Water Transfer Printing Research Articles

Three-dimensional triboelectric nanogenerator manufacturing using water transfer printing

Triboelectric nanogenerators (TENGs) have been widely studied due to their efficient energy harvesting capabilities and fast electrical response signals. In this study, a processing method based on water transfer printing (WTP) is developed for preparing TENG devices with three-dimensional (3D) structures. With this method, electrodes and ink layers can be integrated onto a variety of 3D objects to form a one-piece structure, which offers advantages including application to 3D surfaces, abrasion resistance, handling ease, adaptability, and decorativeness. The process istaken to prepare a 5 × 5 cm2 single-electrode TENG (IF-TENG), with FEP serving as the negative triboelectric layer and ink serving as the positive triboelectric layer. The TENG’s open-circuit voltage and short-circuit current are 184 V and 1.53 μA, respectively. Additionally, a door handle TENG (DH-TENG) device has been built for practical application demonstrations. The DH-TENG device is used in wireless alarm systems that prevent children from accidentally ingesting medication. It is also used in self-powered guidance systems that illuminate LED arrow lights to help the elderly or children at night. Seamless integration of 3D surface TENG devices using WTP is expected to have applications in smart home systems, smart transportation and security, wearable electronics, and energy harvesting.

A water transfer printing method for contact lenses surface 2D MXene modification to resist bacterial infection and inflammation.

Contact lenses (CLs) are prone to adhesion and invasion by pollutants and pathogenic bacteria, leading to infection and inflammatory diseases. However, the functionalization of CL (biological functions such as anti-fouling, antibacterial, and anti-inflammatory) and maintaining its transparency still face great challenges. In this work, as a member of the MXenes family, vanadium carbide (V2C) is modified onto CL via a water transfer printing method after the formation of a tightly arranged uniform film at the water surface under the action of the Marangoni effect. The coating interface is stable owing to the electrostatic forces. The V2C-modified CL (V2C@CL) maintains optical clarity while providing good biocompatibility, strong antioxidant properties, and anti-inflammatory activities. In vitro antibacterial experiments indicate that V2C@CL shows excellent performance in bacterial anti-adhesion, sterilization, and anti-biofilm formation. Last, V2C@CL displays notable advantages of bacteria elimination and inflammation removal in infectious keratitis treatment.

Determining abrasion resistance of decorative coated wood-based panels using retinex model

An Image Processing Based Scrub Tester (IPBST) was used to imitate the effect of household chemicals on furniture and decoration elements. For this purpose, 8 mm-thick, bright white, acrylic coated medium density fiberboard (MDF), polyvinyl chloride coated MDF, MDF lam ready-to-use sheets, and cellulosic, polyurethane, acrylic, and water-based paint applied MDF sheets were used. Carbon fiber patterned decorative coating was applied to the prepared sample surfaces using the water transfer printing and ultraviolet printing methods. The surfaces of the samples were scrubbed with various household chemicals in accordance with the Turkish Standard TS EN ISO 11998. In the image processing phase, the images before and after scrubbing were first converted to hue, saturation, and value color space. The relationship between the abrasion measurement method of the proposed IPBST and the abrasion data obtained from the stereo microscope device was examined using the Pearson Correlation analysis. The relationship between both abrasion test methods was positive, very strong, and significant (0.81). Thus, the IPBST can be used as an alternative to industrial test devices as it obtains similar data.

Breakup-Free and Colorful Liquid Metal Thin Films via Electrochemical Oxidation.

Thin-film metal conductors featuring high conductivity and stretchability are basic building blocks for high-performance conformable electronics. Gallium-based liquid metals are attractive candidates for thin-film conductors due to their intrinsic stretchability and ease of processing. Moreover, the phase change nature of liquid metal provides an opportunity to create conformal electronics in a substrate-free manner. However, thin liquid metal films tend to break during the solid-to-liquid transition due to the high surface tension of liquid metal. Here, we created breakup-free liquid metal thin films by the electrochemical oxidation of solid gallium films. We show that electrochemical oxidation can enhance the mechanical strength of the gallium oxide layer and its interfacial adhesion to the gallium core. When heated to the liquid state, the oxidized gallium films can maintain their structural integrity on various solid substrates, hydrogels, and even the water surface. The solid-liquid phase change-induced stiffness decrease allowed the gallium films to be conformably attached to various nonplanar surfaces upon heating or water transfer printing. Moreover, we also found that enhanced electrochemical oxidation can result in the formation of structure color due to nanoporous structures on the film surface. We also demonstrate the applications of oxidized liquid metal films in functional electronics, electrophysiological monitoring, and tattoo art.

