Fabrication of agarose hydrogel with patterned silver nanowiresfor motion sensor

In this work, a facile strategy is proposed to construct stretchable electronics based on agarose hydrogels. The hot agarose solution is casted onto a template with patterned Ag nanowires, endowing agarose hydrogel with patterned conductive surface. After further heating treatment, Ag nanowires can be embedded into the agarose hydrogel, which improves the stability of Ag pattern and has no obvious e ffect on the conductivity of hydrogels. The agarose hydrogel with patterned Ag nanowires is certi fied to be an e ffective stretchable electrode to record the motion of joints, which has great potential applications in the field of wearable devices.

Polarization dependence of the light coupling to surface plasmons in an Ag nanoparticle & Ag nanowire system

Polarization dependence of the coupling of excitation light to surface plasmon polaritons （SPPs） was investigated in a Ag nanoparticle-nanowire waveguide system （a Ag nanoparticle attached to a Ag nanowire）. It was found that under the illumination of excitation light on the nanoparticle-nanowire junction, the coupling efficiency of light to SPPs depends on the polarization of the excitation light. Theoretical simulations revealed that it is the local near-field coupling between the nanoparticle and the nanowire that enhances the incident light to excite the nanowire SPPs. Because the shapes of the Ag nanoparticles differ, the local field intensity, and thus the excitement of the nanowire SPPs, vary with the polarization of the excitation light.

Morphological characteristics and atomic evolution behavior of nanojoints in Ag nanowire interconnect network

Ag nanowires(AgNWs)have shown great application value in the field of flexible electronics due to their excellent optical and electrical properties,and the quality of its joints of AgNWs in the thin film network directly plays a key role in its performance.In order to further improve the joint quality of AgNWs under thermal excitation,the thermal welding process and atomic evolution behavior of AgNWs were investigated through a combination of in situ experimental and molecular dynamics simulations.The influence of processing time,temperature,and stress distribution due to spatial arrangement on nanojoints was systematically explored.What is more,the failure mechanisms and their atomic interface behavior of the nanojoints were also investigated.

An improved sensitivity non-enzymatic ascorbic acid sensor based on a Ag_2O nanowire modified Ag electrode

In this paper, the Ag2O nanowires had been prepared and applied for the fabrication of ascorbic acid sensors with high enhanced sensitivity by using self-assembly technology. The structures and morphologies of Ag2O nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The direct electrocatalytic oxidation of ascorbic acid in alkaline medium at Ag2O nanowires modified electrodes had been investigated in detail and the condition for determination of ascorbic acid was optimized, such as support-electrolyte, pH and scan speed. The oxidation peak current changed linearly with the concentration of ascorbic acid over the range from 2.0×10-8 mol/L to 1.0 mmol/L, and the detection limit can reach 1.0×10-8mol/L. Compared to a bare Ag electrode, a substantial decrease in the overvoltage of the ascorbic acid oxidation was observed at the Ag nanowires electrodes with oxidation starting at ca. 0.7V vs. Ag/AgCl (saturated KCl). The Ag2O nanowires modified electrode allows highly sensitive, low working potential, stable, and fast amperometric sensing of ascorbic acid, thus is promising for the future development of non-enzymatic ascorbic acid sensors.

Large scale silver nanowires network fabricated by MeV hydrogen (H＋) ion beam irradiation

A random two-dimensional large scale nano-network of silver nanowires （Ag-NWs） is fabricated by MeV hydrogen （H＋） ion beam irradiation. Ag-NWs are irradiated under H＋ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H＋ ion beam-induced welding of Ag-NWs at intersecting positions. H＋ ion beam induced welding is confirmed by transmission electron microscopy （TEM） and scanning electron microscopy （SEM）. Moreover, the structure of Ag NWs remains stable under H＋ ion beam, and networks are optically transparent. Morphology also remains stable under H＋ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H＋ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps： ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices.

