Patch Width Research Articles

Stabilizing quasicrystals composed of patchy colloids by narrowing the patch width

We explore the behavior of two-dimensional patchy colloidal particles with 8 or 10 symmetrically arranged patches by employing Monte Carlo simulations. The particles interact according to an isotropic pair potential that possesses only one typical length. The patches lead to additional attractions that are anisotropic and depend on the relative orientation of two neighboring particles. We investigate the assembled structures with a special interest in quasicrystals. We found that the patch width is of great importance: Only in the case of narrow patch widths we are able to observe metastable octagonal and decagonal quasicrystals, while dodecagonal quasicrystals can also occur for broad patches. These results are important to understand the role of interactions with preferred binding angles in order to obtain quasicrystals. Our findings suggest that in the case of sharp binding angles, as they occur in metallic alloys, octagonal and decagonal symmetries might be observed more often than in systems with less sharp binding angles as it is the case in soft-matter systems where dodecagonal quasicrystals dominate.

Characterization of corrosion morphologies from deteriorated underground cast iron water pipes

AbstractFollowing the completion of the Advanced Condition Assessment and Pipe Failure Prediction project in Australia, it has emerged that cast iron pipes normally experience corrosion damages extending over the large spatial area that resemble a patch, and structural failures are commonly associated with these patches. In this study, we defined a corrosion patch as a cluster of individual defects within or less than the one‐wall‐thickness distance of each other and conducted a morphometric study on patches from several deteriorated cast iron pipes. It was found that the size parameters, viz., the patch length, width, area, and volume potentially attain steady‐state progression over long‐term deterioration and are consistent with current understanding in underground corrosion. The rectangularity, convex deficiency, and solidity shape parameters were found to be related to each other and could be described by power‐law functions. Moreover, the analysis of two‐dimensional (D2D) and three dimensional (D3D) fractal dimension parameters revealed that they serve as useful proxies for different patch properties. In particular, the D3D revealed linear trends with the patch aspect ratio and an ability to delineate between failed and in‐service pipes. It is expected that the results from this study will serve as important baseline information for future works aiming to generate and implement realistic corrosion patches for pipe structural integrity analysis.

Axial Ratio and Gain Enhancement of a Circular-Ring Slot Antenna Using a Pair of Asymmetrical Rectangular Slots and a Parasitic Patch for a Radio Beacon on a Nanosatellite

Radio beacons enable measurements of ionospheric radio scintillations and total electron content (TEC). These beacons transmit unmodulated, phase-coherent waves in S-band frequencies. Many satellite applications require circularly polarized (CP) wideband antennas. Their compact size, lightweight, and simple fabrication method make CP antennas suitable for small satellite systems. The slot antenna has wideband impedance, but the 3 dB axial ratio bandwidth (ARBW) is narrower compared to the impedance bandwidth (IBW). In this paper, a circularly polarized circular-slotted antenna (CSA) is proposed to enhance the ARBW and the antenna gain. A pair of asymmetrical rectangular slots, a simple 50 Ω feedline and a parasitic patch were introduced to a CSA to enhance the 3 dB ARBW and the antenna gain. Rectangular slots were inserted on the diagonal axis of the CSA, the feedline was shifted to the left side of the x-axis, and a parasitic patch was attached to the circular slot. The lengths of the rectangular slots correspond to the resonant frequency, and the parasitic patch width corresponds to the higher frequency of the 3 dB ARBW. The asymmetrical rectangular slots, the shifted feedline, and the parasitic patch successfully improved the measured 3 dB ARBW of the antenna by 787.5 MHz or 35.79%. The measured gain of a CSA with left-hand circular polarization (LHCP) was also improved by shifting the feedline and the rectangular slot, achieving a peak gain of 5 dBic.

