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Review

Cyclone Separator for Air Particulate Matter Personal Monitoring: A Patent Review

by
M. O. Rivera-García
1,*,
M. A. Reyna
1,*,
M. A. Camarillo-Ramos
2,
M. A. Reyna-Vargas
1,
Roberto L. Avitia
1,
Daniel Cuevas-González
1 and
A. R. Osornio Vargas
3
1
Cuerpo Académico de Bioingeniería y Salud Ambiental, Universidad Autónoma de Baja California, Mexicali 21280, Mexico
2
Instituto Tecnológico de Mexicali, Mexicali 21376, Mexico
3
Department of Pediatrics, University of Alberta, Edmonton, AB T6G1C9, Canada
*
Authors to whom correspondence should be addressed.
Atmosphere 2023, 14(4), 624; https://doi.org/10.3390/atmos14040624
Submission received: 20 January 2023 / Revised: 19 March 2023 / Accepted: 20 March 2023 / Published: 25 March 2023
(This article belongs to the Special Issue Facing Air Pollution in Chile and Latin America: Present and Future Challenges)
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Abstract

:
Currently, air pollution is a critical public health problem, which means that the daily measurement of urban air quality can be enriched if measured in a personalized way. Personal environmental monitoring devices can guide the population to take action. They can track their daily activities, avoiding situations that could affect their health, allowing them to precisely know the air quality they breathe in real-time in various microenvironments. In this work, we present a review of cyclonic separation technology patents, such as pre-separators in monitoring devices. We focused on the state-of-the-art commercially available personal monitoring devices, the classification of kinds of patents, and a review of cyclone patents and gas–particle separation behaviors. The World Intellectual Property Organization IP’s portal and Google Patents search engine were used, using international patent classification plus mesh terms involving a cyclone in an air particulate monitor after predefining inclusion and exclusion criteria such as gas–air cyclones, high efficiency, and fine particle separation. Twenty-nine patents were analyzed according to the main characteristics (e.g., cut point, flow rate, and cyclone improvement) available in the patent document. The wide range of cyclones indicates a maximum flow rate of between 0.5 and 4.5 Lpm and a lower cyclone cut point of 0.8 μm. This review includes a discussion of the most relevant features of the patent documents (flow rate, particle cut point, some cyclone improvements, and technology detection). This paper aims to give an overview of the use of cyclones as pre-separators for personal air monitoring devices and to acknowledge the patented improvements of new inventors or developers.

