Heinz Fissan - Academia.edu (original) (raw)
Papers by Heinz Fissan
Journal of Nanoparticle Research, 2012
Journal of Nanoparticle Research, 2013
In many data evaluation procedures for particle measuring devices and in filtration models, spher... more In many data evaluation procedures for particle measuring devices and in filtration models, spherical particles are assumed. However, significant fractions of aerosol particles are agglomerates of small primary spheres. The morphology of particles in filtration processes may not be known a priori and if the filtration data are processed with wrong assumption, errors can be induced. In this work, we have quantified such errors for the case of open-structured agglomerates. Filtration efficiency tests with polydisperse silver nanoparticle agglomerates and their sintered spheres were performed. After the sintering process, particles with a compact structure with the shape close to a sphere are obtained, which are referred to as sintered spheres in the present study. The testing method involved generation of particulate forms, passing the particles through the testing section, and measurement of the particle number concentrations and size distributions before and after the filter. Measurements of the aerosols upstream and downstream of the filter were conducted using scanning mobility particle sizers (SMPS, TSI Inc.), which covered the rage from 10 to 480 nm. Particles were additionally characterized from the electron microscopic images and the average primary particle size was determined to be 16.8 nm. The number-size distribution curves were obtained and used for penetration calculation. The penetration was dependent on the particle size and morphology. Silversintered spheres were captured with a lower efficiency than agglomerates with the same mobility diameter because of the stronger interception effect for agglomerates. Data analysis of the number-size distribution for agglomerates was processed based on sphere assumption and using the model for openstructured agglomerates developed by Lall and Friedlander. The efficiencies based on total concentrations
Journal of Nanoparticle Research, 2011
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use. How can nanobiotechnology oversight advance science and industry: examples from environmental, health, and safety studies of nanoparticles (nano-EHS
Analytical Methods, 2014
A well-known and accepted aerosol measurement technique, the scanning mobility particle sizer (SM... more A well-known and accepted aerosol measurement technique, the scanning mobility particle sizer (SMPS), is applied to characterize colloidally dispersed nanoparticles. To achieve a transfer from dispersed particles to aerosolized particles, a newly developed nebulizer (N) is used that, unlike commonly used atomizers, produces significantly smaller droplets and therefore reduces the problem of the formation of residual particles. The capabilities of this new instrument combination (N + SMPS) for the analysis of dispersions were investigated, using three different dispersions, i.e. gold-PVP nanoparticles ($20 nm), silver-PVP nanoparticles ($70 nm) and their 1 : 1 (m : m) mixture. The results are compared to scanning electron microscopy (SEM) measurements and two frequently applied techniques for characterizing colloidal systems: Dynamic light scattering (DLS) and analytical disc centrifugation (ADC). The differences, advantages and disadvantages of each method are discussed, especially with respect to the size resolution of the techniques and their ability to distinguish the particle sizes of the mixed dispersion. While DLS is, as expected, unable to resolve the binary dispersion, SEM, ADC and SMPS are able to give quantitative information on the two particle sizes. However, while the high-resolving ADC is limited due to the dependency on a predefined density of the investigated system, the transfer of dispersed particles into an aerosol and subsequent analysis with SMPS are an adequate way to characterize binary systems, independent of the density of concerned particles, but matching the high resolution of the ADC. We show that it is possible to use the well-established aerosol measurement technique (N + SMPS) in colloid science with all its advantages concerning size resolution and accuracy.
Aerosol Science and Technology, 2012
The charge distributions of an improved opposed flow unipolar diffusion charger were measured usi... more The charge distributions of an improved opposed flow unipolar diffusion charger were measured using a tandem differential mobility analyzer (DMA) set up in a size range of approximately 20-400 nm. The charger is intended to be used in a portable aerosol sizer to measure particle size distributions. The determined charge distributions were represented by lognormal distributions, and a set of equations and coefficients was developed to calculate the charge distributions. These equations can be easily implemented in software for size distribution measurements. The agreement between the mathematically derived and measured charge distributions is very good, with regression coefficients R 2 > 0.96. The investigations showed that approximately 55% of 20-nm particles remain uncharged, while up to 25 elementary charges need to be considered for multiple charge correction of 400-nm particles. Comparison with the Fuchs theory delivered satisfying agreement with the measured average charge levels, but charge distributions cannot be described by the Fuchs theory, likely caused by the charger geometry.
