Heterogeneous Surface Properties Research Articles

Enhancement of flow boiling heat transfer characteristics on diamond/Cu heterogeneous surface

Surface treatment is an effective method of enhancing the heat transfer performance of flow boiling. Nonetheless, the majority of existing studies on surface treatment primarily concentrated on homogeneous materials and their associated zone design. Diamond/Cu, as a particle‐reinforced composite, exhibits heterogeneous surface properties and surface microstructures that play distinct roles in the heat transfer. To elucidate the synergistic effect of heterogeneous material surfaces and microstructures, pure copper surface (PC), untreated diamond/Cu surface (DC), and surface‐treated diamond/Cu surface (SDC) were prepared for this experiment. These surfaces demonstrate various combinations of diamond, copper, and their corresponding surface microstructures. DC, characterized by heterogeneous wetting properties, demonstrates a heat transfer coefficient that is 9%–24% higher than that of PC. No trend of decreased heat transfer capacity is observed in DC. The surface treatment of SDC results in the formation of a superhydrophilic CuO nanosheet structure, significantly enhancing both surface roughness and energy. SDC develops microcracks on the surface of diamond. The increased roughness provides numerous nucleation area for the hydrophobic diamond, enhancing the overall wettability of the surface when combined with the superhydrophilic CuO region. SDC demonstrates the advantage of enhanced flow boiling on the surface of heterogeneous materials. At the identical heat flux, SDC exhibits a reduction of 5 °C–10 °C in wall superheat and an increase of 38%–47% in heat transfer coefficient.This article is protected by copyright. All rights reserved.

Modeling flow through tubes and annuli with liquid‐infused surfaces for enhanced stability of the fluid‐fluid interface

AbstractSuperhydrophobic (SHS) and liquid‐infused surfaces (LIS) have shown great potential in various engineering applications. Due to their heterogeneous surface properties, a mathematical description of the flow behavior along such surfaces is challenging. Circular textured surfaces are of particular importance. They are modeled as either axially traversed tubes or annuli consisting of no‐slip walls that are padded with rotationally symmetric finite‐shear regions. The latter represents a viscous interaction zone with a second fluid, assumed with layer thickness zero. Zimmermann and Schönecker provide analytical equations that describe the flow field and effective slip length for such geometries. They are applicable to Newtonian fluids of arbitrary viscosity ratio. This article emphasizes the development of principles and guidelines for the design of SHS and LIS to enhance sliding effects, based on these analytical models. The approach presented here facilitates an geometric evaluation of slippery circular surfaces, aiming to offer insights for the design. Through this research, the potential for significant energy savings and enhanced fluid transport performance can be realized, contributing to the development of more efficient fluid engineering systems.

Hybrid modeling of hetero-agglomeration processes: a framework for model selection and arrangement

Modeling of hetero-agglomeration processes is invaluable for a variety of applications in particle technology. Traditionally, population balance equations (PBE) are employed; however, calculation of kinetic rates is challenging due to heterogeneous surface properties and insufficient material data. This study investigates how the integration of machine learning (ML) techniques—resulting in so-called hybrid models (HM)—can help to integrate experimental data and close this gap. A variety of ML algorithms can either be used to estimate kinetic rates for the PBE (serial HM) or to correct the PBE’s output (parallel HM). As the optimal choice of the HM architecture is highly problem-dependent, we propose a general and objective framework for model selection and arrangement. A repeated nested cross-validation with integrated hyper-parameter optimization ensures a fair and meaningful comparison between different HMs. This framework was subsequently applied to experimental data of magnetic seeded filtration, where prediction errors of the pure PBE were reduced by applying the hybrid modeling approach. The framework helped to identify that for the given data set, serial outperforms parallel arrangement and that more advanced ML algorithms provide better interpolation ability. Additionally, it enables to draw inferences to general properties of the underlying PBE model and a statistical investigation of hyper-parameter optimization that paves the way for further improvements.

Surface Engineering of Protein Nanoparticles Modulates Transport, Adsorption, and Uptake in Mucus.