Numerical investigation of the flow characteristics through discontinuous and layered vegetation patches of finite width in an open channel

In this study, a computational method is used to investigate the flow properties and turbulence characteristics through discontinuous and vertically double layered vegetation patches of finite width in an open channel. A three dimensional Reynolds stress turbulence model was implemented utilizing FLUENT (ANSYS). After the validation of the numerical model, flow characteristics were investigated against varying vegetation density (St/d and Ss/d, where St = spacing between taller vegetation elements, d = diameter of vegetation, Ss = spacing between smaller vegetation elements) and vegetation patch width. Various profiles and contour plot distributions of mean stream-wise and depth averaged velocities, turbulent kinetic energy and turbulent intensities at specified critical locations and sections simulated by the model are presented in this paper. In almost all the cases, mean stream-wise velocities directly behind the smaller and larger vegetation elements showed fluctuations, with sharp inflection points at the top of the smaller vegetation elements. Velocities were amplified above the vegetation zones, whereas deceleration in the velocity magnitudes was observed within the vegetation zones i.e., below the top of vegetation. Inside the vegetation patch zones, the turbulent intensity was higher as compared to that in the gap zones. The turbulent intensity was increased for dense vegetation case (St/d = 6.66 and Ss/d = 3.34) as compared to that of sparse arrangement of vegetation (St/d = 10 and Ss/d = 5). Hence, a clear difference in flow characteristics between the vegetated and non-vegetated zones was observed.

Self-Assembly Mechanisms of Triblock Janus Particles.

We present a detailed model to study the nucleation of triblock Janus particles from solution. The Janus particles are modeled as cross-linked polystyrene spheres whose poles are patched with sticky alkyl groups and their middle band is covered with negative charges. To mimic the experimental conditions, solvent, counterions, and a substrate, on which the crystallization takes place, are included in the model. A many-body dissipative particle dynamics simulation technique is employed to include hydrodynamic and many-body interactions. Metadynamics simulations are performed to explore the pathways for nucleation of Kagome and hexagonal lattices. In agreement with experiment, we found that nucleation of the Kagome lattice from solution follows a two-step mechanism. The connection of colloidal particles through their patches initially generates a disordered liquid network. Subsequently, orientational rearrangements in the liquid precursors lead to the formation of ordered nuclei. Biasing the potential energy of the largest crystal, a critical nucleus appears in the simulation box, whose further growth crystallizes the whole solution. The location of the phase transition point and its shift with patch width are in very good agreement with experiment. The structure of the crystallized phase depends on the patch width; in the limit of very narrow patches strings are stable aggregates, intermediate patches stabilize the Kagome lattice, and wide patches nucleate the hexagonal phase. The scaling behavior of the calculated barrier heights confirms a first-order liquid-Kagome phase transition.

Dual-Band Slim Microstrip Patch Antennas

This paper presents a planar dual-band slim microstrip patch antennas. The antenna comprises four sections: patch and shorting, centered, and offset pins with the overall size of $30\times50$ mm2. It is shown that the centered and offset pins help to improve antenna matching while providing efficient radiation performance. With the aid of shorting pins, lower band operation at 1900 MHz is achieved. Moreover, the higher frequency band is expanded from 3480 to 3570 MHz. Simulations show that at the lower band frequencies, the antenna gain and efficiency are 1.0 dBi and 28%, respectively. On the other hand, at the upper frequency band, the antenna maximum gain is 2.4 dBi, and the efficiency of at least 25% is observed. The numerical simulation shows that the number of resonant frequencies is directly related to the patch width. In order to validate the simulation results, a prototype of the proposed antenna is fabricated and measured. Good agreement has been achieved between the simulation and measurement results.

A Low-Profile Differential-Fed Patch Antenna With Bandwidth Enhancement and Sidelobe Reduction Under Operation of TM10 and TM12 Modes

