Microscale Structures Research Articles

A novel method to relieve residual stress in dissimilar brazed joint via micro-scale additive manufacturing

To alleviate residual stress of ZrO2/GH536 brazed joints, the micro-scale structures were fabricated on ZrO2 via selective laser melting technology before its vacuum brazing with GH536 superalloy. The effects of micro-scale structures on the interfacial microstructure and residual stress of brazed joints were studied. The characterization results indicated that due to its reaction with excessive Ti elements from filler, the micro-scale structures prevented the detrimental effect of over-thick brittle reaction layer on the mechanical properties of joints. Furthermore, the Invar effect of the micro-scale structures facilitated the transfer of residual stress from the ceramic side to the micro-scale structures. According to the numerical simulation results, the maximum residual stress in the brazed joint with micro-scale structures decreased from 622 MPa to 310 MPa. As a result, the fracture path was changed from the flat shape to zigzag. This work reveals the stress-relaxed mechanism of micro-scale structures and provides a new method for fabricating the ceramic/metal joints with low residual stress.

Investigation of ablation threshold and microchannel fabrication on stainless steel using ultrafast laser

ABSTRACT Ultrafast laser processing is a highly versatile tool for creating microscale structures in many materials. The ablation and micromachining characteristics of AISI 304 stainless steel were examined using a femtosecond-pulsed laser. Parameters such as power, scanning speed, transverse overlap, scanning strategies, and shielding gases were systematically varied. The ablation threshold fluence for SS 304 was calculated as 0.16 J/cm2. Two ablation regimes were observed: the gentle regime, where smooth crater walls were formed under low pulse energy (below 20 µJ), and the strong regime, characterized by rough walls created under high pulse energy (above 20 µJ). The optimal parameters for fabricating microchannels on SS 304 surfaces comprised a laser power of 100 mW, a scanning speed of 30 mm/s, a line-to-line distance of 5 µm, and a parallel scan strategy along the major axis. This study provides a practical approach for enhancing the microchannel fabrication process on stainless steel.

Superhydrophobic anti-icing/de-icing SR/CNTs surfaces hot-embossed with femtosecond laser machined mold

Anti-icing/de-icing surfaces are dispensable in reducing accidents and economic losses caused by accumulated ice and frost on outdoor facilities in cold and humid environments. In this work, a low-cost, reproducible process was presented to fabricate superhydrophobic anti-icing/de-icing surfaces. For this purpose, concave micro-structures were firstly created on the mold steel surface using femtosecond laser machining, and then the corresponding convex micro-structures were prepared on the surface of a silicone rubber (SR) composite mixed with multi-wall carbon nanotubes (CNTs) using hot embossing. Thanks to the presence of unique micro-scale peak-ridge structures, the as-prepared SR/CNTs surfaces possess superhydrophobic characteristic. Long icing delay time was endowed by the large volume of air pockets inside micro-structures, and the icing time was significantly extended from 67 to 416 s, which is ascribed to the greatly inhibited heat transfer between the droplet and the surface. Moreover, the SR/CNTs surface had excellent photothermal conversion capability with the presence of photothermal particles CNTs, and the temperature of the surface increased rapidly from 21.6 to 86.1 °C in 5 min under a standard sunlight irradiation. In addition, the SR/CNTs surface also possesses superior photothermal defrosting and de-icing performance as the ice and frost on the surface can be quickly melted under a standard sunlight intensity irradiation and the de-icing rate is up to 0.92 mg/s. Finally, the good reusability of the mold steel and the resistance to mechanical wear and chemical corrosion of superhydrophobic SR/CNTs surface found in this work make the proposed approach promising for industrial mass production and anti-icing/de-icing applications in harsh environments.

Energy-dispersive Laue diffraction analysis of the influence of statherin and histatin on the crystallographic texture during human dental enamel demineralization.

