Monodisperse Spheres Research Articles

Photonic glass based structural color

Structural coloration, which is based on spectrally selective scattering from optical structures, has recently attracted wide attention as a replacement of pigment colors based on the selective light absorption in chemical structures. Structural colors can be produced from transparent non-toxic materials and provide high stability under solar radiation. To provide angle independent non-iridescent colors, the structure should combine spectral selectivity with an isotropic response. Photonic glass (PhG), a disordered arrangement of monodisperse spheres, is a versatile structure to achieve that, which provides isotropic spectral selectivity via short-range order and Mie resonances. However, conventional PhGs show low color purity that hinders their future application. The interplay of single-particle scattering, short-range order, broadband absorption, and Fresnel reflection is a route to improve the color. In this perspective, we review the field of PhG based structural colors and discuss the physical mechanism behind the color generation by several established theories. We point out the current challenges in the theory and possible directions to improve color purity.

Optical method for measuring the volume fraction of granular media: Application to faced-centered cubic lattices of monodisperse spheres.

In order to understand the dynamics of granular flows, one must have knowledge about the solid volume fraction. However, its reliable experimental estimation is still a challenging task. Here, we present the application of a stochastic-optical method (SOM) [L. Sarno et al., Granul. Matter 18, 80 (2016)10.1007/s10035-016-0676-3] to an array of spheres arranged according to faced-centered cubic lattices, where spheres' locations are known a priori. The purpose of this study is to test the robustness of the image binarization algorithm, introduced in the SOM for the indirect estimation of the near-wall volume fraction through an optically measurable quantity, defined as two-dimensional volume fraction. A comprehensive range of volume fractions and illumination conditions are numerically and experimentally investigated. The proposed binarization algorithm is found to yield reasonably accurate estimations of the two-dimensional volume fraction with a root-mean-square error smaller than 0.03 for all investigated illumination conditions. A slightly worse performance is observed for samples with relatively low volume fractions (<0.3), where the binarization algorithm occasionally cannot identify the surface elements in the second and third layers of the regular lattice.

Dual-Functionalized Pesticide Nanocapsule Delivery System with Improved Spreading Behavior and Enhanced Bioactivity.

The prevention and control of pests and diseases are becoming increasingly difficult owing to extensive pesticide resistance. The synergistic use of pesticides for disease control is an effective way of slowing pesticide resistance, reducing the number of pesticide applications, and protecting the environment. In this study, a dual-functionalized pesticide nanocapsule delivery system loaded with two active ingredients (AIs)—validamycin and thifluzamide—was developed to prevent and control rice sheath blight; the nanocapsule system was based on a water–oil–water double emulsion method combined with high-pressure homogenization technology. Our results showed that the dual-functionalized pesticide nanocapsules were monodisperse spheres with a mean particle size of ~260 nm and had good storage stability. Compared with commercial formulations, the dual-functionalized pesticide nanocapsules exhibited good foliar spread owing to their small size, which is beneficial for reducing the loss of pesticides on the leaves. The 50% median effect concentration and synergistic ratio against Rhizoctonia solani of the dual-functionalized pesticide nanocapsules and commercial formulation were 0.0082 and 0.0350 μg/mL, and 2.088 and 0.917, respectively. These findings indicate that the bioactivity of the dual-functionalized system was significantly better than that of the commercial formulations and that the dual-functionalized system demonstrated a clear synergistic effect between the two AIs. The system presented here is simple, fast, and capable of dual-pesticide loading with significant synergistic effects. Our findings could help to facilitate the improvement of pesticides efficiency and the slowing of pesticide resistance.

Mesostructured Hollow Siliceous Spheres for Adsorption of Dyes

AbstractA facile and one‐pot strategy for the preparation of novel diamino‐functionalized hollow siliceous spheres (DAF‐HSS) is suggested. Field‐emission scanning electron microscopy (FE‐SEM) images of DAF‐HSS showed a monodispersed hollow sphere morphology. Also, TEM images revealed that the DAF‐HSS has a porous structure with parallel semi‐long‐range channels. DAF‐HSS material was used as an adsorbent for the removal of hazardous monocationic dyes in aqueous solution. Neutral red (NR) and crystal violet (CV) were selected as model compounds. Isotherm and kinetic studies were carried out and their different linear forms were applied and compared. The equilibrium data fitted better with the Langmuir model.

