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Catechol (CT) is a phenolic compound widely used in various industrial sectors, but it is toxic; thus, there is a need for methods that aim to identify and quantify the existence of residues of this material in the environment. In this study a disposable printed electrochemical sensor was developed as an effective alternative for determining CT in water samples. The electrode, called SPEC, was manufactured using the screen-printing method using polyethylene terephthalate (PET) as a support, in which a conductive ink based on carbonaceous materials was used to print the working and auxiliary electrodes and a silver/silver chloride of ink on the reference electrode. The optimal ratio for the conductive ink was 6.25% carbon black, 35.42% graphite, and 58.33% nail polish. The ink obtained was characterized by scanning electron microscopy (SEM). The assessment of the effect of pH on the redox process showed Nernstian behavior (0.057 V pH−1), indicating that the process involves the same number of protons and electrons. Under optimized conditions, with 0.2 mol L−1 acetate buffer at pH 5.0, and by square wave voltammetry, the sensor presented sensitivity values of 0.31 μA L μmol−1, a detection limit of 5.96 μmol L−1, and a quantification limit of 19.87 μmol L−1. The sensor was applied to determine CT in tap water samples, and the results showed recoveries between 97.95 and 100.17%.

In this work, a new and convenient fabrication process for screen-printed reduced graphene oxide-molybdenum disulfide electrode (SPrGO-MoS2E) was proposed. Reduced graphene oxide-molybdenum disulfide (rGO-MoS2) composite was hydrothermally synthesized and then dispersed in deionized water and ethanol with a ratio of 2:3 (v/v) to form a conductive suspension. The suspension was then blended with carbon paste at a ratio of 0.1:9.9 (g/g) to obtain a screen-printable rGO-MoS2 conductive ink. An electrochemical sensing electrode was formed by screening this conductive ink onto a polyethylene terephthalate substrate. The characteristics of this electrode were investigated by scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffractometry, Raman spectroscopy, and electrochemical impedance spectroscopy. Overall, the conductive suspension comprising the rGO-MoS2 composite showed higher electrochemical sensing performance compared with electrodes containing only rGO or MoS2. Cyclic voltammetry revealed that the SPrGO-MoS2 electrode exhibited excellent electrochemical sensing performance toward several electroactive species, namely, potassium hexacyanoferrate (III) ([Fe(CN6)]3−/4−), nicotinamide adenine dinucleotide (NAD+/NADH), and hydrogen peroxide (H2O2) dissolved in 0.1 M PBS (pH 7.4). The limits of detection for [Fe(CN6)]3−/4−, NAD+/NADH, and H2O2 were 0.34, 0.25, and 1.36 μM, respectively. In addition, the reproducibility, repeatability, and stability determined from the relative standard deviations (RSDs, n = 7) of these analytes were less than 12.1 %, 8.6 %, and 7.4 %, respectively. Therefore, the ready-to-use SPrGO-MoS2E could be an alternative material for advanced chemical and biological sensing applications.

Highlights Naturally crosslinked carbonaceous liquid metal aqueous printable ink mediated by biopolymers. E-textile with conductivity, stability, wearability, and aesthetic characteristics. Multi-applications in health monitoring, pressure sensing, and energy harvesting.

The conventional real-time screening in organs-on-chips is limited to optical tracking of pre-tagged cells and biological agents. This work introduces an efficient biofabrication protocol to integrate tunable hydrogel electrodes into 3D bioprinted-on-chips. We established our method of fabricating cell-laden hydrogel-based microfluidic chips through digital light processing-based 3D bioprinting. Our conductive ink includes poly-(3,4-ethylene-dioxythiophene)-polystyrene sulfonate (PEDOT: PSS) microparticles doped in polyethylene glycol diacrylate (PEGDA). We optimized the manufacturing process of PEDOT: PSS microparticles characterized our conductive ink for different 3D bioprinting parameters, geometries, and materials conditions. While the literature is limited to 0.5% w/v for PEDOT: PSS microparticle concentration, we increased their concentration to 5% w/v with superior biological responses. We measured the conductivity in the 3–15 m/m for a range of 0.5%–5% w/v microparticles, and we showed the effectiveness of 3D-printed electrodes for predicting cell responses when encapsulated in gelatin-methacryloyl (GelMA). Interestingly, a higher cellular activity was observed in the case of 5% w/v microparticles compared to 0.5% w/v microparticles. Electrochemical impedance spectroscopy measurements indicated significant differences in cell densities and spheroid sizes embedded in GelMA microtissues.

This work developed a conductive ink composed of carbonaceous material for printing electrochemical sensors. The optimized ink comprises graphite, carbon black, and nail polish, respectively (35.3:11.7:53%), as well as acetone as a solvent. The proportion was optimized with consideration of the binder’s solubilization, the ink’s suitability for the screen-printing process, and lower electrical resistance. The materials used, and the resulting ink, were analyzed by way of Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The charge transfer resistance (Rct) obtained was 0.348 kΩ. The conductive ink was used to print an electrode on a PET substrate, and a flexible and disposable electrode was obtained. The electroactive area obtained was 13.7 cm2, which was calculated by the Randles-Sevcik equation. The applicability of the device was demonstrated with a redox probe, providing a sensitivity of 0.02 µ A L mmol−1. The conductive ink has adequate homogeneity for producing electrodes using the screen-printing technique, with a low estimated production cost of $ 0.09 mL−1.

This study explores the intricate interaction between the properties of textile substrates and screen-printing parameters in shaping fabric circuits using silver conductive ink. Via analyzing key variables such as fabric type, mesh density, and the number of overprinted layers, the research revealed how the porous structure, large surface area, and fiber morphology of textile substrates influence ink absorption, ultimately enhancing the electrical connectivity of the printed circuits. Notably, the hydrophilic cotton staple fibers fabric effectively absorbed the conductive ink into the fabric substrate, demonstrating superior electrical performance compared with the hydrophobic polyester filament fabric after three overprinting, unlike the results observed after a single print. As mesh density decreased and the number of prints increased, the electrical resistance of the circuit gradually reduced, but ink bleeding on the fabric surface became more pronounced. Cotton fabric, via absorbing the ink deeply, exhibited less surface bleeding, while polyester fabric showed more noticeable ink spreading. These findings provide valuable insights for improving screen printing technology for textile circuits and contribute to the development of advanced fabric circuits that enhance the functionality of smart wearable technology.