Protein nanoparticles have been demonstrated as effective carriers for protein antigens and therapeutics due to properties endowed by their protein composition. They exhibit high protein to carrier yields, biocompatibility, and heterogeneous surface properties. While protein nanoparticles have been delivered via multiple routes, including intranasal, their interactions with mucosal barriers have not been well studied or modified. Biological barriers associated with intranasal delivery consist of viscoelastic mucus that hinders material transport through surface interactions and the underlying epithelium. Herein, we altered protein nanoparticle surface properties and characterized interactions with nasal mucus and the subsequent effects on diffusion, cellular uptake, and immune cell maturation. Ovalbumin protein nanoparticles were used, serving as a model vaccine nanoparticle. Unmodified ovalbumin protein nanoparticles were compared to cationic ovalbumin particles functionalized with amine groups, neutral particles functionalized with polyethylene glycol, and zwitterionic particles coated layer-by-layer (LBL) with chitosan and oligonucleotides. Transport analysis indicated rapid diffusion of polyethylene glycol and LBL-modified ovalbumin nanoparticles in porcine nasal mucus, while cationic particles were mucoadhesive. Cellular uptake in the presence of mucus by epithelial and dendritic cells was highest for particles containing positive charges, both LBL and amine-functionalized. These particles also exhibited the most diverse adsorbed protein corona from nasal fluids. The corona impacted both dendritic cell uptake and maturation, with polyethylene glycol and LBL modifications improving CD86 expression. Altogether, surface modifications on protein-based nanocarriers are shown to facilitate distinctive physical and cellular behavior associated with mucosal delivery.

Remote Sensing-Based Estimation on Hydrological Response to Land Use and Cover Change

Hydrological processes are an important driving force of environmental pollutant variation that has aroused global concern. Land use and cover change (LUCC) strongly affects hydrological processes. Remote sensing technology has played an increasingly important role in studying the relationship between LUCC and hydrological processes. This study summarizes the progress of hydrological responses to LUCC. Overall, remote sensing can provide spatially continuous data of land cover and hydrological variables. With the aid of the retrieved data sets, the effects of LUCC on hydrological processes can be evaluated via correlation analysis, multiple regression method, experimental watershed approach and trajectory-based approaches. However, due to the high complexity of geographical systems, it is difficult to quantitatively separate the actual components of the influence of LUCC. The heterogeneous surface properties also lead to various results at different spatial and temporal scales. Future research should meet the challenges in data estimation, research methodology and analysis process.

Effects of Horizontal Resolution, Domain Size, Boundary Conditions, and Surface Heterogeneity on Coarse LES of a Convective Boundary Layer

Abstract Atmospheric properties in a convective boundary layer vary over a wide range of spatial scales and are commonly studied using large-eddy simulations (LES) in various configurations. We examine how the boundary layer depth and distribution of variability across scales are affected by LES grid spacing, domain size, inhomogeneity of surface properties, and external forcing. Two different setups of the Weather Research and Forecasting (WRF) model are analyzed. A semi-idealized configuration uses a periodic domain, flat surface, prescribed homogeneous surface heat fluxes, and horizontally uniform profiles of large-scale advective tendencies. A nested LES setup employs a larger domain and realistic initial and boundary conditions, including an interactive land surface model with representative topography and vegetation and soil types. Subdomains of identical size are analyzed for all simulations. Characteristic structure sizes are quantified using the variability scales L50 and L95, defined such that features smaller than that contain 50% and 95% of the total variance, respectively. Progressive increase in L50 from vertical velocity to temperature and moisture structures is systematically reproduced in all simulation configurations. This dependence of L50 on the considered variable complicates the development of scale-aware parameterizations for models with grid spacing in the “terra incognita”. In simulations using a larger domain with heterogeneous surface properties, the development of internal mesoscale patterns significantly affects variance distributions inside analyzed subdomains. Sizes of boundary layer structures also strongly depend on the LES grid spacing and, in case of heterogeneous surface and topography, on location of the subdomain inside a larger computational domain.

Introduction of active thermography and automatic defect segmentation in the thermographic inspection of specimens of ceramic tiling for building façades

InfraRed Thermography (IRT) has proven to be a valuable diagnostic tool due to its real-time, remote, and non-destructive operation yielding accurate detection of the position of defect areas in building façade ceramic tiling. Ceramic tiles coating building façades are widely used throughout the world because of their technical and aesthetic characteristics. However, the detachment of ceramic tiles and the water infiltration in deep layers are still common problems. So, this paper proposes active infrared thermography as a thermographic acquisition mode, in contrast to the common use of passive thermography, and segmentation of defect areas and automation in the thermal image processing as added values never before proposed in the ceramic tiling thermographic inspection. For that, specimens of ceramic tiling for building façades were tested under different laboratory conditions, with inserted corks (simulating detachments), and by injecting water into holes drilled in the back surfaces (simulating water infiltration), as defects. Good results have been obtained in all the tests, both in dry and wet conditions in the specimens and for surfaces with homogeneous and heterogeneous surface properties, serving the introduction of this workflow for a first and fast inspection in ceramic tiling building façades. Future research will work with the fine-tuning phase of the methodology by applying it to real case studies.

