Nanoparticles Conductive Ink Research Articles

Electromigration and electrical sintering in printed silver from high current at room temperature

Improved understanding of the reliability and failure physics of metal nanoparticle conductive inks would facilitate their large-scale deployment across a range of flexible electronics applications. We conduct room-temperature electromigration experiments on printed silver nanoparticle conductive ink test devices. We observe significant variation in failure time, location, and structure during these tests and during post-failure analysis with optical and electron microscopy. We use in situ Atomic Force Microscopy measurements to track volume changes in the sample as a function of time. These measurements provide additional data and understanding of the failure process within printed silver nanoparticle conductive inks.

Ultrasound-assisted facile and green preparation of Ag nanoparticle conductive ink for printing electronics

The development of low-cost, high-efficiency, and environment-friendly methods for the preparation of Ag nanoparticle (NP) conductive inks is key to promoting the application of such inks for printing flexible electronic components. This article presents an effective method for preparing a AgNP ink by reducing silver compounds in a polyol solution with ultrasonication. When the silver solution was ultrasonicated at 640 W, 21-nm AgNPs were readily produced within 5 min, and the particles grew considerably to 53 nm as the reaction was continued for 15 min. Thereafter, the NP size increased marginally with further increase in reaction time. When the reaction was conducted for a fixed duration of 15 min and the ultrasonic power was increased from 480 to 760 W, the AgNP size decreased from 63 to 48 nm. During ultrasonication, the bubble eruption in the solution generates large temperature and pressure gradients, inducing the rapid reduction of the Ag(I) to Ag(0). Printing experiments revealed that the synthesized AgNP ink has good inkjet printability. During the sintering of the printed film, the bridge connections between large particles increased and the interparticle voids decreased gradually, resulting in a decrease in film resistivity. A relatively low resistivity of 40×10−5 Ωcm was obtained when the flexible AgNP pattern was heated at 250 °C for 80 min. The facile synthesis process and the favorable conductive properties of the obtained ink render this preparation method promising for the low-cost production of flexible electronics.

Inkjet‐Printed Flexible Thin‐Film Thermal Sensors for Detecting Elevated Temperature Range

All inkjet‐printed thermal sensors are manufactured based on a metal–insulator–metal (MIM) interface or capacitor architecture, for the adapted device size ranging from 16 to 36 mm2 active area. Two different material inks, namely a nanoparticle conductive silver ink and an inorganic‐polymer‐based hybrid insulator ink, are applied layer by layer on a thin flexible polyimide substrate, for developing the printed MIM devices. To ensure the desired electronic conductivity and insulation from the layers, the manufacturing process steps and parameters are tuned, accordingly. The results show that the inkjet‐printed MIM devices could constitute up to 15 μm thickness and demonstrate average detection of a change in electrical capacitance ranging from 20 to 100 pF, when the temperature is varied between 100 and 300 °C. The investigations also summarize that the change in the electrical response is enough to detect an increment of 50 °C. The printed sensors also display high operational stability and repeatability, when subjected to thermal cycling.

Performance of water-based printed hybrid graphene/silver nanoparticle conductive inks for flexible strain sensor applications

Flexible electronic devices such as wearable strain sensors have drawn much interest in health monitoring systems. In the present study, hybrid ink-printed flexible strain sensors made of graphene and silver nanoparticles (AgNPs) were formulated. The main aim of the study is to investigate the effect of hybrid graphene and AgNP ratios on the properties of conductive inks and their performance as flexible strain sensors. The new conductive inks were printed on various types of flexible substrates: polyethylene terephthalate (PET), polyimide (PI), and polyvinyl alcohol (PVA). The performance of conductive ink on these substrates was evaluated. The results showed that the ratio of graphene/AgNPs influenced the properties of conductive inks. Graphene/AgNPs with a 0.3/0.2 wt% exhibit higher stability, wettability, and electrical conductivity than 0.4/0.1, 0.2/0.3, and 0.1/0.4 wt%. Hybrid graphene/AgNPs conductive ink printed on PI substrate showed better wettability and electrical performance compared to those on PET and PVA substrates. The gauge factors (GF) of the PI substrate are higher, 6.2% and 32%, compared to PET and PVA, respectively, at the 30% strain range. In short, the hybrid graphene/AgNPs strain sensor on PI that showed good linearity, sensitivity, and stability has a high potential to be used in low-strain health monitoring systems.

