Figure 4. Effect of λ/D on particle patterning. As suggested here, there is a limited range of λ/D in which single particles can be patterned.

The particle capture efficiency is shown for 6.1-μm polystyrene particles for a number of λ/D values, corresponding to odd-number frequencies in the range 163–185 MHz at an applied power of 0.38 W. Particle capture and patterning is limited outside of the range 3.2≥λ/D≥3.6. Fluorescent particle images (250 × 250 px) are obtained from the same central chamber region. Scale bar, 30 μm.