Particle Counter Research Articles

Utilising Machine Learning for the Automated Characterisation of In Situ Electron Microscopy Experiments with Catalytic Systems

The data analysis workflow for in situ electron microscopy experiments can require a lot of human-intensive and repetitive effort. The generation of Python-based scripts that incorporate simple machine learning algorithms are quite well established in biological sciences but not often utilised in the study of catalytic systems. Such scripted analysis is not only more efficient, but readily reproducible and allows a wide range of quantitative results to be reported, including but not limited to average and total particle size, particle counting and particle size distributions. In this work we utilise these tools to examine the effect of cycling reducing and oxidising atmospheres on CuO nanoparticles.

Image processing techniques for measuring primary microplastic abundance in various of dispersant

Microplastics have become one of the world’s most important environmental issues and have received widespread attention as a new type of pollutant. Microplastic quantification methods have evolved from manual to semi-automated and automated methods. These methods still possess drawbacks such costly detecting equipment, lengthy detection durations, and imprecise detection rates, making the detection of microplastics difficult in natural environments. This study aimed to measure the abundance of primary microplastics (microbeads) using Image Processing Techniques (IPT) with various dispersants and validated them using microscopy. Plugable Digital Viewer v.3.1.07 software was used to capture digital images of the IPT tool, while the microscope used Obtilab viewer 3.0. The IPT results were processed and analyzed using ImageJ 1.53t software. The originality of this study is that digital images were taken directly in liquid samples with the preparation sample dispersant so that microplastics in surface water could be directly quantified and identified. This study provides a very strong correlation between the sample mass and particle counting, as seen from R2>0.75. A statistical test of the data obtained (P-Value>0.05) demonstrated a normal distribution of the data. The t-test results between each mass variation obtained (P-Value <0.05) indicated that the microplastic particles from each mass variation were different. The LoD for PP and PE were 1.75 and 0.00009 respectively while the LoQ were 28.5 and 39.5. The %recovery from 10 repetitions produced consistent values for PP and PE, which had less stable values obtained at 0% in repetitions 1.5 and 8. The %RSD from 10 repetitions was below 40%.

On-chip three-dimensional imaging and counting of particles transported in a microfluidic channel based on light-field microscopy

On-chip three-dimensional imaging and counting of particles transported in a microfluidic channel based on light-field microscopy

Microfluidic particle counter visualizing mucosal antibodies against SARS-CoV-2 in the upper respiratory tract for rapid evaluation of immune protection.

Mucosal antibodies in the upper respiratory tract are the earliest and most critical responders to prevent respiratory infections, providing an indication for the rapid evaluation of immune protection. Here, we report a microfluidic particle counter that directly visualizes mucosal antibody levels in nasal mucus. The mucosal anti-SARS-CoV-2 spike receptor binding domain (RBD) antibodies in nasal secretions first react with magnetic microparticles (MMPs) and polystyrene microparticles (PMPs) that are surface-modified to form a "MMPs-anti-spike RBD IgG-PMPs" complex when RBD is present. After magnetic separation and loading into the microfluidic particle counter, the free PMPs, which are reduced with increasing anti-spike RBD IgG antibody levels, are trapped by a microfluidic particle dam and accumulate in the trapping channel. A sensitive mode [limit of detection (LOD): 14.0 ng mL-1; sample-to-answer time: 70 min] and an equipment-free rapid mode (LOD: 37.4 ng mL-1; sample-to-answer time: 20 min) were achieved. Eighty-seven nasal secretion (NS) samples from vaccinees were analyzed using our microfluidic particle counter, and the results closely resemble those of the gold-standard enzyme-linked immunosorbent assay (ELISA). The analysis shows that higher antibody levels were found in convalescent volunteers compared to noninfected volunteers. Together, we demonstrate a rapid kit that directly indicates immune status, which can guide vaccine strategy for individuals and the government.

