Surface Design Research Articles

Developing Microelectrode Arrays for the Point-of-Care Multiplex Detection of Metabolites.

DNA-aptamer-functionalized electrode arrays can provide an intriguing method for detecting pathogen-derived exometabolites. This work addresses the limitations of previous aptamer-based pathogen detection methods by introducing a novel surface design that bridges the gap between initial efforts in this area and the demands of a point-of-care device. Specifically, the use of a diblock copolymer coating on a high-density microelectrode array and Cu-mediated cross coupling reactions that allow for the exclusive functionalization of that coating by any electrode or set of electrodes in the array provides a device that is stable for 1 year and compatible with the multiplex detection of small-molecule targets. The new chemistry developed allows one to take advantage of a large number of electrodes in the array with one experiment described herein capitalizing on the use of 960 individually addressable electrodes.

Micro-mixing enhancement in a Taylor-Couette reactor using the inner rotors with various surface configurations

This study investigates the effects of various inner cylinder configurations on micromixing and fluid dynamics within a Taylor-Couette (TC) reactor using the inner cylinders with different surface designs, including the traditional smooth-surfaced rotor cylinder. The four innovative inner cylinders were specifically designed with axial corrugations (N40 and N80) and three-dimensional rough surfaces (NZ40 and NZ80). Micromixing efficiency was assessed experimentally using the iodide-iodate reaction as a probe. To further understand the impact of the rotors' surface structures on micromixing, computational fluid dynamics (CFD) modelling was utilized to analyse the fluid dynamics within the TC reactor. An incorporation model was employed to calculate the micromixing time. The experimental findings reveal that the segregation index decreases with increasing rotation speed for all inner cylinders. Besides, NZ80′s micro-mixing efficiency surpasses that of its counterparts, NZ40, N40, and N80. The CFD modelling results underscore the significant influence of the inner cylinder's surface configuration on the turbulence dissipation rate and volume probability distribution, which are likely to contribute positively to the micromixing efficiency within the TC reactor. Furthermore, the empirical correlations obtained have been established to understand the micro-mixing time within TC reactors using different rotating cylinders.

Micro-structure design of black ceramic composite surface towards photothermal superhydrophobic anti-icing

Conventional superhydrophobic surfaces have limitations in the melting and icing process in response to ambient temperature. In this study, we fabricated a composite coating using plasma-etched black ceramic as a low layer on the surface of AZ31 magnesium alloy, and loaded-polydimethylsiloxane nanoparticles (PDMS NPs) as a top layer to achieve a photothermal and superhydrophobic anti-icing. The absorbance and forbidden bandwidth of the ceramic layer exhibit the excellent photothermal properties of solid solution (Mg1-XCuXO). The ceramic phase exhibits a bandgap of 3.62 eV and achieves a temperature of up to 69.4 °C, demonstrating desirable light absorption and photothermal properties. The microstructure and polar bonds of Si-O-Si provide excellent superhydrophobic properties, allowing the surface contact angle to reach 156°. The wetting of water droplets on the composite coating’s surface is simulated using molecular dynamics, which is consistent with experimental findings and emphasizes the coating’s exceptional superhydrophobic. Additionally, the transition process between Cassie-Baxter and Wenzel was analyzed by researching the dynamic icing and ice-melting processes. This composite surface converts light energy into heat, melts snow/ice, and uses hydrophobicity to promptly desorb it from the surface, enabling a photothermal active and superhydrophobic passive anti-icing strategy.

Photo-responsive anti-fouling polyzwitterionic brushes: a mesoscopic simulation.

