Search

Printed electronics implies the use of low-cost, scalable, printing technologies to fabricate electronic devices and circuits on flexible substrates, such as paper or plastics. The development of this new electronic is currently expanding because of the emergence of the internet-of-everything. Although lot of attention has been paid to functional inks based on organic semiconductors, another class of inks is based on nanoparticles obtained from exfoliated 2D materials, such as graphene and metal sulfides. The ultimate scientific and technological challenge is to find a strategy where the exfoliated nanoparticle flakes in the inks can, after solvent evaporation, form a solid which displays performances equal to the single crystal of the 2D material. In this context, a printed layer, formed from an ink composed of nano-flakes of TiS2 intercalated with hexylamine, which displays thermoelectric properties superior to organic intercalated TiS2 single crystals, is demonstrated for the first time. The choice of the fraction of exfoliated nano-flakes appears to be a key to the forming of a new self-organized layered material by solvent evaporation. The printed layer is an efficient n-type thermoelectric material which complements the p-type printable organic semiconductors The thermoelectric power factor of the printed TiS2/hexylamine thin films reach record values of 1460 µW m−1 K−2 at 430 K, this is considerably higher than the high value of 900 µW m−1 K−2 at 300 K reported for a single crystal. A printed thermoelectric generator based on eight legs of TiS2 confirms the high-power factor values by generating a power density of 16.0 W m−2 at ΔT = 40 K., Graphical abstract

Advanced high-temperature materials, metals and ceramics, have been widely sought after for printed flexible electronics under extreme conditions. However, the thermal stability and electronic performance of these materials generally diminish under extreme environments. Additionally, printable electronics typically utilize nanoscale materials, which further exacerbate the problems with oxidation and corrosion at those extreme conditions. Here we report superior thermal and electronic stability of printed copper-flexible ceramic electronics by means of integral hybridization and passivation strategies. High electric conductivity (5.6 MS/m) and thermal stability above 400 °C are achieved in the printed graphene-passivated copper platelet features, while thermal management and stability above 1000 °C of printed electronics can be achieved by using either ultrathin alumina or flexible alumina aerogel sheets. The findings shown here provide a pathway toward printed, extreme electronic applications for harsh service conditions.

The enabling electrohydrodynamic (EHD) printing technology in a one-step forming, continuous, and controllable manner has gained wide attention in the field of flexible printed electronics. The evaporation characteristic of ink solvent during the EHD printing greatly affects the shape of the jet as well as the penetration and diffusion of inks on fabrics, which is crucial to the formation of high-quality printed electronics. However, few works have deeply investigated the control of ink solvent evaporation to adjust the formability of EHD printing electronics on rough and porous textiles. Here, conductive inks with different solvent evaporation rates are formulated. The effect of solvent evaporation on the motion of inks is evaluated by the contact angle over time. Furthermore, the morphology and electrical properties under different deformation of EHD-printed conductive lines are observed and measured. The results show that the morphology of conductive lines printed on fabric could be accurately controlled by the ratios of the solvent in inks, and the solvent evaporation rate has a significant inverse-parabolic effect on electrical resistance and its stability under deformation. Moreover, the serviceability of the optimal ink is demonstrated by the performance of an EHD-printed antenna for ultra-high frequency radio frequency identification tags, and its maximum reading range is 9.1 m under typical application examples. These findings will provide a guide for ink formulation and process control of EHD printing in flexible textile-based electronics.

Next-generation printed electronics is required to be of high performance, cost-effective, multifunctional, sustainable, and environmentally benign. Herein, we report the manufacturing of a flexibl...

International audience; Printed electronics are expected to meet an increasing demand for improved functionality and autonomy of products in the context of Internet-of-Things. With this trend, the environmental performance of novel technologies is of growing importance. The current study presents the life cycle assessment of two novel devices: an anticounterfeit label based on the electrochromic display and a shock-detection tag based on the piezoelectric sensor, designed for the use in packaging of pharmaceuticals and luxury items to improve the safety and accountability in the supply chain. The devices are manufactured by means of energy-efficient printing techniques on a low-cost flexible and recyclable paper substrate. Comprehensive cradle-to-grave analysis contributes to industrial-scale energy and material life cycle inventories and identifies the main impact hotspots evaluated for a broad range of categories of the ReCiPe midpoint (H) impact assessment method. Results show that major impact burdens are associated with the near-field communication chip and radio-frequency identification antenna, while the impacts of solvents, process energy, electrochromic display/piezoelectric sensor, Li-ion battery, and substrate are comparatively small. In terms of their global warming potential, both the anticounterfeit label and shock-detection tag embody around 0.23 kg of CO2-equiv. Several material-use reduction and material-substitution strategies are quantified and discussed for their potential to reduce high impacts of the antenna.