Aerosol Science and Technology, 1996
The performance of four differential mobility analyzers (DMAs), namely the TSI-long, the TSI-shor... more The performance of four differential mobility analyzers (DMAs), namely the TSI-long, the TSI-short, the Hauke 31150, and the Spectromktre de Mobilite Electriqut Circulaire (SMEC) were evaluated under the same conditions of flow rates, flow ratio, input monodisperse aerosols, and transport-line lengths. The evaluations were performed under the conditions of 10 Ilmin sheath air and 1 llmin aerosol flow rates, and at a flow ratio of 10: 1. Monodisperse aerosols in the size range of 6 nm to 50 nm were obtained by classifying condensation aerosols using a Hauke DMA operated at 20: 1 flow ratio. The transfer functions of all four DMAs have been obtained by deconvoluting the scan results of the evaluated DMA (DMA2), and by using the empirical transfer function of the first DMA (DMA1, the Hauke DMA at 20: 1 flow ratio). The half-width, height, and area of the transfer functions have been compared for the four DMAs tested. These results provide a quantitative comparison of the mobility resolution and diffusionloss of the nanometer aerosols in the DMAs. AEROSOL SCIENCE AND TECHNOLOGY 24:l-13 (1996)
Aerosol and Air Quality Research, 2011
Measurement techniques which allow the detection of airborne nanoparticles are of great interest ... more Measurement techniques which allow the detection of airborne nanoparticles are of great interest for e.g. exposure monitoring and quality control during nanoparticle production. An increasing number of commercial devices use a unipolar diffusion charger to charge the particles and determine the nanoparticle concentration and sometimes size. The analysis however may be biased by the presence of large particles. We therefore developed a preseparator that removes particles larger than 450 nm, i.e the minimum in the range of particle lung deposition curves, but only causes a low pressure drop. The preseparator uses a total flow rate of 2.5 L/min and consists of two stages. The first stage is a virtual impactor that removes particles larger than approximately 1 µm with a minor flow of 1 L/min. Particles above 450 nm are removed from the remaining 1.5 L/min in the cyclone of the second stage. The combination of a cyclone with a virtual impactor was shown to reduce the pressure drop of the preseparator from 8.1 to 5.6 kPa compared with a cyclone alone and improve the sharpness of the separation curve for cutoff diameters around 450 nm. Furthermore the virtual impactor extends the cleaning intervals of the preseparator, because large particles are no longer deposited in the cyclone. Eventually the preseparator was tested with an opposed flow diffusion charger and it was shown that particle charging is not affected by the pressure drop.
Journal of Nanoparticle Research, 2000
Microelectronic Engineering, 1998
Nanometer-sized PbS particles are deposited in an electrostatic precipitator at cm h. The low-cos... more Nanometer-sized PbS particles are deposited in an electrostatic precipitator at cm h. The low-cost aerosol atmospheric pressure on planar substrates with a rate of about 10 'x-" ' apparatus consists of (i) particle generation by evaporation and subsequent coagulation, (it) charging the particles and selection in size by a Differential Mobility Analyzer (DMA), (iii) crystallisation in an annealing step, and finally (iv) deposition of particles. Specular X-Ray diffraction and Transmission Electron Microscopy (TEM) is used to study the size and morphology of the PbS particles indicating that these particles are fully crystalline with lattice constant of bulk PbS. Laterally selective particle deposition (lithography) is aimed at by means of electrostatic control of the charged particles in the gas-phase. Best results are obtained with an electrostatic mask provided simply by a photoresist pattern.