Numerical Analysis of the Heterogeneity Effect on Electroosmotic Micromixers Based on the Standard Deviation of Concentration and Mixing Entropy Index

One approach to achieve a homogeneous mixture in microfluidic systems in the quickest time and shortest possible length is to employ electroosmotic flow characteristics with heterogeneous surface properties. Mixing using electroosmotic flow inside microchannels with homogeneous walls is done primarily under the influence of molecular diffusion, which is not strong enough to mix the fluids thoroughly. However, surface chemistry technology can help create desired patterns on microchannel walls to generate significant rotational currents and improve mixing efficiency remarkably. This study analyzes the function of a heterogeneous zeta-potential patch located on a microchannel wall in creating mixing inside a microchannel affected by electroosmotic flow and determines the optimal length to achieve the desired mixing rate. The approximate Helmholtz–Smoluchowski model is suggested to reduce computational costs and simplify the solving process. The results show that the heterogeneity length and location of the zeta-potential patch affect the final mixing proficiency. It was also observed that the slip coefficient on the wall has a more significant effect than the Reynolds number change on improving the mixing efficiency of electroosmotic micromixers, benefiting the heterogeneous distribution of zeta-potential. In addition, using a channel with a heterogeneous zeta-potential patch covered by a slip surface did not lead to an adequate mixing in low Reynolds numbers. Therefore, a homogeneous channel without any heterogeneity would be a priority in such a range of Reynolds numbers. However, increasing the Reynolds number and the presence of a slip coefficient on the heterogeneous channel wall enhances the mixing efficiency relative to the homogeneous one. It should be noted, though, that increasing the slip coefficient will make the mixing efficiency decrease sharply in any situation, especially in high Reynolds numbers.

Toward controlled geometric structure and surface property heterogeneities of TiO2 for lipase immobilization

To effectively immobilize an enzyme while maintaining its high activity and stability, the design of supports with controlled geometric structures and heterogeneous surface properties is desirable. Towards this goal, heterogeneous titanium dioxide (TiO2) surfaces with controlled pore sizes were synthesized in this study and used to efficiently immobilize lipase. The immobilized lipase activity increased by a factor of 1.31 with an increase in the TiO2 pore size from 11.46 to 21.14 nm. The highest protein loading of 15.52 mg/g was achieved in ethenyl triethoxy silane (ETS)-modified TiO2 (E-P25) after immobilizing the enzymes at 30 ℃, pH 7.33 for 3 h and using a protein concentration in solution of 0.176 mg/mL. Among the different surface functionalities, the highest activity yield of 428.04 % was accomplished by using TiO2 calcinated at 650 ℃ and modified by ETS as immobilization support. The immobilized enzymes showed excellent storage stability and retained almost 95 % of their activity after being stored at 4 ℃ for 8 weeks. This research provides experimental evidence that highlights the importance of studying of enzyme immobilization on the supports with synergistically designed geometric structures and surface chemical properties.

Description, Kinetic and Equilibrium Studies of the Adsorption of Carbon Dioxide in Mesoporous Iron Oxide Nanospheres

Mesoporous iron oxide nanospheres (MINs) have been successfully synthesized and have proven to be high-efficiency adsorbents. The morphology of the MINs is very uniform in spherical form, with an average particle size of 23-27 nm in the diameter range. MINs content has a fairly high BET surface area of 188.25 m2g−1 and a total volume of 0.14 cm3g−1 pores. Thus, seams were seen as potential CO2 sequestration reservoirs to reduce greenhouse gas emissions. The CO2 adsorption was favorable at low temperature and dry MINs conditions. However, MINs have a high adsorption capacity of 0.15 mmol/g. The CO2 adsorption isotherm of all coal samples according to the IUPAC classification of adsorption isotherms fits category I, which most likely explains adsorption confined to a few layers of molecules (micropores and mesopores). The balancing assessment using Langmuir, Henry, Dubbin, Temkin, Toth, Harkins-Jura, Elovich, Redlich-Peterson, and Josene model provided the best fit for any experimental adsorption data that predict heterogeneous surface properties of MINs.