Active-matrices serve as the backplane circuitry for large-area display technologies and distributed sensors. Recently, there has been significant interest in developing flexible, additively manufactured active matrices for the burgeoning flexible electronics industry. Carbon nanotubes (CNTs) are prime candidate materials for semiconducting elements of transistors due to their solution processability, carrier mobility, and mechanical flexibility. There have been many recent accomplishments in the development of CNT inks and in their deposition via printing that enable their use in thin-film transistors (TFTs), and their appropriate performance make them suitable for use in large-area active matrices. In this review, we provide an overview of the field, with a specific focus on recent advancements in CNT sorting, ink preparation, and printing techniques. We also provide a benchmarking study of printed CNT devices presented in literature after 2017. Next, we discuss printable CNT-TFTs used for active-matrix applications. Finally, we provide a concluding perspective on the outlook and challenges for printed CNT-TFT active matrices.

Graphic abstract Silver nanowires (AgNWs), as one-dimensional nanometallic materials, have attracted wide attention due to the excellent electrical conductivity, transparency and flexibility, especially in flexible and stretchable electronics. However, the microscopic discontinuities require AgNWs be attached to some carrier for practical applications. Relative to the preparation method, how to integrate AgNWs into the flexible matrix is particularly important. In recent years, plenty of papers have been published on the preparation of conductors based on AgNWs, including printing techniques, coating techniques, vacuum filtration techniques, template-assisted assembly techniques, electrospinning techniques and gelating techniques. The aim of this review is to discuss different assembly method of AgNW-based conducting film and their advantages. Conducting films based on silver nanowires (AgNWs) have been reviewed with a focus on their assembly and their advantages.

A new broadband UV light-based processing method for a screen printable silver oxalate molecular ink is developed that enables structural electronics to be produced on complex thermoformed 3D objects. The production of these 3D devices is driven by the light-induced reduction of silver oxalate to form an interfacial silver nanoparticle layer that allows the ink to transition to a viscous liquid intermediate and elongate up to 50% without cracking during thermoforming. Ultimately, this enables the development of 3D electronics devices with significantly less limitations on geometry, shape, size, and depth in comparison to commercially available inks. UV processing is also effective for 2D traces on low temperature PET substrate, where in situ produced silver nanoparticles can subsequently absorb light and further facilitate the rapid conversion of the silver oxalate to metallic silver through a self-limiting thermal decomposition. The resulting traces have superior electrical properties and are produced in significantly less time in comparison to thermal sintering. Together, UV processing and the silver oxalate molecular ink serve as a platform for both the rapid production of conductive silver traces on low temperature substrates and the development of novel thermoformed 3D human-machine interface devices, areas of interest for both academia and industry.

The development of graphene-based materials with good light-curing ability and excellent electrical conductivity is the key to next-generation electronic devices. Herein, we demonstrate the molecular structure modification of photocurable graphene oxide (PGO) by reacting hydroxyl groups with isocyano groups, which is referred to as grafting of the photosensitive group on pristine GO, resulting in photosensitive PGO flakes that can be photocured during 3D printing using water as a solvent and a developer. Complex-shaped and highly precise 2D and 3D structures of GO as well as thin single-layer or few-layer GO films are obtained by optimizing the concentration and photocuring parameters of the PGO precursor. After thermal reduction of PGO microarchitectures, the reduced cross-linked GO (rCGO) exhibits a minimum square resistance of 213.74 mΩ sq−1, which is similar to that of graphene. Moreover, rCGO demonstrates excellent cell compatibility during cell culture experiments and superior hydrophilicity. The latter property can be exploited to prepare solution-based detection electrodes. The proposed strategy is used to print circuits and 3D bulk conductors, and can facilitate the formation of various electronic devices via photocuring 3D printing or photolithography process.