Flexible electronics have revolutionized the field by overcoming the rigid limitations of traditional devices, offering superior flexibility and adaptability. Conductive ink performance is crucial, directly impacting the stability of flexible electronics. While metal filler-based inks exhibit excellent conductivity, they often lack mechanical stability. To address this challenge, we present a novel conductive ink utilizing a ternary composite filler system: liquid metal and two micron-sized silver morphologies (particles and flakes). We systematically investigated the influence of filler type, mass ratio, and sintering process parameters on the composite ink’s conductivity and mechanical stability. Our results demonstrate that flexible wires fabricated with the liquid metal/micron silver particle/micron silver flake composite filler exhibit remarkable conductivity and exceptional bending stability. Interestingly, increasing the liquid metal content results in a trade-off, compromising conductivity while enhancing mechanical performance. After enduring 5000 bending cycles, the resistance change in wires formulated with a 4:1 mass ratio of micron silver particles to flakes is only half that of wires with a 1:1 ratio. This study further investigates the mechanism governing resistance variations during flexible wire bending. Additionally, we observed a positive correlation between sintering temperature and pressure with the conductivity of flexible wires. The significance of the sintering parameters on conductivity follows a descending order: sintering temperature, sintering pressure, and sintering time. Finally, we demonstrate the practical application of this technology by integrating the composite ink-based flexible wires with conductive polymer-based strain sensors. This combination successfully achieved the detection of human movements, including finger and wrist bending.

This text discusses the synthesis of copper nanoparticles via a liquid phase reduction method, using ascorbic acid as a reducing agent and CuSO4·5H2O as the copper source. The synthesized copper nanoparticles are small in size, uniformly distributed, are mostly between 100–200 nm with clear boundaries between particles, and exhibit excellent dispersibility, making them suitable for metal conductive inks. 1. The copper nanoparticles are analyzed for good antioxidation properties, because their surface is coated with PVP and ascorbic acid. This organic layer somewhat isolates the particle surface from contact with air, preventing oxidation, and accounts for about 9% of the total weight. 2. When the prepared copper nanoparticles are spread on a polyimide substrate and sintered at 250 °C for 120 min, the resistivity can be as low as 23.5 μΩ·cm, and at 350 °C for 30 min, the resistivity is only three times that of bulk copper. 3. The prepared conductive ink, printed on a polyimide substrate using a direct writing tool, shows good flexibility before and after sintering. After sintering at 300 °C for 30 min and connecting the pattern to a circuit with a diode lamp, the diode lamp is successfully lit. 4. This method produces copper nanoparticles with small size, good dispersion, and antioxidation capabilities, and the conductive ink prepared from them demonstrates good conductivity after sintering.

This study presents the functionalization of silk fabric with SWCNT ink. The first step was the formation of a polydopamine (PDA) thin coating on the silk fabric to allow for effective bonding of SWCNTs. PDA formation was carried out directly on the fabric by means of polymerization of dopamine in alkali conditions. The Silk/PDA fabric was functionalized with SWCNT ink of different SWCNT concentrations by using the dip-coating method. IR and Raman analyses show that the dominant β-sheet structure of silk fibroin after the functionalization process remains unchanged. The heat resistance is even slightly improved. The hydrophobic silk fabric becomes hydrophilic after functionalization due to the influence of PDA and the surfactant in SWCNT ink. The ink significantly changes the electrical properties of the silk fabric, from insulating to conductive. The volume resistance changes by nine orders of magnitude, from 2.4 × 1012 Ω to 2.3 × 103 Ω for 0.12 wt.% of SWCNTs. The surface resistance changes by seven orders of magnitude, from 2.1 × 1012 Ω to 2.4 × 105 Ω for 0.17 wt.% of SWCNTs. The volume and surface resistance thresholds are determined to be about 0.05 wt.% and 0.06 wt.%, respectively. The low value of the percolation threshold indicates efficient functionalization, with high-quality ink facilitating the formation of percolation paths through SWCNTs and the influence of the PDA linker.

The adhesion with substrate and conductivity of silver (Ag) conductive pattern are critical for practical applications of flexible electronic devices. Polymer vinyl acetate (PVAc) as an important solvent in Ag ink might largely improve the conductive pattern's adhesion property. However, the addition of PVAc in Ag ink also result in decreasing the patterns conductivity to about 210 ± 2 μΩ cm after infrared sintering at air atmosphere. Here, we found a facial method to eliminate the effect of the addition of PVAc for Ag conductive pattern. In this method, the thickness of PVAc layer coated on Ag particles surface was decreased via a washing treatment by ethanol mixed with acetone. After post-sintering treatment of ethanol brushing, a stable and conductive pattern was achieved. Owing to these treatments, compared with the blank sample, the adhesion of patterns was improved by the scratch test with higher damage force from 1 to 3.8 N. Meanwhile, the resistivity of the formed Ag pattern gradually decreased to 22 ± 0.5 μΩ cm after post-sintering treatment for 50 times, and this value did not change after bending 6000 times. The mechanism was given and confirmed by energy dispersive spectroscopy (EDS) analysis, indicating that the residual organic coatings on patterns had been taken away by the evaporation of alcohol molecular. LEDs pasted in the electronic circuit of our university badge were illuminated, indicating their wide application in the field of flexible electronic devices.

The research sheds light on what smart materials are and their types, dealing with the values of jewellery design, especially the functional values through the use of electric painting and used it Different as a smart material. People who are exposed to a dark environment, which exposes them to fear and to find a source of light that restores peace to them, So they need a close source of light that is easily accessible in the form of a piece of jewellery that carries an aesthetic and functional value, allowing it to illuminate the surroundings without occupying the hands, so the research problem can be formulated in a The question: Is it possible to find innovative design for luminous jewellery using smart materials? The importance of the research is summarized in finding new design for luminous jewellery using smart materials. as The research aims to take advantage of the technological development of smart materials such as electric painting to influence the development of the functional, use, aesthetic and economic aspects of luminous ornaments that help the wearer in illuminating the surrounding place in the dark. The results of the research is that smart materials are the next generation that can influence various fields, including the design of contemporary jewellery, the creation of new functional visions in the field of metal jewellery, as the development in smart materials has become fast and variable, so The product designer must keeps pace with this development and employs it optimally to serve the user

