The nano-scanning electrical mobility spectrometer (nSEMS) and its application to size distribution measurements of 1.5–25 nm particles

Abstract. Particle size measurement in the low nanometer regime is of great importance to the study of cloud condensation nuclei formation and to better understand aerosol-cloud interaction. Here we present the design, modeling, and experimental characterization of the nano-scanning electrical mobility spectrometer (nSEMS), a recently developed instrument that probes particle physical properties in the 1.5–25 nm range. The nSEMS consists of a charge conditioner, a novel differential mobility analyzer, and a two-stage condensation particle counter (CPC). The charge conditioner employs a soft x-ray bipolar ion source in a compact housing designed to optimize both nanoparticle charging and transmission efficiency. The mobility analyzer, a radial opposed migration ion and aerosol classifier (ROMIAC), can classify nanometer-sized particles with minimal degradation of its resolution or diffusional losses. The ROMIAC operates on a dual high-voltage supply with fast polarity-switching capability to minimize sensitivity to variations in the chemical nature of the ions used to charge the aerosol. Particles transmitted through the charge conditioner and mobility analyzer are measured using a two-stage CPC. They are first activated in a fast-mixing diethylene glycol (DEG) stage before being counted by a second detection stage, an ADI MAGICTM water-based CPC. The transfer function of the integrated instrument is derived from both finite-element modeling and experimental characterization. The nSEMS performance has been evaluated during measurement of transient nucleation and growth events in the CLOUD atmospheric chamber at CERN. We show that the nSEMS can provide high time and size resolution measurement of nanoparticles, and can capture the critical aerosol dynamics of newly formed atmospheric particles.

Download Full-text

The nano-scanning electrical mobility spectrometer (nSEMS) and its application to size distribution measurements of 1.5–25 nm particles

Atmospheric Measurement Techniques ◽

10.5194/amt-14-5429-2021 ◽

2021 ◽

Vol 14 (8) ◽

pp. 5429-5445

Author(s):

Weimeng Kong ◽

Stavros Amanatidis ◽

Huajun Mai ◽

Changhyuk Kim ◽

Benjamin C. Schulze ◽

...

Keyword(s):

Cloud Condensation Nuclei ◽

Transmission Efficiency ◽

Ion Source ◽

Experimental Characterization ◽

Electrical Mobility ◽

Two Stage ◽

Aerosol Dynamics ◽

Condensation Particle Counter ◽

Aerosol Cloud Interactions ◽

A Charge

Abstract. Particle size measurement in the low nanometer regime is of great importance to the study of cloud condensation nuclei formation and to better understand aerosol–cloud interactions. Here we present the design, modeling, and experimental characterization of the nano-scanning electrical mobility spectrometer (nSEMS), a recently developed instrument that probes particle physical properties in the 1.5–25 nm range. The nSEMS consists of a novel differential mobility analyzer and a two-stage condensation particle counter (CPC). The mobility analyzer, a radial opposed-migration ion and aerosol classifier (ROMIAC), can classify nanometer-sized particles with minimal degradation of its resolution and diffusional losses. The ROMIAC operates on a dual high-voltage supply with fast polarity-switching capability to minimize sensitivity to variations in the chemical nature of the ions used to charge the aerosol. Particles transmitted through the mobility analyzer are measured using a two-stage CPC. They are first activated in a fast-mixing diethylene glycol (DEG) stage before being counted by a second detection stage, an ADI MAGIC™ water-based CPC. The transfer function of the integrated instrument is derived from both finite-element modeling and experimental characterization. The nSEMS performance has been evaluated during measurement of transient nucleation and growth events in the CLOUD atmospheric chamber at CERN. We show that the nSEMS can provide high-time- and size-resolution measurement of nanoparticles and can capture the critical aerosol dynamics of newly formed atmospheric particles. Using a soft x-ray bipolar ion source in a compact housing designed to optimize both nanoparticle charging and transmission efficiency as a charge conditioner, the nSEMS has enabled measurement of the contributions of both neutral and ion-mediated nucleation to new particle formation.

Download Full-text

A two-stage amplified PZT sensor for monitoring lung and heart sounds in discharged pneumonia patients

Microsystems & Nanoengineering ◽

10.1038/s41378-021-00274-x ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Hongbin Chen ◽

Shuai Yu ◽

Haiyang Liu ◽

Jie Liu ◽

Yongguang Xiao ◽

...

