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Pallas Instruments (Shanghai) Co., Ltd
Overview of the Principle and Application of SMPS Scanning Electromigration Particle Size Spectrometer
Date: 2025-12-15Read: 0
SMPS Scanning Electromigration Particle Size SpectrometerIt is an instrument used to measure the particle size distribution of submicron to nanometer sized particles in air. Its principle is based on the correspondence between the electric mobility of charged particles in an electric field and their particle size, and achieves particle size resolution and concentration counting through differential mobility analysis.
1. The core principle of the instrument is electric mobility analysis. Particles naturally carry a small amount of charge in the atmosphere or are assigned a known charge before entering the migration zone of known electric field strength. Under the action of an electric field, charged particles migrate along the direction of the airflow, and the migration rate is proportional to the particle's electric mobility. The electric mobility is inversely proportional to particle size, with smaller particles migrating faster. There are electrodes at both ends of the migration zone, and particles pass through the migration tube under the combined action of electric field and airflow. Particles with different electric mobility will be separated at different positions. The separated particles enter the detector, usually a condensation particle counter or Faraday cup. The detector calculates the corresponding electric mobility based on the number of particles arriving and their migration time, and converts it into particle size. By continuously changing the electric field strength, the instrument can scan a series of electric mobility ranges to obtain a continuous particle size distribution spectrum.
2. The instrument structure mainly includes a neutralizer, differential migration tube, electric field scanning system, and particle detector. Neutralizers are used to charge aerosol particles to a known charge distribution, ensuring measurement consistency. Differential migration tube is a key component for separating particles. The internal airflow is parallel to the direction of the electric field, and particles undergo migration and focusing processes inside the tube, reducing overlap and loss. The electric field scanning system continuously adjusts the voltage according to the set program, so that particles of different sizes reach the detector in sequence. The detector converts particle signals into electrical signals and counts them, combining scanning time and voltage changes to generate particle size concentration corresponding data. The entire system needs to operate under constant temperature and humidity conditions to reduce the impact of environmental changes on migration rate and detection efficiency.
3SMPS Scanning Electromigration Particle Size SpectrometerThe main applications are focused on the study of atmospheric and environmental particulate matter, occupational health monitoring, and combustion and industrial process analysis. In atmospheric research, it can distinguish the concentration changes of fine and ultrafine particles, helping to analyze pollution sources, secondary aerosol formation, and particle evolution processes. In the field of occupational health, the exposure level of nanoscale dust in the workplace can be evaluated to provide a basis for protective strategies. In combustion and industrial emission monitoring, the characteristics of nanoparticles generated from engine exhaust, smelting, or chemical processes can be analyzed to support emission control and process optimization. This instrument can also be used in conjunction with chemical composition analysis equipment to achieve synchronous determination of particle size and chemical composition, providing multidimensional data for the study of health effects and climate impacts of particulate matter.
4. Attention should be paid to the correction of charge efficiency, transmission loss, and detection efficiency when using and processing data. The charging probability of particles with different particle sizes varies, and the concentration needs to be corrected through theoretical or experimental calibration. The geometric shape of migration pipes and connecting pipes can cause particle size dependent transmission losses, and transfer function correction should be introduced in data processing. The counting efficiency of detectors for particles of different sizes is not constant and requires calibration with standard particles. The environmental temperature and humidity can change the air viscosity and particle diffusion characteristics, and should be recorded in real-time during measurement and used for result correction.
SMPS Scanning Electromigration Particle Size SpectrometerBy using electric field migration separation and particle size scanning, high-precision particle size distribution measurement of submicron and nano particles can be achieved. Its principle is clear and its structure is clear, providing effective technical means for studying the characteristics of particulate matter in the fields of environment, health, and industry.