The article presents the ongoing research, which aims to select suitable electrodes and mixtures of conductive inks, which will be used as a converter between the pressure and electrical quantities in the design of planar pressure transducers. In the described research, we continue our previous work and the work of other authors who have previously dealt with the properties of conductive inks and electrodes. Due to the only partial results in the given field, we decided to perform an extensive and original measurement of a total of 172 combinations of different electrode sizes, various conductive ink mixtures and ink layer thicknesses. Thanks to this, it will be possible, in the future, to select a suitable combination of electrodes and inks when designing pressure sensors for industrial and agricultural applications without the need to perform time-consuming preparatory measurements. The aim of the measurements is also to determine the usable working range of the pressures and the corresponding sensitivity for certain combinations of electrodes and inks, and to also exclude those variants which are unsuitable for the given purposes. This paper presents the introductory part of the measurements, which aims to verify the methodology of the measurements on a test plate at robotised workspace that is connected to a PC in real time via the program LabView. The described introductory measurements proved our methodology to be suitable to the given purpose; however, there minor problems emerged with the actual working pressure range of the transducer and the consequential necessary adjustments of the control program.

Currently, inkjet printing of the hybrid conductive inks plays a critical role in the technological advancement to fabricate flexible electronics. In this study, flexible electronics based on water-based graphene, silver nanoparticles (AgNPs), and graphene/AgNPs hybrid printed on polyethylene terephthalate substrate (PET) substrate were developed. The properties of the conductive inks were evaluated based on different concentrations of polyvinylpyrrolidone (PVP) surfactants (0.1, 0.3, 0.5, and 0.7 wt%). Among the conductive ink formulations, G/AgNPs hybrid inks fabricated with 0.5 wt% PVP surfactant exhibited better stability, wettability, and electrical conductivity. Moreover, the electrical conductivity of G/AgNPs hybrid conductive traces performed more than 100 times higher than G and AgNPs conductive traces. In addition, it was observed that under 50% tensile and 100 bending times, the printed hybrid conductive traces exhibited only 4% and 3% drop in conductivity, respectively. Therefore, conductive inks prepared from water-based G/AgNPs hybrid ink are thought to be appropriate for usage in printed flexible electronic applications.

Cracks have a primary effect on the failure of a structure. Therefore, the development of crack sensors with high accuracy and resolution and cracks detection method are important. In this study, the crack sensors were fabricated, and the crack locations were detected with the electrical signal of the crack sensor. First, a metal grid-type micro-crack sensor based on silver was fabricated. The sensor is made with electrohydrodynamics (EHD) inkjet printing technology, which is well known as the next generation of printed electronics technology. Optimal printing conditions were established through experiments, and a grid sensor was obtained. After that, single cracks and multiple cracks were simulated on the sensor, and electrical signals generated from the sensor were measured. The measured electrical signal tracked the location of the cracks in three steps: simple cross-calculation, interpolation, and modified P-SPICE. It was confirmed that cracks could be effectively found and displayed using the method presented in this paper.

Copper-based nanoinks are emerging as promising low-cost alternatives to widely used silver nanoinks in electronic printing. However, the spontaneous oxidation of copper under ambient conditions poses significant challenges to its broader application. To address this issue, this paper presents an economical, large-scale, and environmentally friendly method for fabricating Cu@Ag nanoparticles (Cu@Ag NPs). The as-prepared nanoparticles exhibit a narrow size distribution of approximately 100 nm and can withstand ambient exposure for at least 60 days without significant oxidation. The Cu@Ag-based ink, with a 60 wt% loading, was screen-printed onto a flexible polyimide substrate and subsequently heat-treated at 290 °C for 15 minutes under a nitrogen atmosphere. The sintered pattern displayed a low electrical resistivity of 25.5 μΩ·cm (approximately 15 times the resistivity of bulk copper) along with excellent reliability and mechanical fatigue strength. The innovative Cu@Ag NPs fabrication method holds considerable potential for advancing large-scale applications of copper-based inks in flexible electronics.

In this article, a facile way for the doping of graphene and graphene derivatives with silver nanoparticles at different Ag ratios is described. Ag nanoparticles were formed directly on the surface of two different graphene substrates dispersed in dimethylformamide by the reduction of Ag cations with NaBH4. A few layered graphene nanosheets (FLG) produced from graphite and reduced graphene oxide functionalized with amino arylsulfonates (f-rGO) were used as substrates. The final graphene/Ag nanoparticle hybrid in the form of solid, dense spots showed enhanced electrical conductivity, which can be attributed to the formation of conductive interconnections between the 2D nanosheets. Importantly, electrical conductivities of 20 and 167 103 S m−1 were measured for the hybrids of f-rGO and FLG, respectively, with the higher Ag percentage without an annealing process. A representative hybrid f-rGO with Ag nanoparticles was used for the development of a highly conductive water-based gravure ink with excellent printing properties.

The silver nanoparticle (AgNP) ink synthesized was simple, well-dispersed, did not need sintering, had excellent conductivity and can be used as a conductive ink in several areas, particularly in the fabrication of reference electrodes. The AgNP ink was fabricated by synthesizing AgNP using the polyol method and then dispersing in methanol to fabricate the conductive ink. The synthesis was explained step-by-step, the proposed mechanism was discussed and photos of the entire process were shown. The materials (AgNO3 and AgNP) were characterized by UV–Vis, SEM and XRD. The UV–Vis exhibit a strong broad peak at 417 nm due the surface plasmon resonance (SPR) absorption band of AgNP. The SEM images showed spherical nanoparticles, non-aggregates and with an average diameter of 50 - 140 nm. The XRD of AgNP presented four main characteristic peaks for silver corresponding to (111), (200), (220) and (311) planes, confirming the cubic (FCC) silver. The AgNP ink has an excellent conductivity, with an average ohmic resistance of 1.53 Ω. Finally, the AgNP ink was tested in the fabrication of reference electrodes and the analytical response was higher than the conventional Ag/AgCl reference electrode.

