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Ag nanowire electrodes are promising substitutes for traditional indium tin oxide (ITO) electrodes in optoelectronic applications owing to their impressive conductivity, flexibility, and transparency. This review provides an overview of recent trends in Ag nanowire electrode layer formation, including key developments, challenges, and future prospects. It addresses several challenges in integrating Ag nanowires into practical applications, such as scalability, cost-effectiveness, substrate compatibility, and environmental considerations. Additionally, drawing from current trends and emerging technologies, this review explores potential avenues for improving Ag nanowire layer-forming technologies, such as material advancements, manufacturing scalability, and adaptability to evolving electronic device architectures. This review serves as a resource for researchers, engineers, and stakeholders in nanotechnology and optoelectronics, and underscores the relationship between advancements in patterning and the application of Ag nanowire electrodes. Through an examination of key developments, challenges, and future prospects, this review contributes to the collective knowledge base and encourages continued innovation in the ever-evolving realm of Ag nanowire-based optoelectronics.

Abstract With technological advances in wearable health care monitoring system, there increasing demands for the patterning technology for reliable sensors. Dry-film photoresists (DFRs) have several advantages for the patterning of silver nanowires (AgNWs), including cost-effectiveness, low toxicity of the process, and ease of mass production through a roll-to-roll process. In this study, using DFRs, we achieved the facile fabrication of AgNW-based chips for optical detection of myoglobin (Mb) via surface-enhanced Raman spectroscopy (SERS). Mb is found in accessible biological fluids such as urine and serum, which is a representative protein biomarker for human health monitoring. AgNWs were successfully patterned on polyethylene terephthalate films using DFR to form multiple spots, with a diameter of ~500 µm, that are available for detection. SERS spectra showed that the AgNW chips can efficiently detect myoglobin proteins down to levels of clinical significance. Our results will provide insights for the cost-effective production method of futuristic health care monitoring system.

With the technological progress of wearable electronics operated in 5 G network communication system, a stretchable noise suppressor at GHz bandwidth that is reliable under severe deformation coming from the user’s motion should be developed. However, current material systems for the noise suppressor showed a limited stretchability. This study introduces a carbonyl iron powder – polydimethylsiloxane (CIP – PDMS) composite with partially bonded interface as a solution to enhance the stretchability. Modulation of CIP surface to have the partial interface bonding (CIP-PID) results in the ultra large strain of ~165% even at the 40 vol% of CIP-PIDs, while only ~71% of strain is observed for CIPs with the full interface bonding (CIP-FID). According to a microstructural analysis and FEM simulation of the strained composite specimens, when partially bonded to CIP at the interface, the PDMS matrix forms a free surface that can be deformed like pure PDMS, resulting in high stretchability. The wettability of CIP offers protection against eddy current loss while retaining strong magnetic properties, suppressing the EM noise. Thus, the approach eliminates the tradeoff between EM suppression and stretchability.

Precise measurement of the surface energy of nanoscale metal thin films is crucial for the fabrication of reliable miniaturized electronic devices consisting of multi-stacked thin film strips. However, the conventional method utilizing sessile drops to measure the surface energy is not suitable for nanoscale samples owing to the much larger size of the liquid droplets than those of the samples being measured. Herein, nCA-AFM (nano contact angle-atomic force microscopy) based on PF-QNM (PeakForce quantitative nanomechanical mapping) imaging mode is explored as a novel tool to measure the surface energy of nanoscale Au strips. Au strips with thicknesses of 50 and 100 nm were patterned to have widths in a range from 200 to 500 nm. The surface energy of the nano-patterned Au strips measured with PF-QNM methods revealed that grain size is the most important factor determining the surface energy. The sample having different widths with the same grain size showed similar surface energy values, regardless of the sample dimensions. Our results highlight that grain size control is required to achieve the target surface energy of metal strips for applications in nanoscale electronic devices.

Achieving resistance to sedimentation of carbonyl iron powders (CIPs) in ethanol is important to fabricate reliable magnetorheological suspensions. The traditional method to improve the sedimentation stability is to add dispersants, but this approach can suffer from high costs and toxicity of added surfactants. In this study, the surface of CIPs was modified with 3-aminopropyl triethoxysilane (APTES) or tetraethyl orthosilicate (TEOS) to enhance the sedimentation stability of CIP suspensions without using toxic dispersants. After coating APTES or TEOS on the CIP surface, the surface energy of the CIP powders increased, which was attributed to the increased amino or hydroxyl groups on the CIP surface due to APTES or TEOS, respectively. The Gibbs free wetting enthalpy (ΔG) was calculated to evaluate the wettability of the modified CIPs, and APTES@CIPs or TEOS@CIPs had a low ΔG, indicating that both had a high thermodynamic spontaneity of wetting in ethanol. The enhanced wettability due to APTES or TEOS coating resulted in low CIP agglomeration, which resulted in APTES@CIPs or TEOS@CIPs dispersions having smaller average particle sizes than pure CIP dispersions. Therefore, APTES@CIPs or TEOS@CIPs showed more than 2 times slower sedimentation velocity than pure CIPs, resulting in enhanced sedimentation stability.

