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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - Improving The Adhesion Between Silver Nanowire Transparent Electrode and PET Film Using a Crosslinkable Polymer
摘要： Silver nanowires, carbon nanotubes and graphenes have found applications for flexible electronics. The adhesion and the patterning of those materials on polymer substrates have been a challenge. This paper reports a novel approach for the improvement of the adhesion between silver nanowires and polyethylene terephthalate (PET) film by using a thermally crosslinkable polymer. The technique was found very efficient in improving the adhesion between silver nanowires and PET substrates.
关键词： adhesion,printed electronics,patterning,crosslinkable polymer,silver nanowires
更新于2025-09-23 15:22:29
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Over-Stretching Tolerant Conductors on Rubber Films by Inkjet-Printing Silver Nanoparticles for Wearables
摘要： The necessity to place sensors far away from the processing unit in smart clothes or artificial skins for robots may require conductive wirings on stretchable materials at very low-cost. In this work, we present an easy method to produce wires using only commercially available materials. A consumer grade inkjet printer was used to print a wire of silver nanoparticles with a sheet resistance below 1 Ω/sq. on a non-pre-strained sheet of elastic silicone. This wire was stretched more than 10,000 times and was still conductive afterwards. The viscoelastic behavior of the substrate results in a temporarily increased resistance that decreases to almost the original value. After over-stretching, the wire is conductive within less than a second. We analyze the swelling of the silicone due to the ink’s solvent and the nanoparticle film on top by microscope and SEM images. Finally, a 60 mm long stretchable conductor was integrated onto wearables, and showed that it can bear strains of up to 300% and recover to a conductivity that allows the operation of an assembled LED assembled at only 1.8 V. These self-healing wires can serve as wiring and binary strain or pressure sensors in sportswear, compression underwear, and in robotic applications.
关键词： silver nanoparticles,stretchable,printed electronics,wearables,inkjet printing
更新于2025-09-23 15:22:29
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Understanding Film-to-Stripe Transition of Conjugated Polymers Driven by Meniscus Instability
摘要： Meniscus instability during meniscus-guided solution coating and printing of conjugated polymers has significant impact on the deposit morphology and the charge transport characteristics. The lack of quantitative investigation on meniscus-instability-induced morphology transition for conjugated polymers hindered the ability to precisely control conjugated polymer deposition for desired applications. Herein, we report a film-to-stripe morphology transition caused by stick-and-slip meniscus instability during solution coating seen in multiple donor-acceptor polymer systems. We observe the coexistence of film and stripe morphologies at the critical coating speed. Surprisingly, higher charge carrier mobility is measured in transistors fabricated from stripes despite their same deposition condition as the films at the critical speed. To understand the origin of the morphology transition, we further construct a generalizable surface free energy model to validate the hypothesis that the morphology transition occurs to minimize the system surface free energy. As the system surface free energy varies during a stick-and-slip cycle, we focus on evaluating the maximum surface free energy at a given condition, which corresponds to the sticking state right before slipping. Indeed, we observe increase of the maximum system surface free energy with increase in coating speed prior to film-to-stripe morphology transition and abrupt drop in the maximum system surface free energy post-transition when the coating speed is further increased, which is associated with reduced meniscus length during stripe deposition. Such energetic change originates from the competition between pinning and depinning forces on a partial wetting substrate which underpins the film-to-stripe transition. This work establishes a quantitative approach for understanding meniscus-instability-induced morphology transition during solution coating. The mechanistic understanding may further facilitate the use of meniscus instability for lithography-free patterning or to suppress instability for highly homogeneous thin film deposition.
关键词： conjugated polymer,meniscus instability,printed electronics,morphology transition,solution coating
更新于2025-09-23 15:21:21
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A roller posture adjustment device with remote-center-of-motion for roll-to-roll printed electronics
摘要： Nonuniform web tension has a great negative effect on product quality of roll-to-roll printed electronics. In this paper, a roller posture adjustment device with remote-center-of-motion (RCM) characteristic is proposed to guarantee web tension uniformity. The device combines a high-stiffness spherical air bearing (SAB) and a multi-degree-of-freedom flexure-based mechanism. The nonuniform web tension in lateral direction can be divided into an equivalent force and two equivalent moments. The equivalent moments are caused by the nonuniformity of the web tension. By adjusting the roller angle around y and z-axes, the equivalent moments can be eliminated to guarantee the web tension uniformity. The multi-DOF flexure-based mechanism is composed of a linear mechanism, a rotary mechanism and a 3-DOF off-plane mechanism. Besides, the RCM characteristic of the proposed device is realized to eliminate extra parasitic movement when the roller posture is changed. Based on pseudo-rigid-body model (PRB-M) method, the theoretical analysis is conducted to evaluate the kinematics, stiffness and dynamics of the device. Moreover, the parameter optimization is conducted to maximize the first two resonance frequencies of the system. After that, finite element analysis is conducted to validate the established models. Finally, a prototype of the proposed device is fabricated performance verification. The experimental results show that the proposed device has a workspace of 10.22 mrad and 8.16 mrad about two working axes with center shifts of the RCM point less than 0.75%, which demonstrate the superior property of the proposed device.
