Commercial Particle Counter Research Articles

COVID-19 in the Clinic: Aerosol Containment Mask for Endoscopic Otolaryngologic Clinic Procedures.

ObjectiveTo create an aerosol containment mask (ACM) that contains aerosols during common otolaryngologic endoscopic procedures while protecting patients from environmental aerosols.Study DesignBench testing.SettingMannequin testing.MethodsThe mask was designed in SolidWorks and 3-dimensional printed. Mannequins were fitted with a nebulizer to generate aerosols. Commercial particle counters were used to measure mask performance.ResultsThe ACM has 2 ports on either side for instruments and endoscopes, a port for a filter, and a port that can evacuate aerosols contained within the mask via a standard suction pump. The mask contained aerosols on a mannequin with and without facial hair when the suction was set to 18.5 L/min. Other types of masks demonstrated substantial aerosol leakage under similar conditions. In a subsequent experiment, the ACM contained aerosols generated by a nebulizer up to the saturation of the particle detector without measurable leakage with or without suction.ConclusionThe ACM will accommodate rigid and flexible endoscopes plus instruments and prevent leakage of patient-generated aerosols, thus avoiding contamination of the room and protecting health care workers from airborne contagions.Level of evidence2.

Performance of an Electrothermal MEMS Cantilever Resonator with Fano-Resonance Annoyance under Cigarette Smoke Exposure.

An electrothermal piezoresistive cantilever (EPC) sensor is a low-cost MEMS resonance sensor that provides self-actuating and self-sensing capabilities. In the platform, which is of MEMS-cantilever shape, the EPC sensor offers several advantages in terms of physical, chemical, and biological sensing, e.g., high sensitivity, low cost, simple procedure, and quick response. However, a crosstalk effect is generated by the coupling of parasitic elements from the actuation part to the sensing part. This study presents a parasitic feedthrough subtraction (PFS) method to mitigate a crosstalk effect in an electrothermal piezoresistive cantilever (EPC) resonance sensor. The PFS method is employed to identify a resonance phase that is, furthermore, deployed to a phase-locked loop (PLL)-based system to track and lock the resonance frequency of the EPC sensor under cigarette smoke exposure. The performance of the EPC sensor is further evaluated and compared to an AFM-microcantilever sensor and a commercial particle counter (DC1100-PRO). The particle mass–concentration measurement result generated from cigarette-smoke puffs shows a good agreement between these three detectors.

Volumetric monitoring of airborne particulate matter concentration using smartphone-based digital holographic microscopy and deep learning

Airborne particulate matter (PM) has become a global environmental issue. This PM has harmful effects on public health and precision industries. Conventional air-quality monitoring methods usually utilize expensive equipment, and they are cumbersome to handle for accurate and high throughput measurements. In addition, commercial particle counters have technical limitations in high-concentration measurement, and data fluctuations are induced during air sampling. In this study, a novel smartphone-based technique for monitoring airborne PM concentrations was developed using smartphone-based digital holographic microscopy (S-DHM) and deep learning network called Holo-SpeckleNet. Holographic speckle images of various PM concentrations were recorded by the S-DHM system. The recorded speckle images and the corresponding ground truth PM concentrations were used to train deep learning algorithms consisting of a deep autoencoder and regression layers. The performance of the proposed smartphone-based PM monitoring technique was validated through hyperparameter optimization. The developed S-DHM integrated with Holo-SpeckleNet can be smartly and effectively utilized for portable PM monitoring and safety alarm provision under perilous environmental conditions.

Optimization of Aerosol Sensor Placement in Common Ventilation Ductwork

Aerosol detection in HVAC duct components is a critical component of contaminant detection and analysis. Incorrect placement of a sensor inlet within the ductwork can have a significant, deleterious effect on capture efficiency and sample accuracy. Computational fluid dynamics studies were conducted of straight rectangular cross–section ductwork and a 90° bend to determine flow patterns and simulations of particulate injections were made at various locations across the inlet. The resultant particle distributions were analyzed to determine the optimal placement for a sensor inlet. The study demonstrated that, for the geometries studied, the optimal location for a sensor inlet is approximately ½ to ¾ of a duct diameter downstream from the interior corner of the bend, centred laterally within the duct, and at approximately ⅔ of the duct height. These results were experimentally verified using ductwork constructed in a laboratory environment using a polydisperse aerosol and commercial particle counter.

Current Status of Hybrid Bearing Damage Detection

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high-pressure oxidizer turbopump on the space shuttle main engine led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si3N4 balls. The aerospace industry is currently studying the use of hybrid bearings and, naturally, the failure modes of these bearings become an issue in light of the limited data available. In today's turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Because the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure. The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris in oil using a commercial particle counter.

Intercomparison of number concentration measurements by various aerosol particle counters

Total aerosol particle number concentrations, as measured by means of 16 different measurement systems, have been quantitatively compared during an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (ICCP-IUGG). The range of measuring instruments includes Pollak counters (PCO) in use already for several decades, presently available commercial particle counters, as well as laboratory prototypes. The operation of the instruments considered was based on different measurement principles: (1) adiabatic expansion condensation particle counter, (2) flow diffusion condensation particle counter, (3) turbulent mixing condensation particle counter, (4) laser optical particle counter, and (5) electrostatic particle measurement system. Well-defined test aerosols with various chemical compositions were considered: DEHS, sodium chloride, silver, hydrocarbons, and tungsten oxide. The test aerosols were nearly monodispersed with mean particle diameters between 4 and 520 nm, the particle number concentrations were varied over a range from about 4×10 1 to 7×10 6 cm −3. A few measurements were performed with two-component aerosol mixtures. For simultaneous concentration measurements, the various instruments considered were operated under steady state conditions in a linear flow system. A series of at least 10 single concentration measurements was performed by each individual instrument at each set of test aerosol parameters. The average of the concentration data measured by the various instruments was defined as a common reference. The number concentrations obtained from the various instruments typically agreed within a factor of about two over the entire concentration range considered. The agreement of the measured concentrations is notable considering the various different measurement principles applied in this study, and particularly in view of the broad range of measurement instruments used. Significant deviations and nonlinear response were observed only in a few cases and are possibly related to calibration errors. For certain conditions, a dependence of aerosol counter response on particle composition has been found. The scatter of the number concentrations obtained from each individual instrument during measurements with constant test aerosol typically did not exceed 20% to 25%. At concentrations below 10 3 cm −3, however, several of the instruments, including electrostatic particle measurement systems, tend to show increased experimental scatter.

Counting efficiencies of six commercial particle counters

Counting efficiencies of a condensation nuclei counter (TSI 3020), a white-light optical particle counter (Climet CI-8060) and four laser instruments (PMS LAS-X, LAS-250X, LPC 525 and HP-LAS) were determined relative to the LAS-X. Measurements were made in the geometric diameter range of 0.1–4 μm using latex spheres as well as monodisperse organic and inorganic particles produced by a vibrating orifice generator. The high-pressure in-line counter (HP-LAS) shows a nonlinear response to gas velocity which can be taken into account by a calibration. The lower detection limits (50% points) of the conventional laser counters (LAS-X and LAS-250X) agree within 0.05 μm with their nominal specifications; for the white-light counter (CI-8060) the actual lower limit is at about 0.4 μm. For all counters, the degree of inlet losses for larger particles varies greatly with inlet design and flow velocity of each counter.