Printable Nanomaterials for the Fabrication of High-Performance Supercapacitors

Advancements in synthesis, immobilization, characterization, and multifaceted applications of silver nanoparticles: A comprehensive review

Silver nanoparticles (AgNPs) have attracted significant interest in recent years owing to their unique physicochemical properties, including antimicrobial reduction capabilities, photocatalytic activity, self-cleaning features, superhydrophobicity, and electrical conductivity. Their characteristics render them highly advantageous for various textile, electronics, food and agriculture, water treatment, and biomedical applications. This detailed analysis explores the recent benefits and drawbacks of various synthesis methods, immobilization techniques, and characterization of AgNPs while emphasizing novel strategies that improve their functionality across different substrates. A comprehensive analysis is conducted on various synthesis methods, including physical, chemical, and biological approaches. Additionally, immobilization techniques such as in-situ synthesis, pad-dry-cure, and printing on diverse substrates are thoroughly examined for their role in enhancing the functionality of textile substrates. Advanced characterization techniques, encompassing spectroscopic and microscopic methods, have been reviewed to provide a comprehensive understanding of AgNPs' structural and functional properties. This review highlights the progress made in synthesizing AgNPs, focusing on the ability to control their size and shape for targeted applications. Improved immobilization methods have significantly enhanced the stability of AgNPs in intricate environments. In contrast, advanced characterization techniques facilitate a more accurate control and assessment of the properties of AgNPs. The utilization of AgNPs as an antimicrobial agent for surface and food protection, medical devices, antiviral agents, and therapeutic tools showcases their extensive influence across the field. The cytotoxic effects of AgNPs on the human body have been thoroughly examined. This review examines recent advancements in AgNPs to encourage additional research and the development of innovative formulations. It also highlights future perspectives and research directions to effectively and sustainably utilize the potential of AgNPs.

Recent advances in inkjet-printing technologies for flexible/wearable electronics

The rapid development of flexible/wearable electronics requires novel fabricating strategies. Among the state-of-the-art techniques, inkjet printing has aroused considerable interest due to the possibility of large-scale fabricating flexible electronic devices with good reliability, high time efficiency, a low manufacturing cost, and so on. In this review, based on the working principle, recent advances in the inkjet printing technology in the field of flexible/wearable electronics are summarized, including flexible supercapacitors, transistors, sensors, thermoelectric generators, wearable fabric, and for radio frequency identification. In addition, some current challenges and future opportunities in this area are also addressed. We hope this review article can give positive suggestions to the researchers in the area of flexible electronics.

A Short Review Comparing Carbon-Based Electrochemical Platforms With Other Materials For Biosensing SARS-Cov-2

Due to the 2019 SARS-CoV-2 outbreak, low-cost, fast, and user-friendly diagnostic kits for biosensing SARS-CoV-2 in real samples employing multiple working electrodes are in high demand. Choosing SARS-CoV-2 detecting electrodes is difficult because each has advantages and limitations. Carbon-based electrochemical sensing applications have attracted attention from the electrochemical sensing community because carbon and carbon-based materials have been a godsend for testing utilizing an electrochemical platform. Carbon working electrode electrochemical platforms are cost-effective and fast. Covid-sensors use carbon-based materials because they can be easily changed (with inorganic and organic functionalities), have quick response kinetics, and are chemically resistant. Covid-19 sensing materials include graphene and graphite. This review explains how carbon materials have been employed in N and S protein electrochemical detection. Here, we discussed a carbon-based technology for SARS-CoV-2 biosensing. We've compared carbon-based electrochemical sensing to different electrodes.

Gold nanostructures: synthesis, properties, and neurological applications

Recent advances in technology are expected to increase our current understanding of neuroscience. Nanotechnology and nanomaterials can alter and control neural functionality in both in vitro and in vivo experimental setups. The intersection between neuroscience and nanoscience may generate long-term neural interfaces adapted at the molecular level. Owing to their intrinsic physicochemical characteristics, gold nanostructures (GNSs) have received much attention in neuroscience, especially for combined diagnostic and therapeutic (theragnostic) purposes. GNSs have been successfully employed to stimulate and monitor neurophysiological signals. Hence, GNSs could provide a promising solution for the regeneration and recovery of neural tissue, novel neuroprotective strategies, and integrated implantable materials. This review covers the broad range of neurological applications of GNS-based materials to improve clinical diagnosis and therapy. Sub-topics include neurotoxicity, targeted delivery of therapeutics to the central nervous system (CNS), neurochemical sensing, neuromodulation, neuroimaging, neurotherapy, tissue engineering, and neural regeneration. It focuses on core concepts of GNSs in neurology, to circumvent the limitations and significant obstacles of innovative approaches in neurobiology and neurochemistry, including theragnostics. We will discuss recent advances in the use of GNSs to overcome current bottlenecks and tackle technical and conceptual challenges.