Journal of Aerosol Science, 1998
Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk... more Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk material thereby making them attractive for many new electronic, optical or magnetic applications. They can be used for these functional applications in the form of granular films, nanocomposites or nanophase materials. In this review, the main applications of current interest will be dealt with including some discussions of the underlying phenomena. These applications include quantum dots, luminescent materials, gas sensors, resistors and varistors, conducting and capacitive films, high-temperature superconductors, and thermoelectrical, optical and magnetic materials. In the second part, various experimental techniques for synthesizing nanoparticles in the gas phase are described. Finally, the works on nanoparticle synthesis in the gas phase aiming at any of the abovementioned functional applications is reviewed.
Journal of Aerosol Science, 1996
Journal of Aerosol …, 1998
A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring th... more A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring the size distribution of nanometer aerosols in the particle size range of 350nm. The design is based on a cylindrical configuration and is optimized by means of the ...
Journal of Aerosol …, 1998
A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring th... more A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring the size distribution of nanometer aerosols in the particle size range of 350nm. The design is based on a cylindrical configuration and is optimized by means of the ...
Aerosol Science and Technology, 1999
Due to the lake of in-situ aerosol particle analysis systems, aerosol samples are taken and analy... more Due to the lake of in-situ aerosol particle analysis systems, aerosol samples are taken and analyzed off-line. For detailed analysis of particle properties such as shape, morphology, and composition, off-line operating analytical tools like light microscopes, scanning electron microscopes (SEM), total re ection x-ray uorescence (TXRF), and so on are used. The analysis must be performed on a representative sample of particles homogeneously deposited on a at sample plate. This avoids sample preparation steps which may change the sample. In this paper we describe the design, construction, and evaluation of a continuous sampling device that deposits gasborne particles on an analytically suitable sample plate. The collection ef ciency and the deposition pattern were optimized using a numerical model and experiments. It turned out that representative samples appropriate for further analysis can be taken in the particle size range from 0.03 m m < Dp < 10 m m. Additionally, the sampling ef ciency was investigated for particles smaller than 0.03 m m using electrical and non-electrical deposition mechanisms like diffusion and thermophoresis. The investigations performed demonstrate that the designed electrostatic precipitator (ESP) is a very useful tool for homogeneous particle deposition on analytically suitable at sample plates and can be used as a backup lter. Further, the ESP especially can be used in combination with a differential mobility analyzer (DMA) if detailed investigations of a narrow particle size range of a polydisperse aerosol are required.
Powder and particle
The term nanoparticle is used nowadays to indicate particles with diameters smaller than 100 nm. ... more The term nanoparticle is used nowadays to indicate particles with diameters smaller than 100 nm. The reduced size of nanoparticles is responsible for changed electronic, optical and magnetic properties of nanoparticles and nanostructured materials in comparison with the bulk material. This can be used for new applications such as quantum dots, luminescent maten"als, gas sensors, conductive films, and capacitive, resistive, magnetic and optical materials. An overview is given of the different synthesis processes used to provide nanoparticles with the required properties for functional applications, especially electronic and optical ones. We will concentrate on gas-phase processes to show their advantages. Apart from the synthesis techniques, handling techniques are described. Some examples from our own research are given, in which the use of electrical forces plays a central role: size fractionation, deposition and mixing can all be controlled by using charged particles.
Journal of Aerosol Science, 1998
Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk... more Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk material thereby making them attractive for many new electronic, optical or magnetic applications. They can be used for these functional applications in the form of granular films, nanocomposites or nanophase materials. In this review, the main applications of current interest will be dealt with including some discussions of the underlying phenomena. These applications include quantum dots, luminescent materials, gas sensors, resistors and varistors, conducting and capacitive films, high-temperature superconductors, and thermoelectrical, optical and magnetic materials. In the second part, various experimental techniques for synthesizing nanoparticles in the gas phase are described. Finally, the works on nanoparticle synthesis in the gas phase aiming at any of the abovementioned functional applications is reviewed.