Flexible conductive Ag nanowire/cellulose nano?bril hybrid nanopaper for strain and temperature sensing applications

With the rapid development of smart wearable devices, flexible and biodegradable sensors are in urgent needs. In this study, ‘‘green" electrically conductive Ag nanowire (Ag NW)/cellulose nanofiber (CNF) hybrid nanopaper was fabricated to prepare flexible sensors using the facial solution blending and vacuum filtration technique. The amphiphilic property of cellulose is beneficial for the homogeneous dispersion of Ag NW to construct effective electrically conductive networks. Two different types of strain sensors were designed to study their applications in strain sensing. One was the tensile strain sensor where the hybrid nanopaper was sandwiched between two thermoplastic polyurethane (TPU) films through hot compression, and special micro-crack structure was constructed through the pre-strain process to enhance the sensitivity. Interestingly, typical pre-strain dependent strain sensing behavior was observed due to different crack densities constructed under different pre-strains. As a result, it exhibited an ultralow detection limit as low as 0.2%, good reproducibility under different strains and excellent stability and durability during 500 cycles (1% strain, 0.5 mm/min). The other was the bending strain sensor where the hybrid nanopaper was adhered onto TPU film, showing stable and recoverable linearly sensing behavior towards two different bending modes (tension and compression). Importantly, the bending sensor displayed great potential for human motion and physiological signal detection. Furthermore, the hybrid nanopaper also exhibited stable and reproducible negative temperature sensing behavior when it was served as a temperature sensor. This study provides a guideline for fabricating flexible and biodegradable sensors.

Flexible Transparent Conductive Films on the Basis of Ag Nanowires:Design and Applications:A Review

Transparent conductive films are used ubiquitously in optoelectronic devices.The properties of transparent films are extremely important for device performance,and the specifications vary according to types of devices.Over the past few years,various types of transparent conductive films on the basis of nanomaterials have emerged,and among these materials,silver nanowire networks show promising performance and represent a viable alternative to the commonly used,scarce and brittle indium tin oxide.In this paper,the working principle and the design protocol of Ag nanowire network flexible transparent conductive films are reviewed,and the applications of Ag nanowircs transparent conductive film are also briefly introduced.Concluding remarks are provided to propose future research in this field towards real-world applications.

Remotely excited Raman optical activity using chiral plasmon propagation in Ag nanowires

We experimentally investigated remotely excited Raman optical activity(ROA)using propagating surface plasmons in chiral Ag nanowires.Using chiral fmoc-glycyl-glycine-OH(FGGO)molecules,we first studied the local surface plasmon-enhanced ROA.We found that the Raman intensity can be excited by left-and right-circularly polarized lights and that the circular intensity difference(CID)can be significantly enhanced.Second,by selecting vibrational modes with large Raman and ROA intensities that are not influenced by chemical enhancements,we studied remotely excited ROA imaging and the CID of FGGO molecules by propagating a plasmonic waveguide using Ag chiral nanostructures.When laser light was radiated on one of the Ag terminals,the measured CID of the FGG at the other terminal showed little change compared to the local excited CID.Meanwhile,when the laser light was radiated on the Ag nanowires(not on the terminals)and was coupled to the nearby nanoantenna,the CID of the ROA could be manipulated by altering the coupling angle between the Ag nanowires.To directly demonstrate the propagation of ROA along the nanowire and its remote detection,we also measured the remotely excited ROA spectra.Our experimental method has the potential to remotely determine the chirality of molecular structures and the absolute configuration or conformation of a chiral live cell.