Organic and Metallic Sensors on Complex 3-D Object Using an Original Method: Water Transfer Printing

Organic and Metallic Sensors on Complex 3-D Object Using an Original Method: Water Transfer Printing

Application parameters of water transfer printing on wood-based panel surfaces

Optimum application values of the Water Transfer Printing (WTP) technique were determined on various wood-based panel surfaces. For this purpose, 8-mm-thick, glossy white, acrylic-coated medium-density fiberboard (MDF) panels (high gloss panels), polyvinyl chloride (PVC)-coated MDF panels, MDF Lam ready-to-use panels, and cellulosic, polyurethane, acrylic, and water-based paint applied MDF panels were used. An automatic immersion system with pool was designed and produced. A 30-μm-thick carbon patterned WTP film was applied on sample panel surfaces prepared with the help of this device at four immersion angles (0º, 15º, 30º, and 45º), four immersion speeds (50 cm/min, 100 cm/min, 150 cm/min, and 200 cm/min), and four immersion times (5 to 10 s, 20 to 30 s, 50 to 60 s, and 80 to 90 s). The optimum parameters of the WTP technique regarding the temperature and relative humidity of the application environment, water temperature, laying method, dissolution time, amount of activator, spray gun angle and tip clearance, air pressure, as well as immersion angle, speed, and time were determined using the measurement and observation method. According to the optimum parameters obtained in the study, the WTP technique was successfully applied to all wood-based panel surfaces.

Large‐Area Flexible Organic Solar Cells with a Robust Silver Nanowire‐Polymer Composite as Transparent Top Electrode

AbstractUpscaling of efficient flexible organic solar cells (OSCs) is still a challenging task, where flexible transparent electrode is a key limiting factor. Silver nanowires (AgNWs) are widely used as flexible transparent electrodes to fabricate efficient small‐area flexible OSCs, but the high surface roughness of AgNWs electrodes causes large leakage current and performance deterioration in large‐area OSCs. In this study, it is reported that a strategy of switching the bottom AgNWs electrode and the top Ag film electrode to avoid the detrimental effect of the high surface roughness of AgNWs electrodes. Mechanical robustness of the AgNWs has been enhanced by introducing a cross‐linked poly(sodium 4‐styrenesulfonate) layer. The AgNWs‐polymer transparent film is fabricated by water transfer printing as the top electrode. 21 cm2 flexible organic modules containing 10 sub‐cells are fabricated and delivered power conversion efficiencies of 12.3% with the design of switched electrodes.

High-detectivity organic photodetectors with double bulk heterojunction enabled by water transfer printing

Suppressing the dark current is an effective strategy to boost the detection capability of organic photodetectors (OPDs). In this Letter, the water transfer printing method is demonstrated in double bulk heterojunction (BHJ) OPDs, which is solvent-independent rather than the traditional sequential spin-coating method, enabling the elimination of the negative effects of solvents on the underlying film and the suppressing of the dark current. As a result, a photo detectivity up to 1012 Jones was obtained in the wide spectral range of 400-900 nm with a small working area of 3 mm2.