The antifouling effects of a toothbrush-shaped photo-responsive polyzwitterionic membrane were studied via dissipative particle dynamics simulations in this work. The results reveal that the membrane modified by spiropyran methacrylate brushes displays photo-switchable and antifouling capability due to the photo-induced ring-opening reaction. Namely, surface morphology and hydrophilicity change in response to visible or UV light irradiation, which can be observed visually by protein adsorption and desorption. Further study indicates that: (1) brush-modification density can influence the structure and properties of the membrane. With low modification density, systems cannot establish an intact selective layer, which hinders the antifouling ability; as the modification density increases, the intact selective layer can be formed, which is conducive to the expression of photo-responsiveness and antifouling capability. (2) Factors of toothbrush-hair length and grafting ratio can influence the establishment of a light-responsive surface: as the grafting ratio and toothbrush-hair length increase, the light-responsive surface is gradually formed, meanwhile, the antifouling ability can be continuously reinforced under UV light irradiation. (3) As the brushes switch into a zwitterionic merocyanine state under UV exposure, the selective layer swelling becomes stronger than that with a hydrophobic spiropyran state under visible exposure. This is owing to the enhanced interaction between zwitterionic brushes and water, which is the root of the antifouling effect. The present work is expected to provide some guidelines for the design and development of novel antifouling membrane surfaces.

Mucus Mimic Hydrogel Coating for Lubricous, Antibiofouling, and Anti-Inflammatory Urinary Catheters.

Silicone is a common elastomer used in indwelling urinary catheters, and catheters are widely used in various medical applications due to their exceptional biocompatibility, hypoallergenic properties, and flexibility. However, silicones exhibit hydrophobic characteristics, lack inherent biolubrication, and are susceptible to nonspecific biosubstance adsorption, resulting in complications including but not limited to tissue trauma, postoperative pain, and urinary tract infections (UTIs). The development of effective surface designs for biomedical catheters to mitigate invasive damage and UITs has been a longstanding challenge. Herein, we present a novel approach to prepare a mucus mimic hydrogel coating. A thin layer of hydrogel containing xylitol is fabricated via photopolymerization. The surface modification technique and the interface-initiated hydrogel polymerization method ensure robust interfacial coherence. The resultant coating exhibits a low friction coefficient (CoF ≈ 0.1) for urinary catheter applications. Benefiting from the hydration layer and the antifouling of the xylitol unit, the xylitol hydrogel-coated surfaces (pAAAMXA) demonstrate outstanding antibiofouling properties against proteins (98.9% reduction relative to pristine polydimethylsiloxane (PDMS)). Furthermore, the pAAAMXA shows general adhesion resistance against bacteria primarily responsible for UITs (Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Methicillin-resistant strains of Staphylococcus aureus (MRSA), and Staphylococcus epidermidis (S. epidermidis)) without compromising biotoxicity (cell viability 98%). In vivo, catheters coated with the mucus mimic hydrogel displayed excellent biocompatibility, resistance to adhesion of bio substance, and anti-inflammatory characteristics. This work describes a promising alternative to conventional silicone catheters, offering potential for clinical interventional procedures with minimized complications.

Preparation, optimisation, and properties of O-carboxymethyl chitosan-g-cholesterol succinic acid monoester polymer nanomicelles

Polymer nanomicelles have the advantages of small particle size, improved drug solubility, retention effect and enhanced permeability, so they can be used in the treatment of tumour diseases. The aim of this study was to prepare and optimise a nanomicelle which can improve the solubility of insoluble drugs. Firstly, the carboxyl group of cholesterol succinic acid monoester was grafted with the side chain amino group of O-carboxymethyl chitosan-g-cholesterol succinic acid monoester (CCMC), and its structure was characterized by fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR). Particle size has an important impact on tissue distribution, cell uptake, permeability and inhibition of tumour tissue. In this study, particle size and polydispersity index (PDI) were selected as indexes to optimise the preparation process of CCMC nanomicelles through single factor experiment, Plackett-Burman experiment, the steepest climbing experiment and response surface design experiment. The optimised CCMC nanomicelles showed an average particle size of 173.9 ± 2.3 nm and a PDI of 0.170 ± 0.053. The Cell Counting Kit-8 assay showed no significant effect on cell viability in the range of 0-1000 μg ml-1concentration. Coumarin-6 (C6) was used as a fluorescent probe to investigate the drug-carrying ability of CCMC nanomicelles. C6-CCMC showed 86.35 ± 0.56% encapsulation efficiency with a drug loading of 9.18 ± 0.32%. Both CCMC and C6-CCMC demonstrated excellent stability in different media. Moreover, under the same conditions, the absorption effect of C6 in C6-CCMC nanomicelles was significantly higher than that of free C6 while also exhibiting good sustained-release properties. Therefore, this study demonstrates CCMC nanomicelles as a promising new drug carrier that can significantly improve insoluble drug absorption.

