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Self‐sinterable gallium‐based liquid metal (LM) ink for a handy drop‐casting coating method is developed. The fabricated LM electrode is coffee‐ring‐free and bilayer‐free, which guarantees high electrical conductivity, wettability, flexibility, and stretchability. The ink consists of Galinstan, ethanol‐water mixture, hydrochloric acid, and polyvinylpyrrolidone. The binary mixture provides excellent wetting conditions and suppresses a coffee‐ring stain from Marangoni mixing. The acid removes an oxide layer on the LM interface. The colloidal interaction forces by self‐assembled polyvinylpyrrolidone induce avalanche coalescences of the particles at the end of evaporation, which produces a thin and uniform dried conductive layer. The acid and polymer provide a bilayer‐free structure and electrification without any post sintering. The drop‐casted self‐transformed LM electrode showed excellent electrical resistance of O (0.1–1 Ω) on folding and stretching conditions. It is believed that this method can serve as flexible and stretchable electrodes, on various substances for soft robots and wearable devices, without any complicated post‐process. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights: Recent report on paper-based genosensor for the diagnosis of ZIKV target DNA. Silver nanoparticles were characterized by XRD/UV-Vis/TEM. Cross-reactivity of genosensor was deduced. Electrochemical validation was performed through CV. Zika virus (ZIKV), a positive-sense single-stranded RNA virus, has been declared as the cause of a 'worldwide public health emergency' by the WHO since the year 2016. In cases of acute infections, it has been found to cause Guillain–Barre syndrome and microcephaly. Considering the tropical occurrence of the infections, and the absence of any proper treatments, accurate and timely diagnosis is the only way to control this infectious disease. Currently, there are many diagnostic methods under investigation by the scientific community, but they have some major limitations, such as high cost, low specificity, and poor sensitivity. To overcome these limitations, we have presented a low-cost, simple-to-operate, and portable diagnosis system for its detection by utilizing silver nanoparticles. silver nanoparticles were synthesized via chemical methods and characterization was confirmed by UV/TEM and XRD. The paper platform was synthesized using a graphene-based conductive ink, methylene blue as the redox indicator, and a portable potentiostat to perform the cyclic voltammetry to ensure true point-of-care availability for patients in remote areas. [ABSTRACT FROM AUTHOR]

The development of conformable electronic systems' focuses on the multifunctional smart materials transform areas from the automotive industry to biomedicine, based on improved integration and advanced functionalities. In‐mold electronics (IME) combines thermoforming, injection molding, and printed electronics, resulting in sensing structural parts integrated into smart surfaces, communicating with computer systems, and enabling advanced experiences in terms of human‐machine interaction. Contrary to flexible electronics, designed as bend conductors around a single axis, thermoformed electronics allow deformations in the three‐axial directions for different geometries. Herein, a 2D screen‐printed pattern using conductive silver ink thermoformed into a spherical surface suitable for 3D gesture recognition is reported. The mechanical deformation of the high‐impact polystyrene sheet (HIPS) and polyethylene terephthalate‐glycol (PETG) substrates during the thermoforming process of the electrical circuit is characterized experimentally. The electrical resistance changes through the circuit in the stages of the fabrication process due the thickness decrease and the propagation of the small cracks. Both evaluations contribute to a better understanding of the performance of the materials when subject to the IME process. Validation of the 3D gesture recognition operation is carried out, demonstrating their full operability, as well as the possibilities that the combination of technologies allows. [ABSTRACT FROM AUTHOR]

Featured Application: Nano- and micro-copper particles can be used in artworks, handmade jewelry, ceramic slip, conductive ink, and electronic devices. Copper nanoparticles are being applied in the biosensors, engineering, electronic devices, and technology fields. A key advantage of nanomaterials is that their properties differ from their bulk with the same composition. However, the application of nano-copper particles for jewelry and artwork has not yet been revealed. We discovered and compared the application of nano-sized copper particles in jewelry fabrication with micro-copper particles. The nano- and micro-sized copper particles were synthesized and mixed with the same organic binders and water content to produce an alternative clay-like material for creating handmade jewelry and artwork. The article addresses the effects of thermal treatment on thermal behavior and the development of physical properties of differently sized copper particles. Their physical properties depend strongly on the size of the starting copper particles and heating conditions. We investigated the influence of thermal treatment, heating rate, firing temperature, and holding time to optimize the firing conditions for jewelry fabrication and wearing. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated a tunable metamaterial perfect absorber (MPA) with broadband absorption by tuning the different states of flexible sandwiched structures (graphene conductive ink/rubber/metallic layers). The broadband absorption spectrum was tuned mechanically by changing the concave-up/down states of flexible hemispherical unit-cells. When the unit-cell was concave-up, our proposed MPAs played as a broadband absorber with a fractal bandwidth (FBW) of 107% (since an absorption over 90% ranges from 5.28 to 17.6 GHz) at the normal incidence; at the same time, this broadband absorption feature could remain well at large incident angles up to 40 deg. and regardless of polarization of the incoming electromagnetic waves. In the case of the concave-down state, a narrow FBW of only 6.8% was noticed. These results could promote great application potential, such as regarding advanced stealth devices, advances in the biomedical and the communication fields, and more. [ABSTRACT FROM AUTHOR]

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.

