Printing Substrate Research Articles

High-current decoupled hydrogen and oxygen evolution via nickel–cobalt based redox mediators and bifunctional catalyst of 3D printing substrates

The conversion of renewable energy sources with relatively large energy fluctuations into hydrogen represents a crucial aspect of energy storage. Nevertheless, the direct water electrolysis process is known to require excessive instantaneous energy consumption and high cost. Two-step alkaline water electrolysis is regarded as a secure and effective method of generating hydrogen from renewable energy sources when compared to direct water electrolysis. Here we propose a two-step alkaline water electrolysis using nickel–cobalt based hydroxide (Ni0.9Co0.1(OH)2) as a redox mediator, and a high-performance bifunctional catalyst as gas evolution electrodes (GEE). The substrates for the GEE were prepared using 3D printing and then loaded with in-situ grown Ru-doped MoS2/NiFe-LDH hierarchical heterostructure catalysts (MS-NiFe-Ru-3D). The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) of the MS-NiFe-Ru-3D catalyst can reach up to 500 mA cm−2 at 300 and 250 mV overpotentials, respectively. It can meet the requirement of high catalyst performance for two-step alkaline water electrolysis. The direct water electrolysis using the bifunctional MS-NiFe-Ru-3D catalyst only requires a voltage of 1.85 V at 500 mA cm−2 with minimal attenuation over 300 h. For the two-step alkaline water electrolysis using MS-NiFe-Ru-3D as bifunctional catalysts and Ni0.9Co0.1(OH)2 as redox mediator, only 1.70 V and 0.27 V were required for HER and OER at 500 mA cm−2, respectively. This work offers a promising avenue for the efficient conversion of renewable secondary energy sources into hydrogen.

Inside out: Exploring edible biocatalytic biosensors for health monitoring

Edible biosensors can measure a wide range of physiological and biochemical parameters, including temperature, pH, gases, gastrointestinal biomarkers, enzymes, hormones, glucose, and drug levels, providing real-time data. Edible biocatalytic biosensors represent a new frontier within healthcare technology available for remote medical diagnosis. The main challenges to develop edible biosensors are: i) finding edible materials (i.e. redox mediators, conductive materials, binders and biorecognition elements such as enzymes) complying with Food and Drug Administration (FDA), European Food Safety Authority (EFSA) and European Medicines Agency (EMEA) regulations; ii) developing bioelectronics able to operate in extreme working conditions such as low pH (∼pH 1.5 gastric fluids etc.), body temperature (between 37 °C and 40 °C) and highly viscous bodily fluids that may cause surface biofouling issues. Nowadays, advanced printing techniques can revolutionize the design and manufacturing of edible biocatalytic biosensors.This review outlines recent research on biomaterials suitable for creating edible biocatalytic biosensors, focusing on their electrochemical properties such as electrical conductivity and redox potential. It also examines biomaterials as substrates for printing and discusses various printing methods, highlighting challenges and perspectives for edible biocatalytic biosensors.

Self-regulating pen-needle-based micronozzle for printing array of nanoliter droplets under fluorinated liquid

High-throughput evaluation of materials and cells is crucial for scientific progress. Creating arrays of nanoliter (nL) droplets via contact printing offers an effective method for such evaluations. However, precise calibration between the printing tip and substrate is typically required, which can be time-consuming and affect printing quality. To address this issue, we developed a self-regulating microneedle based on a spring and pen needle and created an automated droplet printer using a Cartesian robot. The self-regulation mechanism eliminated the need for precise tip-substrate calibration. Nanoliter droplets were printed onto a Petri dish beneath a layer of perfluorocarbon (PFC) to maintain shape and prevent evaporation. Droplet volume (V) increased linearly with flow rate (Q) as V = 8.8 Q − 5.4 (nL, µL/min). Droplet volume decreased hyperbolically with robot speed (w) as V = 1613 w −1 + 14.3 (nL, mm/s), while the number of droplets produced per minute (N) increased linearly with speed as N = 2.0 w + 28.5. The system achieved a production rate of 42 droplets/min at 10 mm/s, scaling up to 180 droplets/min at 80 mm/s. This versatile platform enables nL-scale assays for various applications.