Energy-dispersive Laue diffraction (EDLD) is a powerful method to obtain position-resolved texture information in inhomogeneous biological samples without the need for sample rotation. This study employs EDLD texture scanning to investigate the impact of two salivary peptides, statherin (STN) and histatin-1 (HTN) 21 N-terminal peptides (STN21 and HTN21), on the crystallographic structure of dental enamel. These proteins are known to play crucial roles in dental caries progression. Three healthy incisors were randomly assigned to three groups: artificially demineralized, demineralized after HTN21 peptide pre-treatment and demineralized after STN21 peptide pre-treatment. To understand the micro-scale structure of the enamel, each specimen was scanned from the enamel surface to a depth of 250 µm using microbeam EDLD. Via the use of a white beam and a pixelated detector, where each pixel functions as a spectrometer, pole figures were obtained in a single exposure at each measurement point. The results revealed distinct orientations of hydroxyapatite crystallites and notable texture variation in the peptide-treated demineralized samples compared with the demineralized control. Specifically, the peptide-treated demineralized samples exhibited up to three orientation populations, in contrast to the demineralized control which displayed only a single orientation population. The texture index of the demineralized control (2.00 ± 0.21) was found to be lower than that of either the STN21 (2.32 ± 0.20) or the HTN21 (2.90 ± 0.46) treated samples. Hence, texture scanning with EDLD gives new insights into dental enamel crystallite orientation and links the present understanding of enamel demineralization to the underlying crystalline texture. For the first time, the feasibility of EDLD texture measurements for quantitative texture evaluation in demineralized dental enamel samples is demonstrated.

Fault slip and seismic source response characteristics under induced stress wave

As coal mining depth and structural complexity increase, the failure severity of mining-induced fault activation leading to rock bursts escalates. Fault fracture zones, consisting of various secondary structures, are essential for understanding tectonic evolution and seismic wave propagation. The interaction between mining-induced stress waves and in-situ stress complicates the dynamics and activation markers of fault fracture zones. This paper aims to clarify the patterns of stick–slip instability and stress evolution in these zones under coal mining-induced stress waves. Using theoretical models and continuous-discrete coupling simulations, the study explores the dynamic response of fault fracture zones in the meta-instability stage, the micro-scale fracture force chain structure, and the distribution and synergistic instability of fault plane seismic sources. The research shows that fault fracture zones changes stress wave propagation path and energy redistribution due to its heterogeneity leads to multiple times decomposition of wave field. Minor delamination between the hanging wall and footwall can trigger unstable slip. Tensional seismic sources with extensive failure drive fault slip. Dynamic stress waves disrupt force chains near seismic sources, increasing hazard levels. Static in-situ stress affects shear seismic sources by influencing porosity and crack angles. Seismic sources along the fault strike transition from divergent to concentrated, trending horizontally. In the meta-instability stage, the initial fracture area locks, with strong structures causing cohesive fractures in the middle of the fault zone, releasing strain energy and forming a sudden increase in slip intensity. These findings provide crucial insights into fault fracture-development-activation markers, fault region stress deformation evolution mechanisms, and risk control of fault-induced rock bursts.

Multimodal three-dimensional characterization of murine skeletal muscle micro-scale elasticity, structure, and composition: Impact of dysferlinopathy, Duchenne muscular dystrophy, and age on three hind-limb muscles