1. Introduction

Despite the recent improvements in air quality in large parts of the world, poor air quality remains a challenge in many urban areas worldwide. In 2013, the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) concluded that outdoor air pollution and its particulate matter (PM) are carcinogenic to humans, especially in the lung [1]. There is a close relationship between exposure to PM10 and PM2.5 (particulate matter with aerodynamic diameters ≤10 and ≤2.5 μm, respectively) suspended in the air and health effects. Air pollution has health impacts even at very low concentrations in the short- and long-term [2,3,4,5]. However, no threshold has been identified under which no health effect is observed [6]. Therefore, the 2020 WHO Air Quality Guidelines aim to facilitate the setting of standards for permissible concentrations in the air [7].
The USA Environmental Protection Agency (EPA) is a leader in developing and improving instruments, methods, techniques, and other tools to measure and monitor air quality and evaluate air emissions to protect public health and the environment from air pollution [8]. To effectively control air pollutants, it is necessary to implement National Ambient Air Quality Standards (NAAQS) that account for ambient air quality and state-of-the-art methods in using technologies that provide accurate and reliable data. The Federal Reference Method (FRM) and the Federal Equivalency Method (FEM) are the most commonly used. These methods are the gold standard for states and other organizations to assess the implementation of the actions needed to attain NAAQS [9].
A modern cyclone separator is an essential piece of stationary equipment in the air quality field and has been widely used in multifunctional gas–particle separation [10]. Due to its high efficiency, simple structure, easy operation and maintenance, and good environmental adaptability (i.e., temperature, pressure, humidity, and strong corrosion conditions), it has had a strong impact in the fields of chemical and processing engineering, energy technology, environmental science, and material synthesis [11].
Cyclonic separation has displayed an irreplaceably unique role in specific situations and keeps improving separation processes in environmental sciences [12].
A standard cyclone separator generally has: (1) an air inlet, which allows the intake of air with PM; (2) a cylindrical body, which in combination with the inlet, allows the vortex flow to begin (for this reason, it is called a vortex finder); (3) a cone with a determined angle to the vertical axis and whose conical length determines the efficiency of the cyclone; (4) a dust outlet switch, which is a container to collect PM that is separated by the vortex; and (5) an exhaust pipe or PM outlet that is determined by the size of the cyclone cut point, as shown in Figure 1a. After a fluid containing PM enters the cylinder and hits its inner wall, its linear motion becomes a rotating descending spiral. Therefore, the particles are affected by centrifugal forces and impact against the wall. Then, the particles lose inertial force after colliding with the surface and fall along the wall surface of the cone. Figure 1b shows a solid view perspective. Finally, the coarser particles fall into a collector. The airflow reaches the bottom and turns upwards, carrying finer particles toward the exhaust through the exhaust outlet pipe, as shown in Figure 1c.
The main features of the cyclone separator are its simple structure and geometry; it does not have an internal structure, and it has high efficiency, requires minimal maintenance, and is low in manufacturing cost [13]. Nevertheless, the typical cyclone shows a low efficiency for fine particles [14]. Therefore, many attempts have been conducted to improve the separation performance of cyclone separators, for instance: optimizing the structure and geometrical dimension of the vortex length [15,16]; altering the shape and diameter of the vortex finder (i.e., an internal tube that allows the turbulent flow to start) [17,18,19,20]; the use of a single or double inlet [21] or a tangential or spiral inlet [22], modifying the general geometric dimensions of the intake or inlet [23]; a distinct inlet section regarding the cyclone body [24]; a symmetrical inlet and a volute outlet [25]; the cone-tip dimension [26]; the cyclone body height [27]; and the conical length [28].
Different types of cyclone separators have been developed to improve separation efficiency, such as the Lee type [29], the semi-spherical cyclone [30], the Very Sharp Cut Cyclone (VSCC) type [31], the dynamic cyclone [32], the square cyclone [33], and the circumfluent cyclone [34]. A major constraint on the ability to assess personal PM exposures is the cost and physical burden of the monitors themselves, personal air monitors typically consist of a flow pump, a pre-separator as a size selective inlet (e.g., cyclone, impactor, or both) to measure inhalable PM within the wearer’s breathing zone, and detection technology (e.g., light scattering). For this reason, the personal monitoring device must be wearable, considering the limitation of the monitor size and weight. Therefore, designing a high-efficiency cyclone for fine particle separation remains a significant challenge for developing improvements within personal monitoring without sacrificing separation efficiency.
The population can have air pollution control with the help of the air quality monitoring system, which allows the user to know the air quality continuously [35]. The EPA standardizes all methods of measuring air pollution; for example, fixed-site monitoring stations for PM are located 7 to 10 m from the ground. Nevertheless, this method gives a neighborhood-wide and urban-wide air quality estimation that is costly to operate [36]. The advantage of introducing a personal environmental monitoring method would be its capacity to provide information on PM concentrations at the individual level (daily activities and work locations), allowing them to know precisely what they are breathing in real-time in different microenvironments. In addition, such monitoring could provide a basis for evaluating PM exposure. This information may allow individuals, especially those most susceptible to the adverse effects of air pollution, to make decisions to reduce their exposure to PM. Eventually, the information may contribute to new regulations for those specific sources of PM most strongly associated with adverse health effects [37].
This paper aims to review the state-of-the-art cyclone separation technology patents and their potential use in personal monitors. We focused on pre-separators in air monitoring devices, existing cyclone patents, and cyclone separation behaviors. We include a discussion of the most relevant features available in the patent document (flow rate, cut point particle size, some cyclone improvements, and technology detection). The scope of our patent review is defined by inclusion criteria for fine particles (PM less than 10 µm), giving an overview of the use of cyclones in monitoring devices to consider the patented improvements for new inventors or air monitoring developers.

