Ultra Fine Particle Sensor Using Electric Field Segmentation
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Solution Overview
Problem
Existing methods for measuring airborne ultrafine particles (UFPs) with diameters between 5-500 nm are insufficient as they primarily focus on respirable particle mass concentration, neglecting the health impact of smaller particles, and do not provide reliable data on total human health impact parameters or number concentration and average diameter of UFPs.
Innovation Solution
An ultrafine particle sensor with an air inlet, particle charging section, concentration variation section using parallel plates with variable voltage, and a particle sensing section that produces a measurement signal allowing for derivation of particle number and length concentrations, enabling the calculation of number-averaged particle diameter and human health impact parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If particle mass concentration measurement is used, then measurement of respirable particles is achieved, but particle number concentration and size distribution information is lost
Solution Approach 1:
The measurement process is segmented into multiple stages: particle charging section divides particles by size through differential charging, concentration variation section separates particles by mobility, and particle sensing section detects charged particles. This segmentation allows simultaneous acquisition of mass concentration, number concentration, and size distribution data that cannot be obtained through single-stage mass measurement alone.
Solution Approach 2:
Electric charge is introduced as an intermediary property to enable particle separation and detection. The particle charging section imparts charge to particles, and the concentration variation section uses electric fields to separate particles based on their charge-to-mass ratio. This intermediary charging mechanism allows the system to extract multiple parameters (mass, number, size) from the same particle population.
2Quantity of substance
If conventional particle measurement methods are used, then respirable particle mass is measured, but health impact parameters for ultrafine particles are not provided
Solution Approach 1:
The system changes measurement parameters from solely mass-based to include charge-based and mobility-based parameters. By measuring particle charge, mobility, and concentration at different separation stages, the system calculates health impact parameters that reflect both the quantity and biological relevance of ultrafine particles, providing a more comprehensive health risk assessment.
3Loss of information
If particle separation by size is implemented, then particle size distribution is obtained, but measurement complexity increases
Solution Approach 1:
The system replaces complex mechanical particle separation mechanisms with electric field-based separation. Instead of using physical sieves, centrifugal separators, or other mechanical size-sorting devices, the invention uses electric fields in the concentration variation section to separate particles based on their charge-to-mass ratio, achieving size distribution measurement with simpler and more compact equipment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sensor effectively measures UFP concentrations and diameters, providing valuable air quality information and enabling the characterization of ultrafine particle pollution, thereby improving the assessment of human health impacts associated with these particles.
Implementation Method 1
a particle charging section capable of electrically charging at least a portion of the ultra fine particles
Implementation Method 2
The particle charging section may comprise at least one corona-discharge source
Implementation Method 3
a concentration variation section downstream of the particle charging section, the concentration variation section comprising at least one set of substantially parallel plates and means for applying a variable voltage to at least one of the plates to produce a variable electric field capable of causing a variation of the concentration of ultra fine particles
Implementation Method 4
a particle sensing section capable of producing a measurement signal being an electric current varying between at least a first current level corresponding to the first concentration level and a second current level corresponding to the second concentration level
Data Source
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AI summary
The invention relates to an ultra fine particle sensor (1) for sensing airborne particles with a diameter in a range of approximately 1-500 nm. The sensor comprises an air inlet (2) for entry of a flow of ultra fine particles and a concentration variation section (4) capable of causing a variation of the concentration of ultra fine particles between at least a first concentration level and a second concentration level during at least one time interval. A particle sensing section (5) is provided capable of producing a measurement signal (I) varying in dependence of said variation between said first concentration level and said second concentration level. An evaluation unit (6) is provided capable of deriving data relating to said ultra fine particles from said varying measurement signal. As a result of the applied variation in the concentration level, data can be obtained from the resulting variation of the measurement signal which relate to the length concentration and number concentration of airborne ultra fine particles per unit volume.