Synthesis of a green functional carbon dioxide‐based polycarbonate using bio‐based monomers

AbstractA PPC‐dodecyl glucoside (PPC‐APG) polymer was synthesized by the terpolymerization of carbon dioxide (CO2), propylene oxide (PO), and the bio‐based monomer APG for the first time. The thermal stability and mechanical properties of PPC‐APG were significantly improved compared with those of conventional polypropylene carbonate (PPC), and its glass transition temperature (Tg) was increased by 14°C compared with that of PPC. The 5% heat loss temperature (Td,−5%) and total heat loss temperature (Td,max) of PPC‐APG were increased by 89.1 and 92.1°C, respectively, compared with those of PPC. The tensile strength of PPC‐APG was increased to 25.6 MPa, its elongation at break was decreased to 125.1%, and its thermal elongation and permanent deformation were reduced to 97.2% and 62.9%, respectively, which improved the processability of the material. In addition, the introduction of bio‐based monomers also rendered PPC‐APG functional, and its surface tension reached a maximum of 61.3 mN/m at a concentration of 0.05 g/mL, with a good degradability. The higher surface tension and enhanced degradability of PPC‐APG indicate its potential for application as a plastic printing substrate.

Comparison of Chromatic Assimilation Effects Depending on Printing Substrate in the Munker-White Model

Understanding the influence of paper surface structures on color perception is crucial for the printing industry. This research investigates the impact of horizontal and vertical parallel lines on chromatic assimilation using the Munker-White grid model. The study employs the perceived ∆E00 metric to quantify color differences and determine whether these textures affect perceived color accuracy and consistency differently. Results reveal variations in color perception due to surface textures. The biggest color difference (ΔE00) occurred at 60% RTV coverage for cyan, where the vertical structure showed a significantly lower value than the horizontal. For the yellow primary stimulus, the greatest difference was observed at 20% RTV coverage, with both structures showing high initial values that decrease with increased coverage. These findings provide valuable insights for improving color management practices and enhancing the quality and reliability of color reproduction on various substrates, contributing to advancements in printing technology and color science.

Printing Perovskite Solar Cells in Ambient Air: A Review

AbstractThe demand for cost‐effective and rapid processing of large‐area thin films in the photovoltaic industry has recently driven significant research interest. In this context, among the various approaches explored, printing devices, particularly perovskite solar cells (PSCs), have garnered considerable attention due to their potential for scalability and cost efficiency. Besides, solution printing is widely recognized as an appealing strategy for large‐area, cost‐effective, and high‐throughput production of PSCs. However, while substantial progress has been made in this process, challenges related to stability, uniformity, and scalability remain to be addressed. This review critically examines the key printing techniques and substrates employed in PSC fabrication. Then, given the significance of ambient air printing for industrial applications, fundamental challenges associated with achieving ambient air production of PSCs are discussed in detail. Moreover, the formulation strategies of perovskite ink in printing technologies are thoroughly explored, considering its crucial role in determining the performance and stability of printed PSCs. Finally, the printing process for various components of PSCs, including the perovskite absorber layer, charge transport layers (CTLs), and electrodes, is meticulously analyzed, highlighting current achievements and remaining hurdles.

One-step detection of pesticide residues in vegetables using an inkjet printing-based test card

The overuse of pesticides has seriously threatened human safety and health, while their detection is still limited by complex procedures. An inkjet printable test card was created in this study for the quick and broad screening of organophosphorus (OP) and carbamate (CM) pesticides in one step. To ensure sensitivity and accuracy, slow-release polyvinyl alcohol (PVA) films were used as the printing substrate to separate the reaction system from the acetylcholinesterase (AChE) film. When the pesticide-containing sample was introduced to the test card, the activity of AChE was initially inhibited by pesticide residues. Subsequently, the PVA membrane dissolved, and the remaining AChE reacted with the substrate and chromogenic agent, resulting in the production of yellow products. Therefore, the levels of pesticide residues in the sample can be determined by observing color changes. Experimental results demonstrated that this test card exhibited high sensitivity, stability, and reproducibility. Moreover, this method is quick and straightforward, showing great potential in both commercial and domestic applications.

Comparative study of color difference on coated and uncoated paper in digital printing

Digital printing is most prominent printing approach that facilitates numerous advantages. Coated and uncoated media are the most commonly used substrates for conventional and digital printing. The coated and uncoated paper media exhibit different surface characteristics and behave according to print quality. So, evaluating and comparing print quality attributes on these paper substrates is necessary. The color difference is the significant mismatch and evaluation of the accuracy of color while printing. Hence, understanding color differences on coated and uncoated media is crucial aspect. This present analysis is to carry out a comparative study of color differences in digital printing on coated and uncoated paper.