State-of-the-Art Personal Devices for Air PM

Personal monitoring devices use commercially available, low-cost sensors capable of estimating air pollutant concentrations continuously. Potential users include sensor developers, scientists, citizens, teachers, students, community organizations such as neighborhood alliances, environmental justice groups, and federal air quality agencies. In addition, the new generation of low-cost and highly portable air quality sensors allows people to use this technology for various applications beyond traditional or equivalent regulatory monitoring. Some of the potential uses of personal monitors are research (i.e., scientific studies aimed at discovering new information about pollution) and personal exposure monitoring (i.e., air quality to which a single person is exposed while doing their usual activities) [38]. Table 1 shows the performance characteristics of commercially available personal environmental monitor devices for PM measuring.
The current criteria for monitoring stations for environmental pollution consist of devices that meet the FRM or FEM requirements. As shown in Table 1, only models B and E use a cyclone inlet. Model B can use a GK cyclone 2.05 (GK) or a Sharp Cut Cyclone 1.062 (SCC). The GK cyclone separates PM4 through PM10, and the SCC cyclone separates PM1 through PM4 through a series of tangential and round-entry cyclone geometries. The SCC cyclone in particular has a shrouded inlet intended to reduce directionality effects due to breezes in the workplace. The GK 2.05 cyclone was developed for the Finnish Institute of Public Health and designed to be used in a backpack, with the intake tube protruding through a grommet. This design resulted in an excessively long inlet tube for lapel use. Therefore, the unit was redesigned with a more suitable half-length inlet, which required confirmatory testing [44]. Model E uses the Dorr-Oliver cyclone specified by the National Institute for Occupational Safety and Health (NIOSH) monitoring methods, commonly made of plastic and nylon [45,46].
Patent review articles are a tool that helps to understand state-of-the-art inventions, allowing a detailed analysis of the improvements and benefits that different inventors have embodied in their creations. The following patent review focuses on cyclone separators with application in PM monitors.

2. Materials and Methods

2.1. Patents Article Review Search Methodology

Mesh terms that were used to search for patent review articles on cyclone separators with a focus on environmental monitors were “Review article” AND “Patent” OR “Patents,” AND “Cyclone” OR “Cyclone Separator” AND “Environmental monitor” OR “Dust monitor” OR “Environmental Pollution” AND “Particle Matter” OR “PM1” OR “PM2.5” OR “PM10”; zero results were obtained by the SCOPUS database. Using the IEEEXplore database with the exact keywords ALL METADATA “Review article” AND “Patent” OR “Patents,” ALL METADATA “Cyclone” AND “Cyclone Separator” AND “Environmental monitor” OR “Dust monitor” OR “Environmental Pollution” yielded zero results. No review documents were found on patents for cyclone separators oriented to environmental monitoring, so this work will be helpful for all those interested in developing cyclone separators for monitoring applications beyond personal ones.

2.2. Data Sources and Patents Search Strategy

The patent search strategy was based on a scooping study to find how many patents had been registered for personal monitoring using a cyclone as a particulate matter separator. This process involved trialing and defining mesh terms in the literature database and inclusion/exclusion criteria, as shown in Table 2, using Google Patents and WIPO. For Google Patents, the mesh terms used were: “Cyclone,” “Cyclone Separator,” “Matter monitor,” “Particulate matter,” and “PM2.5”. For Patentscope by WIPO, the International Patent Classifications (IPC) were used to search monitors with cyclone separators, which are classified as follows: G01N 15/06—investigating concentration of particle suspensions, (G01N 15/04 and G01N 15/10 take precedence; by weighing, G01N 5/00) or G01N15/10—investigating individual particles (this IPC is for all environmental monitors). The screening was based on the search strategy shown in Figure 2.

3. Results

According to the patent search strategy, the results are shown in Table 3.
A total of 29 patents met the inclusion criteria, as shown in Table 4. Figure 3 shows the distribution of found patents by country. Furthermore, B04C, B01J, B01D, and E21 were found under the search strategy using Google Patents.

