Capillary flow control in a fluidic diagnostic device
First Claim
1. A medical diagnostic device for measuring at least one of an analyte centration and a property of a biological fluid, comprisinga) a sample inlet for introducing a sample of the biological fluid into the medical diagnostic device;
- b) a first capillary channel for conveying the sample from the sample inlet to a branching point;
c) a capillary connecting channel for conveying a first part of the sample from the branching point through a measurement area, in which is measured a physical parameter of the sample that is related to the at least one of the analyte concentration and property of the biological fluid, and, thereafter, to a first stop junction;
d) a capillary bypass channel for conveying a second part of the sample in a first direction from a first region, proximate to the branching point, to an overflow region, distal to the branching point, the first region having a capillary dimension in a second direction substantially perpendicular to the first direction;
e) a second stop junction in the capillary bypass channel, comprising a boundary region that i) separates the first region and overflow region, ii) has a second predetermined dimension in the second direction that is greater than the capillary dimension, and iii) is triangular in shape with two legs that define an angle of less than 90 degrees that points toward the first region, whereby excess sample that enters the sample inlet will pass through the second stop junction into the overflow region; and
wherein the second stop junction impedes sample flow into the overflow region while the first part of the sample is being conveyed through the measurement area and the second stop junction is weaker than the first stop junction such that the excess sample passes through the second stop junction into the overflow region only after sample has filled the measurement area.
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Abstract
A medical diagnostic device for measuring an analyte concentration or property of a biological fluid includes capillary flow channels to convey a sample of the fluid from an inlet to a branching point, and then to a measurement area and, alternatively, through a bypass channel to an overflow region. A first stop junction stops fluid flow after it enters the measurement area. The bypass channel has a capillary dimension in at least one direction. A second stop junction, in the bypass channel, has boundary region that has a dimension that is greater in that direction and forms an angle that points toward the branching point. With this construction, the second stop junction initially prevents flow to the overflow region, but permits the flow after the measurement area is filled. The device is particularly suited for measuring coagulation time of blood.
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Citations
10 Claims
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1. A medical diagnostic device for measuring at least one of an analyte centration and a property of a biological fluid, comprising
a) a sample inlet for introducing a sample of the biological fluid into the medical diagnostic device; -
b) a first capillary channel for conveying the sample from the sample inlet to a branching point;
c) a capillary connecting channel for conveying a first part of the sample from the branching point through a measurement area, in which is measured a physical parameter of the sample that is related to the at least one of the analyte concentration and property of the biological fluid, and, thereafter, to a first stop junction;
d) a capillary bypass channel for conveying a second part of the sample in a first direction from a first region, proximate to the branching point, to an overflow region, distal to the branching point, the first region having a capillary dimension in a second direction substantially perpendicular to the first direction;
e) a second stop junction in the capillary bypass channel, comprising a boundary region that i) separates the first region and overflow region, ii) has a second predetermined dimension in the second direction that is greater than the capillary dimension, and iii) is triangular in shape with two legs that define an angle of less than 90 degrees that points toward the first region, whereby excess sample that enters the sample inlet will pass through the second stop junction into the overflow region; and
wherein the second stop junction impedes sample flow into the overflow region while the first part of the sample is being conveyed through the measurement area and the second stop junction is weaker than the first stop junction such that the excess sample passes through the second stop junction into the overflow region only after sample has filled the measurement area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification