since their sizes exceed the pore size of the filter membrane. the injected PBS volume used in this study varied from 200 to 500 ไมโครลิตร so that the inlet chamber could be completely washed.following the wash,plasma was collected from the outlet chamber using a syringe with a tubing with an inner diameter of 0.05 cm attached. the tubing was pushed from the outlet through the channel to the chamber under the membrane. this approach maximized the collection volume,and the volume of collected plasma was measured using a pipette.