Metering technique for lateral flow assay devices
View Patent ↗A diagnostic test kit for detecting an analyte residing in a test sample is provided. The kit employs a lateral flow device that contains a membrane. A metering channel is formed in the membrane that is capable of delivering a controlled volume of the test sample to a detection zone upon initiation of the assay. Such a metering channel is particularly effective for embodiments in which the test sample has a relatively low volume, such as less than about 100 microliters, in some embodiments from about 0.5 to about 25 microliters, and in some embodiments, from about 1 to about 10 microliters. For example, whole blood drops obtained from patients with a lancet typically have a volume of less than about 3 microliters. Despite their low volume, the present inventors have discovered that the blood drops may still be accurately analyzed for the presence of an analyte using lateral flow detection techniques.
1. A method for performing a lateral flow assay, the method comprising:
contacting a test sample having a volume of less than about 100 microliters with a metering channel that is formed in a membrane;
placing a bridging member over the metering channel and in fluid communication with the membrane; and
supplying a diluent to the membrane to facilitate flow of the test sample to a detection zone.
2. The method of claim 1 , wherein the test sample is whole blood.
3. The method of claim 2 , further comprising separating plasma, serum, or both from the whole blood for analysis.
4. The method of claim 1 , wherein the volume of the test sample is less than about 25 microliters.
5. The method of claim 1 , wherein the volume of the test sample is less than about 10 microliters.
6. The method of claim 1 , wherein the metering channel is formed by laminating separate portions of a membrane onto a support so that the metering channel is formed therebetween.
7. The method of claim 1 , wherein the metering channel is formed using a microfabrication technique.
8. The method of claim 7 , wherein the microfabrication technique includes laser ablation.
9. The method of claim 7 , wherein the microfabrication technique includes applying a solvent treatment to the membrane.
10. The method of claim 1 , wherein the metering channel has a width that is the same or substantially equal to the width of the membrane.
11. The method of claim 1 , wherein length of the metering channel is from about 0.01 to about 4 millimeters.
12. The method of claim 1 , wherein the membrane is laminated to a support, the support defining a bottom surface of the metering channel.
13. The method of claim 1 , further comprising treating at least a portion of the metering channel with a wetting agent, an agglutinating agent, or combinations thereof.
14. The method of claim 1 , wherein the bridging member also functions as a blood separation filter.
15. The method of claim 1 , further comprising disposing an absorbent member within the metering channel.
16. The method of claim 1 , wherein the detection zone is defined by the membrane.