Heterogeneous Fenton-like surface properties of oxygenated graphitic carbon nitride

The photo-Fenton activity of graphitic carbon nitride (g-C3N4) has been widely studied, nevertheless, its Fenton-like catalytic behavior in the dark has not yet been demonstrated. In the present work, it is shown that oxygenated g-C3N4 obtained at different temperatures (500–600 °C) can degrade indigo carmine with hydrogen peroxide in the dark by a reaction similar to a conventional Fenton’s reaction. Based on an extensive characterization of g-C3N4, we conclude that Fenton-like activity is directly related to the oxygenated functional groups on g-C3N4 structure, mainly by –OH functional groups. Oxygenated functional groups (e.g., hydroquinone-like groups) can reduce the H2O2 and generate oxidizing hydroxyl radicals, just like in the Fenton reaction performed by metals. In addition to new information on g-C3N4 surface reactivity revealed by this study, the metal-free oxygenated g-C3N4 catalyst may be an alternative to traditional metal catalysts used in Fenton-like reactions for advanced oxidation.

Current understanding and emerging applications of 3D crumpling mediated 2D material-liquid interactions

Three dimensional (3D) crumpling of two dimensional (2D) materials provides new opportunities to modulate mechanical, optical, surface, and chemical properties. However, investigation of the effect of 3D crumpling on 2D material liquid interaction has been limited. In this perspective, we will review crumple/texture induced heterogeneous surface properties including chemical modification, energy corrugation, and electronic structure perturbation which may modulate fluid interaction. We will then describe simulations of fluid interaction in systems resembling 3D textured 2D materials, principally nanotubes, which have begun to substantiate perturbations to fluid structure driven by texture induced modification of the 2D material surface. Furthermore, we will detail current experimental understanding of how texture induced modulation of interactions with pure solvent affect macroscale wetting characteristics including textured driven transitions in water contact from Wentzel to Cassie Baxter states. Following this discussion of how texturing affects the interaction of 2D materials with pure solvent, we will detail cutting edge explorations of how texturing modifies interaction with ions and other chemical species dispersed in solvent phases. Particular focus will be placed on recent simulations of aqueous phase molecular interaction with crumpled 2D materials which show that crumpling increases the thickness of the electrical double layer (EDL) formed near a 2D material surface. This increased EDL thickness has allowed for the development of biomolecule sensors with gigantic sensitivity and the monitoring and templating of cells including neurons and myotubes. Sill, considerable work is needed to elucidate the effect of different crumpling geometries on the local properties of the full range of 2D materials, how these variation in local properties perturb fluid structure and molecular interaction, and how these tuned interactions enable diverse opportunities such as sensing, energy storage, and control of biological interaction.

Spatially Heterogeneous Water Properties at Disordered Surfaces Decrease the Hydrophobicity of Nonpolar Self-Assembled Monolayers.

Understanding the relationship between hydrophobicity and the properties of functionalized surfaces is vital to the design of materials that interact in aqueous environments. In this Letter, we use atomistic molecular dynamics simulations to investigate the effects of surface order on the hydrophobicity of self-assembled monolayers (SAMs) containing nonpolar ligands. We find that the interfacial hydrophobicity is highly correlated with SAM order and, strikingly, poorly correlated with the solvent-accessible surface area, which typically has been related to interfacial hydrophobicity. Analysis of spatial variations in both SAM and water properties reveals that the SAM-water interface is pinned near regions of disordered SAM surfaces with increased free volume, decreasing the overall interfacial hydrophobicity. Spatial variations in ligand end group positions at disordered SAM surfaces thus translate to spatial variations in hydrophobicity, yielding heterogeneous surface properties. These findings provide new insights into how surface order can alter the hydrophobicity of chemically uniform surfaces.

Surface functionalization of graphene oxide by amino acids for Thermomyces lanuginosus lipase adsorption

Graphene oxide (GO) with oxygen containing functional groups can be selectively modified by small biomolecules to achieve heterogeneous surface properties. To achieve a hyper-enzymatic activity, the surface functionality of GO should be tailored to the orientation adsorption of the Thermomyces lanuginosus (TL) lipase, and the active center can be covered by a relatively hydrophobic helical lid for protection. In this work, amino acids were used to interact with GO through reduction reaction, hydrophobic forces, electrostatic forces, or hydrogen bonding to alter the surface hydrophobicity and charge density. Characterization of the structure and surface properties confirmed that the GO samples decorated with phenylalanine (Phe) and glutamic acid (Glu) exhibited superior hydrophobicity than other modifications, whereas tryptophan (Trp) and cysteine (Cys) provided weaker reduction effects on GO. Moreover, the zeta potential of the samples modified by amino acids of lysine (Lys) and arginine (Arg) is higher than other modified samples. The adsorption amount of lipase on Glu-GO reached 172 mg/g and the relative enzymatic activity reached up to 200%. The thermodynamic data and the Freundlich isotherm model fitting showed that the lipase adsorption process on modified samples was spontaneous, endothermic and entropy increase.