Exploratory measurements of ambient air quality in a residential area applying a diffusion charge based UFP monitor/Orientierende Messungen der Luftqualität in einem Wohngebiet mit einem auf Diffusionsaufladung basierten UFP-Monitor

In the context of the revision of the EU Ambient Air Qualitiy Directive (2008/50/EC), measurement of ultrafine particles (UFP) in ambient air is proposed and discussed. To investigate the local ambient UFP concentration (immis- sion), exploratory measurements of air pollution with UFPs were performed over several months in a residential area. The measurement device is based on charge detection of the measurement aerosol (AQ Guard Smart 2000 of the manufacturer Palas®). The background particle concentrations are within the typical background level for rural residential areas (3,000 to 5,000 cm-3). Increased UFP concentration levels were predominantly measured during the evening and the night. On 53 days of the total measurement duration of 101 days increased par- ticle concentrations above the background level (at least 6,000 cm-3) regarding the 15-minute average values were measured for at least one hour during the evening and night (16:00 to 0:00). The main source of the increased particle concentra- tion is the operation of woodstoves in the neighbourhood of the measuring location. This air pollution in the evening hours is not reflected in the context of daily or monthly averages. Other pollution sources (barbecue, new-years fireworks, traffic – different measurement location) were also identified and differences of the mean particle diameter of the ambient aerosol with regards to the background level (80 nm) could be determined. The device is suitable for UFP measurements and offers a lower detectable size-range compared to conventional scattered-light based optical particle counters.

Toward Rapid Balloon Experiments for Sudden Aerosol Injection in the Stratosphere (REAS) by Volcanic Eruptions and Wildfires

Abstract Stratospheric aerosols are greatly influenced by medium-to-large volcanic eruptions. Over the last few years, extreme wildfires have been identified as new sources of stratospheric particles, in the form of carbonaceous aerosols injected by pyrocumulonimbus (pyroCb) events in the upper troposphere and lower stratosphere, associated with significant impacts on climate and ozone chemistry. To assess the impact of wildfires and volcanic eruptions on stratospheric aerosol loadings in the Northern Hemisphere, the Rapid Balloon Experiments for Sudden Aerosol Injection in the Stratosphere (REAS) project has been initiated. REAS is an international initiative that aims to respond to sudden events impacting stratospheric aerosol composition. Seventeen balloons were launched from Reims, eastern France, between November 2021 and January 2022 to quantify the atmospheric content for both aerosols and trace/greenhouse gases from the ground up to stratospheric levels. The main measurements concerned trace gases (CO/CO2 as tracers of smoke) and aerosol together with ozone using instruments such as a gas collector, optical particle counters, backscatter sondes, an aerosol sampler, an aerosol impactor, and ozonesondes. The Groupe de Spectrométrie Moléculaire et Atmosphérique (GSMA) launch facility provided unique possibilities of combining multiple measurements in one flight thanks to medium flights (corresponding to a 6 kg payload). While no major event impacted the stratosphere during the campaign, we particularly discuss the influence of the aged volcanic plume from La Soufrière volcano (Saint Vincent island) and smoke particles from series of pyroCb events that took place in North America. The burden as well as the optical and microphysical properties of the observed aerosols are quantified from these in situ observations in association with various satellite data.

Integrated microfluidic-based ultrafine water condensation particle counter (UWCPC) for monitoring of airborne nanoparticle generation and growth mechanisms

This study reports a newly developed condensation particle counter for nanoparticle source tracking, growth mechanism analysis, and wide area nanoparticle monitoring.

Study on the Asian dust emitted from the hotspot in the Gobi Desert

We have studied the Asian dust emitted from a hotspot in the Gobi Desert by a lidar network, analyses of Himawari-8 Dust RGB and meteorological fields, and a field survey since 2013. We found a remarkable dust hotspot in the Gobi Desert by the filed survey and analysis. The Himawari-8 Dust RGB imagery shows that the dust storm occurred in an orographic convergence zone sandwiched between the Khangai, Altai, and Gurvan Saikhan Mountains in the Gobi Desert. The lidar network operating in Dalanzadgad, Sainshand, and Zamyn-Uud, Mongolia shows a dust layer development over the Gobi Desert in association with a cold frontal system and the long-range transport of the dust. We estimated the massextinction conversion factor MECF (g m-2) from simultaneous observations using an optical particle counter (OPC) installed on a tethered balloon and a ceilometer in the Gobi Desert. The MECF values decreased from the Asian dust source (Dalanzadgad 1.91 g m-2) to the lee-side areas (e.g., Tsukuba 1.18 g m-2) due to the gravitational settling of large dust particles.