In the last decades, the demand for electronics and, therefore, electronic waste, has increased. To reduce this electronic waste and the impact of this sector on the environment, it is necessary to develop biodegradable systems using naturally produced materials with low impact on the environment or systems that can degrade in a certain period. One way to manufacture these types of systems is by using printed electronics because the inks and the substrates used are sustainable. Printed electronics involve different methods of deposition, such as screen printing or inkjet printing. Depending on the method of deposition selected, the developed inks should have different properties, such as viscosity or solid content. To produce sustainable inks, it is necessary to ensure that most of the materials used in the formulation are biobased, biodegradable, or not considered critical raw materials. In this review, different inks for inkjet printing or screen printing that are considered sustainable, and the materials that can be used to formulate them, are collected. Printed electronics need inks with different functionalities, which can be mainly classified into three groups: conductive, dielectric, or piezoelectric inks. Materials need to be selected depending on the ink’s final purpose. For example, functional materials such as carbon or biobased silver should be used to secure the conductivity of an ink, a material with dielectric properties could be used to develop a dielectric ink, or materials that present piezoelectric properties could be mixed with different binders to develop a piezoelectric ink. A good combination of all the components selected must be achieved to ensure the proper features of each ink.

Herein, we report results of the studies relating to the development of an impedimetric, magnetic bead-assisted supersandwich DNA hybridization assay for ultrasensitive detection of Neisseria gonorrhoeae, the causative agent of a sexually transmitted infection (STI), gonorrhea. First, a conductive ink was formulated by homogenously dispersing carboxylated multiwalled carbon nanotubes (cMWCNTs) in a stable emulsion of terpineol and an aqueous suspension of carboxymethyl cellulose (CMC). The ink, labeled C5, was coated onto paper substrates to fabricate C5@paper conductive electrodes. Thereafter, a magnetic bead (MB)-assisted supersandwich DNA hybridization assay was optimized against the porA pseudogene of N. gonorrhoeae. For this purpose, a pair of specific 5′ aminated capture probes (SCP) and supersandwich detector probes (SDP) was designed, which allowed the enrichment of target gonorrheal DNA sequence from a milieu of substances. The SD probe was designed such that instead of 1:1 binding, it allowed the binding of more than one T strand, leading to a ‘ladder-like’ DNA supersandwich structure. The MB-assisted supersandwich assay was integrated into the C5@paper electrodes for electrochemical analysis. The C5@paper electrodes were found to be highly conductive by a four-probe conductivity method (maximum conductivity of 10.1 S·cm−1). Further, the biosensing assay displayed a wide linear range of 100 aM-100 nM (109 orders of magnitude) with an excellent sensitivity of 22.6 kΩ·(log[concentration])−1. The clinical applicability of the biosensing assay was assessed by detecting genomic DNA extracted from N. gonorrhoeae in the presence of DNA from different non-gonorrheal bacterial species. In conclusion, this study demonstrates a highly sensitive, cost-effective, and label-free paper-based device for STI diagnostics. The ink formulation prepared for the study was found to be highly thixotropic, which indicates that the paper electrodes can be screen-printed in a reproducible and scalable manner.

In this paper, we analyze the effects of textile weaving and finishing processes on the performance of textile-based wearable antennas. Several textile-based patch antennas operating at 2.4 GHz were designed and fabricated for evaluation. All of them had the same geometry comprising a 1-mm-thick felt substrate in the middle, and silver ink screen-printed polyester fabric as the ground and patch at the bottom and on top. However, polyester fabric, the bare textile material for the conductive ground and patch was subjected to different weaving and finishing (tentering, scouring, and calendering) processes. It was observed that the antenna resonant frequency, bandwidth, radiation efficiency, and peak gain were varied by these processes, although the antenna geometry and screen-printing method were identical to each other. The best antenna exhibits a peak gain of 5.2 dBi and a radiation efficiency of 42.4%, while the worst shows corresponding values of 4.17 dBi and 34.8%. This implies that the weaving and finishing processes considerably impact textile-based wearable antenna performances.

Bu araştırmanın amacı elektronik tekstil uygulamalarında kullanılan baskı yöntemlerinin incelenmesi ve bu baskı yöntemlerinde kullanılan farklı özelliklere sahip iletken mürekkeplerin işlem şartlarının, avantaj ve dezavantajlarının incelenmesidir. Araştırmada, iletken mürekkepler ile ilgili bir kavramsal çerçeve oluşturularak elektronik tekstiller alanında kullanımı ve önemi literatür açısından incelenmiştir. Çalışmada, gümüş içerikli iletken mürekkeplerin esnek malzemeler üzerine basılmasıyla, radyo frekansı tanımlama, elektromiyografi ve çeşitli sensör tasarımlarının yapıldığı görülmüştür. Serigrafi ve inkjet baskı teknikleri en çok kullanılan baskı teknikleri olarak değerlendirilmiştir.

Bu araştırmanın amacı elektronik tekstil uygulamalarında kullanılan baskı yöntemlerinin incelenmesi ve bu baskı yöntemlerinde kullanılan farklı özelliklere sahip iletken mürekkeplerin işlem şartlarının, avantaj ve dezavantajlarının incelenmesidir. Araştırmada, iletken mürekkepler ile ilgili bir kavramsal çerçeve oluşturularak elektronik tekstiller alanında kullanımı ve önemi literatür açısından incelenmiştir. Çalışmada, gümüş içerikli iletken mürekkeplerin esnek malzemeler üzerine basılmasıyla, radyo frekansı tanımlama, elektromiyografi ve çeşitli sensör tasarımlarının yapıldığı görülmüştür. Serigrafi ve inkjet baskı teknikleri en çok kullanılan baskı teknikleri olarak değerlendirilmiştir.

The purpose of this work was the fabrication of a conductive carbon nanotube (CNT) ink. The proposed CNT ink remained remarkably stable over several months. The method includes combining the covalent and non-covalent functionalization, resulting in ink that exhibits excellent storage stability. The covalent functionalization was performed in the acid medium using H2SO4 and HNO3, while the non-covalent functionalization used sodium dodecyl sulfate (SDS) and ultrasonication. The materials were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), electro­chemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). FTIR and SEM confirmed that at the non-covalent functionalization, SDS was successfully adsorbed on the f-CNT surface, while at the covalent functionalization, the functional groups (-COOH, C=O and -OH) were inserted into the CNT surface. Voltammetry and EIS indicated that SDS in the presence of functional groups facilitates electron transfer by improved electrical conductivity. The final product was a well-dispersed CNT ink with an average ohmic resistance of 18.62 kΩ. This indicates that CNT ink can be used in the fabrication of electrochemical sensors.