An organic metamaterial absorber (OMA) with a total thickness of 2.98 mm composed by multi-layer flexible frequency selective surface (FSS) and worked in ultra wideband (UWB) is investigated. The proposed absorber is stacked on a metal substrate by organic materials layer by layer, such as polyimide and polyvinyl chloride. According to equivalent circuit and electromagnetic field analysis, periodic FSS patterns are printed on organic materials using organic conductive ink. The absorption rate of the structure is high up to 90 % and the fractional bandwidth (FBW) reached 147.7 % at 11.78–78.32 GHz, which shows incident angle insensitive within 50°. In addition, the fabricated prototype with a single unit cell of 0.17 g is measured in an anechoic chamber using free space method. Furthermore, the measurement is in great agreement with the simulation, which demonstrates the reliability and the practical application prospect of the provided OMA with flexible, lightweight and ultrathin construction. • An organic metamaterial absorber (OMA) is get by frequency selective surface (FSS). • Organic materials are stacked layer by layer on a metal substrate in this OMA. • Periodic FSS patterns are printed on organic materials using organic conductive ink. • The measurement of this OMA is in good agreement with the simulation at 8–67 GHz. • Simulated absorption above 90 % in 12–78 GHz and incident angle insensitive below 50°. [ABSTRACT FROM AUTHOR]

The conductive ink research area has attracted much interest from researchers. The possibility of fabricating flexible and simple electronic devices offers many advantages for electronic devices, such as energy storage, wearable devices, and smart devices. Graphene conductive ink has gained much attention from scientists owing to its excellent electrical, optical, and mechanical properties. Numerous scientists have reported the modification of graphene properties to meet the demand for the application. Among the presented graphene synthesis methods, the electrochemical exfoliation process is simple, low-cost, and environmentally friendly. Moreover, the electrochemical exfoliation approach can be conducted in a water solution, thus decreasing production costs and making it environmentally safe. This review article presents the progress in the electrochemical exfoliation of graphene to produce graphene-conductive ink. Progress on graphene conductive ink and its hybrid is also presented. In particular, the potential application of graphene in energy storage, sensors, and other possible applications is summarized in the last part. • Graphene-based conductive inks show promise for flexible, cost-effective electronics like energy storage and wearable devices. • Electrochemical exfoliation: A simple, eco-friendly method for large-scale graphene production, suitable for conductive inks. • Review of recent advances in electrochemically exfoliated graphene and hybrid inks, their properties, and applications. • Exploration of graphene ink applications in energy storage, sensors, and flexible displays for wearable electronics. [ABSTRACT FROM AUTHOR]

The possibility to print electronics by means of office tools has remarkedly increased the possibility to design affordable and robust point-of-care/need devices. However, conductive inks suffer from low electrochemical and rheological performances limiting their applicability in biosensors. Herein, a fast CO 2 laser approach to activate printed carbon inks towards direct enzymatic bioelectrocatalysis (3rd generation) is proposed and exploited to build biosensors for D-fructose analysis in biological fluids. The CO 2 laser treatment was compared with two lab-grade printed transducers fabricated with solvent (SB) and water (WB) based carbon inks. The use of the laser revealed significant morpho-chemical variations on the printed inks and was investigated towards enzymatic direct catalysis, using Fructose dehydrogenase (FDH) integrated into entirely lab-produced biosensors. The laser-driven activation of the inks unveils the inks' direct electron transfer (DET) ability between FDH and the electrode surface. Sub-micromolar limits of detection (SB-ink LOD = 0.47 μM; WB-ink LOD = 0.24 μM) and good linear ranges (SB-ink: 5–100 μM; WB-ink: 1–50 μM) were obtained, together with high selectivity due to use of the enzyme and the low applied overpotential (0.15 V vs. pseudo-Ag/AgCl). The laser-activated biosensors were successfully used for D-fructose determination in complex synthetic and real biological fluids (recoveries: 93–112%; RSD ≤8.0%, n = 3); in addition, the biosensor ability for continuous measurement (1.5h) was also demonstrated simulating physiological D-fructose fluctuations in cerebrospinal fluid. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Conductive, high adhesion and mechanical strength of 30MCP can be printed as conductive ink on flexible substrates to build flexible circuits. • 30MCP works not only as a friction layer but also as an electrode. • 30MCP is fully biodegradable, recyclable, and reusable. • The V oc of the KMCP-TENG prepared from recycled 30MCP reaches 90 % of the original TENG. Triboelectric nanogenerator (TENGs), which are capable of capturing high-entropy energy dispersed in the environment and converting it into electricity, have received significant attention for their potential as power sources for sensing networks and wearable portable electronics. Conventional triboelectric materials have serious limitations, which can be overcome by using nanostructured materials. Conductivity and semiconductor nanomaterials have been extensively studied as active components for this type of application, but need to be coupled to an elastic matrix, in order to be functional in flexible technologies. In this study, we prepared MWCNTs/PEO (MCP) films with conductive and biodegradable properties. MCP can be used as conductive ink printed on flexible substrates to fabricate flexible circuits. MCP is utilized as a high-performance positively charged material to construct a TENG (KMCP-TENG) with a maximum power density of 593 mW/m2. Furthermore, MCP can be degraded and recycled, and the output performance of the KMCP-TENG prepared using recycled MCP reaches 90 % of the original TENG. Additionally, the multi-array smart bandage (MASB) is designed and fabricated based on KMCP-TENG, which exhibits high sensitivity and stability. This MASB offers broad applications in health monitoring, motion tracking and human–computer interaction. [ABSTRACT FROM AUTHOR]