关键词： Flexure-based mechanism,Micro-positioning,Roll-to-roll printed electronics,Remote-center-of-motion
更新于2025-09-23 15:21:21
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All 3D Printed Flexible ZnO UV Photodetector on Ultraflat Substrate
摘要： An all 3D printed flexible ZnO ultraviolet (UV) photodetector is demonstrated, where the 3D printing method is used not only for the electrode and photosensitive material but also for creating a substrate. An ultra-flat and flexible substrate capable of serving as the backbone layer is developed using a water-dissolvable polymer layer for surface planarization. A two layered printing followed by surface treatment is demonstrated for the substrate preparation. As a mechanical support but flexible, a thick and sparse thermoplastic polyurethane layer is printed. On its surface, a thin and dense polyvinyl alcohol (PVA) is then printed. A precise control of PVA reflow using micro-water droplet results in a flexible and extremely uniform substrate. A Cu-Ag nanowire network is directly 3D-printed on the flexible substrate for the conducting layer, followed by ZnO for photosensitive material. Unlike the planar two-dimensional printing that provides thin films, 3D printing allows the electrode to have a step height, which can be made like a dam to accommodate a thick film of ZnO. Photosentivity as a function of various ZnO thickness values was investigated to establish an optimal thickness for UV response. The device was also tested in natural sunlight along with stability and reliability.
关键词： ultraviolet radiation,UV detector,UV sensor,Printed electronics,3D printing,additive manufacturing
更新于2025-09-23 15:21:01
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[IEEE 2020 Pan Pacific Microelectronics Symposium (Pan Pacific) - HI, USA (2020.2.10-2020.2.13)] 2020 Pan Pacific Microelectronics Symposium (Pan Pacific) - Qualification of NIR, UV and Laser Irradiation as Alternative Photonic Sintering Methods for Printed Electronics
摘要： Printed Electronics creates new areas of applications with a new manner of manufacturing electronics. Due to its technical and 3D design freedom, new markets and innovative products arise that were initially unthinkable. However, the focus of research is currently on mastering and improving the printing process. The subsequent process step of drying and densifying the printed structures to achieve high conductivities in the shortest possible time is up to now hardly considered. This paper treats the inquiry of fitted and optimized parameters of alternative promising photonic sintering methods for printed electronics compared to the much more time-intensive state of the art sintering process in a furnace. These photonic sintering methods comprise the near infrared, ultraviolet light as well as laser irradiation of the printed structures. Photonic sintering promises faster and more efficient curing and sintering due to the direct and selective application of energy to the printing structures without damaging the temperature-sensitive substrates. As substrate materials ABS and PC-ABS, as well as a glass material were used. Both polymer materials are standard and technical thermoplastics which are available at the market in huge quantities at low price. For the manufacture of printed circuits, a dispense printer was used, in order to process a low-cost silver-based micro particle paste. The evaluation of the sintering result was carried out based on the electrical conductivity of the printed conductor path and the adhesion strength on the substrate. In addition, the sintering time required for the curing of the structures as well as impacts on the substrate or the printed tracks due to photonic treatment were taken into account. To perform the experiments, two different print layouts were set up in order to be able to assess the electrical properties on the first layout and the adhesion on the second layout. To obtain a detailed statement on the exploration on the photonic sintering methods, a fully factorial design plan was conducted. For the near-infrared irradiation, the important parameters were the irradiation duration and the irradiation power. While sintered by ultraviolet light, the parameters were irradiation time, as well as the distance between the sample surface and the UV emitter. In the treatment by means of laser radiation, laser power and the motion speed were identified as the relevant parameters. In order to be able to draw a comparison to the mainly used sintering method, samples were also sintered in a furnace. The results show a significant reduction of the sintering time to a few seconds with comparable and even significantly better electrical and mechanical properties.