The article presents end evaluates foil transducers, namely conductive rubber and conductive ink, and their use in the pressure distribution measurement system Plantograf. The ability of both materials to act as transducer between pressure and electrical quantities is assessed by means of measurement on a robotized workspace; two electrode types and various ink layer thicknesses are studied. Basing on the measurements, we present graphically the dependency of the electrical resistance of the materials on the applied pressure. Although both materials proved their ability to act as a transducer in a planar sensor, they both exhibit some limitations. In case of rubber it is limited pressure range up to ca. 1400 kPa and significant hysteresis of the material. The main limiting factor with conductive ink is its poor adherence to the electrodes, which poses important problem for its practical use, although this material evinces better transfer characteristics, particularly in the configuration with 7 μm ink layer and LD type electrode.

This work presents a feasible process for preparation screen-printed electrode (SPE) using a lab-made conductive ink based on cellulose acetate (CAc) and graphite powder (GP) printed on polyvinyl chloride (PVC) sheet. The CAc present in the composition of this SPE is a binding agent for conductive inks with GP, which are relatively low-cost and easily obtainable materials, compared to other similar commercial sensors. The SPE was evaluated through cyclic voltammetry (CV) using an equimolar [Fe(CN)6]3-/4− solution as a redox probe to find an adequate ink composition. Electrode surface was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). To show the analytical potential of SPE proposed it was used for Levodopa (L-dopa) determination. L-dopa is a drug frequently used to reduce the symptoms of Parkinson's disease. The GP-CAc/PVC electrode was evaluated for the determination of L-dopa under square wave voltammetric (SWV) conditions. The electrode presented a linear dynamic range (LDR) from 8.00 to 100 µmol L−1 and a limit of detection (LOD) of 0.06 µmol L−1. As a proof-of-concept, the proposed electrode was used to quantify L-dopa in drug samples as an alternative tool for quality control tests, being applied to two commercial drugs. The electrode construction strategy proved to be reproducible with an analytical performance comparable to other similar electrodes reported in the literature.

The large-scale manufacturing of flexible electronics is nowadays based on inkjet printing technology using specially formulated conductive inks, but achieving adequate wetting of different surfaces remains a challenge. In this work, the development of a silver nanoparticle-based functional ink for printing on flexible paper and plastic substrates is demonstrated. Amphiphilic silver nanoparticles with narrow particle size distribution and good dispersibility were prepared via a two-step wet chemical synthesis procedure. First, silver nanoparticles capped with poly(acrylic acid) were prepared, followed by an amidation reaction with 3-morpholynopropylamine (MPA) to increase their lipophilicity. Density functional theory (DFT) calculations were performed to study the interactions between the particles and the dispersion medium in detail. The amphiphilic nanoparticles were dispersed in solvents of different polarity and their physicochemical and rheological properties were determined. A stable ink containing 10 wt% amphiphilic silver nanoparticles was formulated and inkjet-printed on different surfaces, followed by intense pulsed light (IPL) sintering. Low sheet resistances of 3.85 Ω sq–1, 0.57 Ω sq–1 and 19.7 Ω sq–1 were obtained for the paper, coated poly(ethylene terephthalate) (PET) and uncoated polyimide (PI) flexible substrates, respectively. Application of the nanoparticle ink for printed electronics was demonstrated via a simple flexible LED circuit.

High specific surface is a significant characteristic in zinc coatings that can be highly applicable in batteries and catalysts. Conventional methods to create foams are not cost-efficient, nor could they make a high specific surface. Electroplating has been developed that can produce a very high specific surface foam. On the other hand, conductive ink can create an affordable conductive surface with a high specific surface, so the study on using conductive ink, which has a cost-efficient nature, was necessary to create a conductive surface. This work has investigated the effect of crucial parameters, such as graphite size, coating time and bath composition, on the current efficiency and SEM microstructure. As a result, a 3 µm graphite size was found to be appropriate. Coated zinc escalates linearly with current efficiency for up to 5 h, and then it decreases. Although the zinc concentration increases up to 0.12 mol/L in the electrolyte, making a slight increase in loading, the current efficiency was almost unchanged. However, if it increases more, the loading and current efficiency significantly rise so that the loading grows up to 16 times and the current density increases up to 86%. Additionally, the morphology changes from dendritic to compact plates, sphere and semi-sphere, subsequently.

Electrical conductivity is a key factor in measuring performance of printed electronics, but the conductivity of inkjet-printed silver nanoinks greatly depends on post-fabrication sintering. In this work, two different conductive silver nanoinks, in which the silver nanoparticles were stabilized by two different capping agents – Poly(acrylic acid) (PAA) and Poly(methacrylic acid) (PMA) – were synthesized. The inks were inkjet-printed on flexible PET substrates, coated with an additional polycation layer, which facilitated chemical sintering. The printed features were then exposed to moderately elevated temperatures to evaluate the effect of combined chemical and thermal sintering. Both inks produced conductive features at room temperature, and the conductivity increased with both temperature and duration of sintering. At temperatures above 100 °C, the choice of capping agent had no pronounced effect on conductivity, which approached very high values of 50 % of bulk silver in all cases. The lowest resistivity (2.24 μΩ cm) was obtained after sintering at 120 °C for 180 min. By combining chemical and conventional thermal sintering, we have produced remarkably conductive silver electrodes on flexible substrates, while using low-cost and simple processes.

With the growing number of flexible electronics applications, environmentally benign ways of mass-producing graphene electronics are sought. In this study, we present a scalable mechanochemical route for the exfoliation of graphite in a planetary ball mill with melamine to form melamine-intercalated graphene nanosheets (M-GNS). M-GNS morphology was evaluated, revealing small particles, down to 14 nm in diameter and 0.4 nm thick. The M-GNS were used as a functional material in the formulation of an inkjet-printable conductive ink, based on green solvents: water, ethanol, and ethylene glycol. The ink satisfied restrictions regarding stability and nanoparticle size; in addition, it was successfully inkjet printed on plastic sheets. Thermal and photonic post-print processing were evaluated as a means of reducing the electrical resistance of the printed features. Minimal sheet resistance values (5 kΩ/sq for 10 printed layers and 626 Ω/sq for 20 printed layers) were obtained on polyimide sheets, after thermal annealing for 1 h at 400 °C and a subsequent single intense pulsed light flash. Lastly, a proof-of-concept simple flexible printed circuit consisting of a battery-powered LED was realized. The demonstrated approach presents an environmentally friendly alternative to mass-producing graphene-based printed flexible electronics.