The modification on the surface of neural electrodes is critical for improving the signal-to-noise ratio (SNR) and prolonging the recording time. Electrodeposition is a simple and practical modification technique that has been applied to a wide range of materials. However, the traditional electrodeposition becomes increasingly inefficient as the electrode channels dramatically increase since it is performed one by one. Short-circuiting multiple electrode sites and then modifying them together can significantly improve efficiency. But it remains a significant challenge to reliably connect hundreds or thousands of electrodes before the electrodeposition and to safely and easily disconnect them afterward. An approach of removable electrical connection was adopted to solve this problem. A kind of silver nanowire (AgNW) conductive ink with water as the dispersion was chosen to connect all the electrodes for simultaneous electrodeposition temporarily electrically. This approach makes the electrodeposition process convenient and reliable. Above all, the proposed approach is compatible with a wide range of Multi-electrode arrays (MEAs) fabricated from different materials. [Display omitted] • This paper presents an efficient batch modification approach for large-scale neural microelectrode arrays based on an removable electrical interconnection. • This proposed method can modify hundreds or thousands of electrodes within minutes. • This proposed approach is compatible with many different types of microelectrode arrays and various modification materials. [ABSTRACT FROM AUTHOR]

• Deposition of conductive copper ink using the direct ink writing process. • The deposited track achieved an electrical conductivity of 1.21 × 106 S/m. • The electrical continuity of tracks was tested, and changes in conductance were observed while bending the samples. This work reports the fabrication and electrical characterization of conductive copper ink (CCI) deposited on flexible substrates using an in-house developed direct ink writing (DIW) technique. CCI tracks deposited on two flexible substrates were evaluated for uniformity, continuity, and electrical performance under various temperature and mechanical loads. The results indicated that with optimized printing parameters, uniform, and continuous tracks were successfully deposited, achieving a track width of 355 μm and an electrical conductivity of 1.21 × 106 S/m. Notably, bending caused little change in the electrical conductivity, whereas temperature had a greater effect. To demonstrate the practical applicability in electronics, a single conductive layer was printed by replicating the actual geometries of the printed circuit board. [ABSTRACT FROM AUTHOR]

Conductive inks have been widely used to develop electronic devices, such as sensors, RFID antennas, and transistors. Electronic utilization is a coating that forms conductive films for electromagnetic interference shielding (EMI Shielding). This process also can be employed to cover electronic modules called System in Package (SiP). A technology known as conformal shielding utilizes spray coating with metallic inks to form a conductive layer over the SiP. Traditionally, copper or silver inks have been the primary materials employed due to their high electrical conductivity. Conversely, these metallic inks are associated with significant costs, environmental impacts, and complex production methods. In this context, water-based graphene dispersion could be an alternative to EMI Shielding for electronic chips. Graphene is attractive due to its excellent electrical and thermal properties, reduced cost, and being an environmentally friendly material. In this study, a water-based graphene suspension was developed and applied via spray coating to form films for electromagnetic shielding. The graphene dispersion in water utilized Carboxymethyl cellulose (CMC). Characterizations of the graphene suspension, including morphology, particle size distribution, and chemical analysis, were conducted. The resistivity of the resulting films and their shielding effectiveness (SE) were measured. Electronic chip modules were painted to assess coverage. The study demonstrated the successful formulation of a stable water-graphene suspension exhibiting favorable electrical resistivity (2.8 × 10−2 Ω.cm) after drying at 300 °C for 1 h. The resulting film achieved a shielding effectiveness of −9 dB at 1.0 GHz. Graphene film completely covered the electronic chips, indicating an alternative conformal shielding. • The environmentally friendly method uses lab-scale equipment to produce a water-based graphene suspension for EMI shielding • Developing and applying water-based graphene suspension via spray coating on SiP modules • The film's shielding effectiveness is measured per the ASTM d4935 standard. [ABSTRACT FROM AUTHOR]

[Display omitted] • SPrGO-MoS 2 E exhibited greater electrocatalytic activity than SPCE. • The proposed sensors provided low detection limits of electroactive species. • The electrodes showed high reproducibility, repeatability, and good stability. In this work, a new and convenient fabrication process for screen-printed reduced graphene oxide-molybdenum disulfide electrode (SPrGO-MoS 2 E) was proposed. Reduced graphene oxide-molybdenum disulfide (rGO-MoS 2) 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-MoS 2 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-MoS 2 composite showed higher electrochemical sensing performance compared with electrodes containing only rGO or MoS 2. Cyclic voltammetry revealed that the SPrGO-MoS 2 electrode exhibited excellent electrochemical sensing performance toward several electroactive species, namely, potassium hexacyanoferrate (III) ([Fe(CN 6)]3−/4−), nicotinamide adenine dinucleotide (NAD+/NADH), and hydrogen peroxide (H 2 O 2) dissolved in 0.1 M PBS (pH 7.4). The limits of detection for [Fe(CN 6)]3−/4−, NAD+/NADH, and H 2 O 2 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-MoS 2 E could be an alternative material for advanced chemical and biological sensing applications. [ABSTRACT FROM AUTHOR]

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.