Skeletal muscle tissue function is governed by the mechanical properties and organization of its components, including myofibers, extracellular matrix, and adipose tissue, which can be modified by the onset and progression of many disorders. This study used a novel combination of quantitative micro-elastography and clearing-enhanced three-dimensional (3D) microscopy to assess 3D micro-scale elasticity and micro-architecture of muscles from two muscular dystrophies: dysferlinopathy and Duchenne muscular dystrophy, using male BLA/J and mdx mice, respectively, and their wild-type (WT) controls. We examined three muscles with varying proportions of slow- and fast-twitch myofibers: the soleus (predominantly slow), extensor digitorum longus (EDL; fast), and quadriceps (mixed), from BLA/J and WTBLA/J mice aged 3, 10, and 24 months, and mdx and WTmdx mice aged 10 months. Both dysferlin deficiency and age reduced the elasticity and variability of elasticity of the soleus and quadriceps, but not EDL. Overall, the BLA/J soleus was 20% softer than WT and less mechanically heterogeneous (−14% in standard deviation of elasticity). The BLA/J quadriceps at 24 months was 72% softer than WT and less mechanically heterogeneous (−59% in standard deviation), with substantial adipose tissue accumulation. While mdx muscles did not differ quantitatively from WT, regional heterogeneity was evident in micro-scale elasticity and micro-architecture of quadriceps (e.g., 11.2 kPa in a region with marked pathology vs 3.8 kPa in a less affected area). These results demonstrate differing biomechanical changes in hind-limb muscles of two distinct muscular dystrophies, emphasizing the potential for this novel multimodal technique to identify important differences between various myopathies.

Fe/polymer joining via Fe/TiB2 composite structures via in-situ laser-induced reaction of Fe-Ti-B system: Effect of powder composition

Achieving strong direct joining between steel and polymers through mechanical interlocking is crucial for developing multi-material structures, particularly in the automotive and aerospace industries. This study synthesized micro-scale structures on a pure Fe substrate (simulating interstitial-free (IF) steel) for mechanical interlocking with thermoplastic parts. Numerous submillimeter-scale Fe/TiB2 composite particles were in-situ synthesized by laser scanning on the Fe-Ti-B powder mixture and well-bonded with the Fe substrate. The effects of powder composition (TiB2 volume fraction) on the morphology, microstructure, and joint strength with PA6 were investigated. A TiB2 volume fraction over 60 % was essential for the formation of the composite particles promoted by a TiB2 skeletal structure. Higher TiB2 volume fractions increased the area fraction of the composite particles and decreased the bonding ratio (adhesive) of the particles with the substrate due to poor adhesiveness at the edge of the laser-scanning line. A wider high-temperature region was generated at a higher TiB2 volume fraction, suggesting that the reaction heat to form TiB2 assisted the bonding of the particles with the substrate at the edge of the laser scanning line. The Fe/PA6 joint strength increased to approximately 30 MPa with increasing the TiB2 volume fraction to 100 % and showed a linear correlation with the product of particle area fraction and bonding ratio. A higher TiB2 volume fraction was preferable for enhancing the joint strength via the micro-scale structures synthesized by laser scanning on the Fe-Ti-B powder mixture. A combination of the micro-structuring process using a high fraction of TiB2 with advanced joining technologies will contribute to manufacturing high-strength Fe/polymer hybrid parts.

Numerical study of transpiration cooling at different outlet angles and hole pattern

The effects of transpiration cooling depends on the distribution of micropores in porous materials. The work simplifies the porous medium to a micro-scale pore plate structure that is densely organized, based on the idea of the capillary bundle model. The effects of hole pattern and hole outlet angle on transpiration cooling are investigated using numerical simulation. It is discovered that the hole outlet angle mostly affects the homogeneity of temperature distribution and has minimal effect on the surface cooling efficiency. The temperature uniformity index dropped by 35.9% yet the surface cooling efficiency only declined by 1.1% when the outlet angle was lowered from 45° to −45°. Furthermore, the temperature uniformity and cooling efficiency are directly affected by the hole pattern. When the long axis of the elliptical hole is parallel to the mainstream, it can achieve the best temperature uniformity; however, when the long axis is perpendicular to the mainstream direction, it can achieve higher cooling efficiency. Third, the material’s permeability will be decreased to varying degrees depending on the hole pattern and hole outlet angle. The results have important reference significance for the design of porous materials used for transpiration cooling.