Stöber synthesis of salen-formaldehyde resin polymer- and carbon spheres with high nitrogen content and application of the corresponding Mn-containing carbon spheres as efficient electrocatalysts for the oxygen reduction reaction.

Salen-formaldehyde (SF) resin polymer spheres were synthesized by the Stöber method from 4,4′-dihydroxysalen (N,N′-bis-(4-hydroxysalicylidene)-ethylenediamine; a tetradentate N2O2 Schiff base ligand) and formaldehyde. The salen precursor was prepared by condensation of ethylenediamine with 2,4-dihydroxybenzaldehyde in methanol. The SF resin colloidal spheres were also prepared by using Pluronic F127 and ammonia as a porogenic agent and catalyst, respectively (SF-P). In addition, corresponding Mn(ii)-coordinated polymer spheres of the SF-P were synthesized (SF-P-Mn(ii)). Corresponding monodispersed carbon spheres of all of the abovementioned samples were also obtained by pyrolysis technique. All of the products were characterized with conventional microscopic and spectroscopic techniques, as well as other physical methods such as BET analysis. It was found that carbonization of the SF resin spheres results in carbon spheres with specific surface areas in the range of 499–528 m2 g−1 and average pore sizes in the range of 2.58–3.08 nm. Nitrogen content of the SF-MWHT (obtained hydrothermally in a methanol/water mixture), and SF-P-C@Mn (obtained from carbonization of SF-P-Mn(ii)) samples were as high as 27.5 wt% and 35.02 wt%, respectively. Finally, a glassy carbon electrode (GCE) modified with SF-P-C@Mn (SF-P-C@Mn/GCE) was prepared and its electrocatalytic activity was evaluated for oxygen reduction reaction (ORR) by linear sweep voltammetry (LSV). The LSV results showed that the SF-P-C@Mn/GCE has a higher current density and a lower negative potential in the ORR compared to GCE.

One-step surfactant-free controllable synthesis and tunable up-conversion/down-shifting white light emissions of Sr2YF7 crystals doped with Ln3+ ions

In this work, uniform and monodisperse Sr2YF7 spheres were successfully synthesized via a facile one-step hydrothermal route without employing any surfactant.

Development of nanoparticles coated with cassava bagasse pectin (Manihot esculenta Crantz) containing β-carotene for mucoadhesive applications.

Pectin (PC) extracted from a solid residue from cassava roots (Manihot esculenta Crantz) was used to coat nanoparticles (NP) containing β-carotene (BC) aiming at the gastrointestinal administration of this lipophilic nutraceutical. The NP were prepared by spontaneous emulsification method using food grade components. Pectin-coated NP have been successfully prepared as confirmed by the increased particle size and negative surface charges due to the pectin's anionic nature. NP showed spherical shape and monodisperse distribution, with a mean size of 21.3 nm (polydispersity index (PDI) 0.29) for BC PC T80-NP (nanoparticle with β-carotene, pectin and Tween 80) and 261.4 nm (PDI 0.1) for BC PC T20-NP (nanoparticle with β-carotene, pectin and Tween 20). BC was encapsulated at amounts of 530 and 324 µg/ml for BC PC T80-NP and BC PC T20-NP, respectively, with high encapsulation efficiency (> 95%), increasing its antioxidant capacity in vitro, besides no cytotoxic effect. However, only BC PC T20-NP was stable over a 90 days storage period (4°C) and revealed a strong interaction between pectin and mucin. These results suggest that pectin-coated BC PC T20-NP is a promising strategy to improve the bioavailability and permeation of BC for administration through mucosal surfaces.

One-pot synthesis of monodisperse phenolic resin spheres with high thermal stability and its derived carbon spheres as supercapacitor electrodes

We report a rapid and energy saving one-pot synthesis method to prepare monodisperse phenolic resin spheres (PSs) under high acidic conditions. This method integrates the low-temperature polymerization and solidification processes into one procedure. The PSs have excellently thermal stability, which shown extremely low skeleton shrinkage ratio of 9.2%–15.8% under different carbonization temperature from 600 °C to 1000 °C. The PSs can be directly converted into sulfur-doped hierarchical porous carbon spheres (HPCSs) by carbonization and KOH activation. In these unique HPCSs, the mesopores and macropores contribute to the mass transportation by reducing and smoothing the diffusion pathways, while the rich micropores ensuring the sufficient active sites to effectively charge storage. Combine with the hierarchical porous structure, high specific surface area and suitable S doping content, as a supercapacitor electrodes, the HPCSs-600 exhibit a high specific capacitance of 321 F g−1 at 0.5 A g−1, excellent rate retention of 72.9% from 0.5 to 50 A g−1, and outstanding cycling stability with 97% capacitance retention after 10 000 cycles.