Quantifying the risk of medical evacuation in spaceflight

IntroductionTraditionally, NASA mission planners have used a heuristic and qualitative approach to design medical systems based on prior experience; however, this approach may result in implicit bias in design. The risk of needing to return to definitive care (RTDC) or medevac, has been particularly difficult to quantify due to the complexity of exploration spaceflight. The Informing Mission Planning through Analysis of Complex Tradespaces (IMPACT) tool is a probabilistic risk assessment approach designed by NASA to model medical risk in long duration spaceflight. This paper discusses how this tool can inform RTDC risk and improve the health and safety of astronaut crews. MethodsIMPACT was developed by subject matter experts using an evidence-based approach and can be used to quantify the risk of exceeding the onboard medical capabilities. Within the model, RTDC occurs when a condition meets a specific threshold that exceeds the on-board capabilities and requires a higher level of care. A notional lunar surface design reference mission (DRM) was modeled using IMPACT, and the RTDC rate was analyzed. ResultsOf the 119 medical conditions evaluated, thirty-four were preassigned to have zero probability of RTDC based on lack of acuity. Thirty-one conditions used the need for inpatient hospitalization or admission to intensive care as the RTDC surrogate. Twenty-six conditions used the probability of needing surgery, and ten conditions used treatment failure rates as the RTDC surrogate. The remaining 18 conditions had unique surrogates that did not fall into the above categories or were assigned a 100 % probability of RTDC due to their definition. In the sample DRM, the overall risk for RTDC was 0.32 events per mission. DiscussionQuantifying medical risk for human spaceflight is challenging but important in designing medical systems that support the health and performance of our astronaut crews. IMPACT can use the best available evidence to quantify the risk of an RTDC event based on mission parameters and help mission planners make informed design decisions. More work is underway to further refine the model and evidence that drives the RTDC calculation to improve model fidelity and utility for missions to the Moon, Mars, and beyond.

Controllable Regulation of MoS2 Surface Atomic Exposure for Boosting Interfacial Polarization and Microwave Absorption

AbstractAtomic‐level surface design of 2D materials, which benefits from their ultra‐high occupancy of surface atoms, has demonstrated significant potential for regulating electronic states. Despite efforts to explore heterojunctions on 2D surfaces, the stacking‐dominated surface electronic structures and their influences on dielectric polarization remain unclear. Herein, a confined growth strategy is proposed to accurately adjust the surface atom occupancy of MoS2 nanoflakes and thereby boost the polarization‐dominated microwave absorption (MA). By altering the stacking layer number from single layers to tens of layers of MoS2, the charge transfer from graphite substrate to MoS2 surface atoms, accompanied by the formation of local electric fields, reaches its highest intensity at two layers and then degrades dramatically with thicker MoS2 nanoflakes. The strengthened dielectric properties eventually enhance the MA performance, increasing the maximum absorption intensity (41.9 dB) by 346% and the effective absorption bandwidth (3 GHz) by 750%. These discoveries shed new light on the electronic modification of 2D materials and their electromagnetic functionalization.

Rewritable Surface-Grafted Polymer Brushes with Dynamic Covalent Linkages.

Surface grafting of polymer brushes drastically modifies surface properties, including wettability, compatibility, responsiveness, etc. A broad variety of functionalities can be introduced to the surface via different types of polymers. Bringing together properties of two or more types of polymer brushes to one surface opens up even more possibilities in brush-modified materials. However, while it is generally feasible to introduce several chemical compositions along the brushes via copolymerization, it is challenging to vary the types of polymer brushes along a surface. Although previous studies have demonstrated binary brushes via orthogonal polymerization techniques or partial deactivation/regrafting, they commonly limit the number of polymer types to two. Here, we propose a strategy to introduce dynamic covalent diketoenamine linkages at the root of polymer brushes. The grafting density could be precisely tuned during surface functionalization. The surface-anchored polymer brushes were cleaved by the addition of small molecule amines. New polymer brushes can be regrafted from the surface following refunctionalization of exposed sites. The maneuverability allows tuning of the types and densities of the polymer brushes, pointing the way to the preparation of a new generation of well-defined brush-modified materials with mixed grafts, with potential applications in the design of smart materials and surfaces.