Silver Nanoparticles for Conductive Inks: From Synthesis and Ink Formulation to Their Use in Printing Technologies

Currently, silver nanoparticles have attracted large interest in the photonics, electrics, analytical, and antimicrobial/biocidal fields due to their excellent optical, electrical, biological, and antibacterial properties. The versatility in generating different sizes, shapes, and surface morphologies results in a wide range of applications of silver nanoparticles in various industrial and health-related areas. In industrial applications, silver nanoparticles are used to produce conductive inks, which allows the construction of electronic devices on low-cost and flexible substrates by using various printing techniques. In order to achieve successful printed patterns, the necessary formulation and synthesis need to be engineered to fulfil the printing technique requirements. Additional sintering processes are typically further required to remove the added polymers, which are used to produce the desired adherence, viscosity, and reliable performance. This contribution presents a review of the synthesis of silver nanoparticles via different methods (chemical, physical and biological methods) and the application of silver nanoparticles under the electrical field. Formulation of silver inks and formation of conductive patterns by using different printing techniques (inkjet printing, screen printing and aerosol jet printing) are presented. Post-printing treatments are also discussed. A summary concerning outlooks and perspectives is presented at the end of this review.

A handy reversible bonding technology and its application on fabrication of an on-chip liquid metal micro-thermocouple

We report a novel reversible bonding technique for liquid metal (LM) microelectrode fabrication in this study. This technique greatly simplifies the process of LM micro-electrode fabrication and can be used to achieve the rapid fabrication of LM blind-end electrodes. Three kinds of treatments, including heat treatment, plasma treatment and heat/plasma treatment, were tested for bonding strength. The experimental results showed that the heat/plasma treatment has the strongest bonding strength. All the three treatments can be completely released by simple water treatment. This handy fabrication method can help to integrate micro-liquid metal electrodes vertically in a microchannel. At the end of this work, this fabrication method was used to integrate liquid metal thermocouples in a microchannel, which greatly shortened the fabrication time and lowered the cost compared with traditional deposition or sputtering methods.

Superhydrophobic-Substrate-Assisted Construction of Free-Standing Microcavity-Patterned Conducting Polymer Films

Patterned conducting polymer films with unique structures have promising prospects for application in various fields, such as actuation, water purification, sensing, and bioelectronics. However, their practical application is hindered because of the limitations of existing construction methods. Herein, a strategy is proposed for the superhydrophobic-substrate-assisted construction of free-standing 3D microcavity-patterned conducting polymer films (McPCPFs) at micrometer resolution. Easy-peeling and nondestructive transfer properties are achieved through electrochemical polymerization along the solid/liquid/gas triphase interface on micropillar-structured substrates. The effects of the wettability and geometrical parameters of the substrates on the construction of McPCPFs are systematically investigated in addition to the evolution of the epitaxial growth along the triphase interface at different polymerization times. The McPCPFs can be easily peeled from superhydrophobic surfaces using ethanol because of weak adhesion and nondestructively transferred to various substrates taking advantage of the capillarity. Furthermore, sensitive light-driven McPCPF locomotion on organic liquid surfaces is demonstrated. Ultimately, a facile strategy for the construction of free-standing 3D microstructure-patterned conducting polymer films is proposed, which can improve productivity and applicability of the films in different fields and expand the application scope of superwettable interfaces.

Advanced materials and technologies for supercapacitors used in energy conversion and storage: a review

Supercapacitors are increasingly used for energy conversion and storage systems in sustainable nanotechnologies. Graphite is a conventional electrode utilized in Li-ion-based batteries, yet its specific capacitance of 372 mA h g−1 is not adequate for supercapacitor applications. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period and longer lifetime. This review compares the following materials used to fabricate supercapacitors: spinel ferrites, e.g., MFe2O4, MMoO4 and MCo2O4 where M denotes a transition metal ion; perovskite oxides; transition metals sulfides; carbon materials; and conducting polymers. The application window of perovskite can be controlled by cations in sublattice sites. Cations increase the specific capacitance because cations possess large orbital valence electrons which grow the oxygen vacancies. Electrodes made of transition metal sulfides, e.g., ZnCo2S4, display a high specific capacitance of 1269 F g−1, which is four times higher than those of transition metals oxides, e.g., Zn–Co ferrite, of 296 F g−1. This is explained by the low charge-transfer resistance and the high ion diffusion rate of transition metals sulfides. Composites made of magnetic oxides or transition metal sulfides with conducting polymers or carbon materials have the highest capacitance activity and cyclic stability. This is attributed to oxygen and sulfur active sites which foster electrolyte penetration during cycling, and, in turn, create new active sites.