Synthesis, Transformation, and Utilization of Monodispersed Colloidal Spheres.

Colloidal particles with a spherical shape and diameters in the range of 0.01-1 μm have been a subject of extensive research, with applications in areas such as photonics, electronics, catalysis, drug delivery, and medicine. For most of these applications, it is of critical importance to achieve monodispersity for the size while expanding the diversity in terms of structure and composition. The uniformity in size allows one to establish rigorous correlations between this parameter and the physicochemical properties of the colloidal particles while ensuring experimental repeatability and measurement accuracy. On the other hand, the diversity in structure and composition offers additional handles for tailoring the properties. By switching from the conventional plain, solid structure to a core-shell, hollow, porous, or Janus structure, it offers immediate advantages and creates new opportunities, especially in the context of self-assembly, encapsulation, and controlled release. As for composition, monodispersed colloidal spheres were traditionally limited to amorphous materials such as polystyrene and silica. For metals and semiconducting materials, which are more valuable to applications in photonics, electronics, and catalysis, they tend to crystallize and thus grow anisotropically into nonspherical shapes, especially when their sizes pass 0.1 μm. Taken together, it is no wonder why chemical synthesis of monodispersed colloidal spheres has been a constant theme of research in areas such as colloidal science, materials chemistry, materials science, and soft matter. In this Account, we summarize our efforts over the past two decades in developing solution-phase methods for the facile synthesis of colloidal spheres that are uniform in size, together with a broad range of compositions (including metals and semiconductors) and structures (e.g., solid, core-shell, hollow, porous, and Janus, among others). We start with the synthesis of monodispersed colloidal spheres made of semiconductors, metals with low melting points, and precious metals. Through chemical reactions, these colloidal spheres can be transformed into core-shell or hollow structures with new compositions and properties. Next, we discuss the synthesis of colloidal spheres with a Janus structure while taking a pseudospherical shape. Specifically, metal-polymer hybrid particles composed of one metal nanoparticle partially embedded in the surface of a polymer sphere can be produced through precipitation polymerization in the presence of metal seed. With these Janus particles serving as templates, other types of Janus structures such as hollow spheres with a single hole in the surface can be obtained via site-selected deposition. Alternatively, such hollow spheres can be fabricated through a physical transformation process that involves swelling of polymer spheres, followed by freeze-drying. All these synthesis and transformation processes are solution-based, offering flexibility and potential for large-scale production. At the end, we highlight some of the applications enabled by these colloidal spheres, including fabrication of photonic devices, encapsulation, and controlled release for nanomedicine.

Network analysis of heat transfer in sphere packings

Porosity-dependent models can be used to predict the effective thermal conductivity (ETC) of particulate materials. However, they cannot directly account for microstructural features such as particle connectivity and interparticle contact area. Complex network theory can be used to extract network features as microstructural characteristics. However, these features have not been used to study heat transfer. In this work, both contact network and thermal networks are constructed for mono-disperse and poly-disperse sphere packings. Network features are extracted using complex network theory and machine learning techniques are applied to investigate the correlation between these features and the ETC. The most relevant thermal and contact network features for predicting thermal conductivity are identified. The network features capturing both interparticle connectivity and contact quality, such as “weighted degree”, show high correlation with ETC. Furthermore, random forest regression results show that involving multi-network features in a model enhances the accuracy in predicting ETC.