A low-profile differential-fed microstrip patch antenna (MPA) using TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> modes is proposed in this communication toward simultaneously achieving the impedance-bandwidth enhancement and sidelobe reduction. Based on the transmission-line model, the radiation patterns of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode of the MPA loaded with shorting pins and slots are at first deeply investigated. The results demonstrate that the E-plane sidelobe could be gradually reduced by lowering the resonant frequency of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> ) less than two times of the fundamental frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ). After that, the two adjacent TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> modes of the MPA are relocated to resonate in proximity to each other for bandwidth improvement and sidelobe reduction. By inserting the shorting pins underneath the radiating patch, f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> is progressively pushed up with a slight effect on that of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> mode (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> ). Then, the patch width is enlarged with the parallel slots etched out on it to move f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> closely to f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> . Moreover, a narrow slot is etched at the center of the patch for good impedance matching. With these arrangements, f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> /f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> can be decreased dramatically to about 1.27. Finally, the antenna prototype is fabricated and measured. Experimental results show that the impedance bandwidth of the MPA is tremendously extended to about 10%, while keeping a low profile of 0.039 free-space wavelength. In particular, the sidelobe level of the antenna is dramatically reduced to about -12 dB.

La Sal Daisy,Erigeron mancus,Density and Associated Species from Treeline Ecotone and Alpine Habitats

The La Sal daisy, Erigeron mancus, is endemic to treeline ecotone and alpine meadow habitats of the La Sal Mountains in Utah, an insular, laccolithic mountain range on the Colorado Plateau in southeastern Utah. From 2009 to 2011 we established elevational transects through upper spruce-fir forest, treeline ecotone, and alpine meadow habitats on Laurel Ridge in the Middle Mountain group of the La Sal Mountains to measure (1) periodic changes in E. mancus population density, (2) changes in the elevation of the E. mancus population centroid, (3) changes in patch size occupied by E. mancus, and (4) changes in frequency of occurrence in herbaceous plant species associated with E. mancus along these transects. We measured both E. mancus density and vascular plant species composition within 1-m × 1-m square frames in mid-July, near peak alpine plant flowering time. The E. mancus population density on Mt. Laurel ridge did not significantly change from 2009 to 2015, but the species was most abundant in alpine meadow habitat for both years. Changes in patch width, centroid elevation, and frequency of occurrence of 30 associated plant species were also not statistically significant. Like E. mancus, most species show changes in frequency of occurrence between upper spruce-fir forest, treeline ecotone, and alpine meadow habitats. Individual plants of E. mancus are probably long-lived perennials, so changes in population density and distribution due to global warming are expected to be gradual and/or have an unknown lag time. Although there is no evidence of ongoing change in the Laurel Ridge population of E. mancus, having this information will provide a solid statistical basis for determining significant future changes.

Prototype of Slotted Microstrip Patch Antenna for Multiband Application

In this paper a slotted microstrip patch antenna has been designed that works for two frequencies 1.42GHz and 2.65GHz. Since a microstrip patch antenna works only on one resonant frequency so converting that into a multiband patch antenna would enhance the bandwidth and also utilizes the multiple frequencies of operation. This multiband slotted patch antenna is fabricated on FR4 lossy dielectric substrate whose dielectric constant is 4.3 and height is 1.6mm. The length and width of patch are taken as 51.16mm and 39.86mm respectively. we cut out the slots so that the patch antenna works at multiple frequencies. Another advantage of presented design is it reduced the size of antenna actually required for 1.42GHz frequency. Simulation and analysis of slotted patch antenna is done by CST software. Simulation and fabrication results show that the presented antenna design characteristics meet with the standard characteristics of antenna.

The function of the modified novel 0.1 mm polytetrafluoroethylene hand-made valved conduit through the hydrodynamic test in vitro