The screen‐printing process of conductive ink can realize simple and large‐scale manufacture of micro/nano patterns for producing wearable electronic products. Herein, chitin nanocrystals (ChNCs) are used as a dispersant for the preparation of multiwalled carbon nanotube (MWCNT) ink with high viscosity and uniformity by ultrasound treatment. ChNCs can interact with MWCNT in noncovalent ways, including π–π and hydrophobic interactions. ChNCs/MWCNT (CCNT) ink does not aggregate even after standing for 3 months with a maximum MWCNT concentration of 33 mg mL−1 and dispersion efficiency of 91.1%. Using CCNT ink, a paper‐based thermoelectric generator (TEG) is manufactured by screen‐printing technology. With good thermoelectric and strain sensing properties, CCNT coated paper can stably collect human energy at room temperature to realize self‐powering. The CCNT coated paper‐based TEG can convert thermal voltage signals into musical notes, monitor the changes in human behavior and respiratory rate, and monitor joint movements. Moreover, CCNT coated paper has no cytotoxicity by CCK‐8 and live/dead staining. This work puts forward a strategy of green preparation of MWCNT‐based ink by adding renewable chitin, which opens up a new way to apply MWCNT‐based ink in self‐powering wearable multifunctional sensors. [ABSTRACT FROM AUTHOR]

In the field of printed electronics, electronic components such as varactors are of special interest. As ferroelectric materials, Ba0.6Sr0.4TiO3 (BST) and poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) are promising compounds to be used in functional inks for the fabrication of fully inkjet-printed dielectric layers. In BST/P(VDF-TrFE) composite inks, the influence of the particle and crystallite size is investigated by using different grinding media sizes and thermal treatments at varying temperatures. It was found that with an increasing particle and crystallite size, both the relative permittivity and tunability increase as well. However, the thermal treatment which impacts both the particle and crystallite size has a greater effect on the dielectric properties. An additional approach is the reduction in the dielectric layer thickness, which has a significant effect on the maximal tunability. Here, with a thickness of 0.9 µm, a tunability of 29.6% could be achieved in an external electric field of 34 V µm−1. [ABSTRACT FROM AUTHOR]

Nano‐silver conductive inks have attracted the attention of researchers due to their high electrical conductivity, good chemical stability, and wide applicability. As the mainstream conductive ink, it is mostly used in inkjet printing, but its application is limited due to the high sintering temperature. In this paper, silver nanoparticles were synthesized by reducing silver nitrate with sodium borohydride. Using silver nanoparticles as basic conductive fillers and graphene or copper nanoparticles as auxiliary conductive fillers, silver conductive inks, silver/graphene conductive inks and silver/copper conductive inks suitable for micro‐direct writing printing were prepared. Electrode patterns were printed on photo paper by micro‐pen writing printing. The prepared paper electrode can detect nitrate using electrochemical analysis. The results show that the paper electrodes prepared with the three conductive inks can be used for the analysis of potassium ferricyanide and potassium nitrate. The minimum square resistance of paper electrodes prepared with silver conductive ink is 0.11 Ω/sq. It can be cycled 60 times in electrochemical applications with small standard deviation and high reproducibility and stability. Analysis and detection can also be performed in nitrate concentrations ranging from 60 μM to 1000 μM. This low silver‐containing, green, and low resistivity flexible electrode offers a solution for the simplicity and economy of electronic devices. [ABSTRACT FROM AUTHOR]

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to ensure the service reliability of flexible electronic products, flexible electronic interconnection wires need to have good conductivity and good resistance to deformation and fatigue. In this study, multiscale silver nanoparticle conductive inks were prepared by a one-step microwave approach for printing flexible silver wire. The silver inks with different sizes of silver particle distribution were prepared by adjusting the content ratio of silver nitrate, polyvinyl pyrrolidone, and ethylene glycol in a microwave reaction. The electrical and mechanical properties of the silver wire samples printed by the different inks were investigated. The prepared multiscale silver ink with larger average size of silver particles also had a greater size difference between silver particles, and the printed silver wire obtained a denser microstructure and had lower resistivity after hot-pressing sintering. However, the silver wire printed by multiscale silver inks with large average particle size was not conducive to improving the mechanical reliability. Also, silver wire consisting of particles of small average size with high porosity resulted in low bonding force between particles and reduced its mechanical reliability. Based on the investigation, a proper content ratio of silver nitrate, polyvinyl pyrrolidone, and ethylene glycol is recommended for preparing multiscale AgNP conductive ink to obtain printed silver wire with good electrical and mechanical properties. [ABSTRACT FROM AUTHOR]

Electrohydrodynamic jet (e‐jet) printing technology overcomes some limitations such as the viscosity and resolution of the traditional ink‐jet printing by breaking surface tension of the droplets with high voltage and the formation of Taylor cone. The technique is becoming more and more popular because it can be widely used in the fabrication of the conductive line of electronics, electrode, transistor, sensor, and other electronics as microelectrode, microlen, and heater. This review provides insight into the effect of the influence factors such as voltage, speed, nozzle, jetting ink characteristics, and the representative conductive materials of the ink as metal nanoparticles (NPs) and carbon materials, or organic conductive polymers on the fabrication of the different electronics by the e‐jet printing technology. Specially, the characteristics of different resultant electronics are compared and the possible mechanisms are analyzed. Finally, the challenge and development trend of the e‐jet printing technology are discussed, which will shed a light on the fabrication of the next‐generation flexible electronics with better performance. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) accelerates the need for compact, lightweight and low-cost antennas combining wideband operation with a high integration potential. Although screen printing is excellently suited for manufacturing conformal antennas on a flexible substrate, its application is typically limited due to the expensive nature of conductive inks. This paper investigates how the production cost of a flexible coplanar waveguide (CPW)-fed planar monopole antenna can be reduced by exploiting a mesh-based method for limiting ink consumption. Prototypes with mesh grids of different line widths and densities were screen-printed on a polyethylene terephthalate (PET) foil using silver-based nanoparticle ink. Smaller line widths decrease antenna gain and efficiency, while denser mesh grids better approximate unmeshed antenna behavior, albeit at the expense of greater ink consumption. A meshed prototype of 34.76 × 58.03 mm with almost 80% ink reduction compared to an unmeshed counterpart is presented. It is capable of providing wideband coverage in the IMT/LTE-1/n1 (1.92–2.17 GHz), LTE-40/n40 (2.3–2.4 GHz), 2.45 GHz ISM (2.4–2.4835 GHz), IMT-E/LTE-7/n7 (2.5–2.69 GHz), and n78 5G (3.3–3.8 GHz) frequency bands. It exhibits a peak radiation efficiency above 90% and a metallized surface area of 2.46 cm2 (yielding an ink-to-total-surface ratio of 12.2%). [ABSTRACT FROM AUTHOR]