Keyword(s):

High Sensitivity ◽

Cost Effective ◽

High Ratio ◽

Heart Sounds ◽

Two Stage ◽

Diagnosis And Prognosis ◽

Sensor Device ◽

Cost Effective Alternative ◽

A Charge ◽

Highly Sensitive Detection

AbstractAssessment of lung and heart states is of critical importance for patients with pneumonia. In this study, we present a small-sized and ultrasensitive accelerometer for continuous monitoring of lung and heart sounds to evaluate the lung and heart states of patients. Based on two-stage amplification, which consists of an asymmetric gapped cantilever and a charge amplifier, our accelerometer exhibited an extremely high ratio of sensitivity to noise compared with conventional structures. Our sensor achieves a high sensitivity of 9.2 V/g at frequencies less than 1000 Hz, making it suitable to use to monitor weak physiological signals, including heart and lung sounds. For the first time, lung injury, heart injury, and both lung and heart injuries in discharged pneumonia patients were revealed by our sensor device. Our sound sensor also successfully tracked the recovery course of the discharged pneumonia patients. Over time, the lung and heart states of the patients gradually improved after discharge. Our observations were in good agreement with clinical reports. Compared with conventional medical instruments, our sensor device provides rapid and highly sensitive detection of lung and heart sounds, which greatly helps in the evaluation of lung and heart states of pneumonia patients. This sensor provides a cost-effective alternative approach to the diagnosis and prognosis of pneumonia and has the potential for clinical and home-use health monitoring.

Download Full-text

Two-Stage-Discharge Ion Source

Journal of Nuclear Science and Technology ◽

10.1080/18811248.1979.9730886 ◽

1979 ◽

Vol 16 (3) ◽

pp. 151-160 ◽

Cited By ~ 2

Author(s):

Masanobu NUNOGAKI ◽

Masao NAITO ◽

Hideo AKIMUNE

Keyword(s):

Ion Source ◽

Two Stage

Download Full-text

Negative-Ion Implantation

MRS Proceedings ◽

10.1557/proc-354-99 ◽

1994 ◽

Vol 354 ◽

Cited By ~ 1

Author(s):

Junzo Ishikawa

Keyword(s):

Ion Implantation ◽

Negative Ions ◽

Ion Source ◽

Negative Ion ◽

Rf Plasma ◽

Ion Currents ◽

Promising Technique ◽

Surface Charging ◽

Silicon Carbon ◽

A Charge

AbstractNegative-ion implantation is a promising technique for forthcoming ULSI (more than 256 M bits) fabrication and TFT (for color LCD) fabrication, since the surface charging voltage of insulated electrodes or insulators implanted by negative ions is found to saturate within so few as several volts, no breakdown of insulators would be expected without a charge neutralizer in these fabrication processes. Scatter-less negative-ion implantation into powders is also possible. For this purpose an rf-plasma-sputter type heavy negative-ion source was developed, which can deliver several milliamperes of various kinds of negative ion currents such as boron, phosphor, silicon, carbon, copper, oxygen, etc. A medium current negative-ion implanter with a small version of this type of ion source has been developed.

Download Full-text

Determination of the Error in Transferring of Length Unit’s Size when Measuring the Nanoparticles’ Diameter Using an Analyzer of Particles’ Differential Electrical Mobility

Devices and Methods of Measurements ◽

10.21122/2220-9506-2021-12-3-194-201 ◽

2021 ◽

Vol 12 (3) ◽

pp. 194-201

Author(s):

V. L. Solomakho ◽

A. A. Bagdun

Keyword(s):