In back injection molding, a polymer film (most commonly a decorative label) is inserted into the mold and fused with the polymer product by injection of the polymer melt from behind. By placing a bendable film into a mold cavity and by injection of polymer melt, the film conforms to the outlines of the cavity, thus enabling the decoration of elements with non-planar surfaces. This technique allows for pre-patterning of films by a planar process, and then convert these into the surface skin of a non-planar molded part. In this research we demonstrate the integration of silver wires onto the surface of a curved polymer part. As an example, we used poly (methyl methacrylate) films of different thicknesses that were pre-structured with micrometer-sized V-grooves, filled with silver nanoparticle ink and placed into the cavity of a commercial injection molding tool. The effect of the back injection molding process on unfilled and filled V-grooves was evaluated for different process parameters. In most cases, the silver wires remained undamaged and their electrical conductivities remained essentially similar to those in planar films. The resulting surface-integrated silver wires were characterized by scanning electron microscopy and electrical resistivity measurements.

Prostate cancer is the most significant reason for deaths in men, outside of lung cancer. The clinical examination of cancer proteins or biomarkers is extremely significant in early examination and monitoring of recurrence of disease after treatment. Biomarkers have expanded great clinical significance owing to their extensive spectra in the identification, elimination, early diagnosis and cure of cancer. In this work, novel, ultrasensitive sandwich-type portable bio device based on citrate-capped silver nanoparticles (Citrate-AgNPs) modified graphene quantum dots (GQDs) nano ink for detection of Prostate specific antigen (PSA) was fabricated. Functionalized cysteamine with gold nanoparticles (Cys-AuNPs) was also utilized to amplify the signal. It provides a good and high external area for the immobilization biotinylated antibody of PSA in the large amount. For the first time, citrate-AgNPs-GQDs nano ink was directly written on the cellulose paper surface (ivory sheet and photographic paper) and modified by Cys-AuNPs. So, final structure of the immunodevices was completed after including of Ab1 and PSA (antigen). The immunosensors were used for the recognition of PSA by using DPVs (differential pulse voltammetry) technique. The obtained low limit of quantification (LLOQ) of the first immunodevice (ivory sheet/Citrate AgNPs-GQDs nano-ink/CysA-Au NPs/Ab1/BSA/PSA/Ab2) was 0.07 μg/L and the linear range for the calibration plot was from 0.07 to 60 μg/L. Also, the achieved LLOQ of the second immunodevice (photographic paper/Citrate AgNPs-GQDs nano-ink/Cys-Au NPs/Ab1/BSA/PSA/Ab2) was 0.05 μg/L with the linear range of 10 to 0.05 μg/L. It is noteworthy that, proposed immunoassay was effectively utilized to the monitoring of PSA glycoprotein in unprocessed human plasma sample. Obtained results show that the constructed immunosensor is able to apply as portable bio device for the clinical analysis of PSA in human plasma samples.

In the scientific industry, sustainable nanotechnology has attracted great attention and has been successful in facilitating solutions to challenges presented in various fields. For the present work, silver nanoparticles (AgNPs) were prepared using a chemical reduction synthesis method. Then, a low-temperature sintering process was deployed to obtain an Ag-conductive ink preparation which could be applied to a flexible substrate. The size and shape of the AgNPs were characterized by ultraviolet–visible spectrophotometry (UV-Vis) and transmission electron microscopy (TEM). The experiments indicated that the size and agglomeration of the AgNPs could be well controlled by varying the reaction time, reaction temperature, and pH value. The rate of nanoparticle generation was the highest when the reaction temperature was 100 °C within the 40 min reaction time, achieving the most satisfactorily dispersed nanoparticles and nanoballs with an average size of 60.25 nm at a pH value of 8. Moreover, the electrical resistivity of the obtained Ag-conductive ink is controllable, under the optimal sintering temperature and time (85 °C for 5 min), leading to an optimal electrical resistivity of 9.9 × 10−6 Ω cm. The results obtained in this study, considering AgNPs and Ag-conductive ink, may also be extended to other metals in future research.

In this study, we developed an effective and rapid process for nanoscale ink printing, direct laser interference ink printing (DLIIP), which involves the photothermal reaction of a copper-based metal–organic decomposition ink. A periodically lined copper pattern with a width of 500 nm was printed on a 240 μm-wide line at a fabrication speed of 17 mm/s under an ambient environment and without any pre- or post-processing steps. This pattern had a resistivity of 3.5 μΩ∙cm, and it was found to exhibit a low oxidation state that was twice as high as that of bulk copper. These results demonstrate the feasibility of DLIIP for nanoscale copper printing with fine electrical characteristics.

As a newly emerging additive manufacturing technology, printed electronics based on the printing principle has received more and more attention. Compared to conventional electronics manufacturing, such technique has many advantages such as speediness, flexibility, personalized customization, and low cost. Currently, there are three kinds of typical conductive inks used in printed electronics—conductive carbon ink, conductive polymer, and metal conductive ink. However, the electrical conductivities of the conductive carbon ink and the conductive polymer are typically lower than 105 S/m, which impedes their application in high-sensitivity circuit fabrication. As to the metal conductive ink, post-treatments via long time curing process are often needed, which reduce the printing speed and improve the manufacturing costs. As an alternative, liquid metal is emerging as a new class of conductive ink and is thus becoming an important research focus. Such material has unique merits such as high electrical conductivity, simple preparation process, requesting no post-processing after printing, and so on. To further push forward the research on liquid metal-based printed electronics, this article strives to present an overview on the related research advancement in recent years. Properties of liquid metal such as oxidation, wettability, and conductivity are discussed. Liquid metal techniques including tapping mode electronic printing, atomized spray printing, microcontact printing, laser sintering method of liquid metal nanoparticles, transfer printing, masked deposition, liquid metal corrosion sculpture method, colorful liquid metal circuit fabrication method, and hybrid rolling and transfer printing method are systematically expounded. Prospective direction worth pursuing is outlined.