Study of particulate emissions when using special wires for underwater welding

The article describes the study to evaluate the emissions to atmospheric air of airborne nano- and microparticles generated during underwater welding in seawater from Ajax Bay (Sea of Japan) using special wires and coated electrodes. The most commonly used underwater industrial production processes were selected: semi-automatic (mechanized) underwater welding with a welding wire, manual welding with electrodes, and semi-automatic (mechanized) underwater cutting with a welding wire for cutting. An aerosol particle counter was used to determine the mass concentration of fine aerosol particles in the air of the working area above the aquarium. The highest number of suspended particles in the atmospheric air was observed in the process of underwater welding with a welding electrode. Comparing the welding wire and the welding electrode for underwater welding, it can be concluded that the welding wire is less dangerous for people, which is confirmed by the lower amount of suspended particles emitted into the atmospheric air during its use.

Penerapan Automatic Particle Counter untuk Pemantauan Kondisi Oli Hidrolik

High solid particle contamination in hydraulic oil can cause abnormal damage to hydraulic system components. Monitoring the hydraulic oil solid particle contamination level is necessary to ensure it is always within permissible limits. Monitoring of solid particle contamination in hydraulic oil is still done manually by taking an oil sample and then measuring the level of solid particle contamination in the oil sample. This method still relies on human power. Therefore, there is still a possibility that oil conditions are not monitored due to human negligence. This research aims to design a system that automatically samples hydraulic oil and measures solid particle contamination. The level of solid particles in the hydraulic oil is measured by the Automatic Particle Counter (APC) sensor, and then the data is sent to the microcontroller. The microcontroller will process this data and provide information regarding the level of solid particles in the hydraulic oil in real-time. This research produces a system that automatically monitors and produces ISO Cleanliness Code values and a warning system when solid particle levels exceed specified limits. Therefore, this tool can help users monitor hydraulic oil conditions more easily.

Investigating Indoor Air Pollution Sources and Student’s Exposure Within School Classrooms: Using a Low‐Cost Sensor and Source Apportionment Approach

Indoor air quality is becoming one of the most important factors for public health, as people tend to spend more time indoors, either at home or at work. This paper combines the use of calibrated low‐cost particulate matter (PM) sensors with source apportionment algorithms to understand the factors that affect the indoor air quality within a typical UK school. Low‐cost optical particle counter (OPC) sensors were placed in three different classrooms within the school, measuring PM concentrations during a typical school week and the subsequent holiday period, to understand the role of occupancy within schools for air quality. When students were in attendance during school hours (09:00–15:30), the classroom with the greatest average PM levels had PM2.5 and PM10 mass concentrations of 14.4 and 51.0 μg/m3, respectively. During school hours, when students were present, all classrooms had average PM2.5 concentrations greater than 8.1 μg m−3 and average PM10 concentrations greater than 13.1 μg m−3. Notably, the English studies classroom exceeded the 24‐h WHO ambient PM10 guideline (45 μg m−3). Employing the non‐negative matrix factorization (NMF) algorithm for source apportionment revealed that between 93% and 98% of PM1 observed within classrooms derived from outdoor sources. This contribution diminished as particle size increased, with outdoor sources accounting for 74%–89% of PM2.5, and 19%–40% of PM10, respectively. The differences in classroom PM concentration and source percentages are attributed to differences in lesson activities, lesson frequency, flooring (carpeted versus hard flooring), location within the school, and proximity to outdoor sources such as roads. The approach described within the paper is easily translated to other indoor locations and could also be straightforwardly scaled due to its relatively low cost. Thereby, it allows for air quality management in locations crucial for the public health and educational outcomes of children.

Viability of elutriation for the extraction of microplastics from environmental soil samples.