Comparative study of print quality attributes on bio-based biodegradable plastic using flexography and gravure printing process

Printing has revolutionized not only the religious and educational world by providing printing on paper but also the commercial world by providing end-to-end solutions for packaging by printing on materials like plastics. Print quality refers to level of details and sharpness of printed products for wider acceptability. Print quality has an important role in maintaining consistency during printing on selected surfaces to provide desired satisfaction. Printability and runnability of substrates, substrate surface characteristics, and printing ink properties are attributes of print quality and are considered important for determining good quality printing. Solid ink density (SID), Hue error, grayness and ink trapping are some of the important measurable printability factors that play an important role in determining the print quality irrespective of substrates. Gravure printing and flexography printing are high-speed printing suitable for printing on flexible substrates so, attempts were made for explore the mutual compatibilities of new-generation printing substrates with established printing processes, which will prove to be a boon in the future by replacing conventional plastics with bio-based biodegradable plastics in printing for packaging and its other applications. So, multi-color printing on selected bio-based biodegradable plastics were explored for determining printability by measuring and maintaining print quality attributes during print runs.

Properties and interaction of layers in board-biodegradable primer-printing ink screen-printed system

Surface interactions of the materials during and after the printing process are extremely important for understanding and optimizing the process of graphic reproduction. In screen printing on porous and absorbent substrates, mesh type and ink composition significantly influence the properties of the printed product. To protect the absorbent printing substrates such as board from moisture penetration and to ensure the optimal interaction of the printed ink layer and the substrate, board substrates can be coated with protective primers before printing. In this research, biodegradable primers made of poly(ɛ‐caprolactone) and poly(lactic acid) were applied on the board substrate which was then screen‐printed using two screen rulings of the mesh and two different types of water‐based printing inks on unprimed and primed board substrates. Printed ink layer thickness, surface roughness, water vapor transmission rate, surface free energy and adhesion parameters were measured/calculated on all produced samples. Microscopy of the printed elements was performed to visualize the influence of the primers on the printed line edge. Results of the research have shown that the primers influence the roughness reduction of the printed ink layer. Furthermore, thickness of the printed ink layers increased when the primers were applied on the substrate, pointing to the decreased permeability of the board, which was confirmed by the reduced water vapor transmission rate of the primed and printed substrates. The surface free energies of the tested surfaces and the adhesion parameters between biodegradable primers and prepared printing inks differed depending on the type of the ink and primer, pointing to the optimal combination of the primer and ink for the favorable acceptance of printing ink on the substrate. Results of this research have enabled the optimization of the quality of screen‐printed board product.

Effect of impinging behavior annular jet shielding gas and printing substrate on metal droplet stable ejection

Using coaxial shielding gas for low-oxygen protection in metal droplet-based 3D printing helps to promote flexible production and lightweight manufacturing. However, the presence of the printing substrate causes the shielding gas to exhibit complex annular impinging jet characteristics, making the stability of droplet ejection unpredictable. In the present work, the mechanisms of airflow pattern evolution on droplet formation and metal jet deflection were first revealed by incorporating shielding gas simulations, hydrodynamic modeling, and droplet ejection experiments. An innovative airflow disturbance suppression strategy for metal droplet ejection was proposed, which can remarkably reduce the shielding gas disturbance on droplet printing. Results show that the change in deposition distance leads to a transition between two typical airflow patterns, thus affecting the droplet ejection behavior. When the deposition distance exceeds 2.5 mm, metal jets would be stretched even to a secondary break under airflow pattern 1, accelerating droplets. For the deposition distance below 2.5 mm, metal jet shortening and droplet deceleration would occur under airflow pattern 2, deflecting jet trajectory. The negative airflow effect on droplet ejection could be avoided by controlling the deposition distance to the transition region of two airflow patterns. Furthermore, a ball grid array (BGA) chip ball-mounting and two thin-wall tube printing were realized based on metal droplet ejection in annular impinging jet shielding gas. This work provides theoretical and technical guidance for the stable ejection and accurate printing of metal droplets in an opening low-oxygen environment.

Overprinting of TPU onto PA6 Substrates: The Influences of the Interfacial Area, Surface Roughness and Processing Parameters on the Adhesion between Components.