Objective 0.1 mm polytetrafluoroethylene (PTFE) has been comfirmed to be better biocompatibable comparing to the bovine pericardium. The study aims to explore the appropriate hand sewed way for the 0.1 mm PTFE conduit and to assess the function through the hydrodynamic test in vitro. Methods The modified novel 0.1 mm PTFE hand-made valved conduit was tested with different size of 0.1 mm PTFE patch under TH-2200 machine in vitro. The 19 mm valved conduits were divided group A and B according to different width and lenth of 0.1 mm PTFE patch, comparing to the traditional bioprosthetic valve as group A0 and B0 relatively. In group A, the circumference of the conduit (π×d) mm was defined as the lenth of PTFE patch while (0.65×d+ 0.74) (mm) or (0.84×d) (mm) as width differently (group A1, group A2). In group B, the appropriate width was defined as the width of PTFE patch while π×d (mm) or (1.2π×d) (mm) as length differently (group B1, group B2). Then 14mm, 16mm and 22 mm valved conduits were made with the appropriate width and length from perious study to get tested as well as 19 mm conduits. Results Under the flow of 2, 3, 4, 5L/min, Gradiant pressure (ΔP) in group A1 and A2 was a little bit higher than A0. But there is no significant difference on effective orifice area (EOA) among A1, A2 and A0. The regurgitation fraction (RF) of group A2 is less than A1, but still more than A0 which showed (0.84×d) (mm) width was better than (0.65×d+ 0.74) (mm). There was no significant difference on ΔP and EOA between B1 and B2. But RF of B2 was much lower than B1, even better than B0, which showed (1.2π×d) (mm) length was better than (π×d) (mm) length. The 14, 16, 19 and 22 mm valved conduits made with (0.84×d) (mm) width and (1.2π×d) (mm) also showed low ΔP and few regurgitation. Conclusion Modified novel 0.1 mm PTFE hand-made valved conduits play a satisfying role on anti-regurgitation with the (0.84×d) (mm) width and (1.2π×d) (mm) length PTFE patch. Key words: Expanded polytetrafluoroethylene; In vitro; Handmade; Valve function

Empirical Stress Intensity Factor Equations for Cracked Steel Plates Repaired with Double-Sided FRP Patches

This paper presents an approach that combines the finite element (FE) modeling and genetic programming (GP) to provide accurate empirical stress intensity factor (SIF) equations for center-cracked steel plates repaired with adhesive-bonded double-sided fiber-reinforced polymer (FRP) patches. Several past studies in recent years independently showed that the reduction on the SIF of cracked structures after the patch repair is dependent on many factors such as bonding techniques, material parameters, geometric parameters, environmental factors. In this study, the SIF of the repaired cracked steel plate was considered to be a function of seven parameters including the crack length, elastic modulus of FRP material, shear modulus of adhesive material, dimensions (width, length, and thickness) of rectangular FRP patches, and thickness of adhesive layers. Empirical SIF equations were created by the data mining process of genetic programming analyses performed on a database created from the FE results. The SIF values obtained from these equations were also compared with an analytical equation to assess whether their ability to perform well on a certain design or not. It was found that the proposed SIF equations fitted well with the FE results as the squared Pearson correlation coefficients R2 are higher than 0.9. In addition, the correlations between proposed equations and the analytical equation are approximately 0.8.

Sidelobe-Reduced and Gain-Enhanced Square Patch Antennas With Adjustable Beamwidth Under TM03Mode Operation

A square patch antenna operating under TM03 mode is proposed in this paper to realize gain enhancement, sidelobe reduction, and adjustable beamwidth by reshaping the surface current distribution on the patch resonator. On the one hand, by introducing transverse slots along the central line of patch, the medial part of out-of-phase longitudinal current is interrupted to circulate with little radiation. In this way, the patch serves as a full-wave dipole rather than a $3\lambda $ /2 one, and thus, the sidelobe level (SLL) in the E-plane is substantially reduced. On the other hand, the slots are installed in proximity to the nonradiative edges and at the patch center, respectively, to arouse distinctive effect on the current densities across the width of patch. Consequently, the beamwidth in the H-plane can be freely adjusted by different configurations of these slots. At last, a square patch antenna with three cascaded slots loaded along the central line is designed, fabricated, and tested. The simulated and measured results show that the directivity of a single proposed patch antenna can achieve as high as 13.3 dB with the SLL reduced to about −20 dB.

Effects of gravity on the thermo-hydrodynamics of moving contact lines

In this paper, we demonstrate the effects of gravity on the interfacial thermo-hydrodynamics as modulated by the patterned wettability gradients placed on the surfaces of a narrow fluidic channel. We investigate the dynamics of contact line motion of two-component incompressible immiscible liquid mixtures under the framework of a thermodynamically consistent phase field model. We validate our model with the experimental results available in the literature in the purview of thermocapillary-actuated microscale transport. We show that the gravity-induced forces in the presence of the thermocapillarity effect play a unique role on the interfacial dynamics at small scales, leading to a uniform movement of the interface in the channel, and offer a greater degree of controllability in the filling/wetting rate in the capillary. We show that the change in patch width, placed on the walls of the channel, leads to a change in the filling dynamics into the capillary. Also, we investigate the rate of different dissipations during the movement of the contact line along the channel and show that the kinetic energy modulated dissipation provides maximum energy to the motion of the contact line.