Printable electronic circuits have received a big adoption from a variety of users such as researchers, hobbyists, designers, and children. The designers want to use electronic circuits along with graphic design yet focus on the creativity and aesthetics of the design. However, current technology requires them to take care of the discouraging electrical behaviors of the circuits. Taking the task of lighting up a bunch of light-emmited diodes (LEDs) as an example, it sounds simple, but is posing significant challenges for inexperience users. Given the non-negligible resistance of conductive ink, it is not straightforward to generate a pattern that lights up the LEDs evenly. Furthermore, a large number of LEDs make it difficult and error-prone to wire them efficiently. It is possible to try existing auto-routers in computer aided design tools to automatically route these LEDs. However, being optimized to make circuits with highly conductive materials such as copper and gold, these auto-routers ignore the intrinsic resistance of the conductive ink. In this paper, we propose an LED auto-router which computationally generates a conductive pattern to balance brightness of multiple LEDs without the need of additional resistors. Our routing algorithm is based on the traveling salesman problem to find the shortest cross-less path through the LEDs, and thus minimize the ink consumption. It then adjusts resistances of the conductive patterns to regulate the current which flows through each LED.

The aim of the study is the question, whether printed electronics circuitry from low-cost printers can be improved in quality by certain ink combinations or after-treatments in order to achieve acceptable results in comparison with circuitry from higher-quality printers. For this purpose, the six samples circuitries from different printers (professional and semi-professional) and different ink combinations (PEDOT: PSS, Silver and Carbon) were subjected to an endurance test of 5 million switching cycles under varying climatic conditions. For this purpose test number of N = 5 experimental evaluations were carried out for each samples (in total of 30 experimental evaluations were done). The results show that, respectable results could be achieved with corresponding ink and post-treatment combinations. This opens up new possibilities for future developments in the field of printers, inks and post-treatments under the aspect of “low-cost”.

In this study, we report a novel way to produce carbon-based conductive inks for electronic and sensor technology applications. Carbonized lignin, obtained from the waste products of the Eucalyptus globulus tree paper industry, was used to produce a stable conductive ink. To this end, liquid-phase compositions were tested with different amounts of carbonized lignin powder to obtain an ink with optimal conductivity and rheological properties for different possible uses. The combination that showed the best properties, both regarding electrochemical properties and green compatibility of the materials employed, was cyclohexanone/cellulose acetate/carbonized lignin 5% (w/w), which was used to produce screen-printed electrodes. The electrodes were characterized from a structural and electrochemical point of view, resulting in an electrochemically active area of 0.1813 cm2, compared to the electrochemically active area of 0.1420 cm2 obtained by employing geometrically similar petroleum-based screen-printed electrodes and, finally, their performance was demonstrated for the quantification of uric acid, with a limit of detection of 0.3 μM, and their biocompatibility was assessed by testing it with the laccase enzyme and achieving a limit of detection of 2.01 μM for catechol as the substrate. The results suggest that the developed ink could be of great use in both sensor and electronic industries, reducing the overall ecological impact of traditionally used petroleum-based inks.

The inkjet printing process is a promising electronic printing technique for large-scale, printed, flexible and stretchable electronics because of features such as its high manufacturing speed, environmental friendliness, simple process, low cost, accurate positioning, and so on. As the base material of printed conductive patterns, conductive ink is the foundation of the development of printed electronics technology, and directly affects the performance and the quality of electronic products. In this paper, conductive ink with silver nanowires (AgNWs) was prepared, with AgNWs of lengths of 2–5 µm and diameters of 20 nm or so, isopropyl alcohol and ethylene glycol as the mixed solvents, and modified polysilane as the wetting agent. We discussed the relationship between the formula of the AgNWs ink and the surface tension, viscosity, contact angle between ink droplet and poly(ethylene) terephthalate (PET) surface, as well as the film-forming properties of the ink. Further, we analyzed the effects of the number of printed layers and the ink concentration of the AgNWs on the microstructures, photoelectric properties and accuracy of the printed patterns, as well as the change in the sheet resistance of the film during different bending cycles. The experimental results show that flexible transparent conductive patterns with a light transmittance of 550 nm of 83.1–88.4% and a sheet resistance of 34.0 Ω∙sq−1–78.3 nm∙sq−1 can be obtained by using AgNWs ink of 0.38 mg∙mL−1 to 0.57 mg∙mL−1, a poly (ethylene terephthalate) (PET) substrate temperature of 40 °C, a nozzle temperature of 35 °C, and heat treated at 60 °C for 10 min. These performances indicate the excellent potential of the inkjet printing of AgNWs networks for developing flexible transparent conductive film.

Electrotactile stimulation is a highly promising technique for providing sensory feedback information for prosthetics. To this aim, disposable electrodes which are predominantly used result in a high environmental and financial cost when used over a long period of time. In addition, disposable electrodes are limited in their size and configurations. This paper presents an alternative approach based on a 3D printed reusable flexible concentric electrode coated with a conductive graphene ink. Here, we have characterized the electrode and demonstrated its effective performance in electrotactile stimulation and sensory feedback for robotic prosthetic hands.

This work reported a green method of synthesizing silver nanoparticles (AgNPs) with glucose acting as reducing agents to improve the conductivity of conductive ink. Silver nitrate, glucose, and polyvinylpyrrolidone (PVP), were used as silver precursor, reducing agent, and capping agent, respectively. The optimal condition of synthesizing AgNPs was obtained by varying the reactant ratio and temperature. The AgNPs were characterized by X-ray diffraction (XRD), UV-visible spectroscopy (UV-Vis), and scanning electron microscope (SEM). The obtained AgNPs with diameters of 80 to 100 nm were almost spherical and they were redispersed well in polyurethane acrylate (PUA). Compared with traditional hydrazine hydrate, the prepared AgNPs were better with respect to uniform size, dispersion, stability, and the absence residual solvent. After UV sintering, the conductivity (2.3×105 S/m) and mechanical properties of prepared conductive ink were good. Therefore, using glucose as a reducing agent to prepare AgNPs conductive ink is feasible and noteworthy because it is an extremely common material.

Electrically conducting inks were screen printed on various textile substrates. The samples were dry cleaned with the usual chemicals in order to investigate the influence of the mechanical treatment on the electrical conductivity. It was found that dry cleaning has a tremendous influence on this electrical conductivity. For several samples, it is observed that the electrical resistance increases with the square of the number of dry cleaning cycles. In order to explain this observation a theoretical model and a numerical simulation have been carried out, by assuming that dry cleaning cycles introduce a crack in the conducting layer. The theoretical analysis and the numerical analysis both confirmed the experimental observations.

