explained with a microstructural investigation. The maximum failure strain for Ag NP thin film was 6.6% after initial sintering at 150 °C for 30 min. Thermal annealing at higher temperatures for longer periods resulted in a reduction of the maximum failure strain, presumably due to higher porosity and larger pore size. We also found that solution-processed Ag NP thin films have lower failure strains than those of electron beam evaporated Ag thin films due to their highly porous film morphologies.

Growth Behaviour and Electrical Resistivity Relationship of Silver Nanoparticle Thin Film

Normal grain growth of silver thin film predominates above the critical transition temperature below which bimodal grain growth predominates. In this experiment silver Nano layers were prepared by spin coating on glass substrate and which were annealed at different temperature. The lowest attainable resistance was 1.23 Ohm/sq. The woulf plot of fcc silver suggests that during growth (111) family plane predominated on surface of every grain and that was true according to SEM figure. This is the reason for low resistivity of silver thin film. Not only on surface but also this stable (111) plane was present on grain boundary as singular interface. However, ADF Simulation has been done to construct 40 nm silver nano particle and to construct band structure of silver. The valance band and conduction band overlap shows the metallic characteristic property of silver.