In the field of soft electronics, high-resolution and transparent structures based on various flexible materials constructed via various printing techniques are gaining attention. With the support of electrical stress-induced conductive inks, the electrohydrodynamic (EHD) jet printing technique enables us to build high-resolution structures compared with conventional inkjet printing techniques. Here, EHD jet printing was used to fabricate a high-resolution, transparent, and flexible strain sensor using a polydimethylsiloxane (PDMS)/xylene elastomer, where repetitive and controllable high-resolution printed mesh structures were obtained. The parametric effects of voltage, flow rate, nozzle distance from the substrate, and speed were experimentally investigated to achieve a high-resolution (5 µm) printed mesh structure. Plasma treatment was performed to enhance the adhesion between the AgNWs and the elastomer structure. The plasma-treated functional structure exhibited stable and long strain-sensing cycles during stretching and bending. This simple printing technique resulted in high-resolution, transparent, flexible, and stable strain sensing. The gauge factor of the strain sensor was significantly increased, owing to the high resolution and sensitivity of the printed mesh structures, demonstrating that EHD technology can be applied to high-resolution microchannels, 3D printing, and electronic devices. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Graphene/metal nanocomposites have shown a strong potential for use in electronic applications. In particular, the combination of silver nanowires (AgNWs) with graphene derivatives leads to the formation of an efficient conductive network, thus improving the electrical properties of a composite. This work focused on developing highly conductive hydrophilic hybrids of simultaneously functionalized and reduced graphene oxide (f-rGO) and AgNWs in different weight ratios by following two different synthetic routes: (a) the physical mixture of f-rGO and AgNWs, and (b) the in situ reduction of GO in the presence of AgNWs. In addition, the role of AgNWs in improving the electrical properties of graphene derivatives was further examined by mixing AgNWs with a hybrid of few-layered graphene with functionalized multiwalled carbon nanotubes (FLG/MWNT-f-OH). The studied materials showed a remarkable improvement in the overall electrical conductivity due to the synergistic effect of their components, which was proportional to the percentage of Ag and dependent on the procedure of the hybrid formation. One of the f-rGO/AgNWs composites was also selected for the preparation of gravure printing inks that were tested to determine their rheological and printing properties. All of the f-rGO/AgNWs composites were shown to be very promising materials for use as conductive inks for flexible electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] Carbon nanotube (CNT) dispersion, which enables scalable fabrication of printed and flexible electronic materials, has brought a revolutionary improvement in CNT-based devices. To progress from the laboratory to commercial applications, it will be necessary to develop simple and scalable methods to produce high-quality CNT dispersions. Here, we propose a freezing/thawing strategy assisted by cellulose to produce high-quality CNT dispersion in an aqueous solution on a large scale. The freezing/thawing process simultaneously serves two purposes: (1) one is to cleave CNTs from their bulk via water-freezing expansion force; (2) the other is to dissolve cellulose in NaOH/urea aqueous solution, facilitating the wrapping of cellulose on the surface of CNTs to improve the stability of the dispersion. The obtained cellulose-dispersed CNT (CDCNT) dispersion is highly homogeneous and stable because of the formation of CNT/cellulose/NaOH/urea inclusion complexes. Importantly, the freezing/thawing strategy using cellulose promises scalable production, including a high CNT concentration of 11.3 mg/mL, high yield of 75%, high production capacity, and unlimited system size, much superior to common ultrasonication. Furthermore, it is demonstrated that the CDCNT dispersion can be used as a precursor solution for fabricating different CNT-based materials via various techniques, such as spinning, dyeing, screen printing, and 3D printing, indicating versatile applications. [ABSTRACT FROM AUTHOR]

Kirigami, with a simple mechanical transformation fashion, offers versatile ways and unconventional approaches for realizing cutting‐edge tunable devices. Here, a rotational kirigami tessellation metasurface with tunable chirality using 2D‐to‐2D in‐plane transformation is designed and experimentally demonstrated. The rotational metasurface is built using flexible filament as a supporting dielectric and silver ink as conductive patterns on the top and bottom layers and operated via mechanical transformation. Unlike conventional works where the symmetric‐breaking feature is obtained from 2D to 3D transformation, the proposed structure is designed in such a way that it can break mirror‐symmetric by misaligning the conductive pattern via rotating sub‐elements of the structure led to achieving dual‐band bifunctional tunable chiral transmission responses. Finally, achiral and chiral transmission responses at different rotation angle states are experimentally confirmed. The proposed approach can be applied to various applications, opening new avenues to design 2D‐to‐2D in‐plane transformation mechanical‐based electromagnetic devices. [ABSTRACT FROM AUTHOR]