4. Discussion

The most relevant features extracted from the research of patents were the cyclone cut points and the work air flow rate. However, not all patent details were found in the databases’ patent document register. The reason is that the inventor is not obligated to share these technical details if it is not necessary to explain the invention’s functioning as a security measure against patent plagiarism. Table 4 shows patented cyclones which share cutoff-point and flow-rate details. They all achieve fine particle separation, including less than 10-micrometer particle size.
Patent AC was registered in 1972 as the first portable monitor that included a cyclone separator of fine particles used for environmental monitoring within a factory; however, it was not until 1975 by patent AB that the first portable environmental device was invented that included a cyclone as a separator and consisted of a monitor that the user could carry with them during sampling.
The standard way to describe this separation performance is the D50 cut point, meaning that the particle size has a 50:50 probability of separation when the cyclone is in equilibrium at a given flow rate. Note that the D50 cut point is the characteristic that describes cyclones in particle size separation. This feature performance in cyclones depends on their operating parameters as the flow rate, without neglecting structural design and material properties. Therefore, the monitor’s developer must take into account these characteristics in their monitor since it influences their final detection or quantification system.
Patent B has a low workflow rate with a maximum of 1 Lpm. Patent Q, with the smaller-sized cut-point diameter of 0.8 micrometer, had a maximum flow rate of 2 Lpm. The broad range of cyclones indicates a maximum flow rate between 0.5 to 4.5 Lpm, except for patents N, X, AB, and AC, which work with 90, 800, 566, and 186 Lpm, respectively.
Based on the analysis of the patents, cyclone flow control technology has been changing over time. Most patents used vacuum pumps so the cyclone flow control could determine the correct separation by its cut point. However, patent P uses an acoustic flow generator, and no flow rate data were available in the patent document. Although, the inventor only provides operating frequencies of 800 to 3000 Hz. This acoustic technology represents a significant step forward in using micro-flows to miniature cyclone devices, allowing for a more efficient personal monitor with low power consumption throughout the PM personal monitor. This flow source was found to have a maximum of 10.8 mLpm and low consumption, simple structure, and continuous flow and was without pump body oscillation [76]. The main advantage of these pumps is their low power consumption compared to conventional vacuum pumps; however, the acoustic source needs a separate frequency driver to operate the pump. Nowadays, developers are looking for personal monitors with the lowest possible cost and more ergonomic miniature sizes for the user.
It is a challenge to identify which class of cyclone separator is designed in the patent documents; however, patents A, B, L, and M describe their cyclones as tangential and with a round inlet with the same characteristics as the VSCC class. This type of cyclone could be dimensionally scaled using an empirical family model specific to a given cyclone geometry, and the family model relates the cyclone cut point to the cyclone body diameter and flow rate. Once the family model is known, it can be used to calculate the dimensions of other family members that will result in a specified cut point at a defined working flow rate. Unfortunately, the other patents do not have sufficient information to determine the cyclone class.
Some patents found have a new geometry modification at the inlet; patent E’s inventor modified the rectangular inlet installed obliquely according to the inlet air flow tangential angle (45° to 75°). This modification increases the cyclone separator’s performance. In the case of the patent I, the inlet ports were manufactured to include an angle of less than 15° to the cyclone axis to minimize particle loss during sampling.
Some patents use more than one cyclone to get a better result in the monitoring process; this method was explained by patent Y in 2001, setting a series of cyclones to increase the separation efficiency. This method was applied by patent M, using a dual pre-separator cyclone developed to monitor the ash concentration of the airplane’s indoor air when flying over volcanic areas. In addition, the monitoring applications of patents S and U are used in air sampling devices and can use one or more cyclone separators to collect PM in the same cut-point size. Another example is patent B, where the inventor implemented an arrangement of two cyclones: a first one with a primary cutoff point and a secondary one with an output associated with particles smaller than those targeted by the primary cutoff point. In short, these patents have two cutoffs and outputs for monitoring a range of sized particles. Using multiple cyclones, either in parallel or in series, to treat a more significant workflow rate results in higher efficiencies but at the cost of a significant increase in pressure drop. Higher pressure drops translate to higher energy usage and operating costs. [77].