In this study, we evaluated the suitability of elutriation, a method successfully employed in the extraction of microplastics from marine sediments, for the extraction of microplastics from freshwater and terrestrial soils. Five soils were sampled throughout Oklahoma, USA in order to capture a range of sand, silt, clay, and organic matter composition. Each soil was subjected to microplastic extraction with and without elutriation, followed by digestion in 7.5% NaOCl, and then flotation in 6 M ZnCl2. The mass of each soil was measured after elutriation to determine sample mass reduction, and multiple methods including fluorescence imaging and automated particle counting through ImageJ, Attenuated Total Reflectence-Fourier Transfor Infrared Spectroscopy (ATR-FTIR), and Pyrolysis-coupled Gas Chromatography/Mass Spectrometry (py-GC/MS) were used to determine microplastic quantity, mass, and characteristics. T-test was used to check for statistically-significant differences between methods in terms of mass or particle quantity. For all tested soils, elutriation resulted in greater sample mass reduction than non-elutriated samples, and was between 59.0-97.3% for the tested soils. Furthermore, no statistically significant (p < 0.05) differences were observed in particle quantification or polymer mass between methods, and no differences were observed for polymer or size distribution. Additionally, 33% more polymers were positively identified (R 2 = 70%) by ATR-FTIR analysis in elutriated samples compared to non-elutriated soils. The mass reduction provided by elutriation allows for the processing of larger sample volumes, leading to greater accuracy and sensitivity in detecting microplastics. As such, we recommend elutriation be performed as a pretreatment step to extract microplastics from soils.

Plasticizing Pregnancy: Microplastics Identified in Expectant Mothers' Feces.

Microplastics may be present in food and drinks from various sources, exposing pregnant women to these particles. Consumption of contaminated food can lead to the ingestion of microplastics by pregnant women, potentially causing adverse health effects on the fetus. This study aims to investigate the presence of microplastics in the stools of pregnant women. The research was conducted in the Makassar City region of South Sulawesi, Indonesia. Thirty healthy pregnant women from 2 community health centers, Pattingalloang and Jumpandang Baru, participated in the study. Their stools were analyzed using Fourier Transform Infrared (FTIR) microspectroscopy to detect the presence of microplastics. The analysis revealed the presence of a total of 359 microplastics in the participants' stools, with particle counts ranging from 4 to 21 and sizes ranging from 0.2 to 4.9 mm per 25 g of stool. The polymers identified included Polyethylene Terephthalate (PET), Polyamide/Nylon, Polyethylene Chlorinated, HDPE, and Ethylene Propylene. The amount of microplastics varied significantly among groups with different levels of seafood consumption. Indonesian pregnant women have been exposed to some microplastic polymers.

Electrochemical deposition of gold nanoparticles on carbon ultramicroelectrode arrays.

Electrode surfaces functionalized with gold nanoparticles (AuNP) are widely used in electroanalysis, electrocatalysis, and electrochemical biosensing due to their increased surface area and conductivity. Electrochemical deposition of AuNPs offers advantages over chemical synthesis, including better control over AuNP size, dispersion, and morphology. This study examines the electrodeposition of AuNPs on carbon ultramicroelectrode arrays (CUAs) focusing on electrodeposition parameters, such as deposition potential, deposition time, and gold ion concentration. Detailed analysis based on scanning electron microscopy revealed that higher reductive potentials and shorter deposition times result in smaller AuNP particle sizes and greater particle counts. Unlike previous studies using planar, macro-sized electrodes and millimolar concentrations of gold ion, as well as longer deposition times (e.g., 100-300 s), this research employed micromolar concentration ranges (25-50 μM) of gold ion solution and shorter deposition times (5-60 s) for successful electrodeposition of AuNPs on the array-based CUAs. This is attributed to the physical properties of the ultramicroelectrodes in the array geometry and the distinct material composition of the CUAs. The gold amounts deposited on the CUA electrodes were determined (88.73 ± 0.06 nmol cm-2), which were in correlation with the electrocatalytic responses for the hydrogen evolution reaction (HER) measured on AuNP-modified CUAs. Overall, the array-based geometry, nanometer-scale electrode sizes, and unique material composition of the CUAs significantly influence AuNP electrodeposition. This study underscores the importance of systematically characterizing the electrodeposition parameters on novel electrode surfaces.

