FIGURE 2.

Schematic presentation (top view) of the working mechanism for the continuous isolation and purification of cancer cells from the magnetic microbead-bound Jurkat cells; (A) the first step ODEP cell manipulation process: (I): a static rectangular light bar (L: 3.9 mm, W: 100 μm) with a particular angle (e.g., 15°) to the flow direction of the cell suspension was designed at the defined cell isolation zone of the main microchannel, (I–VIII): most of the magnetic microbead-bound Jurkat cells (black dots) in the sample flow were not trapped by the light bar and thus flowed to the downstream of the main microchannel, whereas most of the SW620 cancer cells (gray dots) flowing through the main microchannel were trapped by the light bar and then delivered along the light bar to the side microchannel for cell collection (indicated by arrows), (B) the second step of the ODEP cell manipulation process: (I) a certain amount of the cancer cells were collected in the side microchannel, (II) the liquid flow in the side microchannel was driven to flux the cells collected so that they were evenly spread within the side microchannel, (III) fluorescence microscopy observation was carried out to identify the species of the cells [i.e., fluorescence stained SW620 cancer cells (the red dots) and immunofluorescence stained magnetic microbead-bound Jurkat cells (the green dots)] collected in the side microchannel for positioning the SW620 cancer cells, (IV) static circular light images were illuminated on each SW620 cancer cell. Meanwhile, the side microchannel was projected with a rectangular light bar to manipulate the magnetic microbead-bound Jurkat cells into the side microchannel, in which O-ring-like non-illuminated patterns were designed as partitions to separate the light-illuminated SW620 cancer cells and the other cells, (V–VII) the rectangular light bar on the side microchannel was then moved to manipulate the magnetic microbead-bound Jurkat cells to remove them from the side microchannel, and this process was repeated for 5 times, (VIII) through the previous process, the cell purity of the SW620 cancer cells in the side microchannel was greatly improved, (C) the working mechanism of using a static rectangular light bar both as a virtual cell filter and a virtual cell track for continuous cancer cell separation and isolation: (I) when the F_ODEP (ODEP manipulation force) acting on a cell is greater than the component force of F_HD (i.e., F_HD^∗sinΘ, Θ: the angle between the rectangular light bar and the flow direction of the cell suspension), the cell could move along the rectangular light bar, driven by another component force of F_HD (i.e., F_HD^∗cosΘ), (II) when the F_ODEP is less than F_HD^∗sinΘ, conversely, a moving cell might not be trapped by the designed light bar image and thus flows through the light image area.