Particle Size ◽

Size Distribution Function ◽

Measuring Instruments ◽

Random Component ◽

Electrical Mobility ◽

Standard Samples ◽

Reference Measuring ◽

Condensation Particle Counter ◽

Uniformity Of Measurements ◽

Unit Of Length

The quality of nanomaterials and nanotechnologies is largely determined by the stability of the applied technologies, which, to a large extent, depend on the constancy of particle sizes. In this regard, metrological problems arise that are associated both with measuring the dimensions of the microstructure of aerosols, suspensions and powders, and with ensuring the uniformity of measurements when transferring a unit of a physical quantity from a standard to working measuring instruments. The purpose of this work was to determine and calculate the error in transferring the size of a unit of length when measuring the diameter of nanoparticles.An analyzer of differential electric mobility of particles was determined as a reference measuring instrument for which the calculation was made. It allows the separation of aerosol particles based on the dependence of their electrical mobility on the particle size. In combination with a condensation particle counter, it allows you to scan an aerosol and build a particle size distribution function. This measurement method is the most accurate in the field of measuring the diameters of particles in aerosols, therefore, the error in the transmission of particle size must be set as for a standard.The paper describes the physical principles of measurement by this method and presents an equation for determining the diameter of nanoparticles. Based on this equation, the sources of non-excluded systematic error were identified. Also, an experimental method was used to determine the random component of the measurement error of nanoparticles and to calculate the error in transferring the size of a unit of length when measuring the diameter of nanoparticles.The obtained results will be used for metrological support of standard samples of particle size, ensuring traceability of measurements of aerosol particle counters and for aerosol research.

Download Full-text

Investigating three patterns of new particles growing to the size of cloud condensation nuclei in Beijing's urban atmosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-183-2021 ◽

2021 ◽

Vol 21 (1) ◽

pp. 183-200

Author(s):

Liya Ma ◽

Yujiao Zhu ◽

Mei Zheng ◽

Yele Sun ◽

Lei Huang ◽

...

Keyword(s):

Cloud Condensation Nuclei ◽

Chemical Species ◽

Particle Growth ◽

Growth Patterns ◽

Urban Atmosphere ◽

Condensation Nuclei ◽

Two Stage ◽

Continuous Increase ◽

One Stage ◽

New Particles

Abstract. The growth of newly formed particles with diameters from ∼ 10 nm to larger sizes was investigated in Beijing's urban atmosphere during 10–23 December 2011, 12–27 April 2012, and June–August 2014. In 11 out of 27 new particle formation (NPF) events during June–August, the maximum geometric median diameter (Dpgmax) of newly formed particles exceeded 75 nm, and the grown new particles may contribute to the population of cloud condensation nuclei. In contrast, no apparent growth in new particles with Dpgmax < 20 nm was observed in all of the events in December, in approximately half of the NPF events in April, and in only two events during June–August. New particles observed in the latter NPF events were too small to be activated as cloud condensation nuclei. Apparent new particle growth with Dpgmax ≤ 50 nm was observed in the remaining 18 NPF events. The 11 NPF events during June–August with Dpgmax exceeding 75 nm were analyzed in detail. The particle growth patterns can be clearly classified into three types: one-stage growth and two-stage growth-A and growth-B patterns. The one-stage growth pattern is characterized by a continuous increase in Dpg with Dpgmax ≥ 80 nm (4 out of 11 NPF events), and the two-stage growth-A and growth-B patterns are characterized by no apparent growth and shrinkage of particles, respectively, in the middle 2–4 h of the growth period (7 out of 11 NPF events). Combining the observations of gaseous pollutants and measured (or modeled) concentrations of particulate chemical species, the three growth patterns were discussed in terms of the spatial heterogeneity of NPF, formation of secondary aerosols, and evaporation of semivolatile particulates. Secondary organic species and NH4NO3 were argued to be two major contributors to the growth of new particles, but NH4NO3 likely contributed to growth only in the late afternoon and/or at nighttime.

Download Full-text

Using convolutional neural network and long short time memory to automatically detect aneurysm on 2D DSA images (Preprint)

10.2196/preprints.28880 ◽

2021 ◽

Author(s):

JunHua Liao ◽

LunXin Liu ◽

HaiHan Duan ◽

YunZhi Huang ◽

LiangXue Zhou ◽

...

Keyword(s):