Parameterization of The Single-Scattering Properties of Dust Aerosols in Radiative Flux Calculations

In this study, we present parameterization schemes of dust single-scattering properties (SSPs) in order to establish a fast and accurate way to obtain the SSPs for dust shortwave radiative flux calculation. Based on the assumption that dust particles are spheroids, we represent a single nonspherical particle with a collection of monodisperse spheres that contain the same total surface area and volume as the original particle to convert the spheroid to a sphere. The SSPs of dust particles were parameterized in terms of the effective radius ( R e ) and imaginary part of the refractive index ( M i ). The averaged relative errors of the parameterized to the “exact” single-scattering properties, which refer to the results from the Mie theory program, are below 1.5%. To further quantify the impact of parametrization on the radiative flux simulation, we computed the radiative fluxes at both the top of the atmosphere (TOA) and the surface by using SSPs from the parameterization and the “exact”, respectively. The maximum relative errors were below 1% at both the TOA and the surface, proving that the SSPs of dust calculated by our parameterization schemes are well suited for radiative flux calculations. This parameterization differs from previous works by being formulated not only with R e but also with M i . We also investigated the sensitivity of dust-aerosol forcing to R e , M i , optical depth (τ), and solar zenith angle (SZA). The results show that the value of shortwave (SW) radiative forcing (RF) at the TOA changes from negative to positive as the M i is increasing, which means that, as the absorption of dust particles becomes stronger, more energy is kept in the atmosphere to heat the earth–atmosphere system. The SW RF gradually becomes less negative at the TOA and more negative at the surface with increasing R e , due to the decreases of reflection and transmission along with the single-scattering albedo decreasing. As the optical depth increases, the values of the SW RF decrease because of the strong attenuation for heavy loading. When SZA increases, the SW RF becomes more negative at both the TOA and the surface due to the long optical path at a large SZA. The errors induced from the parameterized SSPs of dust in the SW RF calculation are very small, which are less than 2.1%, demonstrating the accuracy of the parameterization and its reliability for climate model applications.

Synthesis and characterization of luminescent SiO2 @Eu(phen-Si) core-shell nanospheres.

Four core-shell structured nanometre luminescent composites with different kernel sizes and different shell layer thicknesses (SiO2(500) @Eu (phen-Si)(50) , SiO2(500) @Eu (phen-Si)(15) , SiO2(250) @Eu (phen-Si)(5) and SiO2(250) @Eu (phen-Si)(10) ) were made by changing synthesis conditions. Here, initial subscript numbers in parentheses refer to the particle size of the SiO2 core, whereas the final subscript numbers in parentheses refer to shell layer thickness. In these composites, silica spheres of 500nm or 250nm were identified as the core. The shell layer was composited of silicon, 1,10-phenanthroline and europium perchlorate, abbreviated as Eu(phen-Si); the chemical formula of phen-Si was phen-N-(CONH (CH2 )Si(OCH2 CH3 )3 )2 . The composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and infrared spectroscopy. The monodispersed spherical SiO2 showed characteristics of a regular microstructure and a smooth surface, as well as the advantage of dispersity, shown by SEM. The Eu(phen-Si) complex was able to self-assemble into monodispersed SiO2 spheres, as seen using TEM. Fluorescence spectra indicated that the four composites had excellent luminescence properties. Furthermore, composites composed of a SiO2 core and a 250nm kernel size exhibited stronger fluorescence than 500nm kernel-sized composites. Fluorescence properties were affected by shell thickness: the thicker the shell, the greater the fluorescence intensity. For the four composites, quantum yield values and fluorescence lifetime corresponded to fluorescence emission intensity data as quantum yield values and fluorescence lifetime were higher, and luminescence properties increased.

Light scattering in monodisperse systems – from suspensions to transparent ceramics

Predicting the in-line transmittance of transparent ceramics via model calculations is a useful guide for materials design and optimization of preparation process. However, the absence of reliable input information (volume fractions and size) usually precludes the direct verification of these calculations. On the other hand, suspensions, which can be prepared with well controlled volume fractions of the solids selected, may serve as model systems that are amenable to verification. This paper describes the procedure to perform these calculations, and compares calculated data for suspensions of monodisperse spheres of amorphous silica with spectrophotometric measurements of silica monosphere suspensions with four different concentrations. Moreover, completely analogous model calculations are performed for bubbles in silica glass and pores in spinel ceramics. The results are discussed on the basis on 3D graphs, the use of which is highly recommended. The results may be considered as a benchmark for future model calculations for polydisperse systems.