A filter collects the PM after the separation process according to the monitoring application. Still, in the case of patent N, these particulates are deposited to a liquid substrate to create a liquid with a defined PM concentration. In patent T, the cyclones extract substrates from the atmosphere; this cyclone has a fluid injector at the inlet to make a chemical reaction with the reagent, then it separates this fluid to measure the concentration. Moreover, patent K presents a cyclone that separates particles of less than 10 μm to combine them with a fluorescent liquid target to monitor biological agents (viruses and bacteria) in PM. This patent was considered because it was applied to measure the PM in air. This method was described in 1975 by patent AA, which consisted of a cyclone separator that transfers solids to liquid before the air pollution analysis device. This type of method allows taking advantage of the flow generated by the cyclone to mix the particles with a liquid fluid. If the detection technology used requires it as an input with a specific mass concentration, this would be possible thanks to the fact that the inventors integrated a modification to accomplish it.
The data logging of a personal monitor is one of the functionalities required by the EPA, as well as real-time or online monitoring capabilities. These requirements imply that a cyclone separator should not become saturated prematurely. Most patents use light scattering devices as the PM detection technology, being the most commercially available; however, in our research, we found other detection technologies, such as those in patents G and R, which were designed for online monitoring through an aerosol matter spectrometer and a beta-ray method, respectively. In addition, patent O uses a cyclone to obtain the gas concentration for online monitoring by a microscope analysis technique using a digital camera CCD (charge-coupled device). The disadvantage of these two methods is that the sizes are significantly larger than those of other detection devices, such as light scattering devices.
Some patents are set with an impactor device; patents Q and R combine the cyclone with an impactor, taking advantage of its tangential flow and the capture capacity of an impactor to capture the nanoparticles range. Patent J has a different arrangement where the cyclone body belongs to the impactor cap to integrate a small device. As we have seen, two types of PM pre-separators for monitors exist. The first type is a cyclone separator, and the second one is an impactor or a combination of both. They work similarly since they use physical forces to separate particles. In the case of cyclones, the large-sized particles possess more significant momentum and undergo the primary rotating airflow. Due to the centrifugal inertia that hits the smooth inner surface of the cyclone body, the particles slide into the cup attached at the bottom and separate. The internal rotating airflow carrying smaller particles exits the cyclone and then passes through a filter or interior to the monitor.
On the other hand, impactors separate particles from the main air stream using the principle of inertial mass impaction. As a result, ambient air is allowed to enter the monitor assembly, and the flow path suddenly changes by providing a pressure gradient in a different direction. Large particles with higher momentum move in a straight line due to mass inertia and thus leave the airflow path to enter an empty chamber or pit. The empty chamber is called a “borehole impactor,” which contains oil or grease to prevent particle rebound. The primary airflow encounters the obstruction and thus changes its route and passes through a filter that samples the remaining particles [78]. Table 5 lists the advantages and disadvantages of impactors and cyclones.
In addition, cyclones have been modified to the point of being combined in a series of arrangements or by an impactor. This combination allows developers to reinforce monitors that require impactors as pre-separators. For example, cyclones are not sensitive to wind speed, which means that cyclones can be used both indoors and outdoors.
Cyclones have been adapting to new sampling technologies such as microscopes and others. For example, patents O and R use beta-ray methods and spectrometers (like the one used in patent G), which is indicative of a continued effort to improve adaptation to different types of technology. Moreover, they can be used indirectly by forming air masses with a determined concentration of particles and later mixing with some liquid to quantify the material involved, as in patent T.
Cyclones tend to develop to the most efficient point using the least amount of flow possible, achieving PM2.5 separations. It can be achieved using different technologies in flow control and cyclone geometry. Fluid mechanics indicate that the smaller the dimensions of a cyclone, the smaller the amount of flow will be needed to reach its cutoff point. For example, patent J is a clear example of an improving trend for cyclones and personal monitors; if you are interested in developing a personal monitor, it is highly recommended that you look for a patent for a low-cost miniature PM sensor.
According to the definition by the EPA, low-cost PM sensors are classified by costs below 1000 USD and are built with miniaturized electronic devices [81]. In this research, the most updated patents are A and B. Patent A considers a cyclone as an accessory that is interchangeable; with more efficient control, the device could control the cyclone operation through a passing valve. Model B from Table 1 is based on Patent A using cyclone models SCC and GK. Patent B has an array of real and virtual cyclones operating in parallel, conserving an ultralow workflow. This represents a challenge for new researchers and developers to improve from a 1 to 10 μm cut point and a working flow rate of 0.05 to 1 Lpm.

