Capillary driven and volume-metred blood-plasma separation

Blood plasma samples are widely used in clinical analysis but easy-to-use sampling methods for defined volumes are lacking. We introduce the first capillary driven microfluidic device that separates a specific volume of plasma from a blood sample of unknown volume. The input to the device is a small amount of whole blood in the range of 30-60 μl which results in a 4 μl isolated plasma sample within 3 minutes, available for subsequent processing and/or analysis, as demonstrated by collecting the sample in a paper substrate.