The electrochemical performance of reduced graphene oxide prepared from different types of natural graphites

Graphene, as a new type of carbon material in the forefront of research, has been applied widely in the area of supercapacitors with the advantages of a large positive specific surface, high conductivity, stable chemical properties and good supercapacitor performance. In this study, an investigation on the electrochemical performance of reduced graphene oxides (rGOs) prepared from various natural graphites was conducted. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, atomic force microscopy and electrochemical performance analysis were performed to characterize the as-prepared GOs and rGOs. The results demonstrated that a reduction modification of GO was necessary to optimize its electrochemical performance. The rGO has a great electrochemical performance with a good repair ability, better oxygen-containing functional group removal effect, lower structural defects, larger average size of the in-plane sp2 region and great specific capacitance.

Fabricating High-Resolution Metal Pattern with Inkjet Printed Water-Soluble Sacrificial Layer

The metal pattern plays a crucial role in various optoelectronic devices. However, fabrication of high-resolution metal patterns has serious problems including complicated techniques and high cost. Herein, an inkjet printed water-soluble sacrificial layer was proposed to fabricate a high-resolution metal pattern. The water-soluble sacrificial layer was inkjet printed on a polyethylene glycol terephthalate (PET) surface, and then the printed surface was deposited with a metal layer by evaporating deposition. When the deposited surface was rinsed by water, the metal layer deposited on the water-soluble sacrificial layer could be removed. Various high-resolution metal patterns were prepared, which could be used in electroluminescent displays, strain sensors, and 3D switches. This facile method could be a promising approach for fabricating high-resolution metal patterns.

Effect of the Common Solvents on UV-Modified Photopolymer and EPDM Flexographic Printing Plates and Printed Ink Films

The aim of this research was to analyze the influence of the solvents commonly used in flexography on photopolymer and ethylene propylene diene monomer (EPDM) flexographic printing plates and prints. EPDM plates are recommended when the reproduction process includes a higher amount of the solvents or aggressive solvents. Since additional UV treatment of flexographic printing plates could decrease the interaction between the plate and solvent, photopolymer and EPDM plates were treated with varied UV radiation and exposed to different types of solvents. Effects of the UV treatment and of the solvents on printing plate properties and on prints were analyzed. Results show that EPDM plates are more resistant to solvents in terms of the degree of swelling; however, surface properties of the plates were affected for both plate materials. In addition, the degree of swelling and increased hardness due to UV radiation were crucial for changes of the width of printed lines, and altered surface free energy affected the thickness of deposited ink film for both plate materials. Therefore, depending on the qualitative requirements of specific printed film, the duration of UV treatment can be adjusted for use with specific types of printing plate and solvent.

Study on Direct Synthesis of Energy Efficient Multifunctional Polyaniline-Graphene Oxide Nanocomposite and Its Application in Aqueous Symmetric Supercapacitor Devices

The synthesis of promising nanocomposite materials can always be tricky and depends a lot on the method of synthesis itself. Developing such synthesis routes, which are not only simple but also can effectively catch up the synergy of the compositing material, is definitely a worthy contribution towards nanomaterial science. Carbon-based materials, such as graphene oxide, and conjugative polymers, such as conductive polyaniline, are considered materials of the 21st century. This study involves a simple one pot synthesis route for obtaining a nanocomposite of polyaniline and graphene oxide with synergistic effects. The study was carried out in a systematic way by gradually changing the composition of the ingredients in the reaction bath until the formation of nanocomposite took place at some particular reaction parameters. These nanocomposites were then utilized for the fabrication of electrodes for aqueous symmetric supercapacitor devices utilizing gold or copper as current collectors. The device manifested a good capacitance value of 264 F/g at 1 A/g, magnificent rate performance, and capacitance retention of 84.09% at a high current density (10 A/g) when gold sheet electrodes were used as the current collectors. It also showed a capacitance retention of 79.83% and columbic efficiency of 99.83% after 2000 cycles.