Monodisperse starburst carbon spheres-intercalated graphene nanohybrid papers for supercapacitor electrodes

Here we report a nanohybrid of reduced graphene oxide (rGO) nanosheets at which monodispersed starburst carbon spheres (MSCSs) are intercalated for the use in high-performance supercapacitor electrodes. MSCSs that have large electrolyte ions-accessible surface area enlarge the interspacing between rGO nanosheets as a result of intercalation so that a hybrid electrode can increasingly form electrical double layers that store energy. Such electrode organization provides facilitated transport paths for both electron and ion. The volumetric capacitance of the hybrid electrode is 25 F cm−3 that is obtained at a constant current of 0.073 A cm−3, at least 2.5-fold greater than that of rGO electrode. The hybrid electrode also shows a good rate-retention capability of 81% as specific currents change from 0.073 to 1.5 A cm−3. The initial capacitance of the hybrid electrode remains unchanged, nearly 100% for at least 5000 charge/discharge cycles. The electrode also delivers high energy density, 1.7 × 10−3 Wh cm−3, and power density, 2.7 W cm−3.

Evaluating the internal structure of monodispersed mesoporous silica spheres by small-angle X-ray scattering

Although the spherical morphology and mesoporous structure of monodispersed mesoporous silica spheres (MMSS) have been extensively investigated by scanning electron microscopy and transmission electron microscopy, the statistical distribution of mesopores from the surface to the center of a particle, average density of the spheres, and volume fraction of silica have not been investigated. Herein, small-angle X-ray scattering (SAXS) was performed on aqueous dispersions of MMSS with diverse sphere diameter, mesopore radius, and nanoparticle inclusion. The SAXS spectra fitted by a spherical model showed that the mesopores were homogeneously distributed in each particle. The mass density of the MMSS was obtained from the zero scattering intensity, and the volume fraction of silica was calculated considering the absorbed water in the pores. While the sphere diameter and mesopore radius had little influence, nanoparticle inclusion induced an increase in the volume fraction of silica.

High-Performance Worm-like Mn-Zn Ferrite Theranostic Nanoagents and the Application on Tumor Theranostics.

Previous reports from our team revealed the significant potential advantage of Mn-Zn ferrite nanoparticles (NPs) in magnetic resonance imaging (MRI), whereas anisotropic NPs reportedly increased the blood circulation time of nanocarriers. Thus, anisotropic Mn-Zn ferrite displayed a huge potential in cancer synchronous diagnosis and treatment, that is, enhanced MRI observation was performed simultaneously when drug-targeted delivery therapy was applied to the tumor. Here, we developed three shaped Mn-Zn ferrite (Mn0.63Zn0.37Fe2O4) MNPs used as cancer theranostic nanoagents and compared the effect of the three shaped MNPs on cancer theranostics. Compared to the monodisperse sphere MNPs (S-MNPs-PPR) and clustering MNPs (C-MNPs-PPR), worm-like Mn-Zn ferrite MNPs (W-MNPs-PPR) achieved better results in T2-weighted MRI and achieved more sustained drug release than S-MNPs-PPR and more complete drug release than C-MNPs-PPR in vitro. Additionally, polyethylene glycol (PEG) coating and RGD modification encouraged the three shaped MNPs to evade the recruitment of macrophages more easily and to target the integrin-enriched endothelial cells instead. Meanwhile, W-MNPs-PPR coupled with Paclitaxel (PTX) exhibited more delivery of PTX in the integrin-enriched cells than the other two shaped MNPs, and the content of PTX was far more than that of the wild-type Taxol control group. What is more, in vivo results demonstrated that PTX-coated W-MNPs-PPR not only gained good dual-mode imaging in the tumor (MRI and fluorescence images) but also achieved longer blood circulation time and more PTX-targeted delivery to the tumor, as well as more efficiency in tumor cell killing, which make the simultaneous diagnosis and treatment of tumors to be conducted. Therefore, our works further revealed the importance of the NP shape on its functionality and ultimately provided an alternative and efficient worm-like theranostic nanoagent for tumor theranostics.

Reversibly compressible and freestanding monolithic carbon spherogels

We present a versatile strategy to tailor the nanostructure of monolithic carbon aerogels. By use of an aqueous colloidal solution of polystyrene in the sol-gel processing of resorcinol-formaldehyde gels, we can prepare, after supercritical drying and successive carbonization, freestanding monolithic carbon aerogels, solely composed of interconnected and uniformly sized hollow spheres, which we name carbon spherogels. Each sphere is enclosed by a microporous carbon wall whose thickness can be adjusted by the polystyrene concentration, which affects the pore texture as well as the mechanical properties of the aerogel monolith. In this study, we used monodisperse polystyrene spheres of approximately 250 nm diameter, which result in an inner diameter of the final hollow carbon spheres of approximately 200 ± 5 nm due to shrinkage during the carbonization process. The excellent homogeneity of the samples, as well as uniform sphere geometries, are confirmed by small- and angle X-ray scattering. The presence of macropores between the hollow spheres creates a monolithic network with the benefit of being reversibly compressible up to 10% linear strain without destruction. Electrochemical tests demonstrate the applicability of ground and CO2 activated carbon spherogels as electrode materials.