A stretchable conductor is one of the key components in soft electronics that allows the seamless integration of electronic devices and sensors on elastic substrates. Its unique advantages of mechanical flexibility and stretchability have enabled a variety of wearable bioelectronic devices that can conformably adapt to curved skin surfaces for long-term health monitoring applications. Here, we report a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)-based stretchable polymer blend that can be patterned using an inkjet printing process while exhibiting low sheet resistance and accommodating large mechanical deformations. We have systematically studied the effect of various types of polar solvent additives that can help induce phase separation of PEDOT and PSS grains and change the conformation of a PEDOT chain, thereby improving the electrical property of the film by facilitating charge hopping along the percolating PEDOT network. The optimal ink formulation is achieved by adding 5 wt % ethylene glycol into a pristine PEDOT:PSS aqueous solution, which results in a sheet resistance of as low as 58 Ω/□. Elasticity can also be achieved by blending the above solution with the soft polymer poly(ethylene oxide) (PEO). Thin films of PEDOT:PSS/PEO polymer blends patterned by inkjet printing exhibits a low sheet resistance of 84 Ω/□ and can resist up to 50% tensile strain with minimal changes in electrical performance. With its good conductivity and elasticity, we have further demonstrated the use of the polymer blend as stretchable interconnects and stretchable dry electrodes on a thin polydimethylsiloxane (PDMS) substrate for photoplethysmography (PPG) and electrocardiography (ECG) recording applications. This work shows the potential of using a printed stretchable conducting polymer in low-cost wearable sensor patches for smart health applications.

This Minireview compares two distinct ink types, namely metal‐organic decomposition (MOD) and nanoparticle (NP) formulations, for use in the printing of some of the most conductive elements: silver, copper and aluminium. Printing of highly conductive features has found purpose across a broad array of electronics and as processing times and temperatures reduce, the avenues of application expand to low‐cost flexible substrates, materials for wearable devices and beyond. Printing techniques such as screen, aerosol jet and inkjet printing are scalable, solution‐based processes that historically have employed NP formulations to achieve low resistivity coatings printed at high resolution. Since the turn of the century, the rise in MOD inks has vastly extended the range of potentially applicable compounds that can be printed, whilst simultaneously addressing shelf life and sintering issues. A brief introduction to the field and requirements of an ink will be presented followed by a detailed discussion of a wide array of synthetic routes to both MOD and NP inks. Unindustrialized materials will be discussed, with the challenges and outlook considered for the market leaders: silver and copper, in comparison with the emerging field of aluminium inks., Fresh ink: This minireview considers the highlights and challenges facing both the precursor (MOD) and nanoparticle (NP) approach toward the printing of highly conductive metallic features. Silver, copper and aluminium are some of the most conductive elements and their printing has been applied to a broad field of electronics. Up‐to‐date synthetic routes to MOD and NP formulations are presented and compared to the fundamental requirements of an ink.

Transparent metal oxides are one of the most promising material systems for thin film flexible electronics due to their unique balance of optical transparency and high electron mobility. Rapid progress in the field of solution-processed metal oxides in the last decade has established them as the leading material system for thin film transistors. Fully-integrating metal oxide materials with printing technologies could enable a wide range of applications such as flexible displays, imaging systems, resorbable bioelectronics, and low-power sensors that remain uneconomical or unmanufacturable with incumbent technologies. This thesis contributes materials and methods that can advance the scalable fabrication of transparent thin film transistors by high-speed gravure printing. Through these studies, an understanding of the interactions between ink chemistry, fluid parameters, printed feature formation, and electronic properties is presented.In the past, gravure-printed electronics has been limited to printing organic inks and metal nanoparticles. Here we couple an understanding of the physics of gravure printing on glass with strategies for inorganic sol-gel ink design to extend the scope of high-speed printing to new high-performance inorganic materials including transparent conductive oxides (TCOs). We explore the impact that ink design has on material properties such as crystallinity, conductivity, transparency, and performance under mechanical bending stress, leading to effective co-optimization of patterning and TCO performance. Furthermore, these ink design principles are applied to silver nanowire hybrid sol-gel inks which allow gravure printing of high figure of merit mechanically robust, transparent conducting films using low processing temperatures.Additionally, this thesis will discuss the design and construction of a custom gravure printer for high-speed patterning and accurate registration of printed layers. The novel design allows the decoupling of the individual subprocesses of gravure to allow mechanistic studies of major printing artifacts and improved areal uniformity. A new understanding of the role of gravure contact mechanics in ink transfer and doctoring is presented.This work also develops high-performance materials for scaling down the process temperatures of printed metal oxide devices. Aqueous ink formulations are explored for inkjet printing transparent electrodes and channel materials in transparent thin film transistors. The unique printing physics, electrical contact properties to aqueous semiconductors, and low-temperature processability of these inks are studied to achieve high-resolution printed TCOs at plastic compatible temperatures below 220 °C. Additionally, low-temperature, UV-annealed high-k dielectrics are presented for processing printed metal oxide transistors. High-performance printed transistors are achieved with high operational stability and connections between bias-stress stability and low-temperature processing are studied.