The hybridisation of injection moulding (IM) and additive manufacturing (AM) offers the opportunity to combine the high productivity of IM and the high flexibility of AM into a single process. IM parts can be overprinted through fused filament fabrication (FFF) to allow for the customisation of parts or to add new functionalities. However, the right material pair must be chosen, and processing parameters must be optimised to achieve suitable adhesion between the components. The present study dealt with the investigation of the influence of the interfacial area, substrate surface roughness and overprinting processing parameters on the adhesion between the polyamide 6 (PA6) substrate and thermoplastic polyurethane (TPU) rib overprinted via FFF. PA6 substrates were produced through the IM of plates into a mould with different textures to obtain substrates with three different surface roughnesses. The ribs with varied interfacial areas were overprinted onto produced substrates using a desktop FFF 3D printer. To study the effect of overprinting processing parameters, the ribs were overprinted under varying printing and substrate temperatures and printing speeds according to the Box-Behnken design of experiments (DoE). The chemical composition and thermal properties of used materials were determined via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The surface properties of prepared substrates were studied via digital optical microscopy (OM), through surface roughness measurements using a confocal microscope, through contact angle (CA) measurements and through the determination of free surface energy (SFE). The adhesion between the components was determined by evaluating the tear-off strength using a universal testing machine (UTM). With an increasing interfacial area, the tear-off strength decreased, while substrate surface roughness had no statistically significant effect. Overprinting parameters influenced the tear-off strength in the order of printing speed > printing temperature > substrate temperature. High values of tear-off strength were found for the lowest printing speed, while there were no important differences found between the middle and upper values. With increasing printing and substrate temperatures, the tear-off strength increased linearly. The highest value of tear-off strength (0.84 MPa) was observed at a printing temperature, substrate temperature and printing speed of 250 °C, 80 °C and 2 mm/s, respectively.

Effect of polymethyl methacrylate on in situ patterning of perovskite quantum dots by inkjet printing.

The preparation of perovskite quantum dots (PQDs) using an in situ inkjet printing method is beneficial for improving the problems of aggregation and photoluminescence (PL) quenching during long-term storage. However, the stability of PQDs prepared using this method is still not ideal, and the morphology of in situ-printed patterns needs to be optimized. To address these problems, this study introduced polymethyl methacrylate (PMMA) into the process of in situ inkjet printing of PQDs and explored the effect of PMMA on the in situ patterning effect of PQDs. The results showed that using a mixed precursor solution containing a small amount of PMMA as the printing ink can slow down the shrinkage process of ink droplets and improve the uniformity of film formation. As the printing substrate, PMMA provided a suitable high-viscosity environment for the in situ growth of PQDs. This could effectively suppress the coffee ring effect. In addition, the interaction between the C=O=C group in PMMA and metal ion Pb2+ in the CsPbBr3 precursor molecules was favourable to enhancing the density of PQDs. The prepared PMMA-coated CsPbBr3 quantum dots (QDs) pattern had high stability and could maintain at 90.08% PL intensity after 1 week of exposure to air.

Study on the Printability of Starch-Based Films Using Ink-Jet Printing.

Starch-based films are a valuable alternative to plastic materials that are based on fossil and petrochemical raw resources. In this study, corn and potato starch films with 50% glycerol as a plasticizer were developed, and the properties of films were confirmed by mechanical properties, surface free energy, surface roughness, and, finally, color and gloss analyses. Next, the films were overprinted using ink-jet printing with quick response (QR) codes, text, and pictograms. Finally, the print quality of the obtained prints was determined by optical density, color parameters, and the visual evaluation of prints. In general, corn films exhibit lower values of mechanical parameters (tensile strength, elongation at break, and Young Modulus) and water transition rate (11.1 mg·cm-2·h-1) than potato starch film (12.2 mg·cm-2·h-1), and water solubility is 18.7 ± 1.4 and 20.3 ± 1.2% for corn and potato film, respectively. The results obtained for print quality on starch-based films were very promising. The overprinted QR codes were quickly readable by a smartphone. The sharpness and the quality of the lettering are worse on potato film. At the same time, higher optical densities were measured on potato starch films. The results of this study show the strong potential of using starch films as a modern printing substrate.