5. Conclusions

Quantitative measurement of PM requires complex separation and measurement methods and techniques. The use of cyclones in the pre-separation stage improves the measurement procedure. Air pollution is a critical public health problem, meaning that urban air quality must be measured in a personalized and daily way.
No review documents were found on patents for cyclone separators oriented to environmental monitoring, so this work will be helpful for all those interested in developing cyclone separators.
A total of 29 patents were analyzed in this study after a rigorous search described in the patent search strategy. When reviewing the patent registration files, it was challenging to find the details on the size of the cyclone. For this reason, it was impossible to make a geometric comparison between the patents. However, some patents provided details of the airflow and the cutoff point they used to work, including the pumping method or air control. Patent Q, with the smaller-sized cut-point diameter of 0.8 micrometer, had a maximum flow rate of 2 Lpm. The broad range of cyclones indicates a maximum flow rate of between 0.5 and 4.5 Lpm.
The cyclones in the patents are a crucial part of the measurement process, either separating the material and injecting it directly onto the measurement equipment or combining it with a substrate to generate samples of exact concentrations. When cyclones and impactors work together, they can obtain more efficient results than when working separately. In addition, new technologies are being patented that involve the cyclone as a particle pre-separator and are always looking for the lowest energy consumption, as in the case of acoustic pumps used for flow control with lower consumption than a conventional air pump.
Monitoring PM developers must be oriented to improve the miniaturization of electronic devices, including cyclones to low-cost PM sensors.
China and the United States of America have the most patents recorded, two countries recognized for their environmental pollution concerns.