Phosphorus retention and availability in three contrasting soils amended with rice husk and corn cob biochar at varying pyrolysis temperatures

The reactive nature of phosphorus (P) leads to the formation of insoluble Fe, Al and Ca phosphates in highly weathered tropical soils, thus reducing P availability for plant uptake. Biochar with its heterogeneous surface properties as influenced by feedstock and pyrolysis temperature can affect P retention and availability in tropical soils. In the present study, incubation studies were conducted for 90 days to investigate the effect of corn cob and rice husk biochar on P sorption and desorption in two acid (Typic Plinthustult-A & Plinthic Acrudox-B) and one neutral soil (Quartzipsamment-C). The biochars were pyrolyzed at varying temperatures (300 °C, 450 °C and 650 °C) and applied at a rate of 1% (w/w) to the soils. Phosphorus sorption data were fitted to Langmuir and Freundlich models. Phosphorus desorption was done on the residual samples that received initial P concentrations of 21.5 mg L−1, 43.0 mg L−1 and 86.0 mg L−1 solution using 10 mM KCl. The P sorption capacity of the two acid soils i.e. A (395 mg kg−1) and B (296 mg kg−1) were more than two fold that of the neutral soil (C) (105 mg kg−1). Addition of the biochar types to soil A raised the equilibrium P concentration in solution at decreasing pyrolysis temperature. Similar trend was observed in soil B with the exception of corn cob and rice husk biochar at 650 °C which increased the soil's (B) P sorption capacity. In soil C, both biochar types increased P sorption capacity with increasing pyrolysis temperatures. Phosphorus desorbability increased with increasing initial P concentrations in the three soils. Generally, P desorbability increased in the acid soils but decreased in the neutral soil upon biochar amendment. Decreases in P adsorption and consequently increases in P desorption were more pronounced when the 300 °C biochar types were amended with the soils. The study thus showed that biochar pyrolyzed at 300–450 °C could be used to reduce P sorption and increase P bioavailability especially in acid soils. The addition of biochar to neutral or alkaline soils might increase P retention possibly in the short-term, reducing P bioavailability.

Hyperspectral Imaging Microscopy of Acetaminophen Adsorbed on Multiwalled Carbon Nanotubes.

In this study, enhanced dark-field hyperspectral imaging (ED-HSI) was employed to directly observe acetaminophen (AAP), a model pharmaceutical and personal care product (PPCP), adsorbed on multiwalled carbon nanotubes with large diameters (L-MWCNT) and small diameters (S-MWCNT) under equilibrium conditions. The ED-HSI results revealed that (1) AAP molecules primarily adsorbed onto the external surfaces, rather than the internal surfaces of L- and S-MWCNT aggregates, (2) or on sidewall of the dispersed tubes, but not at their end caps. Besides, ED-HSI images showed that the surface coverage ratio of AAP/S-MWCNT is smaller than that of AAP/L-MWCNT (1.1 vs 3.4), indicating that there are more available adsorption sites on S-MWCNT than L-MWCNT when the adsorption reached equilibrium. This finding was consistent with the adsorption capacities of S-MWCNT and L-MWCNT (252.7 vs 54.6 mg g-1). Direct visualization of sorption sites for PPCP molecules provides new insights into the heterogeneous structures and surface properties of MWCNT and helps elucidate the adsorption mechanisms that are fundamental to the design of functional adsorbents for PPCP contaminants.

Thermoelectricity in Heterogeneous Nanofluidic Channels.

Ionic fluids are essential to energy conversion, water desalination, drug delivery, and lab-on-a-chip devices. Ionic transport in nanoscale confinements and complex physical fields still remain elusive. Here, a nanofluidic system is developed using nanochannels of heterogeneous surface properties to investigate transport properties of ions under different temperatures. Steady ionic currents are observed under symmetric temperature gradients, which is equivalent to generating electricity using waste heat (e.g., electronic chips and solar panels). The currents increase linearly with temperature gradient and nonlinearly with channel size. Contributions to ion motion from temperatures and channel properties are evaluated for this phenomenon. The findings provide insights into the study of confined ionic fluids in multiphysical fields, and suggest applications in thermal energy conversion, temperature sensors, and chip-level thermal management.