The fibrous supercapacitor is a promising candidate for wearable energy-storage systems due to excellent mechanical reliability under deformation. In this study, a mechanically reliable fibrous supercapacitor with high volumetric power density and energy density was developed using fiber electrodes composed of multilayered active materials coated on silk yarns. The conductive silk yarn electrodes are fabricated via a sequential dip-coating process of silver nanowires, multi-walled carbon nanotubes (MWCNT, three to seven walls), and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The composite-coated silk yarn electrodes were stable under cyclic bending as well as under washing in water. Due to the synergetic effect of the three conducting materials, an excellent electrochemical performance was obtained resulting in high volumetric energy and power densities of 8–13 mWh cm−3 and 8–19 W cm−3, respectively. A yarn-type supercapacitor was demonstrated by integrating composite-coated silk yarn electrodes with a hydrogel electrolyte, showing a promising stability as evidenced by the retention of over 94% and 93% of the specific capacitance after 90-degree bending and stretching.

Silver nanowires (AgNWs) are a potential alternative to conventional transparent conductive materials for various applications, such as flexible and transparent electrodes in optoelectronic devices, including touch screens, solar cells, and flexible displays. However, AgNW electrodes face degradation due to environmental factors, electrical instability, and mechanical stress. To overcome these challenges, strategies to protect AgNW-based electrodes via the incorporation of polymeric materials were widely investigated to improve the durability and stability of AgNW-based electrodes. This review paper gives a comprehensive overview of the incorporation of polymeric materials with AgNW electrodes, emphasizing their performance, and applications. We compare the different polymeric materials and their effect on the electrical, optical, and mechanical properties of AgNW electrodes. Furthermore, we evaluate the key factors affecting the choice of protective layers, such as their compatibility with AgNWs, and also we present current challenges and future opportunities for the development of polymeric materials for AgNW electrodes in emerging technologies.

Carbon nanotube (CNT)-based electrodes in flexible supercapacitors have received significant attention in recent years. Carbon nanotube fiber fabrics (CNT-FF) have emerged as promising materials due to their high surface area, excellent conductivity, and mechanical strength. Researchers have attempted to improve the energy density and rate performance of CNT-FF supercapacitor electrodes through various strategies, such as functionalization with conductive materials like MnO2 nanoparticles and/or incorporation of graphene into them. In addition, the utilization of CNTs in combination with thin metal film electrodes has also gained widespread attention. Research has focused on enhancing electrochemical performance through functionalizing CNTs with conductive materials such as graphene and metal nanoparticles, or by controlling their morphology. This review paper will discuss the recent developments in supercapacitor technology utilizing carbon nanotube-based electrodes, including CNT fiber fabrics and CNTs on thin metal film electrodes. Various strategies employed for improving energy storage performance and the strengths and weaknesses of these strategies will be discussed. Finally, the paper will conclude with a discussion on the challenges that need to be addressed in order to realize the full potential of carbon nanotube-based electrodes in supercapacitor technology.

Indium tin oxide (ITO) is currently the most widely used material for transparent electrodes; however, it has several drawbacks, including high cost, brittleness, and environmental concerns. Silver nanowires (AgNWs) are promising alternatives to ITO as materials for transparent electrodes owing to their high electrical conductivity, transparency in the visible range of wavelengths, and flexibility. AgNWs are effective for various electronic device applications, such as touch panels, biosensors, and solar cells. However, the high synthesis cost of AgNWs and their poor stability to external chemical and mechanical damages are significant challenges that need to be addressed. In this review paper, we discuss the current state of research on AgNW transparent electrodes, including their synthesis, properties, and potential applications.

Silver nanowire networks are attractive for flexible transparent electrodes due to their excellent optical transparency and electrical conductivity. Their mechanical reliability under bending is an important feature for the adoption of silver nanowire transparent electrodes for flexible electronics. Therefore, various studies have been conducted to understand the deformation behavior of silver nanowire networks, which are different from those of bulk silver or silver thin films. The focus of this review is to elucidate the deformation mechanism of silver nanowire networks under high cycles of bending and to present ways to improve the mechanical reliability of silver nanowire transparent electrodes.