The ability to fabricate functional 3D conductive elements via additive manufacturing has opened up a unique sector of ‘hybridized printed electronics’. In doing so, many of the rigid standards (i.e., planar circuit boards, potting, etc.,) of traditional electronics are abandoned. However, one critical challenge lies in producing robust and reliable interconnections between conductive inks and traditional hardware, especially when subjected to harsh environments. This research examines select material pairings for the most resilient interconnection. The method of test is wire bond pull testing that would represent a continuous strain on a connection and high acceleration testing of up to 50,000 g that would represent a sudden shock that electronics may experience in a drop or crash. Although these two environments may be similar to an overall energy exerted on the connection, the rate of force exerted may lead to different solutions. The results of this research provide insight into material selection for printed electronic interconnections and a framework for interconnection resiliency assessment, which is a critical aspect in realizing the production of next generation electronics technologies for the most demanding environments.

Presented here is a scalable and aqueous phase exfoliation of graphite to high yield and quality of few layer graphene (FLG) using Bovine Serum Albomine (BSA) and wet ball milling. The produced graphene ink is tailored for printable and flexible electronics, having shown promising results in terms of electrical conductivity and temporal stability. Shear force generated by steel balls which resulted in 2−3 layer defect-free graphene platelets with an average size of hundreds of nm, and with a concentration of about 5.1 mg/mL characterized by Raman spectroscopy, atomic force microscopy (AFM), transmittance electron microscopy (TEM) and UV-vis spectroscopy. Further, a conductive ink was prepared and printed on flexible substrate (Polyimide) with controlled resolution. Scanning electron microscopy (SEM) and Profilometry revealed the effect of thermal annealing on the prints to concede consistent morphological characteristics. The resulted sheet resistance was measured to be R s = 36.75 Ω / sqr for prints as long as 100 mm. Printable inks were produced in volumes ranging from 20 mL to 1 L, with potential to facilitate large scale production of graphene for applications in biosensors, as well as flexible and printable electronics.

This article intends to discuss the possibility of how to quickly improve the functions of in-situ sensing gear conditions. This study proposes a new manufacturing method of the sensors by using a laser beam machine sinters conductive inks sprayed on gear surfaces as a crack sensor. For this purpose, we have developed a three-axis laser-printing machine. The developed three-axis laser printer was based on a three-axis CNC machine, and a 1.6W laser module (445nm wave length) was mounted on the principal axis of the CNC machine. However, the laser power was not enough for sintering the conductive ink sprayed on a 5-micrometer-thick polyimide as an insulated layer on steel plates. Thus, the 1.6W laser module is replaced with a 3.5W laser module, which has the same wavelength. This paper shows laser sintering conditions for the new laser module. In addition, a simple sensor, which is able to detect cracks at roots of gear teeth, is proposed. The sensor is formed of an involute spur gear. The electrical property, such as resistance, of the proposed crack sensors was investigated in this paper, and it was concluded that the relation between the resistance and module of gears was linear, when the number of teeth was fixed.

The Holter monitor is used to measure an electrocardiogram (ECG) signal while a subject moves. However, the Holter monitor is uncomfortable for the subject. Another method of measuring the ECG signal uses a smart shirt. We developed a smart shirt that has six electrodes on the chest and can measure a detailed ECG, obtained with unipolar precordial leads. The electrodes and wires of the shirt are made of conductive ink that is flexible and stretchable. The smart shirt is stretchable and fits the body well. However, because of the gap between the smart shirt and the body, electrodes V1 and V2 do not touch the body consistently. We developed a conductive foam block that fills this gap. We investigated the characteristics of the conductive foam block, and measured ECG signals using the smart shirt. The electrical resistance of the conductive foam block was reduced by pressure. This characteristic could be utilized to measure the ECG signal because the block was pressed by the body and smart shirt. We could measure the ECG signal using the smart shirt and blocks while the subject walked and could detect peaks of the ECG signal while the subject jogged slowly.

The stability of wearable textile antennas after 20 reference washing cycles was evaluated by measuring the reflection coefficient of different antenna prototypes. The prototypes’ conductive parts were screen-printed on several textile substrates using two different silver-based conductive inks. The necessity of coating the antennas with a thermoplastic polyurethane (TPU) coating was investigated by comparing coated with uncoated antennas. It is shown that covering the antennas with the TPU layer not only protects the screen-printed conductive area but also prevents delamination of the multilayered textile fabric substrates, making the antennas washable for up to 20 cycles. Furthermore, it is proven that coating is not necessary for maintaining antenna operation and this up to 20 washing cycles. However, connector detachment caused by friction during the washing process was the main problem of antenna performance degradation. Hence, other flexible, durable methods should be developed for establishing a stable electrical connection.

Conductive inks are key enablers for the use of printing techniques in the fabrication of electronic systems. Focus on the understanding of aspects controlling the electrical performance of conductive ink is paramount. A comparison was made between microparticle Ag inks and an Ag nanoparticle ink. The microstructures resulting from thermal cure processes were characterized morphologically and also in terms of their effect on the resistivity of printed traces. For microparticle inks, the variability of resistivity measurements between samples as defined by coefficient of variation (CV) was greater than 0.1 when the resistivity was 10 to 50 times that of bulk Ag. When the resistivity was lower (~1.4 times that of bulk Ag) the CV of sample sets was less than 0.1. In the case of the nanoparticle ink, resistivity was found to decrease by a factor ranging from 1.2 to 1.5 after doubling the amount of layers printed prior to curing though it was expected to remain the same. Increasing the amount of layers printed also enhanced the sintering process.

Abstract This paper describes an investigation of the possibility of using a new conductive ink, insted of copper clad laminates, in the manufacturing of microstrip patch antennas on glass and fiberglass substrates and of bioinspired frequency selective surfaces (FSSs) on fiberglass substrates for wireless communication systems. The new conductive ink is developed using synthesized nitrocellulose which, in ethyl acetate solution, works as a bonding agent and carrier for the formation of a conductive film. The load used in the fabrication process is silver metallic powder. Simulation and analysis are performed using Ansoft Designer and HFSS softwares. Microstrip antenna and FSS prototypes are fabricated and measured for comparison purpose. An agreement is observed between simulation and measurements results.