FIG. 7.

Microscopy images of the fluorescent particles in the microchannel. The post outline has been redrawn for better visibility. (a) Retention of both particle types with a diameter of $2.4\mu \mathrm{m}$ in front of the first rows of the post array at $1000{\mathrm{V}}_{\mathrm{DC}}$. (b) Selective trapping of gold-coated particles (orange) at $200{\mathrm{V}}_{\mathrm{DC}}$ (at the inlet of the post array). (c) Selective release of PS particles (green) at the post array outlet at $200{\mathrm{V}}_{\mathrm{DC}}$. (d) Release of gold-coated particles at $50{\mathrm{V}}_{\mathrm{DC}}$ (at the outlet of the post array).