Method and apparatus for separation of particles in a microfluidic device
First Claim
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1. A microfluidic device for separating a mixture of a liquid and particles subjecting said mixture to low forces comprising:
- (a) an entry port for receiving a sample of said mixture of a liquid and particles;
(b) a capillary passageway in fluid communication by capillary forces with said entry port, optionally containing a hydrophobic or hydrophilic stop;
(c) an elongated separation chamber having proximal and distal ends, said proximal end being in fluid communication by capillary forces with said capillary passageway of (b), and said distal end being closed, said separation chamber comprising(1) a volume for receiving at least a portion of said sample;
(2) a depth to particle diameter ratio of about 5/1 to 100/1, said ratio being chosen to avoid clogging of the chamber with said particles and as a function of the force to be applied to said mixture; and
(3) a wall surface having a surface energy equal to or less than the surface energy of said particles to facilitate separation of said sample by attraction of said particles to said wall surface;
(d) a vent for removing air from the entry port of (a) and the separation chamber of (c) displaced by said sample.
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Abstract
A microfluidic device provides separation of particles in a liquid sample, particularly, separation of a sample of whole blood into its components for further analysis. Separation into red blood cells and plasma occurs within a few seconds after the blood sample has been transferred into a separation chamber with the application of centrifugal force of less than about five times gravity. With the application of greater force measurement of hematocrit is possible.
200 Citations
29 Claims
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1. A microfluidic device for separating a mixture of a liquid and particles subjecting said mixture to low forces comprising:
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(a) an entry port for receiving a sample of said mixture of a liquid and particles; (b) a capillary passageway in fluid communication by capillary forces with said entry port, optionally containing a hydrophobic or hydrophilic stop; (c) an elongated separation chamber having proximal and distal ends, said proximal end being in fluid communication by capillary forces with said capillary passageway of (b), and said distal end being closed, said separation chamber comprising (1) a volume for receiving at least a portion of said sample; (2) a depth to particle diameter ratio of about 5/1 to 100/1, said ratio being chosen to avoid clogging of the chamber with said particles and as a function of the force to be applied to said mixture; and (3) a wall surface having a surface energy equal to or less than the surface energy of said particles to facilitate separation of said sample by attraction of said particles to said wall surface; (d) a vent for removing air from the entry port of (a) and the separation chamber of (c) displaced by said sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A microfluidic device for separating whole blood into red blood cells and plasma by subjecting said whole blood to low forces comprising:
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(a) an entry port for receiving a sample of whole blood; (b) a hydrophilic capillary passageway in fluid communication by capillary forces with said entry port, said passageway optionally containing a hydrophobic or hydrophilic stop; (c) an elongated separation chamber having proximal and distal ends, said proximal end being in fluid communication by capillary forces with said capillary passageway of (b), said distal end being closed, said separation chamber comprising; (1) a volume for receiving at least a portion of said sample, (2) a depth to red blood cell diameter ratio of about 5/1 to 100/1, said ratio being chosen to avoid clogging of the chamber with said red blood cells and as a function of the force to be applied to said sample; and (3) a wall surface having a contact angle relative to water of about 20°
to 80°
to facilitate separation of said sample by attraction of said red blood cells to said wall surface;(d) a vent for removing air from the entry port of (a), and the separation chamber of (c) displaced by said sample. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A microfluidic device for measuring hematocrit of whole blood samples comprising:
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(a) an entry port for receiving a sample of whole blood; (b) a hydrophilic capillary passageway in fluid communication by capillary forces with said entry port, said passageway containing a hydrophobic or hydrophilic stop; (c) an elongated separation chamber having proximal and distal ends, said proximal end being in fluid communication by capillary forces with said capillary passageway of (b), said distal end being closed, said separation chamber comprising; (1) a volume for receiving at least a portion of said sample, (2) depth to red blood cell diameter ratio of about 5/1 to 100/1, said ratio being chosen to avoid clogging of the chamber with red blood cells and as a function of the force to be applied to said sample; and (3) a wall surface having a contact angle relative to water of about 20°
to 80°
to facilitate separation of said sample by attraction of said red blood cells to said wall surfaces;(d) a vent from the entry port of (a) and the separation chamber of (c) for removing air displaced by said sample. - View Dependent Claims (26, 27, 28, 29)
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Specification