Fig. 1.

Microfluidic devices used in the study and the operation procedures. (a), (b) Schematics showing the geometry of the single channel (a) and two stage (b) devices used for cell counting in this paper. The CD4+ T cell capture channels of both devices were functionalized with an anti-CD4 antibody for target cell isolation. The two stage device also contains 4 parallel chambers upstream to the CD4 channel for monocyte depletion. (c) The operation procedures of the two counting devices. For the double-stage devices, two considerations were taken into account for the rinsing buffers: one is to quickly displace monocyte depleted blood to the CD4 capture channel and the second is to avoid shearing off specifically captured cells. These two considerations were studied in detail in this work.