Modeling and optimization of EBG structure using response surface methodology for antenna applications

Electromagnetic Bandgap (EBG) structures are widely used with microstrip antennas for improving antenna efficiency due to their ability to suppress surface waves. To have proper control of surface wave band-gap, it is necessary to have efficient models of the dispersion characteristics of EBG in the irreducible Brillouin zone. A new methodology for optimization of a modified mushroom EBG is presented, based on Response Surface Modeling (RSM) along with Design of Experiments (DoE). Four geometrical parameters which control the surface wave band gap namely the patch width (w), gap between the patches (2g), via radius(r) and the slot width(s) are considered as independent factors and DoE is carried out using Finite Element Analysis (FEA) simulation. The lower (F1) and upper (F2) frequencies of the band gap are extracted from the dispersion characteristics. Mathematical models for F1 and F2 are developed using non-linear regression analysis. Analysis of Variance (ANOVA) is used to study the effect of EBG parameters on the stop band frequencies. The optimum EBG parameters for a stop band in 5–8 GHz frequency range are determined and are found to be: patch width, 6.48 mm, gap, 0.49 mm, via radius, 0.25 mm and slot width, 0.48 mm. The statistical model is validated by experimental results.

Tuning rectangular microstrip antenna through scan and zoom algorithm

Microstrip antennas have been widely studied and can be applied to a large number of wide frequency domain in wireless communication. Microstrip antennas are featured with light weight, small volume, and low cost advantages. Planar or spatial structures could substantially affect the frequency reliability and sidelobe level of microstrip antennas. Designing high performance microstrip antennas requires the tuning of the length and width of microstrip patch, the equivalent permittivity, the feed position of the coaxial line, and so on. Although electromagnetic theory could provide a solution for antenna design, such solution is probably not optimal solution due to complex environment and the affection of multiple factors. This paper attempts to tuning the design of microstrip antennas by using scan and zoom algorithm. It does not require derivative information of antenna model. This algorithm consists of search space scan and search domain zoom stages. The effectiveness of the scan and zoom algorithm is firstly tested on mathematical functions. The algorithm is then verified on rectangular microstrip antenna design. Compared with theoretical solution, the novel algorithm attains better design solution. The algorithm can also be easily extended to tackle other antenna design problems.

Variations Of Wide Band E-shape And U-slot Cut Rectangular Microstrip Antennas

Wide band designs of E-shape and U-slot cut Rectangular Microstrip antennas are discussed which yields bandwidth of 207 (23%%) and 174 (19%) MHz, respectively. For further bandwidth enhancement, various designs of E-shape and U-slot cut rectangular patch antenna with tapered patch width are proposed. Tapering in patch width alters the input impedance at TM10 mode in E-shape patch and at TM10 and TM02 modes in U-slot cut rectangular patch that yields increase in the bandwidth. Tapered design of E-shape patch gives bandwidth of 225 MHz (~26%) and that of U-slot cut patch yields bandwidth of 202 MHz (~22%). In another tapered width design of E and U-slot cut RMSAs, patch width is reduced at both the ends and these designs yields bandwidth of above 270 MHz (29%) and 212 MHz (22.2%), respectively. The varying width patches exhibit broadside radiation pattern with moderate increment in the values of broadside antenna gain.