3-oxetanylmethanol as additive to PEDOT:PSS for improved conductivity and water-resistance and applications in ink-jet printed electrochemical transistors

3-oxetanylmethanol is used as additive to poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) water dispersions and the properties of thin films, prepared by spin-coating and ink-jet printing, either on glass or flexible polyethylene terephthalate (PET) substrates, are investigated. 1H NMR studies revealed that 3-oxetanylmethanol is reactive within the PEDOT:PSS medium during the film drying step at 120 °C, to form polyether compounds. Chemical cross-linking established through the esterification reaction of pendant hydroxyl groups in polyether chains, resulting from the 3-oxetanylmethanol in situ polymerization, and sulfonate groups from PSS, is also identified by the 1H NMR studies. Spin-cast films prepared from this formulation on either glass or PET exhibited electrical conductivity enhanced by more than two orders of magnitude, when compared to films obtained with the pristine PEDOT:PSS dispersion, reaching maximum values of around 596 and 682 Scm−1 for films on glass and PET, respectively, together with improved water-resistance. Atomic force microscopy and Raman spectroscopic studies, indicating that PEDOT chains are organized in more ordered domains in the films of the oxetane-based formulations, suggest that the polyether compounds modify the PEDOT:PSS phase segregation and promote charge transport across conducting PEDOT segments. Subsequently, improved conductivities and stability were also found for films prepared by high-resolution ink-jet printing of the formulations that led to the most conductive spin coated films. The potential application of the new ink formulations in printed electrodes interfacing aqueous media was assessed by ink-jet printing PEDOT-based electrochemical transistors operating with aqueous KCl electrolyte.

Laser-Based Additive Nanomanufacturing: Rigid to Flexible Substrates

Current printed electronics manufacturing techniques, including inkjet and aerosol jet printing, use ink to produce electronics devices. The inks are formulated with pigments, additives, and solvents, which make the inks impure. Also, small changes in the composition of the inks will result in different chemical and physical properties, which might affect the printing process as well as the final performance of the device. In addition, the ink formulations are rather complex, with a limited source of functional materials for printing functional devices. Annealing during printing or post-processing for solvent removal is another challenge of these techniques, which limit printing on low temperature and biodegradable substrates. Herein, we present a novel additive nanomanufacturing (ANM) technique compatible with a wide range of substrates for dry printing and patterning of a variety of materials, including on different rigid and flexible substrates. Bending tests show good mechanical stability and electrical conductivity, confirming the potential of ANM technique for printing different materials for flexible hybrid electronics and sensors.

Effect of TiO2@CaCO3 Waterborne Primer on the Coloring Performance of Inkjet-Printed Wood Product Coatings

Calcium carbonate (CaCO3) is a widely used inorganic filling pigment used in coatings, and it is known for its nontoxicity, odorlessness, and environmental friendliness. The application of CaCO3 as a filler can effectively reduce raw material costs, and optimization of the filler formula enhances the coating film performance. In this study, oak planks were prepared as substrates for water-based inkjet printing. Three composite water-based primers with different TiO2-to-CaCO3 ratios and a polyurethane resin primer were used to prepare the substrate for the printing surface. The properties of the water-based primer coating and the water-based inkjet printing coating were characterized and analyzed via Fourier-transform infrared spectroscopy, video-based contact angle analysis, and environmental scanning electron microscopy. The aim was to investigate the effects of the composite waterborne primer coatings on the ink absorption and coloring properties of the interface between wood substrates and waterborne inkjet coatings. Sample WDCC-3#, with a TiO2-to-CaCO3 ratio of 15:35, exhibited the most comprehensive characteristics. The wood surface coated with 15 g/m2 of the polyurethane resin primer and 15 g/m2 of WDCC-3# exhibited a 5.8° contact angle of the water-based ink, first-grade adhesion, 4 H hardness, 70.52 whiteness value, and a roughness of ~2.33. The surface of the printed water-based inkjet-coated substrate was uniform and smooth, featuring rounded and transparent edges of the water-based ink droplets and a small CMYK color difference value. Therefore, the composite waterborne primer, incorporating TiO2 and CaCO3 in specific ratios, can be effectively combined with waterborne polyurethane primer coatings. This combination significantly improves the interfacial compatibility between the oak surface and waterborne inkjet coatings, leading to enhanced ink absorption on the oak plank surface during printing. This results in a high degree of color reproduction and clearer printed images. Overall, this study provides valuable insights for the development of primer programs for the industrial application of waterborne digital inkjet technology on wood products.