Journal of Nanoparticle Research, 2012
Journal of Nanoparticle Research, 2013
In many data evaluation procedures for particle measuring devices and in filtration models, spher... more In many data evaluation procedures for particle measuring devices and in filtration models, spherical particles are assumed. However, significant fractions of aerosol particles are agglomerates of small primary spheres. The morphology of particles in filtration processes may not be known a priori and if the filtration data are processed with wrong assumption, errors can be induced. In this work, we have quantified such errors for the case of open-structured agglomerates. Filtration efficiency tests with polydisperse silver nanoparticle agglomerates and their sintered spheres were performed. After the sintering process, particles with a compact structure with the shape close to a sphere are obtained, which are referred to as sintered spheres in the present study. The testing method involved generation of particulate forms, passing the particles through the testing section, and measurement of the particle number concentrations and size distributions before and after the filter. Measurements of the aerosols upstream and downstream of the filter were conducted using scanning mobility particle sizers (SMPS, TSI Inc.), which covered the rage from 10 to 480 nm. Particles were additionally characterized from the electron microscopic images and the average primary particle size was determined to be 16.8 nm. The number-size distribution curves were obtained and used for penetration calculation. The penetration was dependent on the particle size and morphology. Silversintered spheres were captured with a lower efficiency than agglomerates with the same mobility diameter because of the stronger interception effect for agglomerates. Data analysis of the number-size distribution for agglomerates was processed based on sphere assumption and using the model for openstructured agglomerates developed by Lall and Friedlander. The efficiencies based on total concentrations
Journal of Nanoparticle Research, 2011
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use. How can nanobiotechnology oversight advance science and industry: examples from environmental, health, and safety studies of nanoparticles (nano-EHS
Analytical Methods, 2014
A well-known and accepted aerosol measurement technique, the scanning mobility particle sizer (SM... more A well-known and accepted aerosol measurement technique, the scanning mobility particle sizer (SMPS), is applied to characterize colloidally dispersed nanoparticles. To achieve a transfer from dispersed particles to aerosolized particles, a newly developed nebulizer (N) is used that, unlike commonly used atomizers, produces significantly smaller droplets and therefore reduces the problem of the formation of residual particles. The capabilities of this new instrument combination (N + SMPS) for the analysis of dispersions were investigated, using three different dispersions, i.e. gold-PVP nanoparticles ($20 nm), silver-PVP nanoparticles ($70 nm) and their 1 : 1 (m : m) mixture. The results are compared to scanning electron microscopy (SEM) measurements and two frequently applied techniques for characterizing colloidal systems: Dynamic light scattering (DLS) and analytical disc centrifugation (ADC). The differences, advantages and disadvantages of each method are discussed, especially with respect to the size resolution of the techniques and their ability to distinguish the particle sizes of the mixed dispersion. While DLS is, as expected, unable to resolve the binary dispersion, SEM, ADC and SMPS are able to give quantitative information on the two particle sizes. However, while the high-resolving ADC is limited due to the dependency on a predefined density of the investigated system, the transfer of dispersed particles into an aerosol and subsequent analysis with SMPS are an adequate way to characterize binary systems, independent of the density of concerned particles, but matching the high resolution of the ADC. We show that it is possible to use the well-established aerosol measurement technique (N + SMPS) in colloid science with all its advantages concerning size resolution and accuracy.
Aerosol Science and Technology, 2012
The charge distributions of an improved opposed flow unipolar diffusion charger were measured usi... more The charge distributions of an improved opposed flow unipolar diffusion charger were measured using a tandem differential mobility analyzer (DMA) set up in a size range of approximately 20-400 nm. The charger is intended to be used in a portable aerosol sizer to measure particle size distributions. The determined charge distributions were represented by lognormal distributions, and a set of equations and coefficients was developed to calculate the charge distributions. These equations can be easily implemented in software for size distribution measurements. The agreement between the mathematically derived and measured charge distributions is very good, with regression coefficients R 2 > 0.96. The investigations showed that approximately 55% of 20-nm particles remain uncharged, while up to 25 elementary charges need to be considered for multiple charge correction of 400-nm particles. Comparison with the Fuchs theory delivered satisfying agreement with the measured average charge levels, but charge distributions cannot be described by the Fuchs theory, likely caused by the charger geometry.
