FIG. 1.
(a) Fluorescence micrograph of individual cells (labeled green) inside the microchannel. Cell traps, where the rectification bias is reversed, have a higher concentration of cells. (b) False-color image showing the number of cells in each chamber as a function of time. Note that three spontaneously forming migrating bands of bacteria are observed, launching at T = 0, 2, and 4 h, and that the first one is scattered back after it reaches the end of the microchannel (between T = 4 and T = 6 h).