Silkworm Silk Fibers with Multiple Reinforced Properties Obtained through Feeding Ag Nanowires

Silkworm silk fbers have been woven into textiles for thousands of years,because of their attractive luster,good mechanical properties,excellent biocompatibility,and large-scale production.With the development of human society,preparation of silk fbers with modifed or enhanced properties are highly desirable for potential applications in structural materials and smart textiles.Herein,we realized the reinforcement of multiple properties of silk fbers by feeding silkworms with Ag nanowire(Ag NW)modifed diets.The obtained silk fbers show obviously enhanced comprehensive mechanical properties,including improved tensile strength,elongation at break,tensile modulus,and toughness,which are increased by 37.2%,37.6%,68.3%,and 69.8%,respectively.Furthermore,compared with unmodifed silk,the electrical conductivity and thermal conductivity of modifed silk fbers are improved by 246.4%and 32.1%,respectively.The analysis on the components and structure shows that the incorporated Ag NWs lead to increased content of random coil/α-helix,improved orientation of crystallites,and increased content of Ag compared to pristine silk fbers,which may contribute to the enhanced mechanical,electrical,and thermal properties.

Iodine ion modification enables Ag nanowire film with improved carrier transport properties and stability as high-performance transparent conductor

Ag nanowire(NW)film is the promising next generation transparent conductor.However,the residual long-chain polyvinylpyrrolidone(PVP,introduced during the synthesis of Ag NWs)layer greatly deteriorates the carrier transport capability of the Ag NW film and as well its long-term stability.Here,we report a one-step I−ion modification strategy to completely replace the PVP layer with an ultrathin,dense layer of I^(−)ions,which not only greatly diminishes the resistance of the Ag NW film itself and that at interface of the Ag NW film and a functional layer(e.g.,a current collect electrode)but also effectively isolates the approaching of corrosive species.Consequently,this strategy can simultaneously improve the carrier transport properties of the Ag NW film and its long-term stability,making it an ideal electric component in diverse devices.For example,the transparent heater and pressure sensor made from the I^(−)-wrapped Ag NW film,relative to their counterparts made from the PVP-wrapped Ag NW film,deliver much improved heating performance and pressure sensing performance,respectively.These results suggest a facile post treatment approach for thin Ag NW film with improved carrier transport properties and long-term stability,thereby greatly facilitating its downstream applications.

Uniform,Highly Conductive,and Patterned Transparent Films of a Percolating Silver Nanowire Network on Rigid and Flexible Substrates Using a Dry Transfer Technique

Silver nanowire films are promising alternatives to tin-doped indium oxide(ITO)films as transparent conductive electrodes.In this paper,we report the use of vacuum filtration and a polydimethylsiloxane(PDMS)-assisted transfer printing technique to fabricate silver nanowire films on both rigid and flexible substrates,bringing advantages such as the capability of patterned transfer,the best performance among various ITO alternatives(10Ω/sq at 85%transparency),and good adhesion to the underlying substrate,thus eliminating the previously reported adhesion problem.In addition,our method also allows the preparation of high quality patterned films of silver nanowires with different line widths and shapes in a matter of few minutes,making it a scalable process.Furthermore,use of an anodized aluminum oxide(AAO)membrane in the transfer process allows annealing of nanowire films at moderately high temperature to obtain films with extremely high conductivity and good transparency.Using this transfer technique,we obtained silver nanowire films on a flexible polyethylene terephthalate(PET)substrate with a transparency of 85%,a sheet resistance of 10Ω/sq,with good mechanical flexibility.Detailed analysis revealed that the Ag nanowire network exhibits two-dimensional percolation behavior with good agreement between experimentally observed and theoretically predicted values of critical volume。

Design and fabrication of a new fluorescence enhancement system of silver nanoparticles-decorated aligned silver nanowires

A new substrate,aligned Ag nanowires decorated with silver nanoparticle composite structure(AgNWs@AgNPs),was fabricated to investigate metalenhanced fluorescence(MEF) and its mechanism.The new composite structure was fabricated via a three-phase interface assembly method followed by SnCl2 sensitization and AgNO3 reduction process.The size and distribution of the nanoparticles on silver nanowires increased with the sensitization and reduction cycles.The formation of AgNPs on the surfaces of AgNWs was confirmed by multiple characterization methods including scanning electron microscopy(SEM),transmission electron microscope(TEM),atomic force microscopy(AFM) and X-ray diffraction(XRD).The results show that the fluorescence intensity of the poly(3-hexylthiophene)(P3HT) on the composite structure was greatly enhanced compared with that on bare glass substrate,and the intensity increased with the increase in particle sizes and density.The mechanism was basedo n the increase in excitation rate and the radiation decay rate.The new type of substrate could serve as a good and efficient MEF substrate for high-performance fluorescence-based devices.

