Particle Measuring Device Using Bent Flow Cell for Brownian Motion Analysis
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Solution Overview
Problem
Existing particle measuring methods face challenges in accurately determining particle size due to the difficulty in obtaining precise flow velocity distribution, leading to errors in measuring particle movement by Brownian motion.
Innovation Solution
A particle measuring device and method that utilize a flow cell with a bent structure and imaging units to capture scattered light from particles, allowing for the specification of particle movement in a two-dimensional direction by Brownian motion without correcting for sample fluid flow velocity, using multiple still images captured at a predetermined frame rate to accurately determine particle size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the image of sample fluid is captured from the vertical direction against the sample fluid flow direction, then the particle movement amount can be measured, but the captured image includes both Brownian motion and fluid flow velocity, making it difficult to obtain accurate flow velocity distribution and causing errors in particle size measurement
Solution Approach 1:
The patent extracts only the necessary component (flow velocity in the flow passage extension direction) from the complex three-dimensional flow velocity distribution. By using a flow cell with a bent flow passage and capturing images from the extension direction, the system isolates and measures only the flow velocity component along the flow passage, eliminating the need to measure and correct for complex three-dimensional flow distributions.
Solution Approach 2:
The patent changes the image capture direction to be substantially parallel to the flow passage extension direction (from vertical capture to longitudinal capture). This dimensional change allows the imaging unit to capture particle movement primarily in the flow direction, where the flow velocity component is dominant and easier to characterize, simplifying the measurement approach.
2Measurement precision
If light is irradiated to sample fluid and scattered light is captured to measure particle size, then particle size can be determined, but accurate measurement requires subtracting fluid flow velocity from particle movement amount, which is difficult to obtain precisely
Solution Approach 1:
The patent applies local quality by designing the flow cell with a specific bent structure that creates a localized measurement region. In this specific location, the flow velocity distribution has particular characteristics that simplify measurement. The bent flow passage geometry creates a region where the flow velocity component along the extension direction is dominant and more uniform, making it easier to measure and correct.
3Measurement precision
If a linear flow cell is used to capture particle images for Brownian motion analysis, then particle size can be obtained from movement amount, but the sample fluid flow velocity contaminates the Brownian motion measurement
Solution Approach 1:
The patent performs preliminary action by pre-characterizing the flow velocity distribution in the flow cell through flow simulation or measurement. This flow velocity information is obtained in advance and stored, so that during particle measurement, the pre-obtained flow velocity data can be directly used to correct the particle movement measurements without requiring real-time flow velocity measurement, thereby eliminating the harmful interference of fluid flow.
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
This approach enables accurate measurement of particle size and number concentration with improved precision by isolating Brownian motion movement from fluid flow velocity, facilitating accurate particle size determination.
Implementation Method 1
A particle counter using a light scattering phenomenon has been broadly known
Implementation Method 2
a particle measuring method for obtaining a particle size from a measured movement amount has been proposed, focusing on a particle movement amount (displacement amount) by Brownian motion
Data Source
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AI summary
Provided is a particle measuring device and a particle measuring method for measuring a particle size with favorable accuracy. A flow cell (1) includes a flow passage (1a) of sample fluid. An irradiation optical system (3) irradiates, with light from a light source (2), the sample fluid in the flow passage (1a). An imaging unit (4) captures, from an extension direction of the flow passage (1a), an image of scattered light from the particle in a detection region in the flow passage (1a), the light passing through the detection region. A particle size specifying unit specifies a movement amount of the particle in a two-dimensional direction by Brownian motion based on multiple still images of a particle image captured at a predetermined frame rate by the imaging unit (4), thereby specifying the particle size of the particle from the movement amount in the two-dimensional direction.