Silica‐Rich Sol‐Gel Ink for Two‐Photon Direct Laser Writing of Microscale Structures and Optical Elements

AbstractInnovative materials enable two‐photon polymerization for precise additive fabrication of intricate optical components. Existing polymeric inks suffer from poor optical performance due to their high organic content. Silica‐rich sol‐gel ink (75 wt%, under ambient conditions) is presented for high‐precision three‐dimensional (3D) printing of microscale structures and optical devices. A photoinitiator with high‐efficiency nonlinear absorption is introduced to initiate two‐photon polymerization. Utilizing a commercial direct laser writing system, 3D‐printing is demonstrated including the optimization of printing parameters and ink characterization. The optical performance of the printed microscale elements using the new sol‐gel ink surpasses commercially available polymeric inks on key metrics: Printed elements exhibit extremely low surface roughness, 3nm; visible and near‐IR light transmission is greater than 90%; Printed elements present enhanced mechanical and chemical resistance to common organic solvents; Structures exhibit low isotropic shrinkage, <10%; Elements withstand continuous‐wave laser intensities exceeding 7 × 105 W cm−2. Direct writing onto an optical fiber tip with no need for surface functionalization is presented, with the demonstration of a tall waveguide taper (≈1:5 aspect ratio) with low losses and modal crosstalk, and a freestanding photonic lantern mode multiplexer. The new ink can be utilized in a variety of applications and across many materials, requiring compact, durable, and complex optical elements.

Bubble-Guidance Breaking Gas Shield for Highly Efficient Overall Water Splitting.

Overall water splitting is a promising technology for sustainable hydrogen production, but the primary challenge is removing bubbles from the electrode surface quickly to increase hydrogen production. Inspired by the directional fluid transport properties of natural biological surfaces like Nepenthes peristome and Morpho butterfly's wings, here a strategy is demonstrated to achieve highly efficient overall water splitting by a bubble-guidance electrode, that is, an anisotropic groove-micro/nanostructured porous electrode (GMPE). Gradient groove micro/nanostructures on the GMPE serve as high-speed bubble transmission channels and exhibit superior bubble-guidance capabilities. The synergistic effect of the asymmetric Laplace pressure generated between microscale porous structure and groove patterns and the buoyancy along the groove patterns pushes the produced bubbles directionally to spread, transport, and detach from the electrode surface in time. Moreover, the low adhesive nanosheet arrays are beneficial to reduce bubble size and increase bubble release frequency, which cooperatively improve mass transfer with the microscale structure. Notably, GMPE outperforms planar-micro/nanostructured porous electrode (PMPE) in hydrogen/oxygen evolution reactions, with GMPE||GMPE showing better water splitting performance than commercially available RuO2||20 wt.% Pt/C. This work improves electrodes for better mass transfer and kinetics in electrochemical reactions at solid-liquid-gas interfaces, offering insight for designing and preparing gas-involved photoelectrochemical electrodes.

Optimizing polymethyl methacrylate (PMMA)-based stretchable microneedle arrays by vat photopolymerization for efficient drug loading

Advancements in vat photopolymerization printing technology have enabled the fabrication of components with varying mechanical properties within a single print job. Using a digital light projector to cure photopolymer resins layer by layer, it allows the fabrication of parts with both flexibility and rigidity, in different regions. It simplifies the manufacturing process by eliminating the need for multiple steps. Specifically, for applications such as microneedles, printing onto a stretchable substrate is crucial compared to a rigid substrate, as it conforms better to the contours of the skin, ensuring more effective and comfortable drug delivery. However, a notable limitation of vat photopolymerization printing is the current lack of biocompatible materials, which restricts its application for microneedle fabrication. The challenge lies in developing materials that meet biocompatibility standards, while also being compatible with the printing technique and capable to achieve precise microscale structures. Therefore, we have developed an ultraviolet (UV)-curable polymethyl methacrylate (PMMA) suitable for the vat photopolymerization printing and the microneedles were designed to have a hollow side structure, enhancing drug loading efficiency. Comprehensive testing has been conducted, including durability test, drug loading efficiency, and skin penetration capability.

