Fig. 3. Microscopy images of PI-stained trapped versus nontrapped E. coli at low frequency (50 ± 20 kHz), various applied voltages, and operation times.

PI uptake (red fluorescence) indicates cell electroporation. Microscopic images of (A) trapped E. coli and (B) untrapped E. coli. (C) Percentage of both trapped and untrapped PI-stained E. coli over time at various applied voltages (~33 kHz). Error bars represent SD computed from three independent tests. JP of 10 μm in diameter was used. E. coli strain XL1-Blue bacteria with GFP labeling were used. Scale bars, 5 μm.