Mutually facilitated co-transport of two different viruses through reactive porous media

In this study, we quantified transport and retention behaviors of a human pathogenic virus (Adenovirus 41, abbreviated as Ad-41) and a model bacteriophage (ϕX174) through metal oxide-removed and goethite-coated sand under saturated flow conditions. Two sets of bench scale column experiments were conducted: transport of each type of viruses alone and co-transport of both viruses. All experiments were conducted at pH 7.5 using 2 mM artificial ground water (AGW) buffer as background solution. Experimental results revealed that goethite-coated sand (i.e., reactive sand) retained much more viruses relative to metal oxide-removed sand (i.e., non-reactive sand), with the difference more pronounced for ϕX174 (effluent concentration decreased by 92.1%) than for Ad-41 (effluent concentration decreased by 59.7%). Interestingly, lower retention of both viruses on goethite-coated sand was observed when they co-existed in the influent. The mutual promotion to the transport of the two viruses may be attributed to attachment site competition and steric hindrance effect (illustrated in the graphical abstract). Mass recovery results revealed that ϕX174 was largely reversibly attached, whereas Ad-41 was mostly irreversibly bound or inactivated. Force measurements using atomic force microscopy (AFM) demonstrated that ϕX174 had doubled affinity to goethite-coated sand compared with Ad-41, consistent with the transport behavior of each type of viruses when they existed alone. As expected, the extended DLVO theory cannot accurately estimate interfacial energy profiles for viruses and reactive sand that have heterogeneous surface properties (i.e., roughness and charge heterogeneity). The results of this study clearly demonstrate that caution must be taken when applying laboratory results, which are generally obtained from experiments employing a single virus species, to predict the mobility and environmental risks in natural systems where multiple agents are present.

Description of Carbon Dioxide Adsorption and Desorption onto Malaysian Coals under Subcritical Condition

Coal bed seams have been considered as promising sequestration reservoirs for CO2 disposal to mitigate the green house gas emissions. The CO2 adsorption and desorption attributes of CO2 on dry Malaysian coals (Sarawak, volatile bituminous) were performed using a sorptomat apparatus (ASAP 2010, Micromeritics, USA) and BELSORP-mini II machine (BEL Japan, Inc.) at 273K, 298K and pressure up to 1bar. The CO2 adsorption was favourable at low temperature and dry coal conditions. However, S3 and S4 coals have the highest adsorption capacity by 0.71 and 0.73 mmol/g respectively. According to IUPAC classification of adsorption isotherms, CO2 adsorption isotherm of all coal samples follow type I which most probably describe the adsorption limited to a few molecular layers (micropores). The results of adsorption and desorption isotherm demonstrate a positive hysteresis in all coal samples. The S1 coal and S2 coal have the highest hysteresis between adsorption and desorption isotherm compared to S3 coal and S4 coal. According to hysteresis classifications, the hysteresis during CO2 adsorption and desorption process for all coal samples follows type H3 which describes micropores and mesopores. The evaluation of the equilibrium adsorption data where fitted using by Langmuir, Freundlich, Redlich-Peterson, Koble-Corrigan, Toth and Sips models. Toth model provided the best fit for all adsorption experimental data that predicting all coals having heterogeneous surface properties.

Fabricating high-resolution offset color-filter black matrix by integrating heterostructured substrate with inkjet printing

This paper presents a self-aligning ink by integrating an inkjet printing technique and heterostructures to fabricate a black matrix with a micrometer-scale tunable thickness. The black matrix is a grid-like structure used in color filters. Traditionally, a black matrix has been fabricated using photolithography techniques, the disadvantages of which are high material consumption, less fabrication flexibility, complex processing procedures, and high chemical pollution. Inkjet printing technology has garnered attention because of its low material costs, high fabrication flexibility, and reduced processing procedures and pollution. In this study, a fabricating process combining an inkjet printing technique with heterostructures to form stripe-arranged and delta-arranged thickness-tunable black matrices has been demonstrated. The deformation and self-aligning process of ink droplet impingement onto gutters are driven by designed heterogeneous surface properties. The minimum track width attained is 10 µm, which is competitive for color filter resolutions for thin-film transistor liquid crystal displays. The developed technology surmounts the bottlenecks of inkjet printing resolution, and saves more than 75% black material than modern photolithography.