Uniaxial tensile‐induced deformation of spherulite: combining experimental and simulation methods

AbstractA combination of experimental and simulation methods is adopted to study the relationship between micro‐stress and micro‐strain of a single spherulite upon uniaxial tensile deformation. To verify the simulation results and establish a suitable spherulite model, large‐sized isotactic polypropylene spherulite is first cultured with isothermal crystallization, whose structural deformation upon application of uniaxial tension is recorded using a polarizing optical microscope. A nanoindenter is used to measure the elastic modulus of the spherulite and amorphous region, preparing the property parameters for numerical simulation. Modeling and meshing of the single spherulite are conducted with the finite element software ABAQUS. The entire deformation of the spherulite is analyzed with fixed strain as the boundary condition, and the microscopic stress and strain distribution inside and outside of the spherulite is obtained. The higher micro‐stress region mainly locates at two poles in the equatorial direction, where might be the origin of craze. Generally, the simulation result is basically consistent with the experimental deformation process, which provides a new idea for the study of microscale structure and performance. © 2024 Society of Chemical Industry.

A Rapidly Self-Healing Superhydrophobic Coating Made of Polydimethylsiloxane and N-nonadecane: Stability and Self-Healing Capabilities

Superhydrophobic surfaces have garnered significant attention in various industrial applications, such as photovoltaic power generation, anti-icing, and corrosion resistance, due to their exceptional water-repellent properties. However, the poor durability of conventional superhydrophobic coatings has severely impeded their practical implementation. To achieve the dual self-recovery of microscale and nanoscale surface structures and maintain low surface energy after damage to superhydrophobic coatings, thereby enhancing their durability, a rapidly self-healing superhydrophobic coating was developed using polydimethylsiloxane (PDMS) and n-nonadecane in this study. The coating surface demonstrated exceptional hydrophobic characteristics, as evidenced by a water contact angle (WCA) of 157.5° and a sliding angle (SA) of 4.2° achieved at optimized proportions. Through scanning electron microscopy, it was observed that the coating surface exhibited a rough structure at both the microscale and nanoscale. The stability test results showed that the WCA only decreases by 5.7° and the SA only increases by 3.6° after 100 instances of external friction. The stability test results demonstrated that the superhydrophobic coating maintains excellent hydrophobicity under mechanical external forces and in acidic and alkaline environments. The results of the self-healing capability test showed that the WCA rebounded to 151.5° and 149.5° after we subjected the samples to 20 MPa of vertical pressure damage and chloroform exposure for 4 h, respectively. The coating regained a robust hydrophobic state even after experiencing repeated mechanical and chemical damage. The above results indicate that the resulting coating demonstrates outstanding durability, including high resistance to friction, stability against acids and alkalis, and the ability to self-recover hydrophobicity after repeated damage.

Parametric investigation of wire-EDM parameters for micro channel as a foundation of high-quality micro needle array fabrication

Micro channels are widely used in microfluidics, and medical science for the extraction of DNA, electrophoresis, and blood protein analysis. In the current work, the wire electrical discharge machining (WEDM) process was used to fabricate micro channels on the stainless steel 316 (SS316) substrate. To check the feasibility of fabricating high-quality micro channels and thereafter micro-scale structures with the WEDM process the effect of different process parameters such as pulse-off time, pulse-on time, servo gap reference voltage and wire feed rate were investigated. The quality attributes taken were namely surface roughness of the channel base, overcut, micro channel depth, and material removal rate (MRR). The pulse-on time significantly affects surface roughness and MRR. The servo gap reference voltage is the key process parameter affecting the overcut and micro channel depth. It was observed from the parametric study that 15 µs pulse-on time, 35 µs pulse-off time, 17 v servo gap reference voltage, and 8 m/min wire feed rate are the optimum levels for getting high MRR, low surface roughness, less overcut and high micro channel depth. Additionally, the topographical, morphological, surface, and sub-surface characterization were also carried out to assess the surface integrity and extent of thermal damage caused by the WEDM process. With the optimum combination of process parameters a 6 × 6 micro needle array was successfully fabricated on the same substrate using micro channels as a basis of the fabrication process for the first time using the WEDM process.