Mechanical Properties and Characterization of Graphene Nanoparticles Conductive Ink at Different Pattern

The development of variety printing methods and compatible conductive inks is to support the emerging high demand production of printed electronic devices. Conductive ink is used to create conductive paths as interconnecting tracks for the printed electronic devices. The method of integrating various conductive materials using thermoplastic viscous paste was introduced in order to enhance the ability of conductive ink to conducts electricity. Carbon nanomaterial’s offer many opportunities in the conductive ink application especially for printed and flexible electronics. This study aims to produce highly functional conductive ink using graphene nanoparticles (GNP) with Bisphenol-A (BPA) resins as a binder by investigate the mechanical properties and characterization of graphene nanoparticles conductive ink at of different patterns. The effect of nano-indentation, for straight line shape, curve shape, square shape and zigzag shape circuit printed on thermoplastic polyurethane (TPU) substrate were observed. The hardness and elastic modulus for the formulated graphene nanoparticles conductive ink shows that square patterns displayed a better mechanical properties compared to the other patterns. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) finding also show that square pattern has a uniform distribution of (GNP) filler and lowest amount of atomic weight with fine granular particle indicating of lower resistance value which can contribute to have higher conductivity property. Overall obtained results showed that a square pattern produced good performance in term of mechanical properties that can enhance the conductivity of the conductive ink.

Current capabilities of prototyping technologies for multilayer printed circuit boards on a 3D printer

A new direction in 3D printing was investigated – prototyping of single-sided, double-sided and multilayer printed circuit boards. The current capabilities and limitations of 3D printed circuit board printing technology were identified. A comparative analysis of the characteristics of two desktop 3D printers presented in the industry for prototyping radio electronics, as well as the first professional machine DragonFly LDM 2020, which is a mini-factory for prototyping multilayer printed circuit boards, was carried out. The first practical experience of working and printing on DragonFly LDM 2020 supplied to the megalaboratory “3D prototyping and control of multilayer printed circuit boards” of the Institute of Radio Engineering and Telecommunication Systems MIREA – Russian Technological University is presented. The first samples of electronic boards printed on a 3D printer by the method of inkjet printing were obtained. An additive technology for the production of multilayer printed circuit boards is considered: printing with two printheads with conductive and dielectric nano-ink with two curing systems: an infrared sintering system for conductive ink and a UV curing system for dielectric ink. The LDM (Dragonfly Lights-out Digital Manufacturing) production method with the necessary maintenance is presented. The method allows the system to work roundthe-clock with minimal human intervention, significantly increasing the productivity of 3D printing and expanding the possibilities of prototyping. The materials used for 3D printing of multilayer printed circuit boards and their characteristics were investigated: dielectric acrylate nano-ink (Dielectric Ink 1092 – Dielectric UV Curable Acrylates Ink), conducting ink with silver nanoparticles (AgCite™ 90072 Silver Nanoparticle Conductive Ink). The research carried out allows us to compare the technological standards of printed electronics with traditional methods of manufacturing multilayer printed circuit boards for a number of parameters.

Chemical sintering of Ag nanoparticle conductive inks at room temperature for printable electronics

Chemical sintering of Ag nanoparticle conductive inks at room temperature for printable electronics

A novel 4-DOF wide-range tunable frequency selective surface using an origami “eggbox” structure

AbstractShape-changing mechanical metamaterials have drawn the attention of researchers toward the development of continuous-range tunable frequency selective surfaces (FSSs). In this paper, a novel tunable FSS utilizing an origami-inspired “eggbox” structure is presented featuring four-degrees of freedom that can change the frequency response of two orthogonal linear polarizations. The centrosymmetric “eggbox” structure can be folded or rotated along two axes that lead to unprecedented reconfigurability compared to traditional Miura-Ori-based structures which have fewer degrees of control. The utilized cross-shaped dipole FSS element shows enhanced bandwidth, support for orthogonal linear polarization, and ease of fabrication. The prototype is fabricated using a low-cost fully additive inkjet printing process with silver nanoparticle conductive ink. The outcome of this study shows a 25% frequency tunable range over two polarization directions. The design can be an ideal spatial filtering candidate for advanced ultra-wideband terrestrial and space applications.

Disposable Electrochemical Sensor Using Graphene Oxide–Chitosan Modified Carbon-Based Electrodes for the Detection of Tyrosine

Despite the many recent advances in disposable and wearable sensing technologies for point of care testing (POCT), few affordable, flexible, and disposable sensors are available for the detection of tyrosine (Tyr), a valuable biomarker for metabolic and neurodegenerative diseases. In this regard, the disposable screen-printed electrodes on flexible substrates are attractive. However, current screen-printed approaches for the detection of Tyr use rigid ceramic substrates, expensive metal nanoparticle conductive inks and stiff metal or metal oxide-based sensitive materials, that are not suitable for single-use disposable or wearable POCT devices. To address these challenges, this work presents a flexible and disposable electrochemical sensor using graphene oxide – chitosan (GO-CS) modified carbon-based electrodes for the detection of Tyr. The affordable and easy to fabricate sensor consists of a three-carbon electrode system screen printed on a flexible, low-cost polyvinyl chloride (PVC) substrate. GO and CS were chosen as the sensitive nanocomposite due to their natural abundance and excellent electrochemical sensing properties. Quantitative determination of Tyr using DPV revealed a linear proportional response between 1 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~\mu \text{M}$ </tex-math></inline-formula> , with a correlation coefficient of 0.9993. The GO-CS-screen-printed carbon sensor (SPCS) also offers a linear range detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.86~\mu \text{M}$ </tex-math></inline-formula> , and excellent sensitivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.0846\,\,\mu \text{A}\,\,\mu \text{M}^{-1}$ </tex-math></inline-formula> ) and repeatability (RSD =4.02%). The GO-CS-SPCS thereby provides a promising platform for the active sensing elements of single-use, disposable, and wearable POCT devices suitable for early diagnosis and monitoring of metabolic or neurodegenerative diseases or nutritional management.

Fabrication of flexible copper patterns by electroless plating with copper nanoparticles as seeds

Flexible conductive copper patterns with low electric resistance, good adhesion, and high stability were successfully prepared on heat-sensitive polyethylene terephthalate (PET) substrate by combining the inkjet print with copper nanoparticles (Cu NPs) conductive ink and electroless plating (ELP) copper at room temperature. The Cu NPs served as the catalysts to promote copper ions electroless deposition on PET surface. Dimethylaminoborane (DMAB) was used as the reductant to place poisonous formaldehyde in the electroless plating process. The Cu patterns had a strong adhesion with PET substrate modified by 3-Mercaptopropyltriethoxysilane (MPTES) and would not fall even after 4000 cycles bending test. The electric resistivity of patterns could be as low as 5.43 μΩ·cm, which is about three times that of bulk copper. The minimum sheet resistance of the patterns was 54 mΩ/sq and had little change in the atmosphere for five months, that showed the patterns had an excellent anti-oxidation performance.

Printability and electrical conductivity of silver nanoparticle-based conductive inks for inkjet printing

Inkjet printing conductive ink was prepared with the as-prepared silver nanoparticles as conductive fillers and deionized water as the solvent and leveling agent (MY-3000) and silicone defoamer (NXZ) and wetting agent (TRITONX-405) and moisturizer (glycerol) as functional additives. We investigated the effects of viscosity and surface tension of conductive ink and the inkjet print parameters including number of nozzle, print speed, and ink droplet spacing on inkjet printability of conductive ink. The research results show that the inks with the viscosity range of 2.8–9.1 mPa·s and the surface tension of 33.4 mN·m−1 are suitable for inkjet printing. The printing accuracy of the print pattern is related to the number of nozzles and droplet space and the printing layer, but not to the printing speed, but can be changed appropriately to improve the print efficiency. When the mass content of silver nanoparticles is 6.91 wt%, the sheet resistance of the printing pattern with four layers is 2.71 Ω·cm−1, which is in appropriate printing conditions of the inkjet printing voltage of 21 V, printing speed of 60 m· S−1, ink droplet space of 20 μm, and nozzles of 2. The systematic studies of printability and electrical conductivity of inkjet printing silver nanoparticles conductive ink prove the feasibility of the ink and provide some ideas for future applications.

Silver nanoparticle conductive inks: synthesis, characterization, and fabrication of inkjet-printed flexible electrodes

Flexible electronics can be developed with a low-cost and simple fabrication process while being environmentally friendly. Conductive silver inks have been the most applied material in flexible substrates. This study evaluated the performance of different conductive ink formulations using silver nanoparticles by studying the material properties, the inkjet printing process, and application based on electrical impedance spectroscopy using a buffer solution. Silver nanoparticles synthesis was carried out through chemical reduction of silver nitrate; then, seven conductive ink formulations were produced. Properties such as resistivity, viscosity, surface tension, adhesion, inkjet printability of the inks, and electrical impedance of the printed electrodes were investigated. Curing temperature directly influenced the electrical properties of the inks. The resistivity obtained varied from 3.3 × 100 to 5.6 × 10−06 Ω.cm. Viscosity ranged from 3.7 to 7.4 mPa.s, which is suitable for inkjet printing fabrication. By using a buffer solution as an analyte, the printed electrode pairs presented electrical impedance lower than 200 Ω for all the proposed designs, demonstrating the potential of the formulated inks for utilization in flexible electronic devices for biological sensing applications.

Reactive Sintering of Cu Nanoparticles at Ambient Conditions for Printed Electronics.

A new approach is presented to overcome the disadvantages of oxidation and harsh sintering conditions of Cu nanoparticle (Cu NP) conductive inks simultaneously. In this process, oleylamine (OAM) adsorbed on particles was effectively eliminated via the reactive desorption by formic acid in alcohols; meanwhile, Cu ion was generated on the surface. The desorption of OAM resulted in more severe surface oxidation of Cu NPs. The oxide (Cu2O) and Cu2+ distributed on the Cu NP surface could be reduced to Cu(0) by NaBH4 solution and take on the role of soldering flux to weld particles into a blocky structure. With the compact coalescence of particles without oxides, the resistivity of metal patterns could fall below 20 μΩ·cm and exhibit proper adhesion. Thanks to the sintering of Cu NPs at ambient conditions, the conductive patterns could be facilely formed on thermosensitive substrates. As the oxide state of Cu would be reduced during sintering, the partially oxidized Cu nanoparticles could be directly applied to conductive inks.

3D Printed Fingernail Antennas for 5G Applications

3D printing of antennas on removable fingernail for on-body communications at microwave and millimetre waves is proposed. Aerosol Jet technology, a fine-feature material deposition solution, has been used to directly print microstrip patch antennas on an acrylonitrile butadiene styrene (ABS) removable finger nail substrate. Two antennas have been printed and assessed, one operating at 15 GHz and the other at 28 GHz. Nanoparticle conductive silver ink has been employed to create the microstrip patch antennas and corresponding transmission line using an Optomec machine. The inks are then cured using a PulseForge machine. A further copper layer is added to the millimeter wave antenna via an electroplating process. The antennas have been simulated and measured off-the-finger and on-the-finger. Simulated and measured reflection coefficients ( $S_{11}$ ) and radiation patterns are found to be in good agreement. The proposed on-body antennas can find application in the Internet of Things (IoT) where large amount of sensing data can be shared at the microwave and millimetre wave spectrum of future 5G communications. The removable finger nails could include other electronic devices such as on-body sensors, computational, storage and communication systems.

Evaluation of Planar Inkjet-Printed Antennas on a Low-Cost Origami Flapping Robot

An investigation on antenna solutions for expendable origami paper flapping robots is presented. An origami flapping robotic bird that can be produced using standard A4 paper is employed. Antennas resonating at the two commonly used frequency bands, 2.4 GHz and 5.2 GHz, are designed for the limited space available on the folded origami structure. Two developments of the same dual-band monopole antenna are discussed. The first antenna is located on the robot's spine and the second on its tail. A space diversity configuration is also studied. The antennas are printed directly onto a photo paper substrate and then folded into an origami robotic crane's body structure. An ordinary desktop inkjet printer fitted with silver nanoparticle conductive ink cartridges has been employed. CST Microwave Studio TM has been used to design the antennas. A good agreement between the measured and simulated S11 results is achieved with a reasonable -10dB impedance bandwidth realized in the three cases studied. The radiation patterns are omnidirectional in the XZ plane which is desirable for the specific application. The diversity configuration has a mutual coupling of <; -23dB and a gain of 1.4 dB and 2.8 dB at 2.4 GHz and 5.2 GHz respectively. The aim is to provide a new vision for antennas embedded into expandable flying robots based on traditional origami structures.

Hilbert metamaterial printed antenna based on organic substrates for energy harvesting

In this study, an investigation is conducted to realise the possibility of organic materials use in radio frequency (RF) electronics for RF-energy harvesting. Iraqi palm tree remnants mixed with nickel oxide nanoparticles hosted in polyethylene, INP substrates, is proposed for this study. Moreover, a metamaterial (MTM) antenna is printed on the created INP substrate of 0.8 mm thickness using silver nanoparticles conductive ink. The fabricated antenna performances are instigated numerically than validated experimentally in terms of S 11 spectra and radiation patterns. It is found that the proposed antenna shows an ultra-wide band matching bandwidth to cover the frequencies from 2.4 to 10 GHz with bore-sight gain variation from 2.2 to 3.43 dBi at maximum. The antenna size is compacted to a 32 mm × 24 mm using a fractal-shaped MTM when mounted on the INP substrate with a relative permittivity e r = 3.106-j0.0314 and a relative permeability μ r = 1.548-j0.0907. Finally, the maximum obtained voltage from the proposed antenna is found about 2 V at 2.45 GHz and 2.5 V at 5.8 GHz, where, the corresponding measured equivalent isotropic radiated power is about 2.35 W at 2.45 GHz and 6.12 W at 5.8 GHz.

Microwave-assisted two-steps method for the facile preparation of silver nanoparticle conductive ink

A microwave-assisted two-steps method was proposed for the facile and fast preparation of silver nanoparticle conductive ink. The nanoparticles in the ink are of multi-sized, which is beneficial to getting higher packing density and better conductivity of the printed/written pattern. The effects of the reaction parameters of microwave and additives on the written pattern resistivity were studied on the basis of scanning electron microscope, X-ray diffraction and surface porosity results. Both of the microwave energy and the addition of PVP as the capping agent were found to be critical for the formation of face-centered cubic silver nanoparticles in the conductive ink. The surface porosity and the pore distribution form were also demonstrated to affect the pattern conductivity. The electrical resistivity or the pattern written with the ink prepared at microwave irradiation time of 90 s was calculated to be 364 μΩ cm. The second step of simple centrifugation process could improve the pattern conductivity effectively. After concentrated the conductive ink for two times, the electrical resistivity of the written pattern reduced from 364 to 77 μΩ cm. The proposed two-steps of microwave combined with centrifugation method is a simple and useful way for the preparation of silver nanoparticle conductive ink that can be used in printed electronics.