Author Contributions

Conceptualization, M.O.R.-G. and M.A.R.; methodology, D.C.-G.; software, M.A.R.-V.; validation, M.A.C.-R., M.A.R. and A.R.O.V.; formal analysis, R.L.A.; investigation, M.O.R.-G.; resources, D.C.-G.; data curation, M.A.R.-V.; writing—original draft preparation, M.O.R.-G.; writing—review and editing, M.A.C.-R.; visualization, D.C.-G.; supervision, M.A.R.; project administration, M.A.R.; funding acquisition, M.A.R. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by CONACyT CVU: 541031.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

We thank CONACyT for the Scholar fellowship of the first author.

Conflicts of Interest

The authors declare no conflict of interest.

Abbreviations

ACSM Aerosol Chemical Speciation Monitor
EPA Environmental Protection Agency
FEM Federal Equivalency Methods
FRM Federal Reference Methods
IARC International Agency for Research on Cancer
IPC International Patent Classifications
NAAQS Ambient Air Quality Standards
NIOSH Occupational Safety and Health
PM Particulate matter
SCC Sharp Cut Cyclone
VSCC Very Sharp Cut Cyclone
WHO World Health Organization
WIPO World Intellectual Property Organization

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Atmosphere 14 00624 g001 550
Figure 1. Components of the cyclone: (a) numbering cyclone separator elements; (b) solid external of a cyclone; (c) cyclone internal flow pattern.
Figure 1. Components of the cyclone: (a) numbering cyclone separator elements; (b) solid external of a cyclone; (c) cyclone internal flow pattern.
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Atmosphere 14 00624 g002 550
Figure 2. Flow chart of the search methodology in databases.
Figure 2. Flow chart of the search methodology in databases.
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Atmosphere 14 00624 g003 550
Figure 3. Patent distribution by country: GB (Great Britain), CN (China), US (United States), JP (Japan), EP (European), and AU (Australia).
Figure 3. Patent distribution by country: GB (Great Britain), CN (China), US (United States), JP (Japan), EP (European), and AU (Australia).
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Table
Table 1. Commercial personal environmental monitors.
Table 1. Commercial personal environmental monitors.
IDMonitorOperating
Principle		MakerPrecisionDetection LimitCyclone
A831 Aerocet handle particle counter [39]Light scattering for mass concentration MetOne InstrumentsN/A0.5 µmN/A
BPersonal DataRAM, model pDR1500 [40]Light scattering for mass concentration Thermo Scientific ±0.2% of reading or ±0.5 µg/m30.1 µmCyclone SCC y GK
CDC1100 air quality monitor [41] Light scattering with a laser particle counterDylos Corp.N/A0.5 µmN/A
DmicroAeth®® model AE51 [42]Light absorption, 880 nmAeth Labs; Black Carbon±0.1 μg/m3<0.16 µg/m3, 2.5 mL/s, 60-s avgN/A
ESidepack personal aerosol monitor AM520 [43]Light scattering for mass concentrationTSI Incorporated±0.1 μg/m30.1 µmCyclone type DORRR-Oliver
Table
Table 2. Inclusion and exclusion criteria.
Table 2. Inclusion and exclusion criteria.
InclusionExclusion
Must be an application for fine particle separation less than PM10Non-personal monitoring applications
Air–gas cyclonesIndustrial applications
High separation efficiency
Table
Table 3. Results from the search strategy.
Table 3. Results from the search strategy.
Mesh TermsHitsMeet Inclusion and Exclusion CriteriaSource
“Cyclone,” “Cyclone Separator,” “Matter monitor,” “Centrifugal Separator,” “Particulate matter,” “PM2.5”58219Free search in Google Patents
IC: G01N 15/06 and Cyclone and Separator and Air754Patentscope by WIPO (IPC)
IC: G01N 15/04 and IC: G01N 15/10 and Cyclone and Separator and Air802Patentscope by WIPO (IPC)
IC: G01N 5/00 and Cyclone and Separator and Air1243Patentscope by WIPO (IPC)
Table
Table 4. List of patents that met the inclusion criteria. Data extracted from patents’ records [47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75].
Table 4. List of patents that met the inclusion criteria. Data extracted from patents’ records [47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75].
IDCountryPatent #Patent NameDateInventorCompanyICPDetection TechnologyFlow Rate
Lpm		Cut-Point µmCyclone Improvement
ACN215931601UCyclone separator for gas particles and gas particles detection01/03/2022Wu HuaweiThermo Fisher ScientificB04C/514Not MentionedNot Mentioned2.5 and 10Dual cyclone controlled by a passing valve in the same body
BUS20210405007A1Low-flow size-selective inlet for air quality sensors30/12/2021Paul Alan SolomonUSA GovernmentG01N 1/28Light Scattering, quartz balance0.05 to 11 to 10Ultra-low flow real cyclone and a virtual cyclone operating together in a parallel array
CUS10775354B2Autonomous ambient air sampling system for monitoring15/09/2020Jaron HensenBrigham UniversityG01N/30Mass Spectrometer4 to 82.5Cyclone adapted to a heater chamber
DCN210690331UGas PM detection system (utility model)05/06/2020Wang YanhuiShenzhen Eyesky TechnologyG01N 15/06Light ScatteringNot Mentioned2.5 and 10Cyclones include a dehydrator unit to remove humidity from the inlet gas
ECN209697194 U2A kind of cyclone separator29/11/2019Li Yongzhao Li BinjieQindao Chuangke EquipmentB04C 5/00N/ANot Mentioned5 to10The cyclone inlet air flow tangential angle (45° to 75°)
FUS20190339185PM measuring apparatus07/11/2019Francois VelgeKolisch Hartwell, P.CG01N 15/06Light Scattering0.5 to 30.8 to 2.2Cyclone has adaptation to work or just filter air at the outlet
GCN208953340UAutomatically switch sampling apparatus for atmospheric particulate matter07/06/2019Chen QiPeking UniversityG01N/24ASCM4.50 to 3 or 0–2.5Cyclone has different inlet nozzle
HEP2569069B1PM monitor10/04/2019Kevin J. GoohsThermo Fisher ScientificG01N 1/22Light scatteringNot mentioned2.5 and 10Cyclone generates gas with a determinate PM concentration