Experimental demonstration of cyclotron emissions in micro-scale graphene structures

A solid-state implementation of a cyclotron radiation source consisting of arrays of semicircular geometries was designed, fabricated, and characterized on commercially available graphene on hBN substrates. Using a 10 µm design radius and device width, respectively, such devices were expected to emit a continuous band of radiation spanning from 3 to 6 GHz with a power 3.96 nW. A peak emission was detected at 4.15 GHz with an effective array gain of 22 dB. This is the first known experimental measurement of cyclotron radiation from a curved planar graphene geometry. With scaling, it may be possible achieve frequencies in the THz range with such a device.

Influence of binder content on gas-water two-phase flow and displacement phase diagram in the gas diffusion layer of PEMFC: A pore network view

Understanding the gas-water flow dynamics in the gas diffusion layer (GDL) is one of the keys to improving the proton exchange membrane fuel cell's (PEMFC) overall performance and avoiding water flooding. Yet, the relationship between the two-phase flow and micro-scale GDL structures (including binder, PTFE, and fiber skeleton) is not well understood. In this study, three-dimensional GDL structures with different fractions of binder contents (φb=0%∼50%) and a fixed porosity of 75.6 % are confidently reconstructed based on high-resolution images from the confocal microscope, implying that the addition of binder will increase the number of large pores and cause a bimodal throat size distribution through morphology analysis. Thereafter, drainage simulations are performed under a wide range of capillary number (−9 < log Ca <0) and viscosity ratio (−3 < log M < 2) by the pore network model (PNM), which robustly predicts the displacement phase diagram of viscous fingering, capillary fingering, stable displacement, and transitional regime. In the viscous fingering and stable displacement regime, the nonwetting phase saturation (Snw) is nearly the same for different φb, implying the fluid invading pathway does not change much with the addition of binder. However, in the capillary fingering regime (refer to the actual operating conditions), Snw increases rapidly with φbat the breakthrough time and its transient value continues to increase until the steady state, which may be attributed to the increased fractions of pores above the capillary threshold attributed by the bimodal throat size distribution. In addition, the effective water permeability increases sharply with φb, whereas the gas permeability remains almost constant, which means such pore structure alteration by adding the binder is beneficial to water disposal in PEMFC. This research provides insights into delineating the effect of pore and throat size distribution alteration by adding binder on two-phase dynamics in GDL.

Responsive Liquid Crystal Network Microstructures with Customized Shapes and Predetermined Morphing for Adaptive Soft Micro-Optics.

Stimuli-responsive materials have garnered substantial interest in recent years, particularly liquid crystal networks (LCNs) with sophisticatedly designed structures and morphing capabilities. Extensive efforts have been devoted to LCN structural designs spanning from two-dimensional (2D) to three-dimensional (3D) configurations and their intricate morphing behaviors through designed alignment. However, achieving microscale structures and large-area preparation necessitates the development of novel techniques capable of facilely fabricating LCN microstructures with precise control over both overall shape and alignment, enabling a 3D-to-3D shape change. Herein, a simple and cost-effective in-cell soft lithography (ICSL) technique is proposed to create LCN microstructures with customized shapes and predesigned morphing. The ICSL technique involves two sequential steps: fabricating the desired microstructure as the template by using the photopolymerization-induced phase separation (PIPS) method and reproducing the LCN microstructures through templating. Meanwhile, surface anchoring is employed to design and achieve molecular alignment, accommodating different deformation modes. With the proposed ICSL technique, cylindrical and spherical microlens arrays (CMLAs and SMLAs) have been successfully fabricated with stimulus-driven polarization-dependent focusing effects. This technique offers distinct advantages including high customizability, large-area production, and cost-effectiveness, which pave a new avenue for extensive applications in different fields, exemplified by adaptive soft micro-optics and photonics.