The effect of carbonyl components of printing substrates on the durability of UV thermochromic prints

Special effects on a printed product can increase consumer’s interest in a product and therefore lead to higher revenues in consumer industries. For that purpose, graphic industry introduced various technologies and materials that would have such an effect and enhance consumer-goods interaction. One of those solutions is thermochromic printing. Although bringing added value, thermochromic inks have some challenges in application due to their higher sensitivity, especially when exposed to UV light. Therefore, the goal of this work is to determine whether amount of the UV radiation during curing of UV thermochromic prints, as well as exposure after printing would degrade the thermochromic print on various substrates. UV thermochromic prints were made on three different paper printing substrates using the screen printing method and dried in a laboratory controlled unit. Synthetic paper, recycled paper containing 100 % recycled cellulose fibers and bulky voluminous paper were used as printing substrates. During the UV curing of the ink, no photooxidation of the prints occurred. Additional exposure of the prints to UV radiation (after the ink has hardened) leads to their photooxidative degradation, i.e., a change in the initial color. The obtained colour difference (ΔE) is increasing with the increase of the irradiation amount. The highest colour difference is on the synthetic paper while prints on two other substrates are more resistant to UV light. A print on synthetic paper photooxidizes the fastest due to the presence of most carbonyl groups in it. Generated free radicals promote the instability of prints on synthetic paper. Research has proven that when using synthetic paper or substrates with similar characteristics, care should be taken to accurately determine the amount of UV energy required for curing in order to prevent photodegradation of the ink. The results also show that to explain any degradation of prints, the chemical components of the paper needs to be taken into account, which is rarely done.

A seed and bridge layer method for inkjet printing of narrow traces on receding ink-substrate combinations

Inkjet printing of electronic materials is of interest for digital printing of flexible electronics and sensors, but the width of the inkjet-printed lines is still large, limiting device size and performance. Decreasing the drop volume, increasing the drop spacing, and increasing the ink-substrate contact angle are all approaches by which the line width can be lowered, however these approaches are limited by the nozzle geometry, ink coalescence and bead instabilities, and contact angle hysteresis, respectively. Here we demonstrate a novel approach for stable inkjet printing of very narrow lines on ink-substrate combinations with a high contact angle, utilizing the de-wetting of the ink due to the decreased contact angle hysteresis. After printing and drying an initial layer of disconnected seed drops of silver nanoparticle ink, we print an additional layer of bridging drops of the same ink in between the dried seed drops. The bridging drops expand to touch the dried seed drops and then retract into a line, due to the pinning of the wet ink on the dried seed ink but not on the substrate, forming a continuous silver trace. The trace width is decreased from 60 μm with a traditional printing approach down to 12.6 μm with this seed-bridge approach. The electrical conductivity of the silver trace is similar to that of a conventionally printed trace. Due to poor adhesion on the print substrate, the trace was transferred to a separate polymer substrate with a simple hot-pressing procedure, which preserves the electrical conductivity of the trace.

Lignin‐Based Encapsulation of Liquid Metal Particles for Flexible and High‐Efficiently Recyclable Electronics

AbstractRoom‐temperature liquid metals (RTLMs) have excellent shape reconfiguration capabilities, which make them ideal for flexible electrodes, sensors, and energy devices. However, due to the high surface tension and weak adhesion of RTLM, the types of printing substrates, patterning, and recovery processes are limited. It is essential to develop advanced encapsulation techniques for the patterning of RTLMs. Lignin has great potential for promotion as nanodispersants and nanocarriers because of its abundant hydroxyl groups and good self‐assembly properties. In this work, a green and facile encapsulation method using industrial lignin is reported for stable, uniform, and reproducible patterning of eutectic gallium–indium (EGaIn). Lignin‐encapsulated EGaIn particles exhibit good stability and can be patterned on the surface of various substrates with a simple ballpoint pen. The electrical resistance of the conductive tracks shows little change under bending and twisting (720°) conditions. More importantly, the lignin‐encapsulated system can be easily dissolved and regenerated, which is also supported by molecular dynamics simulations and density functional theory calculations. 96.9% of the EGaIn can be recovered from the system. These characteristics make it very environmentally friendly throughout the preparation process and find applications in flexible sensors, transient circuits, and many other areas.