Suction cups (SCs) are used extensively by the industrial sector, particularly for a wide variety of automated material-handling applications. To enhance productivity and reduce maintenance costs, an online supervision system is essential to check the status of SCs. This paper thus proposes an innovative method for condition monitoring of SCs coated with printed electronics whose electrical resistance is supposed to be correlated with the mechanical strain. A simulation model is first examined to observe the deformation of SCs under vacuum compression, which is needed for the development of sensor coating thanks to the 3D printing process. The proposed design involves three circle-shaped sensors, two for the top and bottom bellows (whose mechanical strains are revealed to be the most significant), and one for the lip (small strain, but important stress that might provoke wear and tear in the long term). For the sake of simplicity, practical measurement is performed on 2D samples coated with two different conductive inks subjected to unidirectional tensile loading. Graphical representations together with analytical models of both linear and nonlinear piezoresistive responses allows for the characterization of the inks' behavior under several conditions of displacement and speed inputs. After a comparison of the two inks, the most appropriate is selected as a consequence of its excellent adhesion and stretchability, which are essential criteria to meet the target field. Room temperature extrusion-based 3D printing is then investigated using a motorized 3D Hyrel printer with a syringe-extrusion modular system. Design optimization is finally carried out to enhance the surface detection of sensitive elements while minimizing the effect of electrodes. Although several issues still need to be further considered to match specifications imposed by our industrial partner, the achievement of this work is meaningful and could pave the way for a new generation of SCs integrated with smart sensing devices. The 3D printing of conductive ink directly on the cup's curving surface is a true challenge, which has been demonstrated, for the first time, to be technically feasible throughout the additive manufacturing (AM) process. [ABSTRACT FROM AUTHOR]

Printed electronics are a set of additive manufacturing methods for creating future flexible electronics on thin polymeric sheets. We proposed the toner-type, dry, page-printing of Ag–Ni composite conductive particles on flexible plastic sheets without pre-treatment. No chemical solvents are necessary to compose the inks of the electronic materials used for the toner-type printing, and no chemical treatment is required for the plastic film substrate surface. In addition, multilayer printing is simple when using toner printing because previously printed materials do not need to be resolved; furthermore, composing the thick films of the electronic materials is relatively simple. In this study, we fabricated an Ag–Ni composite toner to improve the fluidity of the toner particles compared to bare Ag particles. We successfully printed IC peripheral circuits at a resolution of 0.20 mm and demonstrated that the actual electrical circuit pattern can be formed using our method. [ABSTRACT FROM AUTHOR]

Printed and flexible electronics is rapidly developing to cater the large demands of wearable and consumer electronic needs. However, among the wide variety of printed electronic and energy storage/energy conversion devices, only conductive inks, sensors and light-emitting diodes (LEDs) have achieved commercial success. Notably, the printable conducting inks are not only essential for the passive components in electronic devices; their widespread use covers electrical interconnects, transparent touch sensors, heaters, antistatic coating, antenna etc. Further to ascertain flexibility and commercial relevance, it is important to be able to print devices onto inexpensive substrates; the most preferred choice of substrates would, therefore, be paper or polyethylene terephthalate (PET), which are widely used in consumer products and in packaging industries. However, this requires stringent process temperature control (≤ 120 °C). Worldwide extensive research on inkjet printable conductive silver inks has resulted in large variety of inks, nevertheless, there are not many choices for such low-temperature curing conditions. Here we demonstrate a precisely controlled synthesis of a polymer ligand stabilized mixed-phase Ag–Ag2O nanoparticles, where each individual particle has a protective shell, hence, offering an excellent shelf life. Furthermore, the synthesised nanoink in a suitable solvent allows the Ag2O phase to convert to silver at a temperature as low as 80 °C. Meanwhile, the large volume change associated with the Ag2O to Ag conversion ensures removal of the stabilizing ligands from the particle surface and offers resistivity of 4.5 × 10–4 Ω cm and 3.3 × 10–5 Ω cm, when annealed at 80 °C and 120 °C, respectively. In this work, the Ag2O–Ag mixed-phase nanoink has been inkjet-printed onto standard photo-paper and typical bending-fatigue tests have demonstrated excellent strain tolerance up to 4% and for 104 cycles. [ABSTRACT FROM AUTHOR]

There is growing interest in transitioning electronic components and circuitry from stiff and rigid substrates to more flexible and stretchable platforms, such as thin plastics, textiles, and foams. In parallel, the push for more sustainable, biocompatible, and cost‐efficient conductive inks to coat these substrates has led to the development of formulations with novel nanomaterials. Among these, 2D materials, particularly graphene and MXenes, have received intense research interest due to their increasingly facile and scalable production, high electrical conductivity, and compatibility with existing manufacturing techniques. They enable a range of electronic devices, including strain and pressure sensors, supercapacitors, thermoelectric generators, and heaters. These new flexible and stretchable electronic devices developed with 2D material coatings are poised to unlock exciting applications in the wearable, healthcare and Internet of Things sectors. This review surveys key data from more than 200 articles published over the past 6 years to provide a quantitative analysis of recent progress in the field and shed light on future directions and prospects of this technology. It is found that despite the different chemical origins of graphene and MXenes, their shared electrical properties and 2D morphology guarantee intriguing performance in end applications, leaving plenty of space for shared progress and advancements in the future. [ABSTRACT FROM AUTHOR]