Sessile droplets of colloidal dispersions tend to exhibit the coffee-ring phenomenon in the drying process. The suspended particles are transported especially at the final stage of the drying process, which is called the rush hour. Conventional inkjet printers require the ink liquid to have a sufficiently low viscosity for inkjet discharge, but such liquids tend to be subject to the coffee-ring effect. The coffee-ring effect is an issue for conventional printing applications and drawing wires in printed electronics. We show by microscopy movie data analysis based on single particle tracking that the addition of a small amount of cellulose nanofibers (CNFs) to the colloidal dispersion works in such a way that the initial low concentration satisfies the low viscosity requirement, and the three-dimensional structural order of the CNFs formed during the final stage of droplet drying owing to the high concentration hinders the transport of particles to the periphery, suppressing the coffee-ring effect. This is a spatio-temporally controlled process that makes use of the inherent process of ordinary ink printing situations by the simple protocol. This is also an approach to seamlessly link the ink and substrate since CNFs are regarded as a promising substrate material for flexible devices in printed electronics because of their fine texture that keeps conductive nanoparticles on the surface.

Reusable electronics have received widespread attention and are urgently needed. Here, nanocellulose-based liquid metal (NC-LM) printed circuit has been fabricated by the evaporation-induced transfer printing technology. In this way, the liquid metal pattern is embedded into the nanocellulose membrane, which is beneficial for the stability of the circuit during use. Besides, the NC-LM circuit is ultrathin with just tens of microns. In particular, the finished product is environmentally friendly because it can be completely dissolved by water, and both the liquid metal ink and the nanocellulose membrane can be easily recollected and reused, thereby reducing waste and pollution to the environment. Several examples of flexible circuits have been designed to evaluate their performance. The mechanism of evaporation-induced transfer printing technology involves the deposition, aggregation, and coverage tightly of the nanosized cellulose fibrils as the water evaporated. This study provides an economical and environmentally friendly way for the fabrication of renewable flexible electronics.

Many researchers claim that graphene, a specially studied carbon allotrope, has a single layer of atoms organized in a two-dimensional honeycomb lattice. Because of its exceptional electronic and mechanical properties, it has a significant job to perform in redefining future technologies. Although graphene has made a major breakthrough to be considered for a wide area of applications, most of the interesting properties of graphene are still at the early stage of research. Graphene dependent attenuators and single and multi-frequency constructible antennas are designed employing the tunability of graphene. As the name indicates, the form of RF technology that uses electromagnetic fields for automatic identification purposes of tags attached to objects is termed as radio frequency identification (RFID). For years, the use of pricy raw materials and intricate fabrication processes in metal coating and metal based conductive inks in printed electronics kept the involved cost very high. So, it is inevitable to replace the existing fabrication process with cheaper materials and simpler techniques. Researchers assert that printed graphene has the potential to be a competent alternative for RFID applications.