Aerosol Science and Technology, 1996
The performance of four differential mobility analyzers (DMAs), namely the TSI-long, the TSI-shor... more The performance of four differential mobility analyzers (DMAs), namely the TSI-long, the TSI-short, the Hauke 31150, and the Spectromktre de Mobilite Electriqut Circulaire (SMEC) were evaluated under the same conditions of flow rates, flow ratio, input monodisperse aerosols, and transport-line lengths. The evaluations were performed under the conditions of 10 Ilmin sheath air and 1 llmin aerosol flow rates, and at a flow ratio of 10: 1. Monodisperse aerosols in the size range of 6 nm to 50 nm were obtained by classifying condensation aerosols using a Hauke DMA operated at 20: 1 flow ratio. The transfer functions of all four DMAs have been obtained by deconvoluting the scan results of the evaluated DMA (DMA2), and by using the empirical transfer function of the first DMA (DMA1, the Hauke DMA at 20: 1 flow ratio). The half-width, height, and area of the transfer functions have been compared for the four DMAs tested. These results provide a quantitative comparison of the mobility resolution and diffusionloss of the nanometer aerosols in the DMAs. AEROSOL SCIENCE AND TECHNOLOGY 24:l-13 (1996)
Aerosol and Air Quality Research, 2011
Measurement techniques which allow the detection of airborne nanoparticles are of great interest ... more Measurement techniques which allow the detection of airborne nanoparticles are of great interest for e.g. exposure monitoring and quality control during nanoparticle production. An increasing number of commercial devices use a unipolar diffusion charger to charge the particles and determine the nanoparticle concentration and sometimes size. The analysis however may be biased by the presence of large particles. We therefore developed a preseparator that removes particles larger than 450 nm, i.e the minimum in the range of particle lung deposition curves, but only causes a low pressure drop. The preseparator uses a total flow rate of 2.5 L/min and consists of two stages. The first stage is a virtual impactor that removes particles larger than approximately 1 µm with a minor flow of 1 L/min. Particles above 450 nm are removed from the remaining 1.5 L/min in the cyclone of the second stage. The combination of a cyclone with a virtual impactor was shown to reduce the pressure drop of the preseparator from 8.1 to 5.6 kPa compared with a cyclone alone and improve the sharpness of the separation curve for cutoff diameters around 450 nm. Furthermore the virtual impactor extends the cleaning intervals of the preseparator, because large particles are no longer deposited in the cyclone. Eventually the preseparator was tested with an opposed flow diffusion charger and it was shown that particle charging is not affected by the pressure drop.
Journal of Nanoparticle Research, 2000
Microelectronic Engineering, 1998
Nanometer-sized PbS particles are deposited in an electrostatic precipitator at cm h. The low-cos... more Nanometer-sized PbS particles are deposited in an electrostatic precipitator at cm h. The low-cost aerosol atmospheric pressure on planar substrates with a rate of about 10 'x-" ' apparatus consists of (i) particle generation by evaporation and subsequent coagulation, (it) charging the particles and selection in size by a Differential Mobility Analyzer (DMA), (iii) crystallisation in an annealing step, and finally (iv) deposition of particles. Specular X-Ray diffraction and Transmission Electron Microscopy (TEM) is used to study the size and morphology of the PbS particles indicating that these particles are fully crystalline with lattice constant of bulk PbS. Laterally selective particle deposition (lithography) is aimed at by means of electrostatic control of the charged particles in the gas-phase. Best results are obtained with an electrostatic mask provided simply by a photoresist pattern.
