Particle imaging system with a varying flow rate
AssigneeBrightwell Technologies
InventorFrederick King
Life of this patent
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Abstract
A particle imaging system and a method provided for analyzing particles in a fluid; the system comprising a means for capturing image data of the fluid within a sample cell, and a means for flow control, a valve and a pump, wherein the fluid within the sample cell is periodically stopped, or slowed down, for image capturing and moved rapidly between image capturing events. Advantageously, the present invention allows to increase exposure times, which is particularly significant for fluorescent imaging at low illumination levels.
Claims24
An imaging system for imaging particles in a fluid, the particles characterized by an average diameter or size, the imaging system comprising:
- a sample cell for containing samples of fluid flowing therethrough;
- an imaging means for sequentially capturing images of particles within the sample cell with a pre-determined exposure time per image of at least 1 msec and an image capture rate of at least 0.1 image per second to obtain a plurality of images, wherein each of the images is characterized by a field of view in the direction of the fluid flow of at least 0.1 mm;
- a flow control means for
- slowing down the fluid flow within the sample cell during capturing of the images so that an average displacement of the particles within the field of view in the sample cell in the direction of the fluid flow during each of the image captures is less than 10% of the average particle diameter or size, and
- accelerating the fluid flow through the sample cell between capturing the images, so that the fluid within the field of view is substantially replaced between capturing of consecutive two of the plurality of images.
An imaging system for imaging particles in a fluid, the system comprising:
- a sample cell for containing samples of fluid flowing therethrough;
- a flow control means for controllably varying the fluid flow through the sample cell;
- an imaging means for sequentially capturing a plurality of images of particles within the sample cell at a pre-determined image capture rate Rimage of at least 0.1 frame per second with an exposure time τ per image capture of at least 0.1/Rimage, the images characterized by a field of view of length D in the direction of the fluid flow;
- a processor for synchronizing the flow control means and the imaging means so that the images are captured during first time intervals wherein the fluid flow is substantially slowed down so that an average displacement of the particles within the field of view in the sample cell in the direction of the fluid flow during each of the image captures is substantially less than 0.1·Rimage·D·τ, and the fluid flow is accelerated during second time intervals between the first time intervals so that during each of the second time intervals a fluid sample within the field of view in the sample cell is replaced with a new fluid sample;
- and,
- wherein an average flow velocity within the first time intervals is at least 100 times less than an average flow velocity within the second time intervals.
A method for obtaining data related to particles in a fluid, the particles characterized by an average diameter or size, the method comprising the steps of:
- a) providing a fluid sample to a sample cell by flowing the fluid therethrough at a first fluid flow velocity;
- b) slowing down the fluid flow within the sample cell using a fluid control means so that the fluid flows within the sample cell at a second fluid flow velocity that is at least 100 time smaller than the first fluid flow velocity;
- c) capturing an image of one or more of the particles within the sample cell during a pre-determined exposure time, the image characterized by a field of view in the direction of the fluid flow;
- d) increasing the fluid velocity within the sample cell to the first fluid flow velocity for replacing the fluid within the field of view in the sample cell with a new fluid sample;
- e) repeating steps (b) through (d) a plurality of times at least ones every 10 seconds to obtain a plurality of images;
- and,
- f) processing the plurality of images to obtain a characteristic of particle distribution in the fluid;
- wherein during step (a) a Reynolds number of the fluid flow in the sample cell is less than 2000, and wherein the second fluid flow velocity is such that an average displacement of the particles within the field of view in the sample cell in the direction of the fluid flow during each of the image captures is less than 10% of the average particle diameter or size.
Dependencies are inferred from the claim text.