Structure Inheritance in Nanoparticle Ink Direct-Writing Processes and Crack-Free Nano-Copper Interconnects Printed by a Single-Run Approach.

When nanoparticle conductive ink is used for printing interconnects, cracks and pores are common defects that deteriorate the electrical conductivity of the printed circuits. Influences of the ink solvent, the solid fraction of the ink, the pre-printing treatment and the sintering parameters on the interconnect morphology and conductivity were investigated. It was found that the impacts of all these factors coupled with each other throughout the whole procedure, from the pre-printing to the post-printing processes, and led to a structure inheritance effect. An optimum process route was developed for producing crack-free interconnects by a single-run direct-writing approach using home-made nano-copper ink. A weak gel was promoted in the ink before printing in the presence of long-chain polymers and bridging molecules by mechanical agitation. The fully developed gel network prevented the phase separation during ink extrusion and crack formations during drying. With the reducing agents in the ink and slow evaporation of the ink solvent, compact packing and neck joining of copper nanoparticles were obtained after a two-step sintering process. The crack-free interconnects successfully produced have a surface roughness smaller than 1.5 μm and the square resistances as low as 0.01 Ω/□.

Printed Microwave Metamaterial-Antenna Circuitries on Nickel Oxide Polymerized Palm Fiber Substrates

In this paper, the novelty of exploring the applications of the Iraqi Palm Tree Remnants (IPTR) mixed with Nickel Oxide Nanoparticles (NONP) hosted in Polyethylene (PE), called INP substrates, is utilized by printing metamaterial (MTM) based high gain microwave antennas on them. The proposed INP substrates are mainly created from pressed flexible organic fibers to suite the ink jet printing technologies. The complex relative constitutive parameters are characterized in terms of permittivity (ε) and permeability (μ) within the frequency range from 2 GHz up to 6 GHz using an open end dielectric probe and a T-stub transmission line technique. To validate the feasibility of the INP substrates, a very fine antenna structure of based a miniaturized Hilbert MTM based dipoles is printed on. A material printer with Sliver Nanoparticles Conductive Ink (SNPCI) is used to print the antenna structure. Commercial software packages, CST Microwave Studio (MWS) and Ansys High Frequency Structure Simulator (HFSS), are used to simulate the proposed antenna based on the measured constitutive parameters. A negligible difference is found between the measured and simulated results. Finally, an attractive effect on the retrieved constitutive parameters of the proposed MTM is found due to the proposed INP substrate.

Novel UWB printed metamaterial microstrip antenna based organic substrates for RF-energy harvesting applications

In this paper, an intensive study is proposed to recycle the organic materials use for microwave applications including RF-energy harvesting. Thus, the Iraqi Palme Tree Remnants (IPTR) is exemplified for this study to create dielectric substrates. The main texture of the fabricated substrates is IPTR mixed with Nickel Oxide Nanoparticles (NONP) hosted in Polyethylene (PE) to be called INP substrates. Nevertheless, a metamaterial (MTM) printed antenna on the proposed substrate is fabricated by material printer with Sliver Nanoparticles Conductive Ink (SNPCI). The antenna performance is tested numerically/experimentally in terms of S11 spectrum and radiation patterns. It is found excellent matching bandwidths at 2.45 GHz and 5.8 GHz frequencies with acceptable gains of 1.56 dBi and 2.48 dBi, respectively. The proposed antenna bandwidth is found to start from 2.4 GHz up to more than 10 GHz. The maximum achieved gain and efficiency are found about 3.456 dBi and 78% at 9 GHz. For this, the proposed antenna provides novel performance with ultimate antenna size reduction due to the introduction of the MTM based the proposed INP substrate. Finally, the harvested RF energy by the fabricated antenna is measured and found about 15 mV with a conversation efficiency of 85% at 2.45 GHz and 17.5 mV with a conversion efficiency of 91% at 5.8 GHz.