Modelling of Flank and Crater Wear during Dry Turning of AISI 316L Stainless Steel as a Function of Tool Geometry Using the Response Surface Design

Modelling of Flank and Crater Wear during Dry Turning of AISI 316L Stainless Steel as a Function of Tool Geometry Using the Response Surface Design

Quadratic Bézier curve method for continuous freeform optical surface design

A novel approach is introduced for the design of freeform axisymmetric optical surfaces using an optimization technique based on quadratic Bézier curves. Notably, the continuity (or lack thereof) of the freeform surface produced using the proposed technique is largely unaffected by the source-target mapping function. The validity of the proposed methodology is demonstrated through its application to the design of several laser beam shapers. The results show that the proposed technique requires only a small number of structural points to converge to the optimum design solution. The freeform design method presented herein is mathematically straightforward and can be easily implemented in code. Thus, it offers significant advantages for the design and analysis of a diverse range of optical systems.

Optimization and clinical evaluation of hyaluronic acid proniosome loaded in-situ gel for the management of recurrent aphthous stomatitis

Recurrent aphthous stomatitis (RAS) is a frequent unpleasant oral condition that causes ulcers. Hyaluronic acid (HY) is an inherent polymer owing antioxidant, anti-inflammatory, and anti-bacterial patterns. D-optimal response surface design was used to investigate the impact of surfactant type (Span 80 or Brij®35) and the concentration of HY (0.5 % or 1), on three selected dependent variables: zeta potential (ζ, ZP, R1), particle size (PS, R2), and entrapment efficiency (%EE, R3). The optimized HYPN was then loaded in thermosensitive in-situ gel. The clinical efficacy in patients with RAS was evaluated by measuring the improvement in pain levels (using the Visual Analog Scale), reduction in ulcer size, enhancement in quality of life (measured by OHIP-14 scores), and analysis of pro-inflammatory Tumor Necrosis Factor Alpha (TNF-α) and total antioxidant capacity (TAC) in saliva samples. The optimized formula obtained a mucoadhesive strength of 26 ± 1.76 N/m2. A burst release of 38 ± 1.56 % after 2 h was obtained followed by 80 ± 2.21 % till 24 h, with a transbuccal flux (Jss) 425 ± 7.9 μg/h.cm2. Clinically, a significant difference (P ≤ 0.001) in pain scores, ulcer diameter, OHIP-14 scores, TAC, and TNF-α between the in-situ gel containing HYPN and the placebo gel was found. The mean values for the number of recurrences at 6 months follow-up were 2.55 ± 1.13 and 4.63 ± 1.75, respectively, before and after treatment. The thermosensitive mucoadhesive in-situ gel seems to be a promising therapeutic choice for RAS treatment.

Application of Hydrothermal Synthesized Titanium Dioxide-Doped Multiwalled Carbon Nanotubes on Filtration Properties-Response Surface Methodology Study.

