Micropillar Surface Research Articles

High-Throughput Chemotherapeutic Drug Screening System for Gastric Cancer (Cure-GA).

Three dimensional (3D) cell cultures can be effectively used for drug discovery and development but there are still challenges in their general application to high-throughput screening. In this study, we developed a novel high-throughput chemotherapeutic 3D drug screening system for gastric cancer, named 'Cure-GA', to discover clinically applicable anticancer drugs and predict therapeutic responses. Primary cancer cells were isolated from 143 fresh surgical specimens by enzymatic treatment. Cell-Matrigel mixtures were automatically printed onto the micropillar surface then stabilized in an optimal culture medium for 3 days to form tumoroids. These tumoroids were exposed in the drug-containing media for 7 days. Cell viability was measured by fluorescence imaging and adenosine triphosphate assays. On average, 0.31±0.23g of fresh tumor tissue yielded 4.05×106 ± 4.38×106 viable cells per sample. Drug response results were successfully acquired from 103 gastric cancer tissues (success rate = 72%) within 13±2 days, averaging 6.4±2.7 results per sample. Pearson correlation analysis showed viable cell numbers significantly impacted drug data acquisition (p<0.00001). Tumoroids retained immunohistochemical characteristics, mutation signatures, and gene expression consistent with primary tumors. Drug reactivity data enabled prediction of synergistic drug correlations. Additionally, a multiparameter index-based prognosis model for patients undergoing gastrectomy followed by adjuvant XELOX was developed, showing significant differences in 1-year recurrence-free survival rates between drug responders and non-responders (p<0.0001). The Cure-GA platform enables rapid evaluation of chemotherapeutic responses using patient-derived tumoroids, providing clinicians with crucial insights for personalized treatment strategies and improving therapeutic outcomes.

Optimizing oil-water separation using fractal surfaces.

Oil has become a prevalent global pollutant, stimulating the research to improve the techniques to separate oil from water. Materials with special wetting properties-primarily those that repel water while attracting oil-have been proposed as suitable candidates for this task. However, one limitation in developing efficient substrates is the limited available volume for oil absorption. In this study, we investigate the efficacy of disordered fractal materials in addressing this challenge, leveraging their unique wetting properties. Using a combination of a continuous model and Monte Carlo simulations, we characterize the hydrophobicity and oleophilicity of substrates created through ballistic deposition (BD). Our results demonstrate that these materials exhibit high contact angles for water, confirming their hydrophobic nature while allowing significant oil penetration, indicative of oleophilic behavior. The available free volume within the substrates varies from 60% to 90% of the total volume of the substrate depending on some parameters of the BD. By combining their water and oil wetting properties with a high availability of volume, the fractal substrates analyzed in this work achieve an efficiency in separating oil from water of nearly 98%, which is significantly higher compared to micro-pillared surfaces made from the same material but lacking a fractal design.

Liquid Nitrogen Thin-Film Evaporation on Metal Micropillar Arrays

This paper presents an experimental characterization of liquid nitrogen (LN2) thin-film evaporation on additively manufactured and Computer Numerical Control (CNC)-machined metal micropillar arrays. Five different additively manufactured and CNC-machined titanium (Ti-64) and stainless-steel (SS-304) micropillar surfaces with 1 cm2 heating area were tested at a pressure of 1.38 MPa and a saturation temperature of 110 K. The micropillars had widths of 400, 500, and 600 μm wall-to-wall spacing and 600 μm height. An optimum micropillar spacing was observed where the heat flux was maximized to 90.1 W/cm2 at approximately 500 μm for the additively manufactured Ti-64 surface owing to the increased mean wicking velocity. A 44.5% decrease in dry-out heat flux was observed for the micropillar surface with the higher thermal conductivity material SS-304 compared to that with Ti-64, which can be attributed to the reduced bubble nucleation time and superheat. A 34% enhancement in dry-out heat flux was observed for the additively manufactured surface compared to the CNC-machined counterpart, which can be attributed to the augmented intrinsic surface roughness. A comparison of the experimental results with the literature model showed that the model overpredicts the dry-out heat flux limit of LN2 thin-film evaporation on both additively and conventionally manufactured metal surfaces.