Microscale damper prototype: A preliminary study on suppressing air flow oscillations within microchannels

This research introduces a novel micro-damper designed to mitigate pressure and velocity oscillations from a piezoelectric micropump in microfluidic environments. Unlike existing research focusing on damping in incompressible liquid flows with methods like elastic films and PDMS membranes, this study proposes a novel micro-damper prototype. Integrated into a microdevice for particle granulometric separation and detection, the damper connects to a piezoelectric micropump outlet and to a focusing microchannel inlet, followed by a capacitive sensor for size-based particle counting. Preliminary analysis determined an optimal airflow velocity at w = 0.5 m/s for accurate focusing and counting under laminar conditions. The micro-damper, constrained by the piezoelectric pump’s geometry, features a 27 µm high and 1000 µm wide cross section. Its outlet supports two potential focusing microchannel inlet configurations of 30 µm or 40 µm. Distinctively, it incorporates two symmetrical backward micro-channels connecting to the atmosphere, allowing direct piezometric contact between the main flow and an infinite compliant volume. OpenFOAM simulations confirm the damper’s effectiveness in maintaining laminar outlet flow and suppressing micropump disturbances. Thus, the proposed micro-damper ensures optimal inlet conditions for subsequent microchannel processes, enabling stable particle separation and detection in controlled airflow samples.

Label-free quantification of gold nanoparticles at the single-cell level using a multi-column convolutional neural network (MC-CNN).

Gold nanoparticles (AuNPs) are extensively used in cellular imaging, single-particle tracking, disease diagnosis, studying membrane protein interaction, and drug delivery. Understanding the dynamics of AuNP uptake in live cells is crucial for optimizing their efficacy and safety. Traditional manual methods for quantifying AuNP uptake are time-consuming and subjective, limiting their scalability and accuracy. The available fluorescence-based techniques are limited to photobleaching and photoblinking. Optical microscopy techniques are limited by diffraction limits. Electron microscopy-based imaging techniques are destructive and unsuitable for live cell imaging. Furthermore, the resulting images may contain hundreds of particles with varied intensities, blurring, and substantial occlusion, making it difficult to manually quantify AuNP uptake. To overcome this issue and measure AuNP uptake by live cells, we annotated a dataset of dark-field images of 50 nanometer-radius AuNPs at different incubation durations. Then, to count the number of particles present in a cell, we created a customized multi-column convolutional neural network (MC-CNN). The customized MC-CNN outperformed typical particle counting architectures when compared to spectroscopy-based counting. This will allow researchers to gain a better understanding of AuNP behavior and interactions with cells, paving the way for advancements in nanomedicine, drug delivery, and biomedical research. The code for this paper is available at the following link: https://github.com/Namerlight/LabelFree_AuNP_Quantification.

Numerical Analysis of Indoor Air Characteristics and Window Screen Influence on Particulate Matter Dispersion in a Childcare Center Using Computational Fluid Dynamics.

Indoor exposure to outdoor pollutants adversely affects health, varying with building dimensions and particularly ventilation that have critical role on their indoor dispersion. This study assesses the impact of outdoor air on indoor air quality in a child care center. Computational fluid dynamics was utilized to analyze the dispersion of particulate matter, with a specific focus on window screens featuring 6 distinct pore sizes ranging from 0.8 mm to 2 mm and 2 different thicknesses of 0.5 mm and 0.1 mm. Results indicate that the presence of a window screen offers significant advantages in controlling particle infiltration compared to scenarios without a screen, as larger particles tend to pass directly through the window within the breathing zone. The scenario without window screens minimizes pressure drop but lacks enhanced particle capture capabilities. However, for effective particle reduction, the window screen with a pore size of 0.8 mm (R0.8T2) and a thickness of 0.5 mm proves to be the most beneficial, achieving the particle filtering efficiency of approximately 54.16%, while the larger window screen with a pore size of 2 mm and a thickness of 1 mm exhibits the lowest efficiency at about 23.85%. Nonetheless, screens with very small sizes are associated with a high-pressure drop, impacting energy efficiency, and overall window performance. Larger pores with smaller thicknesses (0.5 mm) reduced particle count by approximately 45.97%. Therefore, the significance of window screen thickness beyond pore size for particle reduction efficiency is highlighted, emphasizing screens' role in indoor air quality and health protection.