The success of any drilling activity mainly depends on the characteristics of the drilling fluid. Therefore, a high-performance drilling fluid is substantial for any drilling operation. During overbalance drilling operations, the drilling mud invades the permeable formations and causes the loss of circulation, which is responsible for nonproductive time events. Hence, the filtration characteristics of the drilling mud are an imperative property. The purpose of this study is to evaluate the filtration characteristics of water-based mud systems in the presence of polyanionic cellulose (PAC) and multiwalled carbon nanotubes (MWCNTs)/TiO2 nanoparticles. The nanoparticles were synthesized by using the hydrothermal technique. For the first time, a composite of MWCNTs and TiO2 has been utilized as a fluid loss control additive in the petroleum sector, marking a significant development in the field. The filtration properties of water-based mud were assessed at two concentrations (0.35 g and 3.5 g). Furthermore, based on the two levels (concentrations) and two factors (particles), the novel application of the central composite response surface design of experiment (CCD) was implemented. The results showed that the predicted model from CCD was in good agreement with the filter press experimental result with R 2 = 0.8446. Furthermore, based on the ANOVA analysis, the concentration of MWCNTs/TiO2 nanoparticles was the most significant parameter with p-value < 0.05. In addition, 10 out of 13 experimental points fall under the ±10% error window, thus indicating a higher accuracy of the regression model. The 2D interactive plots further show that the concentration of PAC is insignificant and has no considerable influence on fluid loss control, which was also validated by p-value > 0.05. The performance of MWCNTs/TiO2 nanoparticles is superior to PAC because these nanodimension particles plug the pore-spacing and block the permeation channels on the filter paper. However, the PAC, because of its long molecular chain, entangles around the pore spaces and plugs the microsize pores, which eventually reduces the filtration loss volume up to some extent. By observing the synergistic interaction between MWCNTs/TiO2 nanoparticles and PAC, this study develops valuable insights that assist in improving the performance of drilling fluid and minimizes the wellbore instability issues in the oil and gas sector.

Biphilic Functional Surfaces for Frost Prevention and Efficient Active Defrosting

AbstractThe present work addresses the systematic accurate fabrication and design of biphilic surfaces having superhydrophobic circular islands surrounded by a hydrophilic background by investigating their condensation frosting and defrosting behavior. A significant delay in frost formation is observed on samples with higher superhydrophobicity ratio A*, defined as superhydrophobic area to total area ratio. As the superhydrophobic island diameter D increases from D = 500 µm to D = 700 µm (A* from 19.62% to 38.46%), a 50% improvement/delay is observed in terms of frost formation or densification. Besides delaying icing/frosting, the presence of superhydrophobic areas empowers the formation of porous and nonuniform frost structure, which facilitates ice removal during the defrosting process. To this end, as the surface is recovered the ambient temperature, almost complete passive cleaning performance within only 23 s is observed on the biphilic design having superhydrophobic islands with the diameter of D = 500 µm, that is, a superhydrophobicity ratio A* of 19.62%. This work concludes on the optimum biphilic ratio, which is not only effective as a passive method by hindering frosting but also leads to a slush/water free surface after defrosting eased by the Laplace pressure gradient which is imposed by the different biphilic wettability patterns.

Posterior capsule opacification with two similar-design hydrophobic acrylic intraocular lenses: 3-year results of a randomized controlled trial.

To compare intraindividually the incidence and intensity of posterior capsule opacification (PCO) and Nd:YAG capsulotomy rates between two similar open-loop single-piece hydrophobic acrylic intraocular lenses (IOLs) differing slightly in their particular material, optic surface and sharp posterior edge design over a period of 3 years. Department of Opthalmology, Medical University Vienna. Randomized, prospective, patient- and examiner-masked clinical trial with intraindividual comparison. 100 patients randomly received a Vivinex XY1 IOL in one eye and a Clareon CNA0T0 IOL in the fellow eye. The amount of PCO (score: 0 - 10) was assessed subjectively and objectively with digital retroillumination picturs using automated image analysis software (AQUA). Best-corrected distance visual acuity (CDVA) as well as the presence of glistenings, subjective visual symptoms and Nd:YAG laser capsulotomy rate were noted. 67 of 100 patients were available for the 3-years follow-up examination. The objective PCO score of the Vivinex XY1 IOLs was 1.0 ± 1.0 compared to the PCO score of 1.5 ± 1.2 for the Clareon CNA0T0 IOLs (p < 0.001). 7.5% of patients had a neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy in the Vivinex XY1 eye, and 9.0% had a capsulotomy in the Clareon CNA0T0 eye (p = 1.0). Both hydrophobic acrylic IOLs showed low PCO and YAG rates with a small but significant favor of the Vivinex XY1 IOL compared to the Clareon CNA0T0 IOL. The interaction of various factors such as hydrophobic material, smooth optic surface and sharp posterior optic edge is the major key for PCO prevention.