Journal of Aerosol Science, 1998
Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk... more Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk material thereby making them attractive for many new electronic, optical or magnetic applications. They can be used for these functional applications in the form of granular films, nanocomposites or nanophase materials. In this review, the main applications of current interest will be dealt with including some discussions of the underlying phenomena. These applications include quantum dots, luminescent materials, gas sensors, resistors and varistors, conducting and capacitive films, high-temperature superconductors, and thermoelectrical, optical and magnetic materials. In the second part, various experimental techniques for synthesizing nanoparticles in the gas phase are described. Finally, the works on nanoparticle synthesis in the gas phase aiming at any of the abovementioned functional applications is reviewed.
Journal of Aerosol Science, 1996
Journal of Aerosol …, 1998
A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring th... more A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring the size distribution of nanometer aerosols in the particle size range of 350nm. The design is based on a cylindrical configuration and is optimized by means of the ...
Journal of Aerosol …, 1998
A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring th... more A nanometer aerosol differential mobility analyzer, Nano-DMA, has been developed for measuring the size distribution of nanometer aerosols in the particle size range of 350nm. The design is based on a cylindrical configuration and is optimized by means of the ...
Aerosol Science and Technology, 1999
Due to the lake of in-situ aerosol particle analysis systems, aerosol samples are taken and analy... more Due to the lake of in-situ aerosol particle analysis systems, aerosol samples are taken and analyzed off-line. For detailed analysis of particle properties such as shape, morphology, and composition, off-line operating analytical tools like light microscopes, scanning electron microscopes (SEM), total re ection x-ray uorescence (TXRF), and so on are used. The analysis must be performed on a representative sample of particles homogeneously deposited on a at sample plate. This avoids sample preparation steps which may change the sample. In this paper we describe the design, construction, and evaluation of a continuous sampling device that deposits gasborne particles on an analytically suitable sample plate. The collection ef ciency and the deposition pattern were optimized using a numerical model and experiments. It turned out that representative samples appropriate for further analysis can be taken in the particle size range from 0.03 m m < Dp < 10 m m. Additionally, the sampling ef ciency was investigated for particles smaller than 0.03 m m using electrical and non-electrical deposition mechanisms like diffusion and thermophoresis. The investigations performed demonstrate that the designed electrostatic precipitator (ESP) is a very useful tool for homogeneous particle deposition on analytically suitable at sample plates and can be used as a backup lter. Further, the ESP especially can be used in combination with a differential mobility analyzer (DMA) if detailed investigations of a narrow particle size range of a polydisperse aerosol are required.
Powder and particle
The term nanoparticle is used nowadays to indicate particles with diameters smaller than 100 nm. ... more The term nanoparticle is used nowadays to indicate particles with diameters smaller than 100 nm. The reduced size of nanoparticles is responsible for changed electronic, optical and magnetic properties of nanoparticles and nanostructured materials in comparison with the bulk material. This can be used for new applications such as quantum dots, luminescent maten"als, gas sensors, conductive films, and capacitive, resistive, magnetic and optical materials. An overview is given of the different synthesis processes used to provide nanoparticles with the required properties for functional applications, especially electronic and optical ones. We will concentrate on gas-phase processes to show their advantages. Apart from the synthesis techniques, handling techniques are described. Some examples from our own research are given, in which the use of electrical forces plays a central role: size fractionation, deposition and mixing can all be controlled by using charged particles.
Journal of Aerosol Science, 1998
Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk... more Nanoparticles, smaller than 100 nm, have many properties which differ from the corresponding bulk material thereby making them attractive for many new electronic, optical or magnetic applications. They can be used for these functional applications in the form of granular films, nanocomposites or nanophase materials. In this review, the main applications of current interest will be dealt with including some discussions of the underlying phenomena. These applications include quantum dots, luminescent materials, gas sensors, resistors and varistors, conducting and capacitive films, high-temperature superconductors, and thermoelectrical, optical and magnetic materials. In the second part, various experimental techniques for synthesizing nanoparticles in the gas phase are described. Finally, the works on nanoparticle synthesis in the gas phase aiming at any of the abovementioned functional applications is reviewed.