Occurrence, characterization, and transport mechanism of welding fumes particles emitted during the welding process

In metalworking processes, welding fumes are a prevalent type of particle aerosols. Particle characteristics, physical factors, and the generation process influence the transport of welding fumes in the air. This research delves into the investigation of welding fumes particles during two types of currents: low current (60A) and high current (130A). The study encompasses the determination of the occurrence and characterization of these particles, as well as estimating their transport mechanisms during the welding process. Direct reading instruments were utilized to measure the mass concentration and the number concentration of welding fumes particles alongside environmental parameters such as relative humidity, air velocity, and air temperature. The size distribution and morphology of the particles were collected through a sampling pump and subsequently analyzed using a Field Emission Scanning Electron Microscope (FESEM). Welding fumes particle transport was predicted by employing variables such as Reynolds number (Re), settling velocity, mechanical velocity, and stopping distance. The welding process’s high current (130 A) generates a higher mass concentration (0.122mg/m3) than the low current (60 A) (0.064mg/m3). Notably, for particle size fractions ranging from 0.5μm to 2.0μm, the number of particles generated during high current surpassed that of low current, except for the 0.3μm size fraction. Analysis of the size distribution through FESEM revealed particle sizes of 2.25μm, 2.33μm, and 2.63μm for welding fumes collected during 130A. In contrast, fumes collected during 60A exhibited sizes of 0.45μm, 0.61μm, and 0.60μm. Notably, accumulation of particles were observed, indicating that the fumes collected during 60A consisted of smaller particles classified as fine particles. The particle counts for high and low currents were 283,232,661 count/m3 and 300,604,341 count/m3, respectively. The observed particle shapes appeared agglomerate, comprised of primary spherical particles adhering together through Van Der Waals forces. Reynolds number values (Re=0.0046-0.0223, less than 1) indicated that the motion of fume particles occurred within a laminar flow regime. Furthermore, the movement of particles was influenced by their diameter, with larger particles exhibiting higher settling velocities, smaller mechanical mobility, and shorter travelled distances. In summary, this research sheds light on the intricate transport mechanisms of welding fumes, providing insights into their occurrence, characterization, and transport during the metalworking process.

Microplastic characteristics in several land covers in Banda Aceh and Aceh Besar

Plastic is one of the materials that is often used by people who are difficult to decompose. The decomposed plastic will become several parts which are termed macro plastic and micro plastic. Plastic will accumulate in soil and water can release chemicals that will endanger plant health. The purpose of this paper is to identify the accumulation of microplastics in several land covers. The research started with sampling on land cover at Mini Sport center Universitas Syiah Kuala (Gelanggang Park), Experimental Farm of Faculty of Agriculture, Urban Forest, Community Park (Tahura), and Edge of cross road (sibreh). Each replicate was sampled amount to 30 top soil samples (0-5 cm) and 30 subsoil samples (5-20 cm). Total soil samples per location point were 6 samples. The stages carried out were starting from drying the sample, separating the sediment, removing the organic material, separating the solid and identifying microplastic. Results found that the most dominant type of microplastics found at each sample point is the Fragment type of microplastics with 164 particles. Then fiber type microplastics with a particle count of 103 particles. While the least found is the type of microplastic film with a particle count of 92 particles. At Gelanggang Park, we found a high abundance of Film species and a moderate abundance of Fiber species. The Urban Forest had a low abundance of all particle types. The most common colour appearing in the data are Brown and Grey, with a total of 210 and 73 respectively. The colours dominate compared to other colour across locations and layers, there are differences in the number of colours between the Lower and Upper layers at each site.

Experimental Measurement of Secondary Particle Count for Real-Time Proton Range Verification

Experimental Measurement of Secondary Particle Count for Real-Time Proton Range Verification