Deep Learning ◽

Intracranial Aneurysm ◽

Spatial Information ◽

Diagnostic System ◽

Two Stage ◽

Regional Localization ◽

Detection Stage ◽

Aneurysm Detection ◽

Sensitivity Specificity ◽

Computation Load

BACKGROUND It is hard to distinguish cerebral aneurysm from overlap vessels based on the 2D DSA images, for its lack the spatial information. OBJECTIVE The aim of this study is to construct a deep learning diagnostic system to improve the ability of detecting the PCoA aneurysm on 2D-DSA images and validate the efficiency of deep learning diagnostic system in 2D-DSA aneurysm detecting. METHODS We proposed a two stage detecting system. First, we established the regional localization stage (RLS) to automatically locate specific detection region of raw 2D-DSA sequences. And then, in the intracranial aneurysm detection stage (IADS) ,we build three different frames, RetinaNet, RetinaNet+LSTM, Bi-input+RetinaNet+LSTM, to detect the aneurysms. Each of the frame had fivefold cross-validation scheme. The area under curve (AUC), the receiver operating characteristic (ROC) curve, and mean average precision (mAP) were used to validate the efficiency of different frames. The sensitivity, specificity and accuracy were used to identify the ability of different frames. RESULTS 255 patients with PCoA aneurysms and 20 patients without aneurysm were included in this study. The best results of AUC of the RetinaNet, RetinaNet+LSTM, and Bi-input+RetinaNet+LSTM were 0.95, 0.96, and 0.97, respectively. The sensitivity of the RetinaNet, RetinaNet+LSTM, and Bi-input+RetinaNet+LSTM were 81.65% (59.40% to 94.76%), 87.91% (64.24% to 98.27%), 84.50% (69.57% to 93.97%), respectively. The specificity of the RetinaNet, RetinaNet+LSTM, and Bi-input+RetinaNet+LSTM were 88.89% (66.73% to 98.41%), 88.12% (66.06% to 98.08%), and 88.50% (74.44% to 96.39%), respectively. The accuracy of the RetinaNet, RetinaNet+LSTM, and Bi-input+RetinaNet+LSTM were 92.71% (71.29% to 99.54%), 89.42% (68.13% to 98.49%), and 91.00% (77.63% to 97.72%), respectively. CONCLUSIONS Two stage aneurysm detecting system can reduce time cost and the computation load. According to our results, more spatial and temporal information can help improve the performance of the frames, so that Bi-input+RetinaNet+LSTM has the best performance compared to other frames. And our study can demonstrate that our system was feasible to assist doctor to detect intracranial aneurysm on 2D-DSA images.

Download Full-text

Characterization of the mass-dependent transmission efficiency of a CIMS

Atmospheric Measurement Techniques ◽

10.5194/amt-9-1449-2016 ◽

2016 ◽

Vol 9 (4) ◽

pp. 1449-1460 ◽

Cited By ~ 34

Author(s):

Martin Heinritzi ◽

Mario Simon ◽

Gerhard Steiner ◽

Andrea C. Wagner ◽

Andreas Kürten ◽

...

Keyword(s):

Mass Spectrometer ◽

Chemical Ionization ◽

Transmission Efficiency ◽

Ion Source ◽

Mass Discrimination ◽

Perfluorinated Acids ◽

Relative Transmission ◽

The Absolute ◽

Primary Ions

Abstract. Knowledge about mass discrimination effects in a chemical ionization mass spectrometer (CIMS) is crucial for quantifying, e.g., the recently discovered extremely low volatile organic compounds (ELVOCs) and other compounds for which no calibration standard exists so far. Here, we present a simple way of estimating mass discrimination effects of a nitrate-based chemical ionization atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometer. Characterization of the mass discrimination is achieved by adding different perfluorinated acids to the mass spectrometer in amounts sufficient to deplete the primary ions significantly. The relative transmission efficiency can then be determined by comparing the decrease of signals from the primary ions and the increase of signals from the perfluorinated acids at higher masses. This method is in use already for PTR-MS; however, its application to a CI-APi-TOF brings additional difficulties, namely clustering and fragmentation of the measured compounds, which can be treated with statistical analysis of the measured data, leading to self-consistent results. We also compare this method to a transmission estimation obtained with a setup using an electrospray ion source, a high-resolution differential mobility analyzer and an electrometer, which estimates the transmission of the instrument without the CI source. Both methods give different transmission curves, indicating non-negligible mass discrimination effects of the CI source. The absolute transmission of the instrument without the CI source was estimated with the HR-DMA method to plateau between the m∕z range of 127 and 568 Th at around 1.5 %; however, for the CI source included, the depletion method showed a steady increase in relative transmission efficiency from the m∕z range of the primary ion (mainly at 62 Th) to around 550 Th by a factor of around 5. The main advantages of the depletion method are that the instrument is used in the same operation mode as during standard measurements and no knowledge of the absolute amount of the measured substance is necessary, which results in a simple setup.

Download Full-text