Hall-Petch relationship in multiscale cellular structures of Al-Si alloy fabricated by laser powder bed fusion

Material-structure-property integration is a promising development trend of additive manufacturing (AM). Nowadays, the material-property (M-P) relationships and structure-property (S-P) relationships of AM components have been extensively investigated. However, it is still unclear whether there is a relationship between M-P and S-P. Microscale cellular structure (ICS) is a typical microstructure in laser powder bed fusion (LPBF) processed metals, while macroscale cellular structure (ACS) is often fabricated by LPBF and are widely applied in industrial fields. Here, the solid material of AlSi10Mg alloy and ACS inspired by the ICS of AlSi10Mg were fabricated by LPBF. The scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) analysis revealed that reducing the laser power from 400 W to 300 W would increase the mean diameter of ICS from 0.4 μm to 0.9 μm, but the grain size remained almost unchanged. The micro-CT results indicated that the LPBF fabricated ACS had high relative density and dimensional accuracy. Through Hall-Petch equation, the relationship between M-P of AlSi10Mg alloy and S-P of cellular structure was established. The present investigations provide a way to predict microstructure properties from the macrostructure properties, and vice versa, which will facilitate the material-structure-property integration of AM technology.

Microscale structure optimization of catalyst layer for comprehensive performance enhancement in proton exchange membrane fuel cell

The catalyst layer plays a significant role in promoting the redox reaction of proton exchange membrane fuel cells (PEMFC). Especially at high current densities, as the oxygen reduction rate increases and more water is produced, the pores of the catalyst layer are easily clogged, thus preventing the oxygen from reaching the reactive sites. In this work, a cathode catalyst layer with micro-grooved structure is proposed to optimize the water-gas transport and output performance of PEMFC. Three-dimensional two-phase numerical simulation results show that the catalyst layer with grooves significantly improves the water-gas transport performance of PEMFC, with a maximum increase of 4.76 % in output performance. Combining the response surface methodology and non-dominated sorting genetic algorithm-II for multi-objective optimization (MOO), the optimal solution corresponding to anode/cathode relative humidity and ionomer volume fraction is confirmed to be 86.73 %, 80.10 %, and 0.2592, respectively. The optimization objectives (oxygen concentration, liquid saturation, and net power density) are improved by 3.88 %, 1.95 %, and 1.79 %, respectively. The differences between the three optimization objectives obtained by numerical simulation verification are only 0.61 %, 0.32 %, and 0.55 %, indicating that the MOO results are reliable and accurate.

Quantifying the Microstructure of Dried Deposits Using Height-Height Correlation Function.

Colloidal self-assembly has garnered significant attention in recent research, owing to applications in medical and engineering domains. Understanding the arrangement of particles in self-assembled systems is crucial for comprehending the underlying physics and synthesizing complex nano- and microscale structures. In this study, we introduce a novel methodology for analyzing the spatial distribution of particles in colloidal assemblies, focusing specifically on quantifying the microstructure of deposits formed by the evaporation of colloidal particle-laden drops. Utilizing a height-height correlation-function-based approach, we quantify variations in the height profile of deposits in radial and azimuthal directions. This approach enables the classification of the patterns into typical examples encountered in an evaporation-driven assembly. The method is demonstrated to be robust for quantifying synthetic and experimentally obtained deposit patterns, exhibiting excellent agreement in the estimated parameters. The mapping developed between pattern morphology and the quantitative measures introduced in this work may be used in a variety of applications including disease diagnosis as well as in developing pattern recognition tools.