On The Design of Array Microstrip Antenna with S-Band Frequency for Radar Communication

The research aims to design the prototype of microstrip array antenna with S-Band frequency for radar communication. The design methodology has done in several stages. The first stage was conducted the calculation of antenna parameter using manual calculation. The parameters are simulated using Computer Simulation Technology (CST). The optimization processes have done by various parameters are patch width, patch length, and the distance between patches. After finding the best result, the antenna was implemented and the parameter values are tested in the laboratory and compared with the simulation result. The simulation result showed that antenna performance at 3 GHz frequency with 7,07 dB gain, value VSWR 1.0272176, return loss -37,441025, and bandwidth 163,7 MHz the implementation of array microstrip antenna has size 210 × 84.5 mm, with parameter worked on the frequency of 3.04 GHz with gain value 8.6 dB, VSWR 1.068, return loss -29.790, and the bandwidth of 120 MHz. Its showed that the fabrication antenna can work on S-Band frequency as well as the research purpose.

Sampling Strategies and Soil Characteristics for Estimation of Plant Patches Dimensions (Case Study: Inchebroun Rangelands, Golestan Province, Iran)

ABSTRACTSurvey and monitoring rangelands projects is one the important plans in rangelands management. For this purpose, the survey and monitoring methods could be time-consuming and costly. Sampling strategies of plant patches are effective in sampling procedures that cause minimizing sampling variance and time. In this study, for decreasing sampling time and cost, increasing speed, plant patches parameters (including length, width, height, area, and distance between the patches) were compared. Three transects with 50 m length at three aspect slopes were located randomly systematic at the selected site with different grazing intensities. Soil samples for nitrate (NO3−), total nitrogen (TN), ammonium (NH4+), phosphorus (P), sodium absorption ration (SAR), soil acidity or soil reaction (pH), sodium (Na), electrical conductivity (EC), organic carbon (OC), and potassium (K) content were taken in these transects. The data were subjected to analysis of variance (ANOVA), and the average of the measured parameters in the transects was compared by Duncan Multiple Range test using SPSS16 software. The soil characteristics compared between the regions were analyzed with Discriminant Function Analysis using STATISTICA10 software. Results showed that the transect slope aspect and soil characteristics had an effect on measured parameters. It was suggested to withdraw the located transect at one of the North or South and West or East Slope aspects for increasing sampling efficiency. It was also suggested that to avoid time consumtion, sampling can be recorded on plant patches’ width instead of area. It is also suggested that it would be better to record the length of the plant patches instead of their area in the non-grazed zones and record the length and the width of the plant patches in the moderate- and the high-grazed zones.

Tuning Patchy Bonds Induced by Critical Casimir Forces.

Experimental control of patchy interactions promises new routes for the assembly of complex colloidal structures, but remains challenging. Here, we investigate the role of patch width in the assembly of patchy colloidal particles assembled by critical Casimir forces. The particles are composed of a hydrophobic dumbbell with an equatorial hydrophilic polymer shell, and are synthesized to have well-defined patch-to-shell area ratios. Patch-to-patch binding is achieved in near-critical binary solvents, in which the particle interaction strength and range are controlled by the temperature-dependent solvent correlation length. Upon decreasing the patch-to-shell area ratio, we observe a pronounced change of the bonding morphology towards directed single-bonded configurations, as clearly reflected in the formation of chain-like structures. Computer simulations using an effective critical Casimir pair potential for the patches show that the morphology change results from the geometric exclusion of the increasingly thick hydrophilic particle shells. These results highlight the experimental control of patchy interactions through the engineering of the building blocks on the way towards rationally designed colloidal superstructures.

Parametric Study of an Electroosmotic Micromixer with Heterogeneous Charged Surface Patches.

A T-shaped micromixer featuring electroosmotic flow with heterogeneous charged surface patches on the channel walls was analyzed, and an improved design was proposed to enhance mixing performance. Numerical analysis was performed using steady Navier-Stokes equations with an additional electrokinetic body force. The numerical results for species concentration were validated with available experimental data. A parametric analysis of the micromixer was performed by varying channel height, channel width, patch width, and externally applied voltage. The effects of these parameters on the flow structure and mixing performance were analyzed in detail. A quantitative measurement based upon the mass variance was employed to quantify the mixing performance. Numerical results of the parametric study were used to propose an improved micromixer design with spacing between adjacent charged patches. The proposed design provided a more favorable flow structure to allow for enhanced mixing performance.