Dynamics of drop impact and contact line motion on micro-pillared surfaces

Physical texturing creates patterned and pillared surfaces that display superhydrophobicity in drop spreading and drop impact studies. Often, such surfaces are accompanied by large hysteresis since the three-phase contact line may get trapped over and within the pillars. In this context, wetting characteristics of a water drop spreading over a micro-pillared surface of copper are investigated. Apart from drop spreading on a bare pillared surface, two companion studies where the pillars are fully and partially coated using superhydrophobic and hydrophobic coatings have been carried out. The Weber number and Reynolds number based on the drop diameter and impact speed are varied over the range 1–41 and 440–2870, respectively, while the Bond number remains constant, ∼1.03. Imaging sequences show spreading behavior that is distinctive of the surface chosen. For a fully coated surface, the drop is seen to jump-off upon impact while a residual drop remains over uncoated and partially coated pillars during the receding phase. These observations are compared against three-dimensional numerical simulations that resolve the pillar shapes. Simulations are seen to be qualitatively in good agreement with experiments. Simulations additionally probe the contact line movement over coated and uncoated pillars for comparison with experiments. The filling of the interpillar space with liquid and the resulting interface deformation are examined. Jointly, the emptying of the interpillar gap is also discussed. Experiments and simulation show a jump in drop footprint when the contact line leaves the pillar, and the associated velocity becomes large.

Hot embossed micropatterned slippery Al 5083 alloys in stagnant and laminar saltwater

Hot embossed micropatterned slippery Al 5083 alloys in stagnant and laminar saltwater

Adsorption and Morphology Analysis of Bovine Serum Albumin on a Micropillar-Enhanced Quartz Crystal Microbalance.

The adsorption of bovine serum albumin (BSA), a widely used blood plasma protein, onto poly(methyl methacrylate) (PMMA) surface is a fundamental phenomenon attracting increasing interests in molecular biology, cell culture, immunology, diagnostics, and vaccinology. The nanostructured PMMA surfaces have shown a considerable effect on the BSA adsorption process. However, the effect of microstructures (e.g., micropillars) on BSA adsorption has seldom been studied. This research reports on the development of an acoustic resonance based method to explore the adsorption of BSA proteins on PMMA micropillars in terms of surface coverage, apparent binding constants, and pH-induced morphology variation. A theoretical model is developed to understand the frequency changes of QCM induced by BSA adsorption by taking into consideration the effects of the hydrodynamic force and an equivalent BSA/liquid layer formed on the micropillar surface. In addition, it was found that the resonance of micropillars with a quartz crystal microbalance (QCM) substrate significantly influenced BSA adsorption on micropillar surfaces.

Dropwise condensation on subcooled micropillar surfaces with 3D lattice Boltzmann method

Dropwise condensation on subcooled micropillar surfaces with 3D lattice Boltzmann method

Sustainable EDM production of micro-textured die-surfaces: Modeling and optimizing the process using machine learning techniques

Sustainable EDM production of micro-textured die-surfaces: Modeling and optimizing the process using machine learning techniques

Numerical investigation on heat transfer and pressure drop characteristics of Micro-Pillar array surface

Numerical investigation on heat transfer and pressure drop characteristics of Micro-Pillar array surface