关键词： Printed Electronics,Polymer,Photonic Sintering,Conductivity,Alternative Sintering
更新于2025-09-23 15:21:01
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Inorganic Printed LEDs for Wearable Technology
摘要： A new form of inorganic printed electronics has been developed that allows for high speed production of solid-state lighting on flexible substrates. Light emitting diodes (LED) become more efficient as their size is decreased. However, the difficulties in making the electrical connection to micro LEDs has previously prevented these benefits being exploited outside the laboratory. Standard InGaN film, grown on a defined substrate (heteroepitaxy), was fabricated into micro LEDs (approx. 27 μm) and dispersed in a carrier fluid to form an ink, which can then be printed using established printing technologies. During printing and curing, the geometry of the individual micro LEDs causes them to orientate into a single preferential direction. Connections can then be made via further printed layers of conductive and dielectric ink to create flexible lamps consisting of areas of discrete LEDs. These lamps have low power consumption and high light output making them ideal for incorporating into garments and for packaging. The “Thunderstorm” dress (a Rainbow Winters project) was developed for the “Wired to Wear” exhibition in the Museum of Science and Industry, Chicago (MSI) to demonstrate the potential of this technology. The concept was to turn the wearer into a living representation of a thunderstorm. The concept had previously been realised in 2010 using electroluminescent elements (EL) to create a lightning flash in the panels of the dress. However, this required the wearer to carry high voltage devices, bulky electronics and heavy batteries. Instead, using inorganic printed LEDs afforded the potential to create a truly wearable piece of haute couture, using low voltages, miniature electronics and small batteries. The work reported here describes the fabrication technique used to create the micro LED lamps and the issues related to their integration into a piece of wearable technology. The lamps could be driven in such a way as to create a more realistic flash compared to the EL version. Other potential applications such as smart packaging, are also discussed.
关键词： wearable technology,inorganic LEDs,printed electronics
更新于2025-09-23 15:21:01
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High-Resolution, High-Aspect-Ratio Printed and Plated Metal Conductors Utilizing Roll-to-Roll Microscale UV Imprinting with Prototype Imprinting Stamps
摘要： Micron-scale, high-aspect-ratio features were imprinted by a roll-to-roll process into a UV-curable polymer and used to create high-current-carrying conductive networks on plastic substrates. A stamp fabrication method was developed to create low-cost, rapidly produced roll-to-roll imprinting stamps, which can mold features from 3 μm to 1 mm wide. Isolated raised features 50 μm high were molded from a 25-μm-thick layer of UV-curable resin by displacing resin into raised features in the stamp. Substrates with imprinted capillary channels were used to form electrical conductors by printing a silver ink into reservoirs connected to the channels and allowing capillary flow to coat the channel. Copper electroless plating then filled the channels. The conductors demonstrate high resolution, high aspect ratio (～5:1 height:width), low resistance per length, and easy integration into networks. This roll-to-roll imprinting process provides a foundation for high-throughput manufacturing of high-resolution printed electronics.
关键词： high-aspect-ratio,conductive networks,roll-to-roll imprinting,UV-curable polymer,printed electronics
更新于2025-09-23 15:21:01
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Lasera??Induced Forward Transfer: A Digital Approach for Printing Devices on Regular Paper
摘要： Inkjet printing (IJP) is the most widespread direct-write technique in paper electronics. However, this technique cannot be used for printing devices on untreated regular paper, since its low-viscosity nanoinks leak through the cellulose fibers. Thus, a planarization coating is frequently used as a barrier, even though this makes substrates more expensive and less eco-friendly. Alternatively, high solid content screen printing (SP) inks could allow printing on regular paper due to their high viscosity and large particle size; however, they cannot be printed through IJP. Another digital technique is then required: laser-induced forward transfer (LIFT). This work aims at proving the feasibility of LIFT for printing devices on regular paper. The main transfer parameters are systematically varied to obtain uniform Ag-SP interconnects, whose performance is improved by a multiple-printing approach. It results in low resistances with much better performance than those typical of IJP. After optimizing the functionality of the printed lines, a proof-of-concept consisting of a radio-frequency inductor is provided. The characterization of the device shows a substantially higher performance than that of the same device printed with IJP ink in similar conditions, which proves the potential of LIFT for digitally fabricating devices on regular paper.
关键词： paper electronics,laser printing,screen printing ink,laser forward transfer,printed electronics
更新于2025-09-23 15:19:57
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Laser sintering of Cu@Ag core-shell nanoparticles for printed electronics applications
摘要： Bimetallic Cu@Ag core-shell nanoparticles (NPs) were synthesized by the reduction of copper 2-[2-(2-methoxyethoxy)ethoxy]acetate with hydrazine hydrate in benzyl alcohol followed by the reduction of silver ions on the copper surface using a galvanic replacement reaction. Ink consisting of the as-synthesized Cu@Ag NPs dispersed in a mixture of nontoxic solvents with different boiling temperatures (butanol and propylene glycol ethers) was prepared. Thin layers were spin coated on polyimide films using the developed ink. The conductive layer formed in air in the optimized conditions showed an electrical resistivity of 28.5 lX·cm.
关键词： Conductive inks,Laser sintering,Printed electronics,Copper,Core-shell nanoparticles,Silver
更新于2025-09-23 15:19:57