Optical Planar Waveguide Sensor with Integrated Digitally-Printed Light Coupling-in and Readout Elements

Optical planar waveguide sensors, able to detect and process information from the environment in a fast, cost-effective, and remote fashion, are of great interest currently in different application areas including security, metrology, automotive, aerospace, consumer electronics, energy, environment, or health. Integration of networks of these systems together with other optical elements, such as light sources, readout, or detection systems, in a planar waveguide geometry is greatly demanded towards more compact, portable, and versatile sensing platforms. Herein, we report an optical temperature sensor with a planar waveguide architecture integrating inkjet-printed luminescent light coupling-in and readout elements with matched emission and excitation. The first luminescent element, when illuminated with light in its absorption band, emits light that is partially coupled into the propagation modes of the planar waveguide. Remote excitation of this element can be performed without the need for special alignment of the light source. A thermoresponsive liquid crystal-based film regulates the amount of light coupled out from the planar waveguide at the sensing location. The second luminescent element partly absorbs the waveguided light that reaches its location and emits at longer wavelengths, serving as a temperature readout element through luminescence intensity measurements. Overall, the ability of inkjet technology to digitally print luminescent elements demonstrates great potential for the integration and miniaturization of light coupling-in and readout elements in optical planar waveguide sensing platforms.

Digital Luminescence Patterning via Inkjet Printing of a Photoacid Catalysed Organic-Inorganic Hybrid Formulation

Accurate positioning of luminescent materials at the microscale is essential for the further development of diverse application fields including optoelectronics, energy, biotechnology and anti-counterfeiting. In this respect, inkjet printing has recently attracted great interest due to its ability to precisely deposit with high throughput and no contact, functional materials on different types of substrates. Here, we present a novel photoacid catalysed organic-inorganic hybrid luminescent ink. The formulation, containing monomers bearing epoxy and silane functionalities, a photoacid generator and a small percentage of Rhodamine-B, shows good jetting properties and adequate wetting of the deposited droplets on the receiving substrates. Ultraviolet exposure of the deposited material triggers the cationic ring-opening polymerization reaction of the epoxy groups. Concomitantly, if atmospheric water is available, hydrolysis and condensation takes place, overall leading to a luminescent crosslinked hybrid organic-inorganic polymeric material obtained through a simple one-step curing process, without post baking steps. Advantageously, protection of the ink from actinic light delays the hydrolysis and condensation conferring long-term stability to the ink. Digital patterning leads to patterned emissive surfaces and elements with good adhesion to different substrates, mechanical and optical properties for the fabrication of optical and photonic elements and devices.

Initial Studies Directed toward the Rational Design of Aqueous Graphene Dispersants

This study presents preliminary experimental data suggesting that sodium 4-(pyrene-1-yl)butane-1-sulfonate (PBSA), 5, an analogue of sodium pyrene-1-sulfonate (PSA), 1, enhances the stability of aqueous reduced graphene oxide (RGO) graphene dispersions. We find that RGO and exfoliated graphene dispersions prepared in the presence of 5 are approximately double the concentration of those made with commercially available PSA, 1. Quantum mechanical and molecular dynamics simulations provide key insights into the behavior of these molecules on the graphene surface. The seemingly obvious introduction of a polar sulfonate head group linked via an appropriate alkyl spacer to the aromatic core results in both more efficient binding of 5 to the graphene surface and more efficient solvation of the polar head group by bulk solvent (water). Overall, this improves the stabilization of the graphene flakes by disfavoring dissociation of the stabilizer from the graphene surface and inhibiting reaggregation by electrostatic and steric repulsion. These insights are currently the subject of further investigations in an attempt to develop a rational approach to the design of more effective dispersing agents for rGO and graphene in aqueous solution.

A Facile Approach for Fabricating Microstructured Surface Based on Etched Template by Inkjet Printing Technology

Microstructures are playing an important role in manufacturing functional devices, due to their unique properties, such as wettability or flexibility. Recently, various microstructured surfaces have been fabricated to realize functional applications. To achieve the applications, photolithography or printing technology is utilized to produce the microstructures. However, these methods require preparing templates or masks, which are usually complex and expensive. Herein, a facile approach for fabricating microstructured surfaces was studied based on etched template by inkjet printing technology. Precured polydimethylsiloxane substrate was etched by inkjet printing water-soluble polyacrylic acid solution. Then, the polydimethylsiloxane substrate was cured and rinsed, which could be directly used as template for fabricating microstructured surfaces. Surfaces with raised dots, lines, and squares, were facilely obtained using the etched templates by inkjet printing technology. Furthermore, controllable anisotropic wettability was exhibited on the raised line microstructured surface. This work provides a flexible and scalable way to fabricate various microstructured surfaces. It would bring about excellent performance, which could find numerous applications in optoelectronic devices, biological chips, microreactors, wearable products, and related fields.