Figure 3

(a) Photograph of the electrofluidic device in which two pairs of opposing microelectrodes are formed on the bottom surface of a cross-shaped closed glass microchannel for 2D electromanipulation of Euglena cells. The inset is a tilted view of the same chip, showing the preparation of continuous metal structures from inside of the microchannel to the glass chip surface. The depth of the channel bottom from the glass surface is ~300 μm. Swimming behaviors of Euglena cells in a microfluidic environment in the absence of an electric field (b) and under an applied electric field (20 Vp-p, 0.8 MHz) between electrodes ‘1 and 3’ (c) and ‘1 and 3’ and ‘2 and 4’ (d and e). (c), (d), and (e) represent, respectively, 90°, +45°, and −45° orientations of cell motion with respect to the x-axis. ‘ON’ and ‘OFF’ correspond to experiments with and without electric power, respectively. The numbers in gray in (b and c) indicate that no AC voltage was applied. The numbers in yellow and red in (c–e) represent the opposite polarities. The blue arrows in (c–e) indicate the directions of the electric field. The scale bars in (b–e) indicate 200 μm.