Silver particles are key materials for the production of conductive inks, which are typically thermally sintered to obtain high conductivity. However, it remains a big challenge to achieve high conductivity at temperatures lower than 150 °C, for the protection of heat‐sensitive components in printed electronic devices. In this study, a novel frigid synthesis strategy at subzero temperature (Celsius) to produce Ag NPs with rich, rose‐like nanostructures (Ag nano‐flowers) is developed. The growth mechanism of Ag nano‐flowers under frigid conditions is analyzed and discussed. Due to the fine nanoscale structure of Ag nano‐flowers, they exhibit low sintering temperature below 120 °C. The electrical conductivity of printed Ag nano‐flower foil reaches 8.64 × 104 S cm−1 at 120 °C, and 1.20 × 105 S cm−1 at 150 °C. This study provides an attractive approach to the facile fabrication of Ag nano‐flowers with high electronic conductivity sintered at low temperatures and grants new insights into nanocrystallization under low‐temperature conditions. [ABSTRACT FROM AUTHOR]

A digital microfluidic device fabricated with a thin and pliable polyester film is reported with control by a custom-made battery-powered high voltage amplification circuit. Droplet movement on the tilt or curved surface was achieved. A low-cost approach for the fabrication of digital microfluidic device was used: the electrodes on the digital microfluidic device were fabricated with conductive carbon ink screen-printed on a polyester substrate, a layer of thin polyethylene film was used to seal and insulate the electrodes, and a layer of water repellent was coated on the surface of polyethylene film to enhance the hydrophobicity. The device is transparent and pliable, with a total thickness of approximately 70 μm. The controlled droplet movement on the curved polymer surface based on electrowetting was achieved with the compact voltage amplification circuit and the corresponding control algorithm. The fabrication for the proposed digital microfluidic device is low-cost and without sophisticated microfabrication instrumentation. Furthermore, the system is portable and may have widespread point-of-care in biological and medical applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Flexible vibration sensors extend vibration sensor applications to wearable devices that can detect the body's mechano‐vibration signatures. In addition, the sensors act as a good interface in the curved shapes of machinery for better measurement. Such flexible vibration sensors that comprise ultrahigh displacement sensitivity and good dynamic response can be developed by using highly sensitive mechanisms such as crack‐based sensors (CBS) or hair‐like sensors (HLS). In this work, a porous piezoresistive sensor is fabricated by coating porous poly‐dimethyl siloxane (PDMS) with graphene elastomer ink to create a conductive network in the porous structure. Squamous microstructured scales are observed on the pore walls due to a coating of graphene elastomer ink on the expanded porous structure and contracting back to its original shape. It is assumed that the scales on the pore walls impact electromechanical characterization by imparting strain‐rate adaptability and dynamic resistance. Additionally, the developed sensors display a highly distinct segmented gauge factor in different strain rates in quasi‐static characterization, and the gauge factor increases proportionally to the strain rate. Consequently, the sensor can detect vibrations in a bandwidth of 1–1000 Hz and respond to acceleration from 0.01–1.01 g. [ABSTRACT FROM AUTHOR]

Multilayer circuits, especially in stretchable electronic devices, are considered to be an effective way to integrate various components and modules for complex functions. However, the existing manufacturing methods for multilayer flexible and stretchable electronics have problems such as complex technology, expensive equipment, and low production efficiency. Here, a direct ink writing 3D printing method is proposed to fabricate multilayer stretchable electronic devices by using high‐viscosity stretchable silver paste as the material for interconnecting wires, and stretchable polydimethylsiloxane as the dielectric layer. The optimal range of printing parameters is explored to realize the stable and repeatable manufacturing of wires. A protective layer is printed on the interconnection wires and rigid components to connect the soft substrate and the rigid electronic components. The results show that stress concentration is reduced and stable electrical response of the device is achieved under more than 49% tensile deformation. Vertical interconnect accesses and arc‐shaped wires are applied to a multilayer flexible thermal imaging display device and a NE555 timer device, and the outcomes prove that the direct ink writing 3D printing method provides an efficient, simple, and low‐cost manufacturing method for fabricating multilayer stretchable electronics. [ABSTRACT FROM AUTHOR]

Direct Ink writing, one of the types of 3D-printing technologies is a novel method for fabricating electronic circuits. This method of printing electronic circuits is a one-step process and overcomes the limitations of fused deposition modelling where the fabrication of circuits is possible if the material is in filament form and the usage of material is limited to thermoplastic. This work proposes the fabrication of strain gage circuit using functionalised Multi-walled carbon nanotubes (MWCNTs) and Polyvinyl alcohol (PVA) conductive ink by direct writing method. In this work, Fourier-transform infrared analysis is performed to study the existence of functional groups on acid treated MWCNT. According to micro-structural studies, it is observed that MWCNTs were homogeneously distributed. Rheology tests carried out using cone and plate method concluded that the prepared inks exhibited shear thinning behaviour, which is a very important parameter to state the ink made is appropriate for printing electronic circuits. The effects of functionalised MWCNT (a-MWCNT) concentration on the printed strain gage circuitry are analysed using two-point probe method and electrical properties like resistance, resistivity and electrical conductivity are studied. The electrical conductivity of the 3D-printed strain gage circuit is found to be 2.53 × 102 S/m for PVA/a-MWCNT(0.5) ink. Varying the concentration of a-MWCNT, electrical conductivity is observed to be increased to 4.08 × 102 S/m for PVA/a-MWCNT(1.0) and 7.87 × 102 S/m for PVA/a-MWCNT(1.5). Flexibility of PVA and conductivity of a–MWCNT contributed to superior performance of the printed circuit. [ABSTRACT FROM AUTHOR]