Low operating voltages, rapid response, and high-throughput fabrication compatibility are key advantages for the development of electrolyte-gated field effect transistors (EGFETs) for biological sensing. Among the key components in EGFET biosensors, electrolyte materials are relatively less investigated, especially alternatives to water-based liquid electrolytes such as ionic liquids, ion gels, polyelectrolytes, and solid polymer electrolytes. These electrolytes enable portable devices and environmental stability superior to their water-based liquid alternatives. In this review, we offer an up-to-date evaluation of the state of EGFET research and gauge the strengths and limitations of high-performance electrolytes for use in EGFET biosensor applications as well as the potential for computer-aided design of such sensing platforms. The recent progress of EGFET biosensors for some popular analytes are reviewed and the performance of these alternative electrolytes in transistor biosensing is assessed. The challenges and opportunities for electrolytes in EGFETs are discussed for future research directions in this field.

The rapid fabrication of artificial skin patches with multiple functions has attracted great attention in various research fields, such as personal health monitoring, tissue engineering and robotics. Intertwined-network structures (blood vessel, lymphatic and nerve networks) play a key role in endowing skin with multiple functions. Thus, considerable efforts have been devoted to fabricating artificial skin patches with mimetic internal channels. Here, we present a one-step 3D printed intelligent silk fibroin artificial skin (i-skin) with built-in electronics and microfluidics. By simultaneously extruding functional materials in polyurethane-silk fibroin precursor using a 3D bioprinter, the i-skin and its internal channels can be fabricated within one step. Photonic crystals (PCs) were integrated into the microfluidic channel, enabling the i-skin to sense multiple biomarkers. Moreover, the printed electronics give the i-skin remarkable conductivity, endowing the i-skin with the capability of sensitive motion sensing. Notably, by using the built-in electronics and PC-integrated microfluidics, sensitive sensing of motions and specific cardiac biomarkers can be achieved simultaneously in the i-skin, indicating the remarkable prospects of the printed multi-functional i-skin in health care-related biomedical fields.

Printed electronics will be essential in the implementation of next-generation electronic devices, because printing facilitates fabrication of devices on various rigid, thin, or flexible substrates. Inkjet printing enables precise placement of fine droplets of different functional materials; moreover, it is inexpensive and adaptable for mass production. Electrohydrodynamic (EHD) jet printing, a type of inkjet technology, can generate very fine ink droplets by applying an electric field between the substrate and the nozzle; therefore, it is a promising candidate for high-resolution direct printing, which is essential in the manufacturing of various devices. More significantly, the characteristics of EHD jet printing can be conveniently adjusted by modulating the electric field strength, and various functional inks can be used in this process. This paper is a comprehensive review of recent progress in EHD jet printing technology to fabricate various electronic devices and circuits. Applications of various functional inks (electrode, semiconductor, dielectric materials) for each electronic component are also described.

Printed sensors are among the most successful groups of devices within the domain of printed electronics, both in terms of their application versatility and the emerging market share. However, reports on fully printed gas sensors are rare in the literature, even though it can be an important development toward fully printed multisensor platforms for diagnostics, process control, and environmental safety-related applications. In this regard, here, we present the traditional tin oxide-based completely inkjet-printed co-continuous and mesoporous thin films with an extremely large surface-to-volume ratio and then investigate their NO2 sensing properties at low temperatures. A method known as evaporation-induced self-assembly (EISA) has been mimicked in this study using pluronic F127 (PEO106-PPO70-PEO106) as the soft templating agent and xylene as the micelle expander to obtain highly reproducible and spatially homogeneous co-continuous mesoporous crystalline SnO2 with an average pore diameter of the order of 15-20 nm. The fully printed SnO2 gas sensors thus produced show high linearity for NO2 detection, along with extremely high average response of 11,507 at 5 ppm NO2. On the other hand, the sensors show an ultralow detection limit of the order of 20 ppb with an easy to amplify response of 31. While the excellent electronic transport properties along such co-continuous, mesoporous structures are ensured by their well-connected (co-continuous) ligaments and pores (thereby ensuring high surface area and high mobility transport at the same time) and may actually be responsible for the outstanding sensor performance that has been observed, the use of an industrial printing technique ascertains the possibility of high-throughput manufacturing of such sensor units toward inexpensive and wide-range applications.

