FIGURE 2. Massively parallel manipulation of single particles.
From the following article:
Massively parallel manipulation of single cells and microparticles using optical images
Pei Yu Chiou, Aaron T. Ohta and Ming C. Wu
Nature 436, 370-372 (21 July 2005)
doi: 10.1038/nature03831
a, 15,000 particle traps are created across a 1.3 mm 
1.0 mm area. The 4.5-µm-diameter polystyrene beads experiencing negative DEP forces are trapped in the darker circular areas. Each trap has a diameter of 4.5 µm, which is adjusted to fit a single particle. b, Parallel transportation of single particles. Three snapshots from the video show the particle motion in part of the manipulation area. The trapped particles in two adjacent columns move in opposite directions, as indicated by the blue and yellow arrows.