Roles of Micropillar Topography and Surface Energy on Cancer Cell Dynamics

Microstructured surfaces are renowned for their unique properties, such as waterproofing and low adhesion, making them highly applicable in the biomedical field. These surfaces play a crucial role in influencing cell response by mimicking the native microenvironment of biological tissues. In this study, we engineered a series of biomimetic micropatterned surfaces using polydimethylsiloxane (PDMS) to explore their effects on primary breast cancer cell lines, contrasting these effects with those observed on conventional flat surfaces. The surface topography was varied to direct cells’ attachment, growth, and morphology. Our findings elucidate that surface-free energy is not merely a background factor but plays a decisive role in cell dynamics, strongly correlating with the spreading behaviour of breast cancer cells. Notably, on micropillar surfaces with high surface-free energy, an increase in the population of cancer cells was observed. Conversely, surfaces characterised by lower surface-free energies noted a reduction in cell viability. Moreover, the structural parameters, such as the gaps and diameters of the pillars, were found to critically influence cellular dispersion and adherence, underscoring the importance of the microstructures’ topography in biomedical applications. These insights pave the way for designing advanced microstructured surfaces tailored to specific cellular responses, opening new avenues for targeted cancer therapies and tissue engineering.

Pool boiling characteristics on the micro-pillar structured surface with nanostructure and heterogeneous wettability

Pool boiling characteristics on the micro-pillar structured surface with nanostructure and heterogeneous wettability

Enhanced marine biofouling and corrosion resistance through springtails-inspired papillate-like micropillar arrays surface modified by antimicrobial peptide

Enhanced marine biofouling and corrosion resistance through springtails-inspired papillate-like micropillar arrays surface modified by antimicrobial peptide

Exploring flow boiling characteristics on surfaces with various micro-pillars using the lattice Boltzmann method

In this study, the lattice Boltzmann method is utilized to simulate flow boiling within a microchannel featuring a micro-pillar surface. This investigation aims to explore the impacts of micro-pillar shape and quantity on the flow boiling characteristics across various superheats and Reynolds numbers (Re). A systematic examination is conducted on three types of micro-pillars, five quantities of micro-pillars, four Re values, and 18 superheat levels. The mechanisms contributing to enhanced heat transfer in flow boiling are elucidated through a comprehensive analysis of bubble dynamics, temperature and velocity fields, local and transient heat fluxes, and boiling curves. Moreover, the critical heat fluxes (CHF) of all surfaces are evaluated to identify the superior micro-pillar configurations. The findings revealed that microchannels with micro-pillar surfaces induce more vortices compared to those with smooth surfaces, attributable to the combined effects of bubble dynamics and micro-pillars. Bubble patterns and boiling curves demonstrated the significant impact of micro-pillar geometrical shapes on the boiling regime and heat transfer performance. As flow boiling progressed, an increase in micro-pillar quantity and Re can mitigate the fluctuation and decline rate in transient heat flux, respectively. Among the three types of micro-pillar surfaces, the circular shape exhibited the highest flow boiling performance, followed by the triangular and rectangular shapes. For all surfaces, the CHF increased with Re, and each micro-pillar type displayed an optimal quantity for achieving maximum CHF, with the highest increase reaching 45.2%. These findings are crucial for optimizing microchannel designs to enhance flow boiling heat transfer efficiency.

Enhancing pool boiling heat transfer of modified surface by 3-D Lattice Boltzmann method

In this study, pool boiling from micro-pillar modified surface has been simulated numerically by a 3-D lattice Boltzmann method. Effects of geometries and wettability of micro-pillar on boiling heat transfer performance were also systematically evaluated. Result showed that compared within micro-pillar surface, heat flux of cubic micro-pillar surface was the highest with the lowest wall temperature. In addition, compared to hydrophilic condition, Heat flux of cubic micro-pillar surface with hydrophobic wettability increased by 98.3%. This is because hydrophobic wettability influenced nucleation site density, vapor-liquid-flow field and heat transfer performance much more than cubic shaped geometry. Finally, heat flux of cubic micro-pillar surface with hybrid wettability increased by 430.7% compared to pure hydrophilic wettability. That is due to optimal hybrid wettability surface could control nucleate site location, restrict bubble growth, and increase obviously heat transfer performance.

Coalescence-Induced Droplet Jumping on Superhydrophobic Surfaces with Annular Wedge-Shaped Micropillar Arrays.

