Microfluidic device and method
A combination of components in a capillary flow channel uses capillary forces to passively control the movement of liquid samples within a microfluidic device. To detect a target, a liquid sample introduced to a proximal portion of capillary channel of a microfluidic device moves by capillary action along the specific components of capillary channel.
1 . A microfluidic device comprising:
a port configured to receive a liquid sample, a filter pocket, a mixing well, and a capillary flow channel;
wherein the capillary flow channel comprises a proximal opening, a distal opening, a dry reagent zone, a pinch region, and a detection zone;
wherein the filter pocket comprises a filter and disposed substantially at the proximal opening;
wherein the mixing well comprises a length, a width, a height, and a perimeter, the width decreasing from a central portion of the mixing well toward the perimeter along at least two opposed directions, wherein the mixing well is disposed distal to the filter pocket;
wherein the dry reagent zone containing a reagent, the dry reagent zone disposed distal to the mixing well;
wherein the pinch region is configured to redirect flow,
wherein the pinch region is disposed distal to the dry reagent zone and has a width that is less than that of the capillary flow channel;
wherein the pinch region has a width that is at most half the width of the capillary flow channel;
wherein the detection zone is disposed distal to a fluid resistance feature,
wherein the distal opening is tapered to control a flow rate, and wherein the filter pocket, the mixing well, the dry reagent zone, pinch region, and the detection zone are in fluidic communication.
2 . The microfluidic device of claim 1 , wherein the filter pocket comprises a sample inlet having a recess configured to receive a liquid sample, a filter landing, and a vent configured to permit air to be displaced upon receiving the liquid sample.
3 . The microfluidic device of claim 2 , wherein the filter landing includes a raised plateau extending from a distal edge of the filter pocket.
4 . The microfluidic device of claim 2 , wherein the filter pocket further comprises a catwalk strip disposed for directing a fluid deposited at the sample inlet to the filter landing.
5 . The microfluidic device of claim 1 , wherein the mixing well is dimensioned to move a filtered liquid sample by capillary action.
6 . The microfluidic device of claim 1 , wherein the dry reagent zone contains walls with a hydrophobic ink.
7 . The microfluidic device of claim 1 , wherein the pinch region is configured with a lobe, optionally wherein the pinch region comprises a portion of the capillary flow channel that is lobed in a direction that is substantially perpendicular to a length of the microfluidic device.
8 . The microfluidic device of claim 1 , wherein the detection zone contains at least one solid phase capture spot configured to bind a specific analyte.
9 . The microfluidic device of claim 1 , further comprising two or more solid phase capture spots arranged in a series along a length of the detection zone.
10 . The microfluidic device of claim 8 , wherein the at least one solid phase capture spot provides a signal measured by a reader.
11 . The microfluidic device of claim 1 , further comprising a waste channel distal to the detection zone.
12 . The microfluidic device of claim 11 , wherein a portion of a substrate covers the waste channel and that portion is printed with hydrophobic ink that increases flow rate and decreases wash time.
13 . The microfluidic device of claim 1 , wherein the capillary flow channel is disposed between an upper substrate and a lower substrate.
14 . The microfluidic device of claim 13 , wherein the lower substrate comprises a first portion having a first depth and a second portion having a second depth that is less than the first depth.
15 . The microfluidic device of claim 14 , wherein a portion having a first depth is convex and a portion having a second depth is planar.
16 . The microfluidic device of claim 1 , wherein the filter pocket is configured to move liquid by capillary action along the capillary flow channel and into the mixing well of the capillary flow channel.
17 . The microfluidic device of claim 7 , wherein the mixing well is configured to move liquid by capillary action along the capillary flow channel and into the pinch region of the capillary flow channel.
18 . The microfluidic device of claim 1 , wherein the mixing well comprises a depth that is greater than a depth of the capillary flow channel.
19 . A method for determining a presence or an absence of a cardiac troponin in a patient sample, comprising:
placing a blood sample on a microfluidic device of claim 1 to label the cardiac troponin, if present in the patient sample, with a label comprising a binding partner for the cardiac troponin and a detectable moiety; and
detecting a presence of cardiac troponin in the patient sample by determining a presence or an absence of the label,
wherein detection of the presence of the label indicates the presence of cardiac troponin in the patient sample, wherein an assay has a limit of quantitation of about 3 μg/mL with a coefficient of variation of less than about 20%.
20 . The method of claim 19 , wherein the cardiac troponin is cardiac troponin I (cTnI).
21 . The method of claim 19 , wherein the cardiac troponin is cardiac troponin T (cTnT).
22 . The method of claim 19 , wherein the cardiac troponin is a complex of cTnI and cTnT.
23 . The microfluidic device of claim 1 , wherein the mixing well is substantially bowl-shaped.