Extraction of Omega-3 Fatty Acids from Atlantic Sea Cucumber (Cucumaria frondosa) Viscera Using Supercritical Carbon Dioxide.

This study explores the potential of Cucumaria frondosa (C. frondosa) viscera as a natural source of omega-3 FAs using supercritical carbon dioxide (scCO2) extraction. The extraction conditions were optimized using a response surface design, and the optimal parameters were identified as 75 °C and 45 MPa, with a 20 min static and a 30 min dynamic extraction, and a 2:1 ethanol to feedstock mass ratio. Under these conditions, the scCO2 extraction yielded higher FAs than the solvent-based Bligh and Dyer method. The comparative analysis demonstrated that scCO2 extraction (16.30 g of FAs/100 g of dried samples) yielded more fatty acids than the conventional Bligh and Dyer method (9.02 g, or 13.59 g of FAs/100 g of dried samples with ultrasonic assistance), indicating that scCO2 extraction is a viable, green alternative to traditional solvent-based techniques for recovering fatty acids. The pre-treatment effects, including drying methods and ethanol-soaking, were investigated. Freeze-drying significantly enhanced FA yields to almost 100% recovery, while ethanol-soaked viscera tripled the FA yields compared to fresh samples, achieving similar EPA and DHA levels to hot-air-dried samples. These findings highlight the potential of sea cucumber viscera as an efficient source of omega-3 FA extraction and offer an alternative to traditional extraction procedures.

NJmat: Data-Driven Machine Learning Interface to Accelerate Material Design.

Machine learning techniques have significantly transformed the way materials scientists conduct research. However, the widespread deployment of machine learning software in daily experimental and simulation research for materials and chemical design has been limited. This is partly due to the substantial time investment and learning curve associated with mastering the necessary codes and computational environments. In this paper, we introduce a user-friendly, data-driven machine learning interface featuring multiple "button-clicking" functionalities to streamline the design of materials and chemicals. This interface automates the processes of transforming materials and molecules, performing feature selection, constructing machine learning models, making virtual predictions, and visualizing results. Such automation accelerates materials prediction and analysis in the inverse design process, aligning with the time criteria outlined by the Materials Genome Initiative. With simple button clicks, researchers can build machine learning models and predict new materials once they have gathered experimental or simulation data. Beyond the ease of use, NJmat offers three additional features for data-driven materials design: (1) automatic feature generation for both inorganic materials (from chemical formulas) and organic molecules (from SMILES), (2) automatic generation of Shapley plots, and (3) automatic construction of "white-box" genetic models and decision trees to provide scientific insights. We present case studies on surface design for halide perovskite materials encompassing both inorganic and organic species. These case studies illustrate general machine learning models for virtual predictions as well as the automatic featurization and Shapley/genetic model construction capabilities. We anticipate that this software tool will expedite materials and molecular design within the scope of the Materials Genome Initiative, particularly benefiting experimentalists.

Optimizing the Extraction of Protein from Defatted Schizochytrium Cell Residues and Studying the Emulsification Characteristics of Protein

In this study, proteins were prepared from Schizochytrium pombe residue after oil extraction using isoelectric point precipitation, and their physicochemical and emulsifying properties were investigated. Our objective was to assess the suitability of these proteins for functional ingredient applications. Through a one-way experiment and optimization using response surface design, the effects of time, temperature, pH, and the material–liquid ratio of NaOH alkaline extraction were explored. The isoelectric point is verified by isoelectric point precipitation; the results revealed that crude protein from Schizochytrium (SCP) is minimally soluble at pH 4.2. Compared with whey protein (WP), it promotes better emulsion stability through the emulsification test. This study suggests that Schizochytrium oil-processing byproducts represent a promising source of protein, with potential applications as functional ingredients, offering implications for the usage of these byproducts in various industries.