Ordering silver nanowires for chiroptical activity

With the development of chiral materials, remarkable progress has been made in the application fields of biology, chemistry, and physics in the past decades. Here we develop a solo-Ag-nanowire(NW)-based, bottom-up chiral construction strategy to fabricate a chiral plasmonic film with strong chiroptical activity in the purple-blue band. Finitedifference time-domain simulations predict that helical structures made by Ag NWs with certain interlayer angles possess strong chiroptical intensity. We then apply a Langmuir-Blodgett technique to construct the layered NW assemblies with both handedness via regulating interlayer angle direction. The Ag NW assemblies show the interlayer-angleand film-thickness-dependent circular dichroism, reaching the highest anisotropic factor of 0.03. These new chiral structures will serve as ideal candidates for chiral sensors thanks to their specific plasmonic properties.

High EMI shielding effectiveness and superhydrophobic properties based on step-wise asymmetric structure constructed by one-step method

It is of significance to prepare biodegradable electromagnetic interference(EMI)shielding materials with high EMI shielding effectiveness(SE)in order to solve electromagnetic and environmental pollution problems.In this paper,environmentally friendly EMI shielding silver nanowires(AgNWs)/poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)/ferroferric oxide(Fe_(3)O_(4))composites with step-wise asymmetric structures were prepared by a facile one-step non-solvent-induced phase separation method.The conductive AgNW network was constructed at a low mass fraction of 5 wt.%on the surface of stereo-complexed crystalline poly(lactic acid)(SC-PLA)film(1.08×10^(4) S/m).Moreover,magnetic Fe_(3)O_(4)is mainly distributed in the skeleton of porous SC-PLA film.Due to the synergistic effect of AgNWs and Fe_(3)O_(4),the EMI SE of SC-PLA films reaches up to 50.3 dB.Interestingly,SC-PLA film modified with triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane(TTO)demonstrates an outstanding water contact angle of about 150.2°compared with the pure PLLA film(134.7°),stemming from the synergistic effect of denser SC-PLA nano-protrusions and low-surface-energy TTO.Thus,we successfully fabricated the high EMI shielding SC-PLA film with wonderful superhydrophobicity,which extends the application performance and service life of portable electronics in moist environments.

External field-strengthened Ostwald nanowelding

The accomplishment of nanowelding typically requires the input of high energy,possibly causing appreciable damages to the brittle nanomaterial.Herein,we report an external field(EF,i.e.,light,direct current(DC),and alternating current(AC))-strengthened Ostwald nanowelding(ONW)strategy to enable low-temperature nanowelding of Au nanoparticles(NPs)with nanoscale spacing in solution and propose an electron localization mechanism to understand it.We reveal that the EF-derived local electrons not only greatly strengthen the dissolution of surface atoms and the reduction of Au3+ions dissolved,but also confine(together with ordered water molecules)the transport of Au^(3+)ions within the nanogap.Consequently,the electrochemical Ostwald ripening(OR)process of the Au NPs is actively strengthened,which,along with the local electron-strengthened surface atom diffusion(as a result of the strong electrostatic repulsion created),enables feasible ONW for solution processing of interdigital electrodes(IDEs)from Au NPs and high-performance transparent conductor(TC)from Ag nanowires(NWs).Our low-temperature nanowelding strategy offers an efficient interconnection technique for the processing of functional nanodevices from individual nanomaterials.