In this paper, we present a wound-dressing-based antenna fabricated via screen-printed and inkjet-printed technologies. To inkjet print a conductive film on wound dressing, it must be screen-printed, UV-curable-pasted, and hard-baked to provide appropriate surface wettability. Two passes were UV-curable-pasted and hard-baked at 100 °C for 2 h on the wound dressing to obtain 65° WCA for silver printing. The silver film was printed onto the wound dressing at room-tempature with 23 μm droplet spacing for three passes, then sintered at 120 °C for 1 h. By optimizing the inkjet printing conditions by modifying the surface morphologies and electrical properties, three-pass printed silver films with 3.15 μm thickness and 1.05 × 107 S/m conductivity were obtained. The insertion losses at the resonant frequency (17 and 8.85 GHz) were −2.9 and −2.1 dB for the 5000 and 10,000 μm microstrip transmission lines, respectively. The material properties of wound dressing with the relative permittivity and loss-tangent of 3.15–3.25 and 0.04–0.05, respectively, were determined by two transmission line methods and used for antenna design. A quasi-Yagi antenna was designed and implemented on the wound-dressing with an antenna bandwidth of 3.2–4.6 GHz, maximal gain of 0.67 dBi, and 42% radiation efficiency. The bending effects parallel and perpendicular to the dipole direction of three fixtures were also examined. The gain decreased from 0.67 to −1.22 dBi and −0.44 dBi for a flat to curvature radius of 5 cm fixture after parallel and perpendicular bending, respectively. Although the maximal gain was reduced with the bending radius, the directivity of the radiation pattern remained unchanged. The feasibility of a wound-dressing antenna demonstrates that inkjet-printed technology enables fast fabrication with low cost and environmental friendliness. Additionally, inkjet-printed technology can be combined with sensing technology to realize remote medical monitoring, such as with smart bandages, for assessment of chronic wound status or basic physical conditions. [ABSTRACT FROM AUTHOR]

Scalable additive manufacturing of printed electronics is a growing field accompanied by increasing demands for reliable and integrable functional flexible printed electronic devices. Herein, a novel type of electrically conducting silver‐based pastes for additive manufacturing is demonstrated. These pastes are designed for stencil‐ and screen‐printing and can be post‐processed at very low temperatures, at ambient. Furthermore, printed lines made with the pastes exhibit an electrical sheet resistance below 60 mΩ sq−1 even after room temperature and only 25 mΩ sq−1 after two minutes of curing at 90 °C. [ABSTRACT FROM AUTHOR]

Carbon-based composite conductive ink (3CI) has some challenges to its properties. Here, combined with the application of 3CI on silicon keypads, a series of studies on the electrical, mechanical and thermal performance of 3CI has been conducted by adding specific concentrations of silver powder, silica powder and SiO2@Ag core-shell particles. The properties of the modified 3CI were characterized by using the four-point probe tester, scanning electron microscope, Rockwell hardness tester, cross-cut tester and laser thermal conductivity analyzer. The experimental results revealed that by adding silver powder with a particle size of 20 microns equivalent to 12% by weight of the 3CI, ink resistance decreased by 76%, from 8.44 kΩ/□ to 2.03 kΩ/□. Meanwhile, adding silica can increase the ink's tensile strength and thermal diffusivity while improving the adhesion of the 3CI on the silicone rubber. It was worth noting that when the particle size of the SiO2@Ag core-shell particle was smaller than that of the added silver powder, the resistance of the 3CI was further reduced. Finally, a modified 3CI with the adhesion of 4B, a conductivity of about1 kΩ/□, a hardness of 232 HV0.5, and a thermal diffusivity of 0.217 cm2s−1 was achieved experimentally, which provided an experimental basis for the modified 3CI suitable for silicone keypads. [ABSTRACT FROM AUTHOR]

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.

Integrating self-healing capabilities into printed stretchable electronic devices is important for improving performance and extending device life. However, achieving printed self-healing stretchable electronic devices with excellent device-level healing ability and stretchability while maintaining outstanding electrical performance remains challenging. Herein, a series of printed device-level self-healing stretchable electronic devices is achieved by depositing liquid metal/silver fractal dendrites/polystyrene-block-polyisoprene-block-polystyrene (LM/Ag FDs/SIS) conductive inks onto a self-healing thermoplastic polyurethane (TPU) film via screen printing method. Owing to the fluidic properties of the LM and the interfacial hydrogen bonding and disulfide bonds of TPU, the as-obtained stretchable electronic devices maintain good electronic properties under strain and exhibit device-level self-healing properties without external stimulation. Printed self-healing stretchable electrodes possess high electrical conductivity (1.6 × 10 5  S m -1 ), excellent electromechanical properties, and dynamic stability, with only a 2.5-fold increase in resistance at 200% strain, even after a complete cut and re-healing treatment. The printed self-healing capacitive stretchable strain sensor shows good linearity (R 2 ≈0.9994) in a wide sensing range (0%-200%) and is successfully applied to bio-signal detection. Furthermore, the printed self-healing electronic smart label is designed and can be used for real-time environmental monitoring, which exhibits promising potential for practical application in food preservation packaging., (© 2024 Wiley‐VCH GmbH.)