Figure 1.

A spiral microfluidic device. (a) Photograph of a spiral microfluidic device; scale bar, 10 mm. Microchannels are highlighted by Trypan blue dye solution. Channel width and height are 707 and 70.7 μm, respectively. Distance between two adjacent microchannels is 303 μm; (b) A magnified micrograph of part of a spiral microchannel, enclosed by the red dotted box in Figure 1a; scale bar, 100 μm. Ten-fold diluted microbeads (10 μm diameter) in phosphate buffered saline were focused at an equilibrium position close to the inner wall of the microchannel.