Characterization of out-of-plane tensile stress–strain behavior for GFRP composite materials at elevated temperatures

Three-dimensional stress–strain constitutive parameters in various environments are essential for understanding the mechanical behavior of thick cross-section composite load-bearing structures. This work aims to expand a short-beam bending test combined with a digital image correlation method to obtain the out-of-plane (interlaminar) stress–strain behavior for polymer–matrix composites at elevated temperatures. A simple and repeatable digital speckle pattern fabrication method was used based on the water transfer printing (WTP) technique to reduce deformation measurement uncertainty induced by the quality of the speckle pattern. The effects of DIC parameters and misalignment of the DIC stereo camera system on the uncertainty of deformation measurement have been studied. The out-of-plane properties, including elastic modulus and tensile strength for a 50-ply thick S6C10/AC318 glass/epoxy unidirectional panel, have been obtained at elevated temperatures for the first time. The experimental results showed that the out-of-plane modulus and tensile strength were 15.95 GPa and 76 MPa at room temperature. The modulus was nearly unchanged at 50 °C and decreased 18% at 80 °C. The out-of-plane tensile strength decreased 9% at 50 °C and 22% at 80 °C, respectively, indicating that the tensile strength degradation is more sensitive to temperature rising than the modulus. The study suggests that the improved short-beam bending test combined with the DIC method can guarantee reproducible results and usability at elevated temperatures.

Robust Tattoo Electrode Prepared by Paper-Assisted Water Transfer Printing for Wearable Health Monitoring

Long-term and stable monitoring of bioelectrical signals represented by electrocardiogram (ECG) has a great application value for wearable electronics. The ECG monitoring require low-cost, flexible and robust electrical system that can work throughout daily activities. In this article, we propose a paper-assisted strategy to fabricate a tattoo ECG electrode based on the low-cost water transfer printing technology. Similar to the tattoo attached on the skin, the fabricated electrode allows complying with the skin deformation comfortably and accommodating the local strains. The ECG signals collected by the tattoo electrode have a high signal to noise ratio, robustness, mechanical stability and strong immunity to motion artifact even under the severe deformation of skin. The tattoo electrode enables convenient and long-period ECG monitoring during various activities, including exercising, sweating, rubbing, and flushing. As a proof-of-concept, a soft wireless ECG system is developed by integrating with the tattoo electrode, commercialized IC chips, and a low-energy Bluetooth module to achieve the functions of signal acquisition, data processing and communication. The measured results show that the proposed strategy has a promising application for wearable health monitoring system.

Water Transfer Printing of Multilayered Near‐Infrared Organic Photodetectors

AbstractTo obtain high‐performance organic near‐infrared (NIR) photodetectors, it is essential to suppress the noise current. Here, high‐performance organic NIR photodetectors based on a multilayered structure fabricated by a water transfer printing strategy are reported. These devices comprise a NIR small molecule electron‐accepting layer (IEICO‐4F) and several repeating polymers stacked electron‐donating layers (PTB7‐Th). These polymer layers are prepared onto water substrate and transferred to the target substrate directly, working as an electron‐donating moiety and also as an electron blocking layer. The water transfer printing fabricated multilayered NIR photodetectors obtain extremely low noise current by suppressing the reverse dark current and decreasing the carriers trapping/de‐trapping. The NIR organic photodiodes with multilayered structure exhibit a noise current as low as about 27 fA Hz−1/2 at −0.5 V, resulting in a specific detectivity of approaching 1012 Jones at the NIR wavelength of 860 nm that is about 3 orders of magnitude higher than that of the control devices with a bulk‐heterojunction structure. Furthermore, the multilayered NIR photodetectors also exhibit a large linear dynamic range, fast response simultaneously. This proposed multilayered structure and the utilization of the water transfer printing method could help create high‐performance organic photodetectors.

Eco-Friendly Water Transfer Printing Free of Primers and Activators

Eco-Friendly Water Transfer Printing Free of Primers and Activators

Marangoni Force Assisted Spreading and Printing of Nanometer‐Thick Polymer Films for Ubiquitous Optoelectronic Devices