Simulation of solid propellant microstructures by combining the collective rearrangement method with the discrete element method

The polydisperse particulate components in solid propellant are incompact and randomly packed, which determines the microstructural features of the propellants. A packing method, combining the discrete element method (DEM) and collective rearrangement method, was applied to model propellant microstructures. The validity of this method was investigated by comparing the calculated and experimental properties of the monodisperse, bidisperse, and polydisperse random close packed sphere systems. The propellant models were generated using a stepwise approach, and their homogeneity, local randomness, and long-range pattern were analyzed. A statistical study of aluminum (Al) particle distribution was also conducted. The results indicated that this packing method can effectively determine the microscopic characteristics of random close packed monodisperse spheres. The maximum packing fraction of bidisperse and polydisperse spheres had similar trends to those reported in experimental studies and using other packing algorithms. In addition, this method was capable of generating non-compacted propellant structures with uniformly distributed polydisperse particles. The radial distribution functions (RDFs) for Al-Al particles provided information about the Al distribution, but this was mainly related to the size and content of the large particle components.

An electrochemical sensing platform based on nitrogen-doped hollow carbon spheres for sensitive and selective isoprenaline detection

In this work, uniform and monodisperse hollow carbon spheres (HCSs) are synthesized through two different processes using polydopamine (PDA), as a carbon precursor, and silica core as a template, under the modified Stöber condition. The surface morphology of the synthesized structures is characterized by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier-transform infrared spectroscopy (FT-IR). In the next step, the electrochemical behavior of isoprenaline (ISPN) is investigated by using glassy carbon electrode modified with a thin film of the synthesized hollow carbon spheres. The electrochemical characterization of the modified electrodes is performed using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). In comparison to bare GCE, an enhanced oxidation peak current for ISPN is observed on the surface of HCSs/GCE. Comparing two different hollow carbonic structures, the HCS(1), which shows high nitrogen contents and high surface area, is selected as the suitable modifier for the sensitive determination of ISPN. The effect of various experimental parameters such as the pH of electrolyte solution, the amount of casted HCS(1) suspension, and time and potential of the accumulation on the electrochemical response of ISPN are investigated and optimized by linear sweep voltammetry method. Under the optimum conditions, the response of the modified electrode exhibited two wide linear ranges of 0.2–2μM and 2–30μM with a low detection limit of 60nM for voltammetric determination of ISPN. Beside high sensitivity, the fabricated electrode represented excellent selectivity toward ISPN in the presence of biological interfering species such as ascorbic acid (AA) and uric acid (UA), which make it more suitable for determination of ISPN in pharmaceutical and clinical samples.

Focusing of Airborne Particles Using Groove-Induced Envelope (GRIP) Flow Air-Microfluidic Concentrator

Monitoring personal exposure to airborne particulate matter (PM) necessitates the need for ubiquitous portable PM sensing systems. Most current microfluidic PM detectors will be significantly improved if the particles suspended in the air-stream are focused into a narrow stream. In this paper, we present a novel microfabricated groove-induced envelope flow (GRIP) air-microfluidic PM focusing system. In this device, the horizontal focusing is achieved by enveloping the main flow using clean sheath flow from the sides of the microchannels, while vertical focusing is achieved using grooved structures on top and bottom of the microchannels. The grooves are fabricated using a novel fabrication technique that is compatible with the DRIE fabrication process of other air-microfluidics PM sensors, making it easier to integrate these two components into small air-microfluidic circuits. The performance of this system was evaluated using the opto-gravimetric method. Mono-dispersed polystyrene latex spheres were injected into the GRIP system and subsequently collected on membrane filters attached to the outlet. Epi-fluorescent microscopy was then used to image the distribution of the particles on the filter. The experimental results confirm that the efficiency of the GRIP device for focusing particles in air-microfluidic channels, enabling increased sensitivity and elimination of wall losses in future micro-electro-mechanical-systems PM sensor.