The coalescence-induced droplet jumping on superhydrophobic surfaces has extensive application potential in water harvesting, thermal management of electronic devices, and microfluidics. The rational design of the surface structure can influence the interaction between the droplet and the surface, thereby controlling the velocity and direction of the droplet's jumping. In this study, we fabricate the superhydrophobic surface with annular wedge-shaped micropillar arrays, examine the dynamic behavior of condensate droplets on the surface, and measure the temporal and spatial variations of droplet density, average radius, and surface coverage with wedge-shaped micropillars of varying sizes. In addition, the energy analysis of the coalescence-induced droplet jumping reveals that the two primary factors influencing the jumping are the relative size and position of the droplets and micropillars. Further numerical simulations find that the wedge-shaped micropillars cause an asymmetric distribution of pressure within the droplet and at the solid-liquid contact surface, which generates an unbalanced force driving the droplet in the gradient direction of the wedge-shaped micropillar, causing the droplet to jump off the surface with both vertical and gradient-direction velocities. The capacity of the wedge-shaped micropillar surface to transport droplets in the gradient direction increases and then decreases as the relative size of the droplets and micropillars increases. The relative position of the droplet center-of-mass line perpendicular to the bottom edge of the wedge micropillars' trapezoidal shape is more favorable for droplet transport. This work reveals the influence mechanism of surface structure on the velocity and direction of droplet jumping, and the results can guide the microstructure design of superhydrophobic surfaces, which has significant implications for the application of droplet jumping.

Enhanced boiling heat transfer on three-dimensional hybrid micropillar array surfaces

Enhanced boiling heat transfer on three-dimensional hybrid micropillar array surfaces

Evaporation of Leidenfrost droplets on microtextured substrates

Evaporation of Leidenfrost droplets on microtextured substrates

Fabrication of a three-dimensional micro/nanocarbon structure with sub-10 nm carbon fiber arrays based on the nanoforming and pyrolysis of polyacrylonitrile-based jet fibers

To produce a three-dimensional micro/nanocarbon structure, a manufacturing design technique for sub-10 nm carbon fiber arrays on three-dimensional carbon micropillars has been developed; the method involves initiating electrostatic jetting, forming submicron-to-nanoscale PAN-based fibers, and maximizing the shrinkage from polyacrylonitrile (PAN)-based fibers to carbon fibers. Nanoforming and nanodepositing methods for polyacrylonitrile-based jet fibers as precursors of carbon fibers are proposed for the processing design of electrostatic jet initiation and for the forming design of submicron-to-nanoscale PAN-based fibers by establishing and analyzing mathematical models that include the diameter and tensile stress values of jet fibers and the electric field intensity values on the surfaces of carbon micropillars. In accordance with these methods, an array of jet fibers with diameters of ~80 nm is experimentally formed based on the thinning of the electrospinning fluid on top of a dispensing needle, the poking of drum into an electrospinning droplet, and the controlling of the needle–drum distance. When converting thin PAN-based jet fibers to carbon fibers, a pyrolysis method consisting of the suspension of jet nanofibers between carbon micropillars, the bond between the fibers and the surface of the carbon micropillar, and the control of micropillar spacing, stabilization temperature, and carbonation rate is presented to maximize the shrinkage from PAN-based fibers to carbon fibers and to form sub-10 nm carbon fiber arrays between three-dimensional carbon micropillars. The manufacturing design of a three-dimensional micro/nanocarbon structure can produce thin PAN-based jet nanofibers and nanofiber arrays aligned on micropillar surfaces, obtain shrinkage levels reaching 96% and incorporate sub-10 nm carbon fibers into three-dimensional carbon micropillars; these actions provide new research opportunities for correlated three-dimensional micro/nanocarbon structures that have not previously been technically possible.

Laser belt processed micropillars with microporous structure and nanoparticles to control the surface wettability of superhydrophobic Inconel 718 alloy

Laser belt processed micropillars with microporous structure and nanoparticles to control the surface wettability of superhydrophobic Inconel 718 alloy

Condensation mode transition and droplet jumping on microstructured surface

Condensation mode transition and droplet jumping on microstructured surface