AbstractPrintable organic electronics are attractive owing to its high throughput and easy fabrication. Traditional coating methods (such as inkjet printing) are liquid‐solid contact‐based that deposit liquid solutions onto solid surfaces. Film quality is limited by surface energy of target surfaces and surface tension of the solvents. Furthermore, these printing methods are challenging to directly fabricate films on non‐flat or curved surfaces owing to the fluidity of liquid solution drops. In this work, a water transfer printing method that is solid‐solid contact‐based and assisted by Van der Waals force is reported. Nanometer‐thick films can be deposited on various surfaces: both high‐ and low‐surface energy, both flat and non‐flat surfaces. Water plays two roles: 1) as the transfer medium substrate and providing weak adhesion force between water and the transferred film; 2) high surface tension of water providing room to create surface tension gradient and producing Marangoni force to unfold the crumpled nanometer‐thick films. Electronic and optoelectronics on wrinkled skin and curved surfaces are demonstrated with this water transfer printing method.

An Ultrasensitive Contact Lens Sensor Based On Self‐Assembly Graphene For Continuous Intraocular Pressure Monitoring

AbstractElevated intraocular pressure (IOP) is the leading cause of glaucoma. As glaucoma is an irreversible neurological eye disease, it is urgent to realize timely and accurate IOP detection for diagnostic and therapeutic purposes. Here, a contact lens sensor for continuous IOP monitoring using self‐assembly graphene (SAG), is developed. The combination of face‐to‐face water transfer printing and micro‐electromechanical systems technology can realize the batch preparation of such a sensor. The sensor has good light transmittance and temperature stability. It exhibits an ultra‐high IOP sensitivity of 1.0164 mV mm Hg−1 on a silicone eye, and 3.166 mV mm Hg−1 in vitro on the porcine eye with remarkable linearity. The sensitivity of the proposed sensor is high enough to be read by a commercial radio frequency identification read–write system for continuous wireless monitoring of IOP. Furthermore, the as‐prepared sensor can work as normal for 24 h in phosphate buffer saline.

An experimental system to evaluate impact shear failure of rock discontinuities.

Conventionally, the evaluation of shear failure of discontinuities in rocks and other geomaterials has been conducted under static shear loading. In such methods, the shear failure behaviors of rock discontinuities are significantly influenced by loading velocities. To evaluate the shear failure process under dynamic loading, in this paper, we propose a new experimental methodology by taking advantages of recently available high-speed optical and mechanical measurement techniques. The methodology utilizes the Hopkinson bar to apply impact loading, and the diagnostics include a dynamic stress wave acquisition system, a digital image correlation (DIC) system, and an acoustic emission (AE) monitoring system. To improve the accuracy of the DIC analysis, an advanced digital speckle pattern and an updated water transfer printing are used to obtain the optimized and consistent speckle pattern. A flexible piezoelectric film sensor is first introduced to acquire AE signals in order to locate AE events accurately. A dynamic impact shear experiment indicates that the normal stress has a significant effect on the peak shear stress of rock discontinuities and the peak shear stress itself is rate dependent. The displacement field along shear directions is quantified using the DIC method, and the initial AE source locations during the impact shear process are determined using the AE monitoring system. We thus conclude that the dynamic impact shear system can systematically characterize the dynamic impact shear process with quantitative details and can further be implemented to study other dynamic impact failure behaviors of rock discontinuities under in situ stresses.

An Improved Fabrication Technique for the 3-D Frequency Selective Surface based on Water Transfer Printing Technology

Manufacturing an array of high-quality metallic pattern layers on a dielectric substrate remains a major challenge in the development of flexible and 3-D frequency selective surfaces (FSS). This paper proposes an improved fabrication solution for the 3-D FSS based on water transfer printing (WTP) technology. The main advantages of the proposed solution are its ability to transform complicated 2-D planar FSS patterns into 3-D structures while improving both manufacturing quality and production costs. WTP technology makes use of water surface tension to keep the thin metallic patterns of the proposed FSS floating flat with the absence of a solid planar substrate. This feature enables these metallic FSS patterns to be transferred onto 3-D structures through a dipping process. To test the effectiveness of the proposed technique, the FSS was designed using computer simulation software Microwave Studio to obtain the numerical performance of the FSS structure. The WTP technology was then used to fabricate the proposed FSS prototype before its performance was tested experimentally. The measurement results agreed well with the numerical results, indicating the proposed manufacturing solution would support the development of complicated 3-D electronics devices, such as conformal antenna arrays and metamaterials.

Water-Transferred, Inkjet-Printed Supercapacitors toward Conformal and Epidermal Energy Storage.

Rapid growth of the internet of things and health monitoring systems have stimulated the development of flexible, wearable, and conformal embedded electronics with the unprecedented need for energy storage systems fully adaptable to diverse form factors. Conventional fabrication methods, such as photolithography for electronics and electrode winding/stacking for energy storage systems, struggle as fabrication strategies to produce devices with three-dimensional, stretchable, and conformal form factors. In this study, we demonstrate the fabrication of supercapacitors on 3D objects through inkjet and water-transfer printing. The devices are initially printed on a water-soluble substrate, which is then placed on the surface of water. Once the substrate is dissolved, the level of water is lowered until the devices are transferred on to the submerged 3D object. As a proof of concept, planar supercapacitors constituted of a silver nanoparticle-based current collector, nickel(II) oxide (NiO) nanoparticle-based active electrodes, and ultraviolet-cured triacrylate polymer-based solid-state electrolyte were used as model materials. The conformal supercapacitors showed a maximum areal capacitance of 87.2 mF·cm-2 at a voltage window of 0-1.5 V. Moreover, the concept of water transfer was further explored with a particular focus on wearable applications by transferring the supercapacitors onto the skin of a human subject to realize epidermal energy storage. This new class of conformal electrochemical energy storage offers a new alternative approach toward monolithically integrated/object-tailored energy storage systems that are essential for complex-shaped devices for internet of things and flexible/on-skin electronic applications.

OPTIMALISASI PENGECATAN MENGGUNAKAN MODEL WATER TRANSFER PRINTING PADA LOGAM

Painting the water transfer printing model on metal is the job of covering the surface of a metal object using water as the medium. The problem that often occurs is that the film does not want to stick on the surface to be painted. This is mostly due to things like the slope of an object, the condition of the water, and even the time needed. To solve these problems it is necessary to use a structured and patterned painting method. The research that has been done produces the right work steps to maximize the painting results using a water transfer printing model. The important point to do in painting using this model is the room that is not windy, the need for primers before painting, the slope of the water condition must be clean and calm and the temperature is around 32̊, the condition of the film is clean, the activation time of the film is about 60 seconds and the angle of the object when dipped 40-50̊. This important point makes painting using the water transfer printing model more optimal. Keywords: Metal, Optimization, Water Transfer Printing

Efficient nonfullerene organic solar cells with active layers fabricated by water transfer printing

Abstract Preparation of high-quality films plays an important role to achieve high-performance nonfullerene (NF) organic solar cells. NF active layer films are typically fabricated by spin coating. Novel fabrication methods to process the NF active layer are desirable to be compatible with large-area production. Herein, we report on the fabrication of NF active layer films via a water transfer printing method. This method delivers a uniform film with controllable film thicknesses. NF active layers of PDBD-T:ITIC and PBDB-T-2F:IT-4F were fabricated via the method to validate its effectiveness. Solar cells with the water transfer-printed active layers show comparable performance (up to 11.7%) to the cells with spin-coated active layers. Furthermore, NF solar modules containing 4-sub cells with the active area of 3.2 cm2 are also fabricated via the method. The module shows VOC of up to 3.4 V and a power conversion efficiency of 8.1% with the PBDB-T-2F:IT-4F active layer.

Screen printed sensors fabricated on non-planar surfaces by water transfer print

Devising a cost effective way to fabricate sensors onto non-planar surfaces is of particular interest in many industrial applications such as condition monitoring or process controlling. This paper presents a low cost and low tech alternative approach for the fabrication of sensors on non-planar substrates in a two-step process. Screen printing is used to create a 2D pattern of the sensor on a water transfer foil which, in a second step, is transferred on a non-planar substrate using water transfer printing. We demonstrate the feasibility of this water transfer technique by fabricating a strain as well as a temperature sensor, which are both characterized and compared with state of the art screen printed sensors on planar substrates.