IUS9945768BMethod and apparatus for a portable PM2.5 monitoring device14/04/2018Zhongchao TanN/AG01N/22Light scatteringNot mentioned2.5The inlet ports were manufactured to include an angle of less than about 15° to minimize particle loss during the sampling process
JUS20170370809Portable air sampling device28/12/2017Daniel D. Miller-LionbergColorado State University Research FoundationG01N 1/22Light scatteringN/A1 to 10The cyclone body belongs to the impactor cap
KUS20170191974Measurement device and measurement method06/07/2017Akitake TamuraTOKYO ELECTRON LIMITEDG01N 21/64Light scattering, plasma emission spectroscopyNot mentionedMax 10Cyclone separates particles to combine with a liquid fluorescent target
LCN106872316AMeasure the particle diameter distribution of super low-concentration dust20/06/2017Liu XiaoweiHuazhong UniversityG01N 15/06Light scatteringNot mentioned2.5No mentioned more features, such as ultralow flow
MGB2544285Ash detector17/05/2017Neetin LadGreenBank Terotech LTDG01N 15/14Microscopy detectorNot mentioned0 to 2.5Dual cyclone operation
NCN103566840BSystem and method for producing high-time diluted PM2.5 aerosol29/04/2015Luo ZhongyangZhejiiang UniversityB01J 13/00Light scattering85 to 902.5Cyclone separator to get mass concentration
OCN104142289AOnline monitoring system for atmospheric aerosol12/11/2014Zeng LiminPeking UniversityG01N 15/06Microscopy detectorNot Mentioned0.3 to 5Cyclone separator to get mass concentration
PCN104128047AFine PM removal device and method with combined action05/11/2014Zhang JianCentral South UniversityB01D 45/16Quantitative mass spectrometerN/A, 800 to 3000Hz acoustic pump2.5Present an acoustic agglomerator and a cyclonic separation synergy fine particle method
QUS20140060213Portable nanoparticle sampler06/03/2014Shi-nian UangMuncy, Geissler, Olds & Lowe, P.CG01N 1/22N/A20.1 to 4Complete sampler with a cyclone combined with a micro-orifice impactor
RCN202916165UInstrument for continually and automatically monitoring fine atmospheric particles01/05/2013Dai BohuaWuhan Yite Environmental Protection TechG01N 15/06Beta ray methodNot mentioned2.5Cyclone separator as a secondary separator with impactors
SUS20120160010/20070068223Air-sampling device and method of use28/06/2012The Hsun B. ChenUSA Health and Human ServicesG01N1/22Light scattering21.94No mentioned
TUS20110159596Substance detector with cyclone30/06/2011Alex KeinanN/AG01N33/22Light scatteringNot mentioned0.1 to 8The inventor has discovered that adjusting a nozzle angle relative to the cyclone axis can increase the efficiency with which substances are caught
UCN1330958CDevice for collecting and monitoring particles of solid source discharged gas08/08/2007Zeng LiminPeking UniversityG01N 1/20Light scatteringNot mentioned2.5 and 10Cyclones are used in series, obtaining two cut-off points
VJP1841044PM concentration measuring apparatus04/10/2006Masara ShinoharaHoriba LTDG01N 15/06Light scatteringNot mentioned2.5Cyclone is used as particle distributor PM2.5 inside of apparatus for particulate density tester
WUS20060000297A1The ambient particulate sampler inlet assembly05/01/2006Robert GussmanBGI InstrumentsG01N/24Light scattering51 to 10Cyclone with a different kind of inlet nozzle jet to increase collection efficiency
XAU2003239506Automatic point source biological agent detection system11/09/2003Difurio Gabriel A.Notthrop Grumman CorporationC12M/134Light scattering8001 to 15Added a dry cyclone collector as a pre-separator base
YUS6221134Apparatus and method for separating particles from a cyclonic fluid flow24/04/2001Ernest ConradG.B.D CorpB01 45/16Light scatteringNot mentionedMax 10Series cyclones array for increased efficiency
ZGB1446760Aerial prospecting18/08/1976 Columbia Scient Ind IncG01N/22Not mentionedNot mentioned2.5 to 10Cyclones using inlet ducts of flying aircraft
AAGB1417481Method and apparatus for transferring particles from one fluid stream10/12/1975N/ABarringer Research LTDB04c/514Light scatteringNot mentionedMax 10Cyclone separator for transferring solids to liquid before analysis in air pollution
ABGB1391373Rock sampling tool23/04/1975N/ACominco LTDE21C 35/22N/A566No MentionedFirst portable cyclone
ACGB1268709Monitoring dust concentration29/03/1972Badzioch StalinslawCoal Industry Patents LTDG01N/22N/A113 to 183N/ACyclone used as control of PM in plant
Table
Table 5. Advantages and disadvantages of impactors and cyclones [79,80].
Table 5. Advantages and disadvantages of impactors and cyclones [79,80].
CyclonesImpactors
Indoor and outdoor useIndoor use
Approved for monitoring by EPAWind speed sensitive
Low costLow cost
Gases and liquids (hydrocyclones)Gas only
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Rivera-García, M.O.; Reyna, M.A.; Camarillo-Ramos, M.A.; Reyna-Vargas, M.A.; Avitia, R.L.; Cuevas-González, D.; Osornio Vargas, A.R. Cyclone Separator for Air Particulate Matter Personal Monitoring: A Patent Review. Atmosphere 2023, 14, 624. https://doi.org/10.3390/atmos14040624

AMA Style

Rivera-García MO, Reyna MA, Camarillo-Ramos MA, Reyna-Vargas MA, Avitia RL, Cuevas-González D, Osornio Vargas AR. Cyclone Separator for Air Particulate Matter Personal Monitoring: A Patent Review. Atmosphere. 2023; 14(4):624. https://doi.org/10.3390/atmos14040624

Chicago/Turabian Style

Rivera-García, M. O., M. A. Reyna, M. A. Camarillo-Ramos, M. A. Reyna-Vargas, Roberto L. Avitia, Daniel Cuevas-González, and A. R. Osornio Vargas. 2023. "Cyclone Separator for Air Particulate Matter Personal Monitoring: A Patent Review" Atmosphere 14, no. 4: 624. https://doi.org/10.3390/atmos14040624

APA Style

Rivera-García, M. O., Reyna, M. A., Camarillo-Ramos, M. A., Reyna-Vargas, M. A., Avitia, R. L., Cuevas-González, D., & Osornio Vargas, A. R. (2023). Cyclone Separator for Air Particulate Matter Personal Monitoring: A Patent Review. Atmosphere, 14(4), 624. https://doi.org/10.3390/atmos14040624

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