Calculation of apparent contact angle for sessile droplets on structured hydrophobic surfaces based on dynamic of contact line during droplet formation

The sessile-droplet method is widely used to characterize surface wettability, however, the measured apparent contact angle (APCA) is usually a non-unique value between the advancing and receding contact angles, which seems hardly to be predicted by the classical Cassie-Baxter model. Thus, a reliable calculation model for APCAs of sessile droplets on structured hydrophobic surfaces is needed to guide the structural design of functional hydrophobic surfaces. Focusing on the force and motion analysis of the contact line during the formation process of sessile droplets, a theoretical model was developed to calculate the APCA of the droplet on hydrophobic surfaces featured with square micropillar arrays. The present model considers the synergistic effect of the droplet shape and the contact-line pinning on the APCA. Compared with the Cassie-Baxter model, the APCAs calculated by the proposed model agree better with the experimental data. This study shows that APCA is generally more susceptible to advancing contact angle, which is not significantly different on structured hydrophobic surfaces with different dimensions, resulting in the inability of APCA to accurately characterize surface wettability. As a complement, receding-contact-angle and adhesion-force measurements, which can reflect the effects of structural dimensions, are recommended to be adopted to characterize surface wettability.

(Invited) Novel Brush Design for Post CMP Cleans

Chemical Mechanical Polishing (CMP) process is one of the key processes in semiconductor wafer processing. A sub 10nm wafer fabrication process may require more than 40 dielectric and metal CMP steps. As CMP process requirements get more stringent, CMP slurries are formulated with smaller and smaller metal oxide abrasive particles. The abrasive particles may also be surface modified or doped with other metal oxides. Post CMP cleaning chemistry formulations are designed to remove polish byproducts, pad residues and abrasive particles from wafer surface. Chemical composition and PH are tuned for modulating wafer surface-particle interactions so brushes can mechanically “sweep” them off the surface. PVA brushes, used of post CMP cleans, are a highly porous network of crosslinked polyvinyl acetate with pore size in the range of 30 – 100 um and 80% - 90% porosity, depending on the type of brush being used. While PVA brushes have largely met the process capability requirements, they have limitations for advanced cleans such as nano-particle removal. As CMP process continues to expand to new dielectric and metal films for different process steps in wafer fabrication, there is a need for customized brush material and surface design for optimal cleaning efficiency.We discuss a new engineered post CMP brush design that shows high efficiency in nano-particle cleans and allows high level of material tunability. New brush design is an engineered composite with an open cell microporous core, overlaid with engineered fibers in form of loops. Brush design is compatible with existing post CMP cleans. Figure 1(a) shows the new design, where in DIW enters the brush through the center of microporous core and flows outwards to the surface. As water exits the surface, it flows over and across the loops and contacts the wafer surface. Flow resistance through core and loops can be independently tuned, which allows better fluid distribution and more effective cleans. Figure 1(b) show a close-up schematic of interaction between loop and particle. Flexing of the loops on brush surface provides improved contact as well as cleaning ability Brush design can be optimized for chemical and mechanical properties with choice of fiber material, fiber diameter and loop height. Figure 2 shows the Zeta potential of PVA and different loop materials. The fiber material maybe selected such that zeta potential of the loops can enhance mechanical action in removing particle. Mechanical action of the Loops can be modeled as a cantilever and force on the particle is exerted by flexing of the loops.Deflection of loops can be approximated with flexure stiffness of rods with point load at free end. For initial purposed loop is approximated as single element. The equation can be rewritten to calculate cleaning force P at the free end for given loop deflection (Y), P = 3EIY/L3 (1)Where E is elastic modulus, I = moment, L = length of fiber and for rod shapes; I = Pi*(r4/4)The adhesion of particles on the surface is due to the effect of van der Waals and electrostatic forces. The total adhesion force on the surface can be written as: F=F vdw + F edl (2) where Ft is total adhesion force, Fvdw is the van der Waals force, and Fedl is the electrostatic force.Fvdw = AR/6r2 (3)Where A is the Hamaker constant, R is particle radius, r is the separation distanceFor effective removal of particles, P >/= F (4)Flex force and adhesion force were modeled based on equation (1) and (3) and are shown in Figure 3. New brush design was used for post CMP cleaning of silicon dioxide wafers polished with ceria slurry. Two different brush designs were tested for cleaning efficiency. Modeling data and comparison with experimental results is presented. Figure 1