Silver based flexible printed electronics offer the possibility to design low-cost environmentally friendly products through versatile manufacturing procedures. In this regard, conductive silver inks are commonly printed on flexible substrates because in contrast to their macroscale analogues, the silver nanoparticles (AgNPs) present different salient physical and chemical properties. However, an extensive application of silver inks is often limited by factors such as a complicated ink preparation process, conflict between ink stability and nanoparticle content, overall ink formulation and selection of suitable sintering techniques. Nevertheless, advances in nanotechnology and printing techniques have opened new rooms to improve the synthesis, stability, processing, and application of silver inks. This review article presents the progress in AgNPs processing, Ag-conductive ink formulation and important printing techniques, especially as it relates to the manufacture of flexible electronics. Furthermore, the significance of the sintering process and the importance of various kinds of sintering methods for improving ink quality and adhesion to substrates are discussed. In addition, some of the notable applications of printed flexible electronics are highlighted.

Manufacturing supercapacitors by printing enables reduced material waste, easy customization, adaptability of form factor with the application, and high compatibility with other printed electronics...

Eco-friendly and cost-effective materials and processes to manufacture functional substrates are crucial to further advance the area of printed electronics. One potential key component in the printed electronics platform is an electrically functionalized paper, produced by simply mixing common cellulosic pulp fibers with high-performance electroactive materials. Herein, an electronic paper including nanographite has been prepared using a standardized and scalable papermaking technique. No retention aid was needed to achieve a conducting nanographite loading as high as 50 wt %. The spontaneous retention that provides the integrity and stability of the nanographite paper, likely originates partially from an observed water-stable adhesion of nanographite flakes onto the fiber surfaces. The resulting paper exhibits excellent electrical characteristics, such as an in-plane conductivity of 107 S/cm and an areal capacitance of 9.2 mF/cm(2), and was explored as the back-electrode in printed electrochromic displays. Funding Agencies|Digital Cellulose Centre, a competence center set up by the Swedish Innovation Agency VINNOVA; consortium of Swedish forest industries; Wallenberg Wood Science Center (Knut and Alice Wallenberg Foundation); VINNOVA "EPIC" projectVinnova [2017-05413]; Karl-Erik Onnesjo Foundation

Summary Current synthetic approaches to metal nanoparticles are mostly batch processes that use a large quantity of reagents and surfactants, producing enormous amount of solid and liquid waste. Here, we developed a rotating electrodeposition and separation (REDS) technique, which entails electrochemically depositing nanoparticles onto a continuously rotating metal foil and subsequently harvesting them through mechanical delamination. A wide array of elemental nanoparticles (e.g., Ag, Au, Ni, Cu), alloys nanoparticles (e.g., FeCoNi and FeCoNiW), and metal oxide nanomaterials (e.g., Co3O4) were synthesized by REDS. We further controlled the growth direction of metals during the electrodeposition to fabricate more complex structures such as polyhedrons, nanoplates, dendrites, and flower nanostructures. Based on the metallic nanoparticles, we obtained conducting inks and fabricated near-field communication tags and touch screen panels. Our technique provides a novel approach for rapid, scalable, and green preparation of low-cost and high-quality nanoparticles in which electrodeposition chemistry can be controlled with a roll-to-roll system.

The Printed Electronics (PE) is expected to revolutionise the way electronics will be manufactured in the future. Building on the achievements of the traditional printing industry, and the recent advances in flexible electronics and digital technologies, PE may even substitute the conventional silicon-based electronics if the performance of printed devices and circuits can be at par with silicon-based devices. In this regard, the inorganic semiconducting materials-based approaches have opened new avenues as printed nano (e.g. nanowires (NWs), nanoribbons (NRs) etc.), micro (e.g. microwires (MWs)) and chip (e.g. ultra-thin chips (UTCs)) scale structures from these materials have been shown to have performances at par with silicon-based electronics. This paper reviews the developments related to inorganic semiconducting materials based high-performance large area PE, particularly using the two routes i.e. Contact Printing (CP) and Transfer Printing (TP). The detailed survey of these technologies for large area PE onto various unconventional substrates (e.g. plastic, paper etc.) is presented along with some examples of electronic devices and circuit developed with printed NWs, NRs and UTCs. Finally, we discuss the opportunities offered by PE, and the technical challenges and viable solutions for the integration of inorganic functional materials into large areas, 3D layouts for high throughput, and industrial-scale manufacturing using printing technologies.

CuInSe2 nanocrystals offer promise for optoelectronics including thin-film photovoltaics and printed electronics. Additive manufacturing methods such as photonic curing controllably sinter particle...