Due to the susceptibility of Ag nanowires to external mechanical and chemical damage, maintaining high optical performance and ambient and mechanical stability during the fabrication process is important for the industrial use of Ag nanowire transparent electrodes (TEs). In this study, urethane acrylate-based photosensitive resin (UAPR) is used as the coating material for Ag nanowire TEs to improve their optical transmittance, ambient stability, and resistance to external wiping damage. In the proposed method, UV-curable UAPR is coated onto Ag nanowire TEs using a simple doctor blade, forming a protective coating that increases the optical transmittance of the electrodes due to the refractive index of the UAPR between the air and the substrate. The UAPR coating successfully protects the Ag nanowires from corrosion in ambient air, with no significant change in their optical or electrical properties observed after 180 h of exposure to ambient air. Mechanical wiping tests also confirm that the UAPR coating is effective in protecting the Ag nanowires from external wiping damage, with no degradation of the optical or electrical properties observed after six wiping cycles.

Printing technology enables not only high-volume, multipurpose, low-impact, low-cost manufacturing, but also the introduction of flexible electronic devices, such as displays, actuators, and sensors, to a wide range of consumer markets. Consequently, in the past few decades, printed electronic products have attracted considerable interest. Although flexible printed electronic products are attracting increasing attention from the scientific and industrial communities, a systematic study on their sensing performance based on printability has not been reported so far. In this study, carbon black/Ag nanocomposites were utilized as pastes for a flexible wearable strain sensor. The effects of the rheological property of the pastes and the pattern dimensions of the printed electrodes on the sensor’s performance were investigated. Consequently, the printed sensor demonstrated a high gauge factor of 444.5 for an applied strain of 0.6% to 1.4% with a durability of 1000 cycles and a linearity of R2 = 0.9974. The sensor was also stable under tough environmental conditions.

Surface energy characterization is important to design the fabrication process of reliable electronic devices. Surface energy is influenced by various factors such as surface functionality and morphology. Owing to the high surface-to-volume ratio, surface energy at the nanoscale can be different from that of the bulk. However, the conventional methods for characterization of surface energy such as a sessile drop or Washburn methods cannot be used for nanoscale samples, owing to the limited volume for characterization. Recently, surface energy characterization on the nanoscale using atomic force microscopy (AFM) with Peak Force-Quantitative Nanomechanical Mapping (PF-QNM) imaging mode has been proposed. The nanoscale AFM tips measure the adhesion forces at the nanoscale, which are converted into surface energy through pre-calibrated curves. Successful surface energy characterization of nanoscale metal samples using AFM with the PF-QNM method has been reported previously. This mini-review discusses the recent progress on surface energy characterization at the nanoscale using AFM with the PF-QNM method. The fundamentals of the PF-QNM mode are introduced, and the results of surface energy characterization are summarized. Consequently, the future research direction for surface energy characterization at the nanoscale is discussed. [ABSTRACT FROM AUTHOR]

This study reviews the potential of flexible strain sensors based on nanomaterials such as carbon nanotubes (CNTs), graphene, and metal nanowires (NWs). These nanomaterials have excellent flexibility, conductivity, and mechanical properties, which enable them to be integrated into clothing or attached to the skin for the real-time monitoring of various activities. However, the main challenge is balancing high stretchability and sensitivity. This paper explains the basic concept of strain sensors that can convert mechanical deformation into electrical signals. Moreover, this paper focuses on simple, flexible, and stretchable resistive and capacitive sensors. It also discusses the important factors in choosing materials and fabrication methods, emphasizing the crucial role of suitable polymers in high-performance strain sensing. This study reviews the fabrication processes, mechanisms, performance, and applications of stretchable strain sensors in detail. It analyzes key aspects, such as sensitivity, stretchability, linearity, response time, and durability. This review provides useful insights into the current status and prospects of stretchable strain sensors in wearable technology and human–machine interfaces. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), one of the conducting polymers, is widely used as a conducting material in various applications. PEDOT:PSS possesses high electrical conductivity, optical transparency in visible light range, good chemical and physical stability in ambient state, etc. Furthermore, PEDOT:PSS offers the advantages of flexibility and possibility of solution-based process, which makes it suitable for use in flexible electronic devices. In this mini review, the applications of PEDOT:PSS as a conductive parts in energy harvesting and storage